Cameco Corporation (SEC Filing Page | XBRL Cloud Viewer | XBRL Instance)

Line	Label	Object Class	Period Type	Balance	Report ElementName
1	000010 - Document - Document and Entity Information	Network	*	*	http://www.cameco.com/role/DocumentAndEntityInformation
2	Implied Table	Table	*	*	implied:Table
3	Document And Entity Information [Abstract]	Abstract			ccj:DocumentAndEntityInformationAbstract
4	Document Type	Concept (Submission Type)	For Period		dei:DocumentType
5	Amendment Flag	Concept (Yes/No)	For Period		dei:AmendmentFlag
6	Document Period End Date	Concept (Date)	For Period		dei:DocumentPeriodEndDate
7	Document Fiscal Year Focus	Concept (Year)	For Period		dei:DocumentFiscalYearFocus
8	Document Fiscal Period Focus	Concept (Fiscal Period)	For Period		dei:DocumentFiscalPeriodFocus
9	Trading Symbol	Concept (Text/String)	For Period		dei:TradingSymbol
10	Entity Registrant Name	Concept (Text/String)	For Period		dei:EntityRegistrantName
11	Entity Central Index Key	Concept (CIK Number)	For Period		dei:EntityCentralIndexKey
12	Current Fiscal Year End Date	Concept (Month/Day)	For Period		dei:CurrentFiscalYearEndDate
13	Entity Well-known Seasoned Issuer	Concept (Yes/No)	For Period		dei:EntityWellKnownSeasonedIssuer
14	Entity Current Reporting Status	Concept (Yes/No)	For Period		dei:EntityCurrentReportingStatus
15	Entity Filer Category	Concept (Filer Category)	For Period		dei:EntityFilerCategory
16	Entity Public Float	Concept (Monetary)	As Of	Credit	dei:EntityPublicFloat
17	Entity Common Stock, Shares Outstanding	Concept (Shares)	As Of		dei:EntityCommonStockSharesOutstanding
18	Entity Emerging Growth Company	Concept (Yes/No)	For Period		dei:EntityEmergingGrowthCompany
19	Entity Shell	Concept (Yes/No)	For Period		dei:EntityShellCompany
20	Entity Small Business	Concept (Yes/No)	For Period		dei:EntitySmallBusiness
21	000100 - Statement - Consolidated statements of earnings	Network	*	*	http://www.cameco.com/role/ConsolidatedStatementsOfEarnings
22	Implied Table	Table	*	*	implied:Table
23	Consolidated statements of earnings [Abstract]	Abstract			ifrs-full:IncomeStatementAbstract
24	Revenue from products and services	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
25	Cost of products and services sold	Concept (Monetary)	For Period	Debit	ccj:Costofgoodssoldexcludingdepreciationdepletionandamortization
26	Depreciation and amortization	Concept (Monetary)	For Period	Debit	ifrs-full:DepreciationAndAmortisationExpense
27	Cost of sales	Concept (Monetary)	For Period	Debit	ifrs-full:CostOfSales
28	Gross profit	Concept (Monetary)	For Period	Credit	ifrs-full:GrossProfit
29	Administration	Concept (Monetary)	For Period	Debit	ifrs-full:AdministrativeExpense
30	Impairment charges	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment
31	Exploration	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseArisingFromExplorationForAndEvaluationOfMineralResources
32	Research and development	Concept (Monetary)	For Period	Debit	ifrs-full:ResearchAndDevelopmentExpense
33	Other operating expense	Concept (Monetary)	For Period	Credit	ifrs-full:OtherOperatingIncomeExpense
34	Loss on disposal of assets	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnDisposalsOfPropertyPlantAndEquipment
35	Earnings (loss) from operations	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromOperatingActivities
36	Finance costs	Concept (Monetary)	For Period	Debit	ifrs-full:FinanceCosts
37	Gain (loss) on derivatives	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnChangeInFairValueOfDerivatives
38	Finance income	Concept (Monetary)	For Period	Credit	ifrs-full:FinanceIncome
39	Share of earnings from equity-accounted investee	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
40	Other income (expense)	Concept (Monetary)	For Period	Credit	ifrs-full:OtherIncome
41	Earnings (loss) before income taxes	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
42	Income tax recovery	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
43	Net earnings (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
44	Net earnings (loss) attributable to:	Abstract			ifrs-full:ProfitLossAttributableToAbstract
45	Equity holders	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToOwnersOfParent
46	Non-controlling interest	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToNoncontrollingInterests
47	Net earnings (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
48	Earnings (loss) per common share attributable to equity holders:	Abstract			ifrs-full:EarningsPerShareAbstract
49	Basic	Concept (Share)	For Period		ifrs-full:BasicEarningsLossPerShare
50	Diluted	Concept (Share)	For Period		ifrs-full:DilutedEarningsLossPerShare
51	000200 - Statement - Consolidated statements of comprehensive income	Network	*	*	http://www.cameco.com/role/ConsolidatedStatementsOfComprehensiveIncome
52	Implied Table	Table	*	*	implied:Table
53	Consolidated statements of comprehensive income [Abstract]	Abstract			ifrs-full:StatementOfComprehensiveIncomeAbstract
54	Net earnings (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
55	Items that will not be reclassified to net earnings:	Abstract			ifrs-full:ComponentsOfOtherComprehensiveIncomeThatWillNotBeReclassifiedToProfitOrLossNetOfTaxAbstract
56	Remeasurements of defined benefit liability	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans
57	Equity investments at FVOCI - net change in fair value	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxGainsLossesFromInvestmentsInEquityInstruments
58	Items that are or may be reclassified to net earnings:	Abstract			ifrs-full:ComponentsOfOtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLossNetOfTaxAbstract
59	Exchange differences on translation of foreign operations	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeNetOfTaxExchangeDifferencesOnTranslation
60	Reclassification of foreign currency translation reserve to net earnings	Concept (Monetary)	For Period	Debit	ifrs-full:ReclassificationAdjustmentsOnExchangeDifferencesOnTranslationNetOfTax
61	Other comprehensive loss, net of taxes	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncome
62	Total comprehensive income (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
63	Other comprehensive income (loss) attributable to:	Abstract			ifrs-full:OtherComprehensiveIncomeAbstract
64	Equity holders	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeAttributableToOwnersOfParent
65	Non-controlling interest	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeAttributableToNoncontrollingInterests
66	Other comprehensive loss for the year	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncome
67	Total comprehensive income (loss) attributable to:	Abstract			ifrs-full:ComprehensiveIncomeAttributableToAbstract
68	Equity holders	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncomeAttributableToOwnersOfParent
69	Non-controlling interest	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncomeAttributableToNoncontrollingInterests
70	Total comprehensive income (loss) for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
71	Income tax on remeasurement of defined benefit liability	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToRemeasurementsOfDefinedBenefitPlansOfOtherComprehensiveIncome
72	Income tax on equity investments at FVOCI - net change in fair value	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxRelatingToInvestmentsInEquityInstrumentsOfOtherComprehensiveIncome
73	000300 - Statement - Consolidated statements of financial position	Network	*	*	http://www.cameco.com/role/ConsolidatedStatementsOfFinancialPosition
74	Implied Table	Table	*	*	implied:Table
75	Consolidated statements of financial position [Abstract]	Abstract			ifrs-full:StatementOfFinancialPositionAbstract
76	Assets	Abstract			ifrs-full:AssetsAbstract
77	Current assets	Abstract			ifrs-full:CurrentAssetsAbstract
78	Cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
79	Short-term investments	Concept (Monetary)	As Of	Debit	ifrs-full:ShorttermDepositsNotClassifiedAsCashEquivalents
80	Accounts receivable	Concept (Monetary)	As Of	Debit	ifrs-full:TradeAndOtherCurrentReceivables
81	Current tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentTaxAssetsCurrent
82	Inventories	Concept (Monetary)	As Of	Debit	ifrs-full:Inventories
83	Supplies and prepaid expenses	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentPrepayments
84	Current portion of long-term receivables, investments and other	Concept (Monetary)	As Of	Debit	ccj:CurrentRecivablesInvestmentsAndOther
85	Total current assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentAssets
86	Property, plant and equipment	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
87	Goodwill and intangible assets	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsAndGoodwill
88	Long-term receivables, investments and other	Concept (Monetary)	As Of	Debit	ccj:LongTermReceivablesInvestmentsAndOther
89	Investment in equity-accounted investee	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentAccountedForUsingEquityMethod
90	Deferred tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:DeferredTaxAssets
91	Total non-current assets	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssets
92	Total assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
93	Liabilities and shareholders' equity	Abstract			ifrs-full:EquityAndLiabilitiesAbstract
94	Current liabilities	Abstract			ifrs-full:CurrentLiabilitiesAbstract
95	Accounts payable and accrued liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:TradeAndOtherCurrentPayables
96	Current tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentTaxLiabilitiesCurrent
97	Dividends payable	Concept (Monetary)	As Of	Credit	ifrs-full:DividendPayables
98	Current portion of long-term debt	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentPortionOfLongtermBorrowings
99	Current portion of other liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherCurrentFinancialLiabilities
100	Current portion of provisions	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentProvisions
101	Total current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentLiabilities
102	Long-term debt	Concept (Monetary)	As Of	Credit	ifrs-full:LongtermBorrowings
103	Other liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherNoncurrentFinancialLiabilities
104	Provisions	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentProvisions
105	Deferred tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilities
106	Total non-current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentLiabilities
107	Shareholders' equity	Abstract			ifrs-full:EquityAbstract
108	Share capital	Concept (Monetary)	As Of	Credit	ifrs-full:IssuedCapital
109	Contributed surplus	Concept (Monetary)	As Of	Credit	ifrs-full:SharePremium
110	Retained earnings	Concept (Monetary)	As Of	Credit	ifrs-full:RetainedEarnings
111	Other components of equity	Concept (Monetary)	As Of	Credit	ifrs-full:AccumulatedOtherComprehensiveIncome
112	Total shareholders' equity attributable to equity holders	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAttributableToOwnersOfParent
113	Non-controlling interest	Concept (Monetary)	As Of	Credit	ifrs-full:NoncontrollingInterests
114	Total shareholders' equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
115	Total liabilities and shareholders' equity	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAndLiabilities
116	000400 - Statement - Consolidated statements of changes in equity	Network	*	*	http://www.cameco.com/role/ConsolidatedStatementsOfChangesInEquity
117	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
118	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
119	Equity [Member]	Member			ifrs-full:EquityMember
120	Share capital	Member			ifrs-full:IssuedCapitalMember
121	Contributed surplus	Member			ifrs-full:SharePremiumMember
122	Retained earnings	Member			ifrs-full:RetainedEarningsMember
123	Foreign currency translation	Member			ifrs-full:ReserveOfExchangeDifferencesOnTranslationMember
124	Equity investments at FVOCI	Member			ifrs-full:ReserveOfGainsAndLossesOnFinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember
125	Attributable to equity holders	Member			ifrs-full:EquityAttributableToOwnersOfParentMember
126	Non-controling interest	Member			ifrs-full:NoncontrollingInterestsMember
127	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
128	Balance beginning period	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
129	Net earnings (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
130	Other comprehensive income (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncome
131	Total comprehensive income (loss) for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
132	Share-based compensation	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions
133	Stock options exercised	Concept (Monetary)	For Period	Credit	ccj:StockIssuedDuringPeriodValueStockOptionsExercised
134	Restricted and performance share units released	Concept (Monetary)	For Period	Credit	ccj:IncreaseDecreaseThroughSharebasedPaymentRestrictedAndPerformanceShares
135	Dividends	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsPaid
136	Change in ownership interst in subsidiaries	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughChangesInOwnershipInterestsInSubsidiariesThatDoNotResultInLossOfControl
137	Balance ending period	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
138	000500 - Statement - Consolidated statements of cash flows	Network	*	*	http://www.cameco.com/role/ConsolidatedStatementsOfCashFlows
139	Implied Table	Table	*	*	implied:Table
140	Consolidated statements of cash flows [Abstract]	Abstract			ifrs-full:StatementOfCashFlowsAbstract
141	Operating activities	Abstract			ifrs-full:CashFlowsFromUsedInOperatingActivitiesAbstract
142	Net earnings (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
143	Adjustments for:	Abstract			ifrs-full:AdjustmentsForReconcileProfitLossAbstract
144	Depreciation and amortization	Concept (Monetary)	For Period	Debit	ifrs-full:DepreciationAndAmortisationExpense
145	Deferred charges	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInDeferredIncome
146	Unrealized loss (gain) on derivatives	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForFairValueGainsLosses
147	Share-based compensation	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForSharebasedPayments
148	Loss on disposal of assets	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForLossesGainsOnDisposalOfNoncurrentAssets
149	Finance costs	Concept (Monetary)	For Period	Debit	ifrs-full:FinanceCosts
150	Finance income	Concept (Monetary)	For Period	Credit	ifrs-full:FinanceIncome
151	Share of earnings from equity-accounted investee	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
152	Impairment charges	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment
153	Other expense (income)	Concept (Monetary)	For Period	Credit	ccj:OtherIncomeNonCashItems
154	Other operating expense	Concept (Monetary)	For Period	Credit	ifrs-full:OtherOperatingIncomeExpense
155	Income tax recovery	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
156	Interest received	Concept (Monetary)	For Period	Debit	ifrs-full:InterestReceivedClassifiedAsOperatingActivities
157	Income taxes paid	Concept (Monetary)	For Period	Credit	ifrs-full:IncomeTaxesPaidRefundClassifiedAsOperatingActivities
158	Other operating items	Concept (Monetary)	For Period	Debit	ifrs-full:OtherInflowsOutflowsOfCashClassifiedAsOperatingActivities
159	Net cash provided by operations	Concept (Monetary)	For Period		ifrs-full:CashFlowsFromUsedInOperatingActivities
160	Investing activities	Abstract			ifrs-full:CashFlowsFromUsedInInvestingActivitiesAbstract
161	Additions to property, plant and equipment	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfPropertyPlantAndEquipmentClassifiedAsInvestingActivities
162	Increase in short-term investments	Concept (Monetary)	For Period	Debit	ifrs-full:OtherInflowsOutflowsOfCashClassifiedAsInvestingActivities
163	Increase in long-term receivables, investments and other	Concept (Monetary)	For Period	Debit	ccj:ChangeInLongTermReceivablesInvestmentAndOther
164	Proceeds from sale of property, plant and equipment	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromSalesOfPropertyPlantAndEquipmentClassifiedAsInvestingActivities
165	Net cash used in investing	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInInvestingActivities
166	Financing activities	Abstract			ifrs-full:CashFlowsFromUsedInFinancingActivitiesAbstract
167	Decrease in debt	Concept (Monetary)	For Period	Credit	ifrs-full:RepaymentsOfBorrowingsClassifiedAsFinancingActivities
168	Interest paid	Concept (Monetary)	For Period	Credit	ifrs-full:InterestPaidClassifiedAsFinancingActivities
169	Proceeds from issuance of shares, stock option plan	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromIssuingShares
170	Dividends paid	Concept (Monetary)	For Period	Credit	ifrs-full:DividendsPaidClassifiedAsFinancingActivities
171	Net cash used in financing	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInFinancingActivities
172	Increase (decrease) in cash and cash equivalents, during the year	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseInCashAndCashEquivalents
173	Exchange rate changes on foreign currency cash balances	Concept (Monetary)	For Period	Debit	ifrs-full:EffectOfExchangeRateChangesOnCashAndCashEquivalents
174	Cash and cash equivalents, beginning of year	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
175	Cash and cash equivalents, end of year	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
176	Cash and cash equivalents is comprised of:	Abstract			ifrs-full:CashEquivalentsAbstract
177	Cash	Concept (Monetary)	As Of	Debit	ifrs-full:Cash
178	Cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashEquivalents
179	010101 - Disclosure - Cameco Corporation	Network	*	*	http://www.cameco.com/role/CamecoCorporation
180	Implied Table	Table	*	*	implied:Table
181	Corporation [Abstract]	Abstract			ccj:CorporationAbstract
182	Cameco Corporation	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfNotesAndOtherExplanatoryInformationExplanatory
183	010201 - Disclosure - Significant accounting policies	Network	*	*	http://www.cameco.com/role/SignificantAccountingPolicies
184	Implied Table	Table	*	*	implied:Table
185	Significant Accounting Policies [Abstract]	Abstract			ccj:SignificantAccountingPoliciesAbstract
186	Significant accounting policies	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSummaryOfSignificantAccountingPoliciesExplanatory
187	010301 - Disclosure - Accounting standards	Network	*	*	http://www.cameco.com/role/AccountingStandards
188	Implied Table	Table	*	*	implied:Table
189	Accounting Standards [Abstract]	Abstract			ccj:AccountingStandardsAbstract
190	Accounting standards	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretations
191	010401 - Disclosure - Determination of fair values	Network	*	*	http://www.cameco.com/role/DeterminationOfFairValues
192	Implied Table	Table	*	*	implied:Table
193	Fair Value Measurement [Abstract]	Abstract			ccj:FairValueMeasurementAbstract
194	Determination of fair values	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFairValueMeasurementExplanatory
195	010501 - Disclosure - Use of estimates and judgments	Network	*	*	http://www.cameco.com/role/UseOfEstimatesAndJudgments
196	Implied Table	Table	*	*	implied:Table
197	Use Of Estimates And Judgments [Abstract]	Abstract			ccj:UseOfEstimatesAndJudgmentsAbstract
198	Use of estimates and judgments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfAccountingJudgementsAndEstimatesExplanatory
199	010601 - Disclosure - Accounts receivable	Network	*	*	http://www.cameco.com/role/AccountsReceivable
200	Implied Table	Table	*	*	implied:Table
201	Trade And Other Receivables [Abstract]	Abstract			ifrs-full:TradeAndOtherReceivablesAbstract
202	Accounts receivable	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTradeAndOtherReceivablesExplanatory
203	010701 - Disclosure - Inventories	Network	*	*	http://www.cameco.com/role/Inventories
204	Implied Table	Table	*	*	implied:Table
205	Classes Of Inventories [Abstract]	Abstract			ifrs-full:ClassesOfInventoriesAbstract
206	Inventories	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInventoriesExplanatory
207	010801 - Disclosure - Property, plant and equipment	Network	*	*	http://www.cameco.com/role/PropertyPlantAndEquipment
208	Implied Table	Table	*	*	implied:Table
209	Property Plant And Equipment [Abstract]	Abstract			ifrs-full:PropertyPlantAndEquipmentAbstract
210	Property, plant and equipment	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfPropertyPlantAndEquipmentExplanatory
211	010901 - Disclosure - Goodwill and intangible assets	Network	*	*	http://www.cameco.com/role/GoodwillAndIntangibleAssets
212	Implied Table	Table	*	*	implied:Table
213	Intangible Assets And Goodwill [Abstract]	Abstract			ifrs-full:IntangibleAssetsAndGoodwillAbstract
214	Goodwill and intangible assets	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfIntangibleAssetsAndGoodwillExplanatory
215	011001 - Disclosure - Long-term receivables, investments and other	Network	*	*	http://www.cameco.com/role/LongtermReceivablesInvestmentsAndOther
216	Implied Table	Table	*	*	implied:Table
217	Categories Of Noncurrent Financial Assets [Abstract]	Abstract			ifrs-full:CategoriesOfNoncurrentFinancialAssetsAbstract
218	Long-term receivables, investments and other	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOtherNoncurrentAssetsExplanatory
219	011101 - Disclosure - Equity-accounted investee	Network	*	*	http://www.cameco.com/role/EquityaccountedInvestee
220	Implied Table	Table	*	*	implied:Table
221	Investments accounted for using equity method [Abstract]	Abstract			ifrs-full:InvestmentsAccountedForUsingEquityMethodAbstract
222	Equity-accounted investee	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInvestmentsAccountedForUsingEquityMethodExplanatory
223	011201 - Disclosure - Accounts payable and accrued liabilities	Network	*	*	http://www.cameco.com/role/AccountsPayableAndAccruedLiabilities
224	Implied Table	Table	*	*	implied:Table
225	Trade And Other Current Payables [Abstract]	Abstract			ifrs-full:TradeAndOtherCurrentPayablesAbstract
226	Accounts payable and accrued liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTradeAndOtherPayablesExplanatory
227	011301 - Disclosure - Long-term debt	Network	*	*	http://www.cameco.com/role/LongtermDebt
228	Implied Table	Table	*	*	implied:Table
229	Noncurrent Liabilities [Abstract]	Abstract			ifrs-full:NoncurrentLiabilitiesAbstract
230	Long-term debt	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDebtSecuritiesExplanatory
231	011401 - Disclosure - Other liabilities	Network	*	*	http://www.cameco.com/role/OtherLiabilities
232	Implied Table	Table	*	*	implied:Table
233	Other Liabilities [Abstract]	Abstract			ifrs-full:LiabilitiesAbstract
234	Other liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOtherLiabilitiesExplanatory
235	011501 - Disclosure - Provisions	Network	*	*	http://www.cameco.com/role/Provisions
236	Implied Table	Table	*	*	implied:Table
237	Provisions [Abstract]	Abstract			ifrs-full:ProvisionsAbstract
238	Provisions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOtherProvisionsExplanatory
239	011601 - Disclosure - Share capital	Network	*	*	http://www.cameco.com/role/ShareCapital
240	Implied Table	Table	*	*	implied:Table
241	Disclosure Of Classes Of Share Capital [Abstract]	Abstract			ifrs-full:DisclosureOfClassesOfShareCapitalAbstract
242	Share capital	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfClassesOfShareCapitalExplanatory
243	011701 - Disclosure - Revenue	Network	*	*	http://www.cameco.com/role/Revenue
244	Implied Table	Table	*	*	implied:Table
245	Revenue [abstract]	Abstract			ifrs-full:RevenueAbstract
246	Disclosure Of Revenue Explanatory	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfRevenueExplanatory
247	011801 - Disclosure - Employee benefit expense	Network	*	*	http://www.cameco.com/role/EmployeeBenefitExpense
248	Implied Table	Table	*	*	implied:Table
249	Classes Of Employee Benefits Expense [Abstract]	Abstract			ifrs-full:ClassesOfEmployeeBenefitsExpenseAbstract
250	Employee benefit expense	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEmployeeBenefitsExplanatory
251	011901 - Disclosure - Finance costs	Network	*	*	http://www.cameco.com/role/FinanceCosts
252	Implied Table	Table	*	*	implied:Table
253	Finance Costs [Abstract]	Abstract			ccj:FinanceCostsAbstract
254	Finance costs	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinanceCostExplanatory
255	012001 - Disclosure - Other income (expense)	Network	*	*	http://www.cameco.com/role/OtherIncomeexpense
256	Implied Table	Table	*	*	implied:Table
257	Other Income Expense [Abstract]	Abstract			ccj:OtherIncomeExpenseAbstract
258	Other income (expense)	Concept (Text Block (HTML))	For Period		ccj:DisclsoureOfOtherIncomeExpenseTextBlock
259	012101 - Disclosure - Income taxes	Network	*	*	http://www.cameco.com/role/IncomeTaxes
260	Implied Table	Table	*	*	implied:Table
261	Income Tax [Absract]	Abstract			ccj:IncomeTaxAbstract
262	Income taxes	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfIncomeTaxExplanatory
263	012201 - Disclosure - Per share amounts	Network	*	*	http://www.cameco.com/role/PerShareAmounts
264	Implied Table	Table	*	*	implied:Table
265	Per Share Amounts [Abstract]	Abstract			ccj:PerShareAmountsAbstract
266	Per share amounts	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEarningsPerShareExplanatory
267	012301 - Disclosure - Supplemental cash flow information	Network	*	*	http://www.cameco.com/role/SupplementalCashFlowInformation
268	Implied Table	Table	*	*	implied:Table
269	Statement Of Cash Flows Disclosure [Abstract]	Abstract			ccj:StatementOfCashFlowsDisclosureAbstract
270	Statements of cash flows	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfCashFlowStatementExplanatory
271	012401 - Disclosure - Share-based compensation plans	Network	*	*	http://www.cameco.com/role/SharebasedCompensationPlans
272	Implied Table	Table	*	*	implied:Table
273	Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Abstract]	Abstract			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementAbstract
274	Share-based compensation plans	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSharebasedPaymentArrangementsExplanatory
275	012501 - Disclosure - Pension and other post-retirement benefits	Network	*	*	http://www.cameco.com/role/PensionAndOtherPostretirementBenefits
276	Implied Table	Table	*	*	implied:Table
277	Disclosure Of Defined Benefit Plans [Abstract]	Abstract			ifrs-full:DisclosureOfDefinedBenefitPlansAbstract
278	Pension and other post-retirement benefits	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfDefinedBenefitAndContributionPlansExplanatory
279	012601 - Disclosure - Financial instruments and related risk management	Network	*	*	http://www.cameco.com/role/FinancialInstrumentsAndRelatedRiskManagement
280	Implied Table	Table	*	*	implied:Table
281	Disclosure Of Financial Instruments [Abstract]	Abstract			ifrs-full:DisclosureOfFinancialInstrumentsAbstract
282	Financial instruments and related risk management	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialRiskManagementExplanatory
283	012701 - Disclosure - Capital management	Network	*	*	http://www.cameco.com/role/CapitalManagement
284	Implied Table	Table	*	*	implied:Table
285	Disclosure of objectives policies and processes for managing capital abstract	Abstract			ifrs-full:DisclosureOfObjectivesPoliciesAndProcessesForManagingCapitalAbstract
286	Capital management	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfObjectivesPoliciesAndProcessesForManagingCapitalExplanatory
287	012801 - Disclosure - Segmented information	Network	*	*	http://www.cameco.com/role/SegmentedInformation
288	Implied Table	Table	*	*	implied:Table
289	Disclosure Of Operating Segments [Abstract]	Abstract			ifrs-full:DisclosureOfOperatingSegmentsAbstract
290	Segmented information	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEntitysReportableSegmentsExplanatory
291	012901 - Disclosure - Group entities	Network	*	*	http://www.cameco.com/role/GroupEntities
292	Implied Table	Table	*	*	implied:Table
293	Disclosure Of Significant Investments In Subsidiaries [Abstract]	Abstract			ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesAbstract
294	Group entities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesExplanatory
295	013001 - Disclosure - Joint operations	Network	*	*	http://www.cameco.com/role/JointOperations
296	Implied Table	Table	*	*	implied:Table
297	Disclosure Of Joint Operations [Abstract]	Abstract			ifrs-full:DisclosureOfJointOperationsAbstract
298	Joint operations	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfJointOperationsExplanatory
299	013101 - Disclosure - Related parties	Network	*	*	http://www.cameco.com/role/RelatedParties
300	Implied Table	Table	*	*	implied:Table
301	Disclosure Of Transactions Between Related Parties [Abstract]	Abstract			ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesAbstract
302	Related parties	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfRelatedPartyExplanatory
303	020202 - Disclosure - Significant accounting policies (Policies)	Network	*	*	http://www.cameco.com/role/SignificantAccountingPoliciesPolicies
304	Implied Table	Table	*	*	implied:Table
305	Significant Accounting Policies [Abstract]	Abstract			ccj:SignificantAccountingPoliciesAbstract
306	Statement of compliance	Concept (Text Block (HTML))	For Period		ifrs-full:StatementOfIFRSCompliance
307	Basis of presentation	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfBasisOfPreparationOfFinancialStatementsExplanatory
308	Consolidation principles	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfBasisOfConsolidationExplanatory
309	Business combinations	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForBusinessCombinationsExplanatory
310	Subsidiaries	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForSubsidiariesExplanatory
311	Investments in equity-accounted investees	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForInvestmentInAssociates
312	Joint arrangements	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInterestsInJointArrangementsExplanatory
313	Transactions eliminated on consolidation	Concept (Text Block (HTML))	For Period		ccj:DescriptionOfAccountingPolicyForTransactionsConsolidationEliminationExplanatory
314	Foreign currency translation	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForForeignCurrencyTranslationExplanatory
315	Cash and cash equivalents	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyToDetermineComponentsOfCashAndCashEquivalents
316	Short-term investments	Concept (Text Block (HTML))	For Period		ccj:Descriptionofaccountingpolicyforshortterminvestments
317	Inventories	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForMeasuringInventories
318	Property, plant and equipment	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForPropertyPlantAndEquipmentExplanatory
319	Buildings, plants, equipment	Concept (Text Block (HTML))	For Period		ccj:DescriptionOfPoliciesForBuildingPlantAndEquipment
320	Mineral properties and mine development costs	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForMiningAssetsExplanatory
321	Depreciation	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForDepreciationExpenseExplanatory
322	Borrowing costs	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForBorrowingCostsExplanatory
323	Repairs and maintenance	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForRepairsAndMaintenanceExplanatory
324	Goodwill and intangible assets	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForIntangibleAssetsAndGoodwillExplanatory
325	Leased assets	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForLeasesExplanatory
326	Finance income and finance costs	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForFinanceIncomeAndCostsExplanatory
327	Research and development costs	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForResearchAndDevelopmentExpenseExplanatory
328	Impairment	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForImpairmentOfAssetsExplanatory
329	Non-derivative financial assets	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForImpairmentOfFinancialAssetsExplanatory
330	Non-financial assets	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForImpairmentOfNonfinancialAssetsExplanatory
331	Exploration and evaluation expenditures	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForExplorationAndEvaluationExpenditures
332	Provisions	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForProvisionsExplanatory
333	Environmental restoration	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForDecommissioningRestorationAndRehabilitationProvisionsExplanatory
334	Waste disposal	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForStrippingCostsExplanatory
335	Employee future benefits	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForEmployeeBenefitsExplanatory
336	Pension obligations	Concept (Text Block (HTML))	For Period		ccj:DescriptionOfPensionObligationsPolicyExplanatoryTextBlock
337	Other post-retirement benefits plans	Concept (Text Block (HTML))	For Period		ccj:DescriptionOfAccountingPolicyForOtherPostRetirementBenefitsTextBlock
338	Short-term employee benefits	Concept (Text Block (HTML))	For Period		ccj:DescriptionOfAccountingPolicyForShortTermEmployeeBenefitsTextBlock
339	Explanation of termination benefits	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForTerminationBenefits
340	Share-based compensation	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForSharebasedPaymentTransactionsExplanatory
341	Revenue recognition	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForRecognitionOfRevenue
342	Financial instruments	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForFinancialInstrumentsExplanatory
343	Non-derivative financial assets and financial liabilities	Concept (Text Block (HTML))	For Period		ccj:DescriptionOfAccountingPolicyForNonDerivativeFinancialAssetsLiabilitiesExplanatory
344	Derivative financial instruments	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForDerivativeFinancialInstrumentsExplanatory
345	Income tax	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForIncomeTaxExplanatory
346	Share capital	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForIssuedCapitalExplanatory
347	Earnings per share	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForEarningsPerShareExplanatory
348	Segment reporting	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForSegmentReportingExplanatory
349	030201 - Disclosure - Significant accounting policies (Table)	Network	*	*	http://www.cameco.com/role/SignificantAccountingPoliciesTable
350	Implied Table	Table	*	*	implied:Table
351	Significant Accounting Policies [Abstract]	Abstract			ccj:SignificantAccountingPoliciesAbstract
352	Basis of presentation	Concept (Text Block (HTML))	For Period		ccj:DisclsoureOfAlternativeBasisMeasurementOfConsolidatedFinancialStatementTableTextBlock
353	Disclosure of estimated useful lives	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDepreciationAndAmortisationExpenseExplanatory
354	030301 - Disclosure - Accounting standards (Table)	Network	*	*	http://www.cameco.com/role/AccountingStandardsTable
355	Implied Table	Table	*	*	implied:Table
356	Accounting Standards [Abstract]	Abstract			ccj:AccountingStandardsAbstract
357	Classification of Financial Instruments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialInstrumentsExplanatory
358	030601 - Disclosure - Accounts receivable (Tables)	Network	*	*	http://www.cameco.com/role/AccountsReceivableTables
359	Implied Table	Table	*	*	implied:Table
360	Trade And Other Receivables [Abstract]	Abstract			ifrs-full:TradeAndOtherReceivablesAbstract
361	Schedule of accounts receivable	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfDetailedInformationAboutTradeAndOtherReceivablesExplanatoryTableTextBlcok
362	030701 - Disclosure - Inventories (Tables)	Network	*	*	http://www.cameco.com/role/InventoriesTables
363	Implied Table	Table	*	*	implied:Table
364	Classes Of Inventories [Abstract]	Abstract			ifrs-full:ClassesOfInventoriesAbstract
365	Schedule of Inventories	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfInventoriesSummaryExplanatoryTableTextBlock
366	030801 - Disclosure - Property, plant and equipment (Tables)	Network	*	*	http://www.cameco.com/role/PropertyPlantAndEquipmentTables
367	Implied Table	Table	*	*	implied:Table
368	Property Plant And Equipment [Abstract]	Abstract			ifrs-full:PropertyPlantAndEquipmentAbstract
369	Schedule of Property plant and equipment table	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutPropertyPlantAndEquipmentExplanatory
370	030901 - Disclosure - Goodwill and intangible assets (Tables)	Network	*	*	http://www.cameco.com/role/GoodwillAndIntangibleAssetsTables
371	Implied Table	Table	*	*	implied:Table
372	Intangible Assets And Goodwill [Abstract]	Abstract			ifrs-full:IntangibleAssetsAndGoodwillAbstract
373	Reconciliation of carrying amount of goodwill and intangibles	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReconciliationOfChangesInIntangibleAssetsAndGoodwillExplanatory
374	Key Assumptions for Discounted Cash Flow Model	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfKeyAssumptionsDiscountedCashFlowModelTableTextBlock
375	Sensitivity test on key assumptions to calculate recoverable amount	Concept (Text Block (HTML))	For Period		ccj:Disclosureofkeyassumptionsmarginalchanges
376	031001 - Disclosure - Long-term receivables, investments and other (Tables)	Network	*	*	http://www.cameco.com/role/LongtermReceivablesInvestmentsAndOtherTables
377	Implied Table	Table	*	*	implied:Table
378	Categories Of Noncurrent Financial Assets [Abstract]	Abstract			ifrs-full:CategoriesOfNoncurrentFinancialAssetsAbstract
379	Long-term receivables, investments and other	Concept (Text Block (HTML))	For Period		ccj:Disclosureofmiscellaneousnoncurrentassetsexplanatory
380	Equity securities designated at FVOCI	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFairValueOfEachInvestmentInEquityInstrumentsDesignatedAsMeasuredAtFairValueThroughOtherComprehensiveIncomeExplanatory
381	031101 - Disclosure - Equity-accounted investee (Tables)	Network	*	*	http://www.cameco.com/role/EquityaccountedInvesteeTables
382	Implied Table	Table	*	*	implied:Table
383	Investments accounted for using equity method [Abstract]	Abstract			ifrs-full:InvestmentsAccountedForUsingEquityMethodAbstract
384	Equity method investment summarized financial information balance sheet explanatory	Concept (Text Block (HTML))	For Period		ccj:EquityMethodInvestmentSummarizedFinancialInformationBalanceSheetExplanatory
385	Equity method investment summarized financial information income statement explanatory	Concept (Text Block (HTML))	For Period		ccj:EquityMethodInvestmentSummarizedFinancialInformationIncomeStatementExplanatory
386	Reconciliation of summarized financial information to carrying amount	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReconciliationOfSummarisedFinancialInformationOfAssociateAccountedForUsingEquityMethodToCarryingAmountOfInterestInAssociateExplanatory
387	031201 - Disclosure - Accounts payable and accrued liabilities (Tables)	Network	*	*	http://www.cameco.com/role/AccountsPayableAndAccruedLiabilitiesTables
388	Implied Table	Table	*	*	implied:Table
389	Trade And Other Current Payables [Abstract]	Abstract			ifrs-full:TradeAndOtherCurrentPayablesAbstract
390	Schedule of payable and accrued liabilities	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfTradePayableAndAcccruedLiabilitiesExplanatoryTableTextBlock
391	031301 - Disclosure - Long-term debt (Tables)	Network	*	*	http://www.cameco.com/role/LongtermDebtTables
392	Implied Table	Table	*	*	implied:Table
393	Noncurrent Liabilities [Abstract]	Abstract			ifrs-full:NoncurrentLiabilitiesAbstract
394	Long-term debt table	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsExplanatory
395	031401 - Disclosure - Other liabilities (Tables)	Network	*	*	http://www.cameco.com/role/OtherLiabilitiesTables
396	Implied Table	Table	*	*	implied:Table
397	Other Liabilities [Abstract]	Abstract			ifrs-full:LiabilitiesAbstract
398	Other liabilities	Concept (Text Block (HTML))	For Period		ccj:DisclsoureOfDetailedInformationAboutOtherLiabiltiesTableTextBlock
399	031501 - Disclosure - Provisions (Tables)	Network	*	*	http://www.cameco.com/role/ProvisionsTables
400	Implied Table	Table	*	*	implied:Table
401	Provisions [Abstract]	Abstract			ifrs-full:ProvisionsAbstract
402	Roll Forward of provisions for reclamation and waste disposal	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfReconciliationOfChangeInProvisionsTableTextBlock
403	Reclamation provisions	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfReclamationProvisionTableTextBlock
404	031601 - Disclosure - Share capital (Tables)	Network	*	*	http://www.cameco.com/role/ShareCapitalTables
405	Implied Table	Table	*	*	implied:Table
406	Disclosure Of Classes Of Share Capital [Abstract]	Abstract			ifrs-full:DisclosureOfClassesOfShareCapitalAbstract
407	Common shares issued	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfIssuedCapitalExplanatory
408	031701 - Disclosure - Revenue (Tables)	Network	*	*	http://www.cameco.com/role/RevenueTables
409	Implied Table	Table	*	*	implied:Table
410	Revenue [abstract]	Abstract			ifrs-full:RevenueAbstract
411	Revenue - Disaggregation	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersExplanatory
412	Revenue - Contract liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfRevenueFromContractsWithCustomersExplanatory
413	Revenue - Remaining performance obligations	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTransactionPriceAllocatedToRemainingPerformanceObligationsExplanatory
414	031801 - Disclosure - Employee benefit expense (Tables)	Network	*	*	http://www.cameco.com/role/EmployeeBenefitExpenseTables
415	Implied Table	Table	*	*	implied:Table
416	Classes Of Employee Benefits Expense [Abstract]	Abstract			ifrs-full:ClassesOfEmployeeBenefitsExpenseAbstract
417	Employee benefit expenses	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfEmployeeBenefitExpensesExplanatoryTableTextBlock
418	031901 - Disclosure - Finance costs (Tables)	Network	*	*	http://www.cameco.com/role/FinanceCostsTables
419	Implied Table	Table	*	*	implied:Table
420	Finance Costs [Abstract]	Abstract			ccj:FinanceCostsAbstract
421	Schedule of finance costs	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfFinanceCostsDetailsExplanatoryTableTextBlock
422	032001 - Disclosure - Other income (expense) (Tables)	Network	*	*	http://www.cameco.com/role/OtherIncomeexpenseTables
423	Implied Table	Table	*	*	implied:Table
424	Other Income Expense [Abstract]	Abstract			ccj:OtherIncomeExpenseAbstract
425	Other income (expense) table	Concept (Text Block (HTML))	For Period		ccj:DisclsoureOfDetailedInformationAboutOtherIncomeExpenseExplanatoryTableTextBlock
426	032101 - Disclosure - Income taxes (Tables)	Network	*	*	http://www.cameco.com/role/IncomeTaxesTables
427	Implied Table	Table	*	*	implied:Table
428	Income Tax [Absract]	Abstract			ccj:IncomeTaxAbstract
429	Schedule of Deferred tax assets and liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDeferredTaxesExplanatory
430	Schedule of Tax rate reconciliation	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfTaxRateReconciliationExplanatoryTableTextBlock
431	Schedule of Earnings and income taxes by jurisdiction	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfEarningsAndIncomeTaxesByJurisdictionExpanatoryTableTextBlock
432	Schedule of Income tax losses	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsExplanatory
433	032201 - Disclosure - Per share amounts (Tables)	Network	*	*	http://www.cameco.com/role/PerShareAmountsTables
434	Implied Table	Table	*	*	implied:Table
435	Per Share Amounts [Abstract]	Abstract			ccj:PerShareAmountsAbstract
436	Schedule of Earnings Per Share computation per common share	Concept (Text Block (HTML))	For Period		ifrs-full:EarningsPerShareExplanatory
437	032301 - Disclosure - Supplemental cash flow information (Tables)	Network	*	*	http://www.cameco.com/role/SupplementalCashFlowInformationTables
438	Implied Table	Table	*	*	implied:Table
439	Statement Of Cash Flows Disclosure [Abstract]	Abstract			ccj:StatementOfCashFlowsDisclosureAbstract
440	Statements of detailed information of cash flow	Concept (Text Block (HTML))	For Period		ccj:StatementsOfDetailedInformationOfCashFlowTableTextBlock
441	Reconciliation of liabilities arising from financing activities	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesExplanatory
442	032401 - Disclosure - Share-based compensation plans (Tables)	Network	*	*	http://www.cameco.com/role/SharebasedCompensationPlansTables
443	Disclosure of terms and conditions of share-based payment arrangement [table]	Table	*	*	ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable
444	Types of share-based payment arrangements [axis]	Axis			ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
445	Share-based payment arrangements [member]	Member			ifrs-full:SharebasedPaymentArrangementsMember
446	Equity-settled plan [Member]	Member			ccj:EquitySettledPlanMember
447	Phantom Stock Option Plan [member]	Member			ccj:PhantomStockOptionPlanMember
448	Disclosure of terms and conditions of share-based payment arrangement [line items]	LineItems			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
449	Inputs measurement fair value of sharebased plans	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfIndirectMeasurementOfFairValueOfGoodsOrServicesReceivedShareOptionsGrantedDuringPeriodExplanatory
450	032501 - Disclosure - Pension and other post-retirement benefits (Tables)	Network	*	*	http://www.cameco.com/role/PensionAndOtherPostretirementBenefitsTables
451	Disclosure of sensitivity analysis for actuarial assumptions [table]	Table	*	*	ifrs-full:DisclosureOfSensitivityAnalysisForActuarialAssumptionsTable
452	Actuarial assumptions [axis]	Axis			ifrs-full:ActuarialAssumptionsAxis
453	Actuarial assumptions [member]	Member			ifrs-full:ActuarialAssumptionsMember
454	1% Change in assumptions [member]	Member			ifrs-full:OtherMaterialActuarialAssumptionsMember
455	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
456	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
457	Defined benefit obligation and net pension and other benefit expense [Member]	Member			ccj:DefinedBenefitObligationAndNetPensionAndOtherBenefitExpenseMember
458	Disclosure of sensitivity analysis for actuarial assumptions [line items]	LineItems			ifrs-full:DisclosureOfSensitivityAnalysisForActuarialAssumptionsLineItems
459	Assumptions to determine defined benefit obligations and expense	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSensitivityAnalysisForActuarialAssumptionsExplanatory
460	032601 - Disclosure - Financial instruments and related risk management (Tables)	Network	*	*	http://www.cameco.com/role/FinancialInstrumentsAndRelatedRiskManagementTables
461	Implied Table	Table	*	*	implied:Table
462	Disclosure Of Financial Instruments [Abstract]	Abstract			ifrs-full:DisclosureOfFinancialInstrumentsAbstract
463	Pre-tax exposure to foreign currency exchange risk	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfForeignExchangeRiskExplanatoryTableTextBlock
464	Interest rate risk on variable rate financial instruments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinancialInstrumentsByTypeOfInterestRateExplanatory
465	Counterparty credit risk, as represented by the carrying amount of the financial assets	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfCreditRiskExposureExplanatory
466	Exposure to credit risk for trade receivables	Concept (Text Block (HTML))	For Period		ifrs-full:AnalysisOfCreditExposuresUsingExternalCreditGradingSystemExplanatory
467	Aged trade receivables	Concept (Text Block (HTML))	For Period		ifrs-full:InformationAboutCreditQualityOfNeitherPastDueNorImpairedFinancialAssets
468	Liquidity risk, company's available debt facilities	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfManagingLiquidityRisk
469	Maturity analysis of financial liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:MaturityAnalysisForDerivativeFinancialLiabilities
470	Carrying amounts and accounting classifications	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDetailedInformationAboutFinancialInstrumentsExplanatory
471	Fair value measurement, carrying amounts	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFairValueOfFinancialInstrumentsExplanatory
472	Fair value of derivative instruments and classification	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDerivativeFinancialInstrumentsExplanatory
473	Summary of components of non-hedge derivative gains losses	Concept (Text Block (HTML))	For Period		ccj:DisclosureOfNonHedgeDerivativeGainsLossesTableTextBlock
474	032701 - Disclosure - Capital management (Tables)	Network	*	*	http://www.cameco.com/role/CapitalManagementTables
475	Implied Table	Table	*	*	implied:Table
476	Disclosure of objectives policies and processes for managing capital abstract	Abstract			ifrs-full:DisclosureOfObjectivesPoliciesAndProcessesForManagingCapitalAbstract
477	Capital management	Concept (Text Block (HTML))	For Period		ccj:Disclosureofnetdebtequityandtotalcapitalexplanatory
478	032801 - Disclosure - Segmented information (Tables)	Network	*	*	http://www.cameco.com/role/SegmentedInformationTables
479	Implied Table	Table	*	*	implied:Table
480	Disclosure Of Operating Segments [Abstract]	Abstract			ifrs-full:DisclosureOfOperatingSegmentsAbstract
481	Business segments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOperatingSegmentsExplanatory
482	Geographic segments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfGeographicalAreasExplanatory
483	032901 - Disclosure - Group entities (Tables)	Network	*	*	http://www.cameco.com/role/GroupEntitiesTables
484	Implied Table	Table	*	*	implied:Table
485	Disclosure Of Significant Investments In Subsidiaries [Abstract]	Abstract			ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesAbstract
486	Ownership interest in subsidiaries	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInterestsInSubsidiariesExplanatory
487	033001 - Disclosure - Joint operations (Tables)	Network	*	*	http://www.cameco.com/role/JointOperationsTables
488	Implied Table	Table	*	*	implied:Table
489	Disclosure Of Joint Operations [Abstract]	Abstract			ifrs-full:DisclosureOfJointOperationsAbstract
490	Joint operations proportionate interest in net assets table	Concept (Text Block (HTML))	For Period		ccj:JointOperationsProportionateInterestInNetAssetsTableTextBlock
491	033101 - Disclosure - Related parties (Tables)	Network	*	*	http://www.cameco.com/role/RelatedPartiesTables
492	Implied Table	Table	*	*	implied:Table
493	Disclosure Of Transactions Between Related Parties [Abstract]	Abstract			ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesAbstract
494	Compensation for key management personnel	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInformationAboutKeyManagementPersonnelExplanatory
495	040601 - Disclosure - Accounts Receivable (Details)	Network	*	*	http://www.cameco.com/role/AccountsReceivableDetails
496	Implied Table	Table	*	*	implied:Table
497	Trade And Other Receivables [Abstract]	Abstract			ifrs-full:TradeAndOtherReceivablesAbstract
498	Trade receivables	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentTradeReceivables
499	GST/VAT receivables	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentValueAddedTaxReceivables
500	Other receivables	Concept (Monetary)	As Of	Debit	ifrs-full:OtherCurrentReceivables
501	Total	Concept (Monetary)	As Of	Debit	ifrs-full:TradeAndOtherCurrentReceivables
502	040701 - Disclosure - Inventories (Details)	Network	*	*	http://www.cameco.com/role/InventoriesDetails
503	Disclosure of operating segments [table]	Table	*	*	ifrs-full:DisclosureOfOperatingSegmentsTable
504	Segments [axis]	Axis			ifrs-full:SegmentsAxis
505	Segments [member]	Member			ifrs-full:SegmentsMember
506	Uranium [Member]	Member			ccj:UraniumMember
507	Fuel Services [Member]	Member			ccj:FuelServicesMember
508	Other Segment [Member]	Member			ccj:OtherSegmentMember
509	Individual assets or cash-generating units [axis]	Axis			ifrs-full:IndividualAssetsOrCashgeneratingUnitsAxis
510	Entity's total for individual assets or cash-generating units [member]	Member			ifrs-full:EntitysTotalForIndividualAssetsOrCashgeneratingUnitsMember
511	Nukem [Member]	Member			ccj:NukemCguMember
512	Disclosure Of Operating Segments [Line Items]	LineItems			ifrs-full:DisclosureOfOperatingSegmentsLineItems
513	Concentrate	Concept (Monetary)	As Of	Debit	ccj:CurrentConcentrateInventory
514	Broken ore	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentOreStockpiles
515	Total inventory	Concept (Monetary)	As Of	Debit	ifrs-full:Inventories
516	Cost of sales	Concept (Monetary)	For Period	Debit	ifrs-full:CostOfInventoriesRecognisedAsExpenseDuringPeriod
517	Net write-down	Concept (Monetary)	For Period	Debit	ifrs-full:WritedownsReversalsOfInventories
518	Inventory pledged as security under financing arrangements	Concept (Monetary)	As Of	Debit	ifrs-full:InventoriesPledgedAsSecurityForLiabilities
519	040801 - Disclosure - Property, plant and equipment (Details)	Network	*	*	http://www.cameco.com/role/PropertyPlantAndEquipmentDetails
520	Disclosure of detailed information about property, plant and equipment [table]	Table	*	*	ifrs-full:DisclosureOfPropertyPlantAndEquipmentTable
521	Classes of property, plant and equipment [axis]	Axis			ifrs-full:ClassesOfPropertyPlantAndEquipmentAxis
522	Property, plant and equipment [member]	Member			ifrs-full:PropertyPlantAndEquipmentMember
523	Land and buildgings [Member]	Member			ifrs-full:LandAndBuildingsMember
524	Plant and equipment [member]	Member			ifrs-full:MachineryMember
525	Furniture and fixtures [Member]	Member			ifrs-full:FixturesAndFittingsMember
526	Under constructions [Member]	Member			ifrs-full:ConstructionInProgressMember
527	Exploration and evaluation [Member]	Member			ifrs-full:ExplorationAndEvaluationAssetsMember
528	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
529	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
530	Cost [Member]	Member			ifrs-full:GrossCarryingAmountMember
531	Accumulated depreciation and impairment [Member]	Member			ifrs-full:AccumulatedDepreciationAmortisationAndImpairmentMember
532	Disclosure Of Property Plant And Equipment [Line Items]	LineItems			ifrs-full:DisclosureOfPropertyPlantAndEquipmentLineItems
533	Property, plant and equipment - Beginning of year	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
534	Additions	Concept (Monetary)	For Period	Debit	ifrs-full:AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment
535	Depreciation charge	Concept (Monetary)	For Period		ifrs-full:DepreciationPropertyPlantAndEquipment
536	Transfers	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughTransfersPropertyPlantAndEquipment
537	Change in reclamation provision	Concept (Monetary)	For Period	Debit	ccj:IncreaseDecreaseDueToChangeInReclamationProvisionPropertyPlantAndEquipment
538	Disposals	Concept (Monetary)	For Period	Credit	ifrs-full:DisposalsPropertyPlantAndEquipment
539	JV Inkai restructuring	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughOtherChangesPropertyPlantAndEquipment
540	Pre-commerical production revenue	Concept (Monetary)	For Period	Credit	ccj:PreCommericalProductionRevenue
541	Impairment charges	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment
542	Effect of movements in exchange rates	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughNetExchangeDifferencesPropertyPlantAndEquipment
543	Property, plant and equipment - End of year	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
544	040802 - Disclosure - Property, plant and equipment (Narrative) (Details)	Network	*	*	http://www.cameco.com/role/PropertyPlantAndEquipmentNarrativeDetails
545	Disclosure of detailed information about property, plant and equipment [table]	Table	*	*	ifrs-full:DisclosureOfPropertyPlantAndEquipmentTable
546	Segments [axis]	Axis			ifrs-full:SegmentsAxis
547	Segments [member]	Member			ifrs-full:SegmentsMember
548	Uranium [Member]	Member			ccj:UraniumMember
549	Measurement [Axis]	Axis			ifrs-full:MeasurementAxis
550	Aggregated measurement [member]	Member			ifrs-full:AggregatedMeasurementMember
551	Non-recurring fair value measurement [member]	Member			ifrs-full:NonrecurringFairValueMeasurementMember
552	Levels Of Fair Value Hierarchy [Axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
553	All levels of fair value hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
554	Level 3 of fair value hierarchy [member]	Member			ifrs-full:Level3OfFairValueHierarchyMember
555	Individual assets or cash-generating units [axis]	Axis			ifrs-full:IndividualAssetsOrCashgeneratingUnitsAxis
556	Entity's total for individual assets or cash-generating units [member]	Member			ifrs-full:EntitysTotalForIndividualAssetsOrCashgeneratingUnitsMember
557	Kintyre [Member]	Member			ccj:KintyreMember
558	Rabbit Lake Mill [Member]	Member			ccj:RabbitLakeMemberMember
559	Inkai [Member]	Member			ccj:InkaiMember
560	US operations [Member]	Member			ccj:UsOperationsMember
561	McArthur River, Key Lake operations [Member]	Member			ccj:McArthurRiverKeyLakeOperationsMember
562	Disclosure Of Property Plant And Equipment [Line Items]	LineItems			ifrs-full:DisclosureOfPropertyPlantAndEquipmentLineItems
563	Contracutal capital commitments	Concept (Monetary)	As Of	Credit	ifrs-full:ContractualCapitalCommitments
564	Ownership interest in JV Inkai	Concept (Percent)	For Period		ifrs-full:ProportionOfOwnershipInterestInAssociate
565	Impairment charges	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment
566	Recoverable amount	Concept (Monetary)	As Of	Debit	ifrs-full:RecoverableAmountOfAssetOrCashgeneratingUnit
567	Fair value less cost to sell discount rate	Concept (Percent)	As Of		ifrs-full:DiscountRateUsedInCurrentMeasurementOfFairValueLessCostsOfDisposal
568	Percentage of increase in management's internal cost estimates	Concept (Percent)	For Period		ccj:PercentageOfIncreaseInManagementInternalCostEstimates
569	Decrease in recoverable amount	Concept (Monetary)	For Period	Credit	ifrs-full:DecreaseInFairValueMeasurementDueToChangeInOneOrMoreUnobservableInputsToReflectReasonablyPossibleAlternativeAssumptionsAssets
570	040901 - Disclosure - Goodwill and intangible assets (Details)	Network	*	*	http://www.cameco.com/role/GoodwillAndIntangibleAssetsDetails
571	Disclosure of reconciliation of changes in intangible assets and goodwill [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfChangesInIntangibleAssetsAndGoodwillTable
572	Classes of intangible assets and goodwill [axis]	Axis			ifrs-full:ClassesOfIntangibleAssetsAndGoodwillAxis
573	Intangible assets and goodwill [member]	Member			ifrs-full:IntangibleAssetsAndGoodwillMember
574	Goodwill [Member]	Member			ifrs-full:GoodwillMember
575	Contracts [member]	Member			ifrs-full:CustomerrelatedIntangibleAssetsMember
576	Intellectual Property [member]	Member			ccj:IntellectualPropertyMember
577	Patents [member]	Member			ifrs-full:CopyrightsPatentsAndOtherIndustrialPropertyRightsServiceAndOperatingRightsMember
578	Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis]	Axis			ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
579	Carrying amount [member]	Member			ifrs-full:CarryingAmountMember
580	Cost [Member]	Member			ifrs-full:GrossCarryingAmountMember
581	Accumulated amortization [member]	Member			ifrs-full:AccumulatedDepreciationAmortisationAndImpairmentMember
582	Individual assets or cash-generating units [axis]	Axis			ifrs-full:IndividualAssetsOrCashgeneratingUnitsAxis
583	Entity's total for individual assets or cash-generating units [member]	Member			ifrs-full:EntitysTotalForIndividualAssetsOrCashgeneratingUnitsMember
584	Nukem [Member]	Member			ccj:NukemCguMember
585	UFP Investments LLC [Member]	Member			ccj:UfpInvestmentsMember
586	Sensivitiy Analysis Test Of Key Assumptions [Axis]	Axis			ccj:SensivitiyAnalysisTestOfKeyAssumptionsAxis
587	Sensitivity analysis [Member]	Member			ccj:SensitivityAnalysisMemberDomain
588	Dicount rate 1% increase [member]	Member			ccj:DicountrateonepercentincreaseMember
589	Terminal growth rate 1% decrease [member]	Member			ccj:TerminalgrowthrateonepercentdecreaseMember
590	Uranium prices $1/lb decrease [member]	Member			ccj:UraniumpricesonedollarperpounddecreaseMember
591	Perpetual annual cash flow $1 million (US) decrease [Member]	Member			ccj:PerpetualannualcashflowonemilliondollarsusdecreaseMember
592	Maturity [Axis]	Axis			ifrs-full:MaturityAxis
593	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
594	2019 [Member]	Member			ifrs-full:NotLaterThanOneYearMember
595	Levels Of Fair Value Hierarchy [Axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
596	All Levels Of Fair Value Hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
597	Level 3 Of Fair Value Hierarchy Member	Member			ifrs-full:Level3OfFairValueHierarchyMember
598	Reconciliation of carrying amount [Line Items]	LineItems			ifrs-full:DisclosureOfReconciliationOfChangesInIntangibleAssetsAndGoodwillLineItems
599	Intangible assets, beginning of year	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsAndGoodwill
600	Amortization charge	Concept (Monetary)	For Period		ifrs-full:AmortisationIntangibleAssetsOtherThanGoodwill
601	Impairment charge	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossIntangibleAssetsAndGoodwill
602	Effect of movements in exchange rates	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughNetExchangeDifferencesIntangibleAssetsAndGoodwill
603	Intangible assets, end of year	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsAndGoodwill
604	Impairment test	Abstract			ifrs-full:DisclosureOfInformationForIndividualAssetOrCashgeneratingUnitWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAbstract
605	The recoverable amount exceeding its carrying value	Concept (Monetary)	As Of	Debit	ifrs-full:AmountByWhichUnitsRecoverableAmountExceedsItsCarryingAmount
606	Discount rate	Concept (Percent)	As Of		ifrs-full:DiscountRateUsedInCurrentMeasurementOfFairValueLessCostsOfDisposal
607	Terminal value growth rate	Concept (Percent)	As Of		ifrs-full:DescriptionOfGrowthRateUsedToExtrapolateCashFlowProjections
608	Decrease in recoverable amount	Concept (Monetary)	As Of	Credit	ccj:DecreaseInRecoverableAmountFromChangesInKeyAssumptions
609	041001 - Disclosure - Long-term receivables, investments and other (Details)	Network	*	*	http://www.cameco.com/role/LongtermReceivablesInvestmentsAndOtherDetails
610	Disclosure of products and services [table]	Table	*	*	ifrs-full:DisclosureOfProductsAndServicesTable
611	Products and services [axis]	Axis			ifrs-full:ProductsAndServicesAxis
612	Products And Services Member	Member			ifrs-full:ProductsAndServicesMember
613	Uranium [Member]	Member			ccj:UraniumMember
614	Disclosure of products and services [line items]	LineItems			ifrs-full:DisclosureOfProductsAndServicesLineItems
615	Product loan maturity	Concept (Text/String)	For Period		ccj:NoncurrentLoansAndReceivablesMaturity
616	Product loan quantity	Concept (num:massItemType)	As Of		ccj:Loanreceivablesquantity
617	041002 - Disclosure - Long-term receivables, investments and other - Equity investments (Details)	Network	*	*	http://www.cameco.com/role/LongtermReceivablesInvestmentsAndOtherEquityInvestmentsDetails
618	Disclosure of fair value measurement of assets [table]	Table	*	*	ifrs-full:DisclosureOfFairValueMeasurementOfAssetsTable
619	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
620	Financial assets, class member	Member			ifrs-full:FinancialAssetsMember
621	Equity investments [Member]	Member			ifrs-full:EquityInvestmentsMember
622	Denison [Member]	Member			ccj:DenisonMember
623	UEX [Member]	Member			ccj:UEXMember
624	GoviEx [Member]	Member			ccj:GoviExMember
625	Other Equity Investments [Member]	Member			ccj:OtherEquityInvestmentsMember
626	Disclosure of FV of investments in equity instruments designated as measured at FVOCI	LineItems			ifrs-full:DisclosureOfFairValueOfInvestmentsInEquityInstrumentsDesignatedAsMeasuredAtFairValueThroughOtherComprehensiveIncomeLineItems
627	Investments in equity securities	Concept (Monetary)	As Of	Debit	ifrs-full:FairValueOfInvestmentsInEquityInstrumentsDesignatedAsMeasuredAtFairValueThroughOtherComprehensiveIncome
628	041101 - Disclosure - Equity-accounted investee - Associate financial position (Details)	Network	*	*	http://www.cameco.com/role/EquityaccountedInvesteeAssociateFinancialPositionDetails
629	Disclosure of significant investments in associates [Table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInAssociatesTable
630	Associates [Axis]	Axis			ifrs-full:SignificantInvestmentsInAssociatesAxis
631	Entity's total for associates [Member]	Member			ifrs-full:EntitysTotalForAssociatesMember
632	JV Inkai [Member]	Member			ccj:JvInkaiAssociateMember
633	Disclosure of significant investments in associates [Line Items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInAssociatesLineItems
634	Cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
635	Other current assets	Concept (Monetary)	As Of	Debit	ifrs-full:OtherCurrentAssets
636	Non-current assets	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssets
637	Current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentLiabilities
638	Non-current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentLiabilities
639	Net assets	Concept (Monetary)	As Of	Debit	ifrs-full:NetAssetsLiabilities
640	041102 - Disclosure - Equity-accounted investee - Associate statement of earnings (Details)	Network	*	*	http://www.cameco.com/role/EquityaccountedInvesteeAssociateStatementOfEarningsDetails
641	Disclosure of significant investments in associates [Table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInAssociatesTable
642	Associates [Axis]	Axis			ifrs-full:SignificantInvestmentsInAssociatesAxis
643	Entity's total for associates [Member]	Member			ifrs-full:EntitysTotalForAssociatesMember
644	JV Inkai [Member]	Member			ccj:JvInkaiAssociateMember
645	Disclosure of significant investments in associates [Line Items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInAssociatesLineItems
646	Revenue from products and services	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
647	Cost of products and services sold	Concept (Monetary)	For Period	Debit	ccj:Costofgoodssoldexcludingdepreciationdepletionandamortization
648	Depreciation and amortization	Concept (Monetary)	For Period	Debit	ifrs-full:DepreciationAndAmortisationExpense
649	Finance income	Concept (Monetary)	For Period	Credit	ifrs-full:FinanceIncome
650	Finance costs	Concept (Monetary)	For Period	Debit	ifrs-full:FinanceCosts
651	Other expense	Concept (Monetary)	For Period	Credit	ifrs-full:OtherIncome
652	Income tax expense	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
653	Net earnings (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
654	Cameco's share	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfContinuingOperationsOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
655	Adjustments	Concept (Monetary)	For Period	Credit	ccj:AdjustmentToShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
656	Cameco's share of net earnings	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
657	041103 - Disclosure - Equity-accounted investee - Reconciliation of carrying amount (Details)	Network	*	*	http://www.cameco.com/role/EquityaccountedInvesteeReconciliationOfCarryingAmountDetails
658	Disclosure of significant investments in associates [Table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInAssociatesTable
659	Associates [Axis]	Axis			ifrs-full:SignificantInvestmentsInAssociatesAxis
660	Entity's total for associates [Member]	Member			ifrs-full:EntitysTotalForAssociatesMember
661	JV Inkai Associate [Member]	Member			ccj:JvInkaiAssociateMember
662	Disclosure of significant investments in associates [Line Items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInAssociatesLineItems
663	Cameco's share of net assets, beginning of year before restructuring	Concept (Monetary)	As Of	Debit	ccj:OpeningShareOfNetAssetsOfInvestmentAccountedForUsingEquityMethodBeforeRestructuring
664	Adjustments	Concept (Monetary)	As Of	Credit	ccj:OpeningAdjustmentToShareOfNetAssetsOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
665	Reconciliation [Abstract]	Abstract			ccj:ReconciliationOfSummarisedFinancialInformationOfAssociateAccountedForUsingEquityMethodToCarryingAmountOfInterestInAssociateAbstract
666	Carrying amount in the statement of financial position, beginning of year before restructuring	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentAccountedForUsingEquityMethod
667	Share of net earnings	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfContinuingOperationsOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
668	Gain on restructuring	Concept (Monetary)	For Period	Credit	ccj:NetGainLossOnCessationOfConsolidationOfSubsidiariesDueToChangeOfInvestmentEntityStatus
669	Impact of foreign exchange	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughNetExchangeDifferencesInvestmentProperty
670	Adjustments	Concept (Monetary)	For Period	Credit	ccj:AdjustmentToShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
671	Carrying amount in the statement of financial position, end of year	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentAccountedForUsingEquityMethod
672	041201 - Disclosure - Accounts payable and accrued liabilities (Details)	Network	*	*	http://www.cameco.com/role/AccountsPayableAndAccruedLiabilitiesDetails
673	Implied Table	Table	*	*	implied:Table
674	Trade And Other Current Payables [Abstract]	Abstract			ifrs-full:TradeAndOtherCurrentPayablesAbstract
675	Trade payables	Concept (Monetary)	As Of	Credit	ifrs-full:TradeAndOtherCurrentPayablesToTradeSuppliers
676	Non-trade payables	Concept (Monetary)	As Of	Credit	ifrs-full:OtherCurrentPayables
677	Payables due to related parties	Concept (Monetary)	As Of	Credit	ifrs-full:TradeAndOtherCurrentPayablesToRelatedParties
678	Total	Concept (Monetary)	As Of	Credit	ifrs-full:TradeAndOtherCurrentPayables
679	041301 - Disclosure - Long term debt - Schedules (Details)	Network	*	*	http://www.cameco.com/role/LongTermDebtSchedulesDetails
680	Disclosure of detailed information about borrowings [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsTable
681	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
682	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
683	Series D [Member]	Member			ccj:SeriesDMember
684	Series E [Member]	Member			ccj:SeriesEMember
685	Series F [Member]	Member			ccj:SeriesFMember
686	Series G [Member]	Member			ccj:SeriesGMember
687	Maturity [Axis]	Axis			ifrs-full:MaturityAxis
688	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
689	2019 [Member]	Member			ifrs-full:NotLaterThanOneYearMember
690	2020 [Member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanTwoYearsMember
691	2021 [Member]	Member			ifrs-full:LaterThanTwoYearsAndNotLaterThanThreeYearsMember
692	2022 [Member]	Member			ifrs-full:LaterThanThreeYearsAndNotLaterThanFourYearsMember
693	2023 [Member]	Member			ifrs-full:LaterThanFourYearsAndNotLaterThanFiveYearsMember
694	Thereafter [Member]	Member			ifrs-full:LaterThanFiveYearsMember
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696	Unsecured debentures	Concept (Monetary)	As Of	Credit	ifrs-full:NotesAndDebenturesIssued
697	Stated interest rates on debentures	Concept (Percent)	As Of		ifrs-full:BorrowingsInterestRate
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700	Long-term debt	Concept (Monetary)	As Of	Credit	ifrs-full:LongtermBorrowings
701	041302 - Disclosure - Long term debt - Schedules (Narrative) (Details)	Network	*	*	http://www.cameco.com/role/LongTermDebtSchedulesNarrativeDetails
702	Implied Table	Table	*	*	implied:Table
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713	Credit Facility Maturity	Concept (Date)	For Period		ccj:CreditFacilityMaturity
714	041401 - Disclosure - Other liabilities (Details)	Network	*	*	http://www.cameco.com/role/OtherLiabilitiesDetails
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718	Derivatives	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
719	Accrued pension and post-retirement benefit liability	Concept (Monetary)	As Of	Credit	ifrs-full:RecognisedLiabilitiesDefinedBenefitPlan
720	Other	Concept (Monetary)	As Of	Credit	ifrs-full:OtherLiabilities
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722	Less current portion	Concept (Monetary)	As Of	Credit	ifrs-full:OtherCurrentFinancialLiabilities
723	Net	Concept (Monetary)	As Of	Credit	ifrs-full:OtherNoncurrentFinancialLiabilities
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729	Waste Disposal [Member]	Member			ifrs-full:OtherEnvironmentRelatedProvisionMember
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768	Class B share par value	Concept (Share)	As Of		ifrs-full:ParValuePerShare
769	Class B share preferences	Concept (Text/String)	For Period		ifrs-full:RightsPreferencesAndRestrictionsAttachingToClassOfShareCapital
770	Dividends Paid Ordinary Shares Per Share	Concept (Share)	For Period		ifrs-full:DividendsPaidOrdinarySharesPerShare
771	Ownership in Cameco	Concept (Percent)	As Of		ccj:PercentageOwnershipInOrdinarySharesOfComapny
772	Percentage Votes Of Ordinary Shares Of Company	Concept (Percent)	As Of		ccj:PercentageVotesOfOrdinarySharesOfCompany
773	041701 - Disclosure - Revenue - Disaggregation (Details)	Network	*	*	http://www.cameco.com/role/RevenueDisaggregationDetails
774	Disclosure of disaggregation of revenue from contracts with customers [Table]	Table	*	*	ifrs-full:DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersTable
775	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
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778	Europe [Member]	Member			srt:EuropeMember
779	Asia [Member]	Member			srt:AsiaPacificMember
780	Types of contracts [Axis]	Axis			ifrs-full:TypesOfContractsAxis
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782	Fixed price Contracts Member	Member			ifrs-full:FixedpriceContractsMember
783	Market Price Contracts Member [Member]	Member			ccj:MarketpricecontractsmemberMember
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787	Fuel Services [Member]	Member			ccj:FuelServicesMember
788	Other Segment [Member]	Member			ccj:OtherSegmentMember
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790	Revenue From Contracts With Customers	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromContractsWithCustomers
791	041702 - Disclosure - Revenue - Deferred revenue (Details)	Network	*	*	http://www.cameco.com/role/RevenueDeferredRevenueDetails
792	Implied Table	Table	*	*	implied:Table
793	Contract Liabilities Abstract	Abstract			ifrs-full:ContractLiabilitiesAbstract
794	Beginning of year	Concept (Monetary)	As Of	Credit	ifrs-full:ContractLiabilities
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797	Effect of movements in exchange rates	Concept (Monetary)	For Period	Credit	ccj:Increasedecreasethroughnetexchangedifferencescontractliabilities
798	End of year	Concept (Monetary)	As Of	Credit	ifrs-full:ContractLiabilities
799	041703 - Disclosure - Revenue - Future sales commitments (Details)	Network	*	*	http://www.cameco.com/role/RevenueFutureSalesCommitmentsDetails
800	Disclosure of transaction price allocated to remaining performance obligations [Table]	Table	*	*	ifrs-full:DisclosureOfTransactionPriceAllocatedToRemainingPerformanceObligationsTable
801	Segments [axis]	Axis			ifrs-full:SegmentsAxis
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803	Uranium [Member]	Member			ccj:UraniumMember
804	Fuel Services [Member]	Member			ccj:FuelServicesMember
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806	Maturity [Axis]	Axis			ifrs-full:MaturityAxis
807	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
808	2019 [Member]	Member			ifrs-full:NotLaterThanOneYearMember
809	2020 [Member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanTwoYearsMember
810	2021 [Member]	Member			ifrs-full:LaterThanTwoYearsAndNotLaterThanThreeYearsMember
811	2022 [Member]	Member			ifrs-full:LaterThanThreeYearsAndNotLaterThanFourYearsMember
812	2023 [Member]	Member			ifrs-full:LaterThanFourYearsAndNotLaterThanFiveYearsMember
813	Thereafter [Member]	Member			ifrs-full:LaterThanFiveYearsMember
814	Currency [Axis]	Axis			srt:CurrencyAxis
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816	USD [Member]	Member			currency:USD
817	Disclosure of transaction price allocated to remaining performance obligations [Line Items]	LineItems			ifrs-full:DisclosureOfTransactionPriceAllocatedToRemainingPerformanceObligationsLineItems
818	Transaction Price Allocated To Remaining Performance Obligations	Concept (Monetary)	As Of	Credit	ifrs-full:TransactionPriceAllocatedToRemainingPerformanceObligations
819	Average Foreign Exchange Rate	Concept (Decimal)	For Period		ifrs-full:AverageForeignExchangeRate
820	041704 - Disclosure - Revenue - Narrative (Details)	Network	*	*	http://www.cameco.com/role/RevenueNarrativeDetails
821	Implied Table	Table	*	*	implied:Table
822	Revenue [abstract]	Abstract			ifrs-full:RevenueAbstract
823	Revenue From Performance Obligations Satisfied Or Partially Satisfied In Previous Periods	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueFromPerformanceObligationsSatisfiedOrPartiallySatisfiedInPreviousPeriods
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825	Statement That Practical Expedient About Incremental Costs Of Obtaining Contract Has Been Used	Concept (Text/String)	For Period		ifrs-full:StatementThatPracticalExpedientAboutIncrementalCostsOfObtainingContractHasBeenUsed
826	Disclosure Of Information About Methods Inputs And Assumptions Used For Determining Transaction Price Explanatory	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInformationAboutMethodsInputsAndAssumptionsUsedForDeterminingTransactionPriceExplanatory
827	ExplanationOfWhetherAnyConsiderationFromContractsWithCustomersIsNotIncludedInDisclosureOfTransactionPriceAllocatedToRemainingPerformanceObligations	Concept (Text/String)	For Period		ifrs-full:ExplanationOfWhetherAnyConsiderationFromContractsWithCustomersIsNotIncludedInDisclosureOfTransactionPriceAllocatedToRemainingPerformanceObligations
828	041801 - Disclosure - Employee benefit expense (Details)	Network	*	*	http://www.cameco.com/role/EmployeeBenefitExpenseDetails
829	Implied Table	Table	*	*	implied:Table
830	Classes Of Employee Benefits Expense [Abstract]	Abstract			ifrs-full:ClassesOfEmployeeBenefitsExpenseAbstract
831	Wages and salaries	Concept (Monetary)	For Period	Debit	ifrs-full:WagesAndSalaries
832	Statutory and company benefits	Concept (Monetary)	For Period	Debit	ifrs-full:SocialSecurityContributions
833	Expenses related to defined benefit plans	Concept (Monetary)	For Period	Debit	ifrs-full:PostemploymentBenefitExpenseDefinedBenefitPlans
834	Expenses related to defined contribution plans	Concept (Monetary)	For Period	Debit	ifrs-full:PostemploymentBenefitExpenseDefinedContributionPlans
835	Equity-settled share-based compensation	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseFromEquitysettledSharebasedPaymentTransactionsInWhichGoodsOrServicesReceivedDidNotQualifyForRecognitionAsAssets
836	Cash-settled share-based compensation	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseFromCashsettledSharebasedPaymentTransactionsInWhichGoodsOrServicesReceivedDidNotQualifyForRecognitionAsAssets
837	Employee benefit expense	Concept (Monetary)	For Period	Debit	ifrs-full:EmployeeBenefitsExpense
838	041901 - Disclosure - Finance cost (Details)	Network	*	*	http://www.cameco.com/role/FinanceCostDetails
839	Implied Table	Table	*	*	implied:Table
840	Borrowing costs [abstract]	Abstract			ifrs-full:BorrowingCostsAbstract
841	Interest on long-term debt	Concept (Monetary)	For Period	Debit	ifrs-full:InterestExpenseOnBorrowings
842	Unwinding of discount on provisions	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseDueToUnwindingOfDiscountOnProvisions
843	Other charges	Concept (Monetary)	For Period	Debit	ccj:FeesRelatedToCreditFacilities
844	Interest on short-term debt	Concept (Monetary)	For Period	Debit	ifrs-full:InterestExpenseOnBankLoansAndOverdrafts
845	Finance costs	Concept (Monetary)	For Period	Debit	ifrs-full:FinanceCosts
846	Borrowing costs capitalised	Concept (Monetary)	For Period		ifrs-full:BorrowingCostsCapitalised
847	042001 - Disclosure - Other income (expense) (Details)	Network	*	*	http://www.cameco.com/role/OtherIncomeexpenseDetails
848	Implied Table	Table	*	*	implied:Table
849	Other Income Expense [Abstract]	Abstract			ccj:OtherIncomeExpenseAbstract
850	Foreign exchange gains (losses)	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnExchangeDifferencesOnTranslationRecognisedInProfitOrLoss
851	Gain on restructuring of JV Inkai	Concept (Monetary)	For Period	Credit	ifrs-full:GainLossOnCessationOfConsolidationOfSubsidiariesDueToChangeOfInvestmentEntityStatus
852	Sale of exploration interests	Concept (Monetary)	For Period	Credit	ifrs-full:GainsOnDisposalsOfInvestmentProperties
853	Contract restructuring	Concept (Monetary)	For Period	Credit	ifrs-full:MiscellaneousOtherOperatingIncome
854	Gain on change in investment accounting	Concept (Monetary)	For Period	Credit	ccj:GainLossFromChangesInInvestmentAccountingMethod
855	Write off of long-term receivables	Concept (Monetary)	For Period	Debit	ccj:ImpairmentLossRecognisedInProfitOrLossNoncurrentReceivables
856	Other	Concept (Monetary)	For Period	Credit	ccj:MiscellaneousOtherIncomeExpense
857	Total other income (expense)	Concept (Monetary)	For Period	Credit	ifrs-full:OtherIncome
858	042002 - Disclosure - Other income (expense) - Narrative (Details)	Network	*	*	http://www.cameco.com/role/OtherIncomeexpenseNarrativeDetails
859	Disclosure of fair value measurement of assets [table]	Table	*	*	ifrs-full:DisclosureOfFairValueMeasurementOfAssetsTable
860	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
861	Financial assets member	Member			ifrs-full:FinancialAssetsMember
862	Equity investments [Member]	Member			ifrs-full:EquityInvestmentsMember
863	Denison [Member]	Member			ccj:DenisonMember
864	Disclosure of financial assets [line items]	LineItems			ifrs-full:DisclosureOfFinancialAssetsLineItems
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866	Number of shares owned	Concept (Shares)	As Of		ccj:Investmentownedbalanceshares
867	042101 - Disclosure - Income Taxes - Significant components of deferred tax assets and liabilities (Details)	Network	*	*	http://www.cameco.com/role/IncomeTaxesSignificantComponentsOfDeferredTaxAssetsAndLiabilitiesDetails
868	Disclosure of temporary difference, unused tax losses and unused tax credits [table]	Table	*	*	ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable
869	Temporary difference, unused tax losses and unused tax credits [axis]	Axis			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis
870	Temporary differences [member]	Member			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember
871	Property, plant and equipment [member]	Member			ccj:DeferredTaxAssetsPropertyPlantAndEquipmentMember
872	Provision for reclamation [member]	Member			ccj:DeferredTaxAssetsProvisionForReclamationtMember
873	Inventories [Member]	Member			ccj:DeferredTaxAssetsInventoriesMember
874	Foreign exploration and development [member]	Member			ccj:DeferredTaxAssetsIncomeForeignExplorationAndDevelopmentMember
875	Income tax losses [member]	Member			ifrs-full:UnusedTaxLossesMember
876	Defined benefit plan actuarial losses [member]	Member			ccj:DeferredTaxAssetsDefinedBenefitPlanActuarialLossesMember
877	Long-term investments and other, deferred tax assets [member]	Member			ccj:DeferredTaxAssetsLongTermInvestmentAndOtherMember
878	Deferred tax assets [member]	Member			ccj:DeferredTaxAssetsMember
879	Property, plant and equipment [Member]	Member			ccj:DeferredTaxLiabilityPropertyPlantEquipmentMember
880	Inventories [member]	Member			ccj:DeferredTaxLiabilityInventoriesMember
881	Deferred tax liabilities [Member]	Member			ccj:DeferredTaxLiabilitiesMember
882	Disclosure of temporary difference, unused tax losses and unused tax credits [line items]	LineItems			ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems
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884	Net deferred tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:NetDeferredTaxAssets
885	Net deferred tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:NetDeferredTaxLiabilities
886	Deferred tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:DeferredTaxAssets
887	Deferred tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilities
888	Net deferred tax asset	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilityAsset
889	042102 - Disclosure - Income Taxes - Movement in net deferred tax assets and liabilities (Details)	Network	*	*	http://www.cameco.com/role/IncomeTaxesMovementInNetDeferredTaxAssetsAndLiabilitiesDetails
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892	Reconciliation of changes in deferred tax liability (asset) [abstract]	Abstract			ifrs-full:ReconciliationOfChangesInDeferredTaxLiabilityAssetAbstract
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895	Recovery (expense) for the year in other comprehensive income	Concept (Monetary)	For Period		ifrs-full:IncomeTaxRelatingToComponentsOfOtherComprehensiveIncome
896	Change to equity accounting - JV Inkai	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughLossOfControlOfSubsidiaryDeferredTaxLiabilityAsset
897	Effect of movements in exchange rates	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughNetExchangeDifferencesDeferredTaxLiabilityAsset
898	Net deferred tax asset, end of year	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilityAsset
899	042103 - Disclosure - Income Taxes - Significant components of unrecognized deferred tax assets (Details)	Network	*	*	http://www.cameco.com/role/IncomeTaxesSignificantComponentsOfUnrecognizedDeferredTaxAssetsDetails
900	Disclosure of temporary difference, unused tax losses and unused tax credits [table]	Table	*	*	ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable
901	Temporary difference, unused tax losses and unused tax credits [axis]	Axis			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis
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903	Income tax losses [member]	Member			ifrs-full:UnusedTaxLossesMember
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906	Long-term investments and other, deferred tax assets [member]	Member			ccj:DeferredTaxAssetsLongTermInvestmentAndOtherMember
907	Disclosure of temporary difference, unused tax losses and unused tax credits [line items]	LineItems			ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems
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909	Tax credits	Concept (Monetary)	For Period	Credit	ifrs-full:TaxBenefitArisingFromPreviouslyUnrecognisedTaxLossTaxCreditOrTemporaryDifferenceOfPriorPeriodUsedToReduceCurrentTaxExpense
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911	042104 - Disclosure - Income Taxes - Tax rate reconciliation (Details)	Network	*	*	http://www.cameco.com/role/IncomeTaxesTaxRateReconciliationDetails
912	Implied Table	Table	*	*	implied:Table
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914	Reconciliation Of Accounting Profit Multiplied By Applicable Tax Rates [Abstract]	Abstract			ifrs-full:ReconciliationOfAccountingProfitMultipliedByApplicableTaxRatesAbstract
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916	Combined federal and provincial tax rate	Concept (Percent)	For Period		ifrs-full:ApplicableTaxRate
917	Computed income tax expense (recovery)	Concept (Monetary)	For Period	Debit	ifrs-full:TaxExpenseIncomeAtApplicableTaxRate
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919	Difference between Canadian rates and rates applicable to subsidiaries in other countries	Concept (Monetary)	For Period	Debit	ifrs-full:TaxEffectOfForeignTaxRates
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922	Share-based compensation plans	Concept (Monetary)	For Period	Debit	ccj:SharebasedCompTaxEffectsForReconciliationBetweenAccountingProfitAndTaxExpenseIncome
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925	Change in legislation	Concept (Monetary)	For Period	Debit	ifrs-full:TaxEffectFromChangeInTaxRate
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928	Other permanent differences	Concept (Monetary)	For Period	Debit	ccj:OtherPermanentDifferencesTaxEffectsForReconciliationBetweenAccountingProfitAndTaxExpenseIncome
929	Income tax recovery	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
930	042105 - Disclosure - Income Taxes - Earnings and income taxes by jurisdiction (Details)	Network	*	*	http://www.cameco.com/role/IncomeTaxesEarningsAndIncomeTaxesByJurisdictionDetails
931	Disclosure of geographical areas [table]	Table	*	*	ifrs-full:DisclosureOfGeographicalAreasTable
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934	Canada [member]	Member			country:CA
935	Foreign [member]	Member			ifrs-full:ForeignCountriesMember
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940	Income tax recovery	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
941	042106 - Disclosure - Income Taxes - Income tax losses carried forward (Details)	Network	*	*	http://www.cameco.com/role/IncomeTaxesIncomeTaxLossesCarriedForwardDetails
942	Disclosure of temporary difference, unused tax losses and unused tax credits [table]	Table	*	*	ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsTable
943	Temporary difference, unused tax losses and unused tax credits [axis]	Axis			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis
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947	Unused tax expiry 2031 [Member]	Member			ccj:UnusedTaxExpiry2031Member
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949	Unused tax expiry 2033 [Member]	Member			ccj:UnusedTaxExpiry2033Member
950	Unused tax expiry 2034 [Member]	Member			ccj:UnusedTaxExpiry2034Member
951	Unused tax expiry 2035 [Member]	Member			ccj:UnusedTaxExpiry2035Member
952	Unused tax expiry 2036 [Member]	Member			ccj:UnusedTaxExpiry2036Member
953	Unused tax expiry 2037 [Member]	Member			ccj:Unusedtaxexpiry203Member
954	Unused tax expiry 2038 [Member]	Member			ccj:Unusedtaxexpiry2038Member
955	Unused tax expiry 2039 [Member]	Member			ccj:Unusedtaxexpiry2039Member
956	Unused tax expiry 2040 [Member]	Member			ccj:Unusedtaxexpiry2040Member
957	Unused tax expiry No expiry [Member]	Member			ccj:UnusedTaxExpiryNoExpiryMember
958	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
959	Geographical areas [member]	Member			ifrs-full:GeographicalAreasMember
960	Canada [member]	Member			country:CA
961	US [member]	Member			country:US
962	Other [member]	Member			ifrs-full:ForeignCountriesMember
963	Disclosure of temporary difference, unused tax losses and unused tax credits [line items]	LineItems			ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsLineItems
964	Unrecognized deferred tax assets	Concept (Monetary)	As Of		ifrs-full:UnusedTaxLossesForWhichNoDeferredTaxAssetRecognised
965	Unused tax loss carry forward	Concept (Monetary)	As Of	Debit	ccj:Unusedtaxlosses
966	042107 - Disclosure - Income Taxes - Narratives (Details)	Network	*	*	http://www.cameco.com/role/IncomeTaxesNarrativesDetails
967	Disclosure of other provisions [table]	Table	*	*	ifrs-full:DisclosureOfOtherProvisionsTable
968	Classes of other provisions [axis]	Axis			ifrs-full:ClassesOfProvisionsAxis
969	Other provisions [member]	Member			ifrs-full:OtherProvisionsMember
970	Provision for uncertain tax positions [member]	Member			ifrs-full:MiscellaneousOtherProvisionsMember
971	Classes of contingent liabilities [axis]	Axis			ifrs-full:ClassesOfContingentLiabilitiesAxis
972	Contingent liabilities [member]	Member			ifrs-full:ContingentLiabilitiesMember
973	Penalties related to tax adjustments [member]	Member			ccj:ContingentPenaltiesRelatedTaxAdjustmentMember
974	Penalties related to transfer pricing [member]	Member			ccj:ContingentPenaltiesTransferPricingMember
975	Penalties related to cash taxes and transfer pricing [member]	Member			ccj:ContingentPenaltiesCashTaxesTransferPricingMember
976	50% Penalties related to cash tax and transfer pricing [member]	Member			ccj:ContingentPenaltiesHalfOfCashTaxesTransferPricingMember
977	Income Tax Authority [axis]	Axis			ccj:IncomeTaxAuthorityAxis
978	Income Tax Authority [member]	Member			ccj:IncomeTaxAuthorityMemberDomain
979	Canadian Revenue Agency [member]	Member			ccj:CanadianRevenueAgencyMember
980	Internal Revenue Service [member]	Member			ccj:InternalRevenueServiceMember
981	Range [axis]	Axis			ifrs-full:RangeAxis
982	Ranges [member]	Member			ifrs-full:RangesMember
983	Bottom of range [member]	Member			ifrs-full:BottomOfRangeMember
984	Top of range [member]	Member			ifrs-full:TopOfRangeMember
985	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
986	Geographical areas [member]	Member			ifrs-full:GeographicalAreasMember
987	Provisions [Line Items]	LineItems			ifrs-full:DisclosureOfOtherProvisionsLineItems
988	Reversal of Deferred tax asset	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseInDeferredTaxLiabilityAsset
989	Amount of potential taxable income consequences from tax dispute	Concept (Monetary)	For Period	Credit	ccj:AmountOfPotentialTaxableIncomeConsequencesFromTaxDispute
990	Corresponding increase in tax expense	Concept (Monetary)	For Period	Debit	ifrs-full:CurrentTaxExpenseIncome
991	Receivables from tax authorities	Concept (Monetary)	As Of	Debit	ccj:ReceivablesFromTaxesAuthorities
992	Letters of credit oustanding	Concept (Monetary)	As Of	Credit	ccj:LettersOfCreditOustanding
993	Percentage of taxes and interest charges	Concept (Percent)	As Of		ccj:PercentageOfTaxesAndInterestCharges
994	Provisions	Concept (Monetary)	As Of	Credit	ifrs-full:Provisions
995	Provision for CRA transfer price dispute	Concept (Monetary)	As Of		ifrs-full:EstimatedFinancialEffectOfContingentLiabilities
996	042201 - Disclosure - Per share amounts (Details)	Network	*	*	http://www.cameco.com/role/PerShareAmountsDetails
997	Implied Table	Table	*	*	implied:Table
998	Earnings (loss) per common share attributable to equity holders:	Abstract			ifrs-full:EarningsPerShareAbstract
999	Basic earnings (loss) per share computation	Abstract			ifrs-full:BasicEarningsPerShareAbstract
1000	Net earnings (loss) attributable to equity holders	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToOwnersOfParent
1001	Weighted average common shares outstanding	Concept (Shares)	For Period		ifrs-full:WeightedAverageShares
1002	Basic earnings (loss) per common share	Concept (Share)	For Period		ifrs-full:BasicEarningsLossPerShare
1003	Diluted earnings (loss) per share computation	Abstract			ifrs-full:DilutedEarningsPerShareAbstract
1004	Net earnings (loss) attributable to equity holders	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossAttributableToOwnersOfParent
1005	Weighted average common shares outstanding	Concept (Shares)	For Period		ifrs-full:WeightedAverageShares
1006	Dilutive effect of stock options	Concept (Shares)	For Period		ifrs-full:DilutiveEffectOfShareOptionsOnNumberOfOrdinaryShares
1007	Weighted average common shares outstanding, assuming dilution	Concept (Shares)	For Period		ifrs-full:AdjustedWeightedAverageShares
1008	Diluted earnings (loss) per common share	Concept (Share)	For Period		ifrs-full:DilutedEarningsLossPerShare
1009	042301 - Disclosure - Supplemental cash flow information (Details)	Network	*	*	http://www.cameco.com/role/SupplementalCashFlowInformationDetails
1010	Implied Table	Table	*	*	implied:Table
1011	Consolidated statements of cash flows [Abstract]	Abstract			ifrs-full:StatementOfCashFlowsAbstract
1012	Changes In Non Cash Working Capital	Abstract			ccj:ChangesInNonCashWorkingCapital
1013	Accounts receivable	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInTradeAccountReceivable
1014	Inventories	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInInventories
1015	Supplies and prepaid expenses	Concept (Monetary)	For Period	Debit	ccj:AdjustmentsForDecreaseIncreaseInSuppliesAndPrepaid
1016	Accounts payable and accrued liabilities	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInTradeAndOtherPayables
1017	Reclamation payments	Concept (Monetary)	For Period	Credit	ccj:CashFlowsUsedInDecommissioningRestorationAndRehabilitationCosts
1018	Amortization of purchase price allocation	Concept (Monetary)	For Period	Debit	ccj:AdjustmentsForAmortizationExpenseForPurchasePriceAllocation
1019	Other	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInOtherAssets
1020	Other operating items	Concept (Monetary)	For Period	Debit	ifrs-full:OtherInflowsOutflowsOfCashClassifiedAsOperatingActivities
1021	042302 - Disclosure - Supplemental cash flow information - Financing activities (Details)	Network	*	*	http://www.cameco.com/role/SupplementalCashFlowInformationFinancingActivitiesDetails
1022	Disclosure of reconciliation of liabilities arising from financing activities [table]	Table	*	*	ifrs-full:DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesTable
1023	Liabilities arising from financing activities [axis]	Axis			ifrs-full:LiabilitiesArisingFromFinancingActivitiesAxis
1024	Liabilities arising from financing activities [member]	Member			ifrs-full:LiabilitiesArisingFromFinancingActivitiesMember
1025	Long-term borrowings [member]	Member			ifrs-full:LongtermBorrowingsMember
1026	Interest payable [Member]	Member			ccj:InterestPayableMember
1027	Dividends Payable [Member]	Member			ccj:DividendsPayableMember
1028	Share capital [Member]	Member			ccj:ShareCapitalMember
1029	Disclosure of reconciliation of liabilities arising from financing activities [line items]	LineItems			ifrs-full:DisclosureOfReconciliationOfLiabilitiesArisingFromFinancingActivitiesLineItems
1030	Beginning balance	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilitiesArisingFromFinancingActivities
1031	Changes from financing cash flows:	Abstract			ifrs-full:CashFlowsFromUsedInFinancingActivitiesAbstract
1032	Dividends paid	Concept (Monetary)	For Period	Credit	ifrs-full:DividendsPaidClassifiedAsFinancingActivities
1033	Interest paid	Concept (Monetary)	For Period	Credit	ifrs-full:InterestPaidClassifiedAsFinancingActivities
1034	Shares issued, stock option plan	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromIssuingShares
1035	Total cash changes	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInFinancingActivities
1036	Non-cash changes:	Abstract			ccj:NonCashChangesFinancingActivitiesAbstract
1037	Amortization of issue costs	Concept (Monetary)	For Period	Debit	ccj:AmortisationOfFinancingCosts
1038	Dividends declared	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsClassifiedAsExpense
1039	Interest expense	Concept (Monetary)	For Period	Debit	ifrs-full:InterestExpense
1040	Shares issued, stock option plan	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseFromSharebasedPaymentTransactionsWithEmployees
1041	Foreign exchange	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughEffectOfChangesInForeignExchangeRatesLiabilitiesArisingFromFinancingActivities
1042	Total non-cash changes	Concept (Monetary)	For Period	Debit	ccj:NonCashChangesArisingFromFinancingActivities
1043	Ending balance	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilitiesArisingFromFinancingActivities
1044	042401 - Disclosure - Share-based complesation plans - Share options number and weighted average price (Details)	Network	*	*	http://www.cameco.com/role/SharebasedComplesationPlansShareOptionsNumberAndWeightedAveragePriceDetails
1045	Disclosure of number and weighted average remaining contractual life of outstanding share options [table]	Table	*	*	ifrs-full:DisclosureOfNumberAndWeightedAverageRemainingContractualLifeOfOutstandingShareOptionsTable
1046	Ranges of exercise prices for outstanding share options [axis]	Axis			ifrs-full:RangesOfExercisePricesForOutstandingShareOptionsAxis
1047	Ranges of exercise prices for outstanding share options [member]	Member			ifrs-full:RangesOfExercisePricesForOutstandingShareOptionsMember
1048	$11.32 - 17.84 [member]	Member			ccj:PriceRange11Dollars32CentsTo17Dollars84CentsMember
1049	$17.85 - 39.53 [member]	Member			ccj:PriceRange17Dollars85CentsTo39Dollars53CentsMember
1050	Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]	LineItems			ifrs-full:DisclosureOfNumberAndWeightedAverageRemainingContractualLifeOfOutstandingShareOptionsLineItems
1051	Option price per share	Concept (Monetary)	As Of		ifrs-full:ExercisePriceOfOutstandingShareOptions
1052	Number Of Outstanding Share Options	Concept (Decimal)	As Of		ifrs-full:NumberOfOutstandingShareOptions
1053	Options outstanding - Weighted average remaining life	Concept (Decimal)	As Of		ifrs-full:WeightedAverageRemainingContractualLifeOfOutstandingShareOptions
1054	Weighted Average Exercise Price Of Share Options Outstanding In Sharebased Payment Arrangement	Concept (Monetary)	As Of		ifrs-full:WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement
1055	Number Of Share Options Exercisable In Sharebased Payment Arrangement	Concept (Decimal)	As Of		ifrs-full:NumberOfShareOptionsExercisableInSharebasedPaymentArrangement
1056	Options exercisable - Weighted average exercisable price	Concept (Monetary)	As Of		ifrs-full:WeightedAverageExercisePriceOfShareOptionsExercisableInSharebasedPaymentArrangement
1057	042401 - Disclosure - Share-based complesation plans - Share options number and weighted average price (Details)	Network	*	*	http://www.cameco.com/role/SharebasedComplesationPlansShareOptionsNumberAndWeightedAveragePriceDetails
1058	Implied Table	Table	*	*	implied:Table
1059	Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Abstract]	Abstract			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementAbstract
1060	Number And Weighted Average Exercise Prices Of Share Options [Abstract]	Abstract			ccj:NumberAndWeightedAverageExercisePricesOfShareOptionsAbstract
1061	Beginning of year	Concept (Decimal)	As Of		ifrs-full:NumberOfOutstandingShareOptions
1062	Options granted	Concept (Decimal)	For Period		ifrs-full:NumberOfShareOptionsGrantedInSharebasedPaymentArrangement
1063	Options forfeited	Concept (Decimal)	For Period		ifrs-full:NumberOfShareOptionsForfeitedInSharebasedPaymentArrangement
1064	Options expired	Concept (Decimal)	For Period		ifrs-full:NumberOfShareOptionsExpiredInSharebasedPaymentArrangement
1065	Options exercised	Concept (Decimal)	For Period		ifrs-full:NumberOfShareOptionsExercisedInSharebasedPaymentArrangement
1066	End of year	Concept (Decimal)	As Of		ifrs-full:NumberOfOutstandingShareOptions
1067	Weighted average exercisable price - beginning of year	Concept (Monetary)	As Of		ifrs-full:WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement
1068	Weighted average exercisable price for options granted	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsGrantedInSharebasedPaymentArrangement
1069	Weighted average exercisable price for options forfeited	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsForfeitedInSharebasedPaymentArrangement
1070	Weighted average exercisable price for options expired	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsExpiredInSharebasedPaymentArrangement
1071	Weighted average exercise price for options exercised	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsExercisedInSharebasedPaymentArrangement
1072	Weighted average exercisable price - end of year	Concept (Monetary)	As Of		ifrs-full:WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement
1073	Exercisable	Concept (Decimal)	As Of		ifrs-full:NumberOfShareOptionsExercisableInSharebasedPaymentArrangement
1074	042403 - Disclosure - Share-based compensation plans - equity-settled and cash-settled (Details)	Network	*	*	http://www.cameco.com/role/SharebasedCompensationPlansEquitysettledAndCashsettledDetails
1075	Disclosure of terms and conditions of share-based payment arrangement [table]	Table	*	*	ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable
1076	Types of share-based payment arrangements [axis]	Axis			ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
1077	Share-based payment arrangements [member]	Member			ifrs-full:SharebasedPaymentArrangementsMember
1078	Stock Option Plan [member]	Member			ccj:StockOptionPlanMember
1079	Performance Share Unit Plan [member]	Member			ccj:PerformanceShareUnitPlanMember
1080	Restricted Share Unit Plan [member]	Member			ccj:RestrictedShareUnitPlanMember
1081	Employee Share Ownership Plan [member]	Member			ccj:EmployeeShareOwnershipPlanMember
1082	Deferred Share Unit Plan [member]	Member			ccj:DeferredShareUnitPlanMember
1083	Phantom Stock Option Plan [member]	Member			ccj:PhantomStockOptionPlanMember
1084	Disclosure of terms and conditions of share-based payment arrangement [line items]	LineItems			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
1085	Total compensation expenses under equity settled plans	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseFromEquitysettledSharebasedPaymentTransactionsInWhichGoodsOrServicesReceivedDidNotQualifyForRecognitionAsAssets
1086	Expenses (recoveries) under its cash-settled plan	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseFromCashsettledSharebasedPaymentTransactionsInWhichGoodsOrServicesReceivedDidNotQualifyForRecognitionAsAssets
1087	042404 - Disclosure - Share-based compensation plans - Inputs used in the measurement (Details)	Network	*	*	http://www.cameco.com/role/SharebasedCompensationPlansInputsUsedInTheMeasurementDetails
1088	Disclosure of terms and conditions of share-based payment arrangement [table]	Table	*	*	ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementTable
1089	Types of share-based payment arrangements [axis]	Axis			ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
1090	Share-based payment arrangements [member]	Member			ifrs-full:SharebasedPaymentArrangementsMember
1091	Stock Option Plan [member]	Member			ccj:StockOptionPlanMember
1092	Performance Share Unit Plan [member]	Member			ccj:PerformanceShareUnitPlanMember
1093	Restricted Share Unit Plan [member]	Member			ccj:RestrictedShareUnitPlanMember
1094	Phantom Stock Option Plan [member]	Member			ccj:PhantomStockOptionPlanMember
1095	Disclosure of terms and conditions of share-based payment arrangement [line items]	LineItems			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
1096	Number of options granted	Concept (Decimal)	For Period		ifrs-full:NumberOfShareOptionsGrantedInSharebasedPaymentArrangement
1097	Average strike price	Concept (Monetary)	For Period		ifrs-full:WeightedAverageExercisePriceOfShareOptionsGrantedInSharebasedPaymentArrangement
1098	Expected dividend	Concept (Monetary)	For Period		ifrs-full:ExpectedDividendShareOptionsGranted
1099	Expected volatility	Concept (Percent)	For Period		ifrs-full:DescriptionOfExpectedVolatilityShareOptionsGranted
1100	Risk-free interest rate	Concept (Percent)	For Period		ifrs-full:DescriptionOfRiskFreeInterestRateShareOptionsGranted
1101	Expected life of option	Concept (Decimal)	For Period		ifrs-full:DescriptionOfOptionLifeShareOptionsGranted
1102	Expected forfeitures	Concept (Percent)	For Period		ccj:DescriptionOfExpectedForfeituresShareOptionsGranted
1103	Weighted average grant date fair values	Concept (Monetary)	For Period		ifrs-full:WeightedAverageSharePriceShareOptionsGranted
1104	Number of options, reporting date	Concept (Decimal)	As Of		ifrs-full:NumberOfOutstandingShareOptions
1105	Average strike price, reporting date	Concept (Monetary)	As Of		ifrs-full:WeightedAverageExercisePriceOfShareOptionsExercisableInSharebasedPaymentArrangement
1106	Expected dividend, reporting date	Concept (Monetary)	As Of		ccj:ExpectedDividendShareOptionsReportingDate
1107	Expected volatility, reporting date	Concept (Percent)	As Of		ccj:ExpectedVolatilityShareOptions
1108	Risk free interest rate, reporting date	Concept (Percent)	As Of		ccj:RiskFreeInterestRateShareOptionsOustanding
1109	Expected life of option, reporting date	Concept (Decimal)	As Of		ccj:DescriptionOfOptionLifeShareOptions
1110	Expected forfeitures, reporting date	Concept (Percent)	As Of		ccj:DescriptionOfExpectedForfeituresShareOptionsOustading
1111	Weighted average share price, reporting date	Concept (Monetary)	For Period		ifrs-full:WeightedAverageSharePrice
1112	042405 - Disclosure - Share-based compensation plans - Narrative (Details)	Network	*	*	http://www.cameco.com/role/SharebasedCompensationPlansNarrativeDetails
1113	Disclosure of number and weighted average remaining contractual life of outstanding share options [table]	Table	*	*	ifrs-full:DisclosureOfNumberAndWeightedAverageRemainingContractualLifeOfOutstandingShareOptionsTable
1114	Types of share-based payment arrangements [axis]	Axis			ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
1115	Share-based payment arrangements [member]	Member			ifrs-full:SharebasedPaymentArrangementsMember
1116	Stock Option Plan [member]	Member			ccj:StockOptionPlanMember
1117	Performance Share Unit Plan [member]	Member			ccj:PerformanceShareUnitPlanMember
1118	Restricted Share Unit Plan [member]	Member			ccj:RestrictedShareUnitPlanMember
1119	Employee Share Ownership Plan [member]	Member			ccj:EmployeeShareOwnershipPlanMember
1120	Deferred Share Unit Plan [member]	Member			ccj:DeferredShareUnitPlanMember
1121	Phantom Stock Option Plan [member]	Member			ccj:PhantomStockOptionPlanMember
1122	Cash Settled Plan [Member]	Member			ccj:CashSettledPlanMember
1123	Range [axis]	Axis			ifrs-full:RangeAxis
1124	Ranges [member]	Member			ifrs-full:RangesMember
1125	Bottom of range [member]	Member			ifrs-full:BottomOfRangeMember
1126	Top of range [member]	Member			ifrs-full:TopOfRangeMember
1127	Disclosure of terms and conditions of share-based payment arrangement [line items]	LineItems			ifrs-full:DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
1128	Vesting period	Concept (Text/String)	For Period		ifrs-full:DescriptionOfVestingRequirementsForSharebasedPaymentArrangement
1129	Authorized shares	Concept (Shares)	As Of		ifrs-full:NumberOfSharesAuthorised
1130	Outstanding shares	Concept (Shares)	As Of		ifrs-full:NumberOfSharesIssued
1131	Stock options held	Concept (Decimal)	As Of		ifrs-full:NumberOfShareOptionsExercisableInSharebasedPaymentArrangement
1132	Employers contribution per employee	Concept (Text/String)	For Period		ccj:EmployersContributionPerEmployeeShareBasedPaymentArrangement
1133	Number of participants	Concept (Decimal)	As Of		ifrs-full:NumberOfEmployees
1134	Total number of shares purchased	Concept (Shares)	For Period		ifrs-full:IncreaseDecreaseInNumberOfOrdinarySharesIssued
1135	Total amount of employer's contribution	Concept (Monetary)	For Period	Credit	ifrs-full:EmployerContributions
1136	Description of method of settlement for share-based payment arrangement	Concept (Text/String)	For Period		ifrs-full:DescriptionOfMethodOfSettlementForSharebasedPaymentArrangement
1137	Exercise prices range	Concept (Monetary)	As Of		ifrs-full:ExercisePriceOfOutstandingShareOptions
1138	Options exercisable - Weighted average exercisable price	Concept (Monetary)	As Of		ifrs-full:WeightedAverageExercisePriceOfShareOptionsExercisableInSharebasedPaymentArrangement
1139	Liabilities from share-based payment transactions	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilitiesFromSharebasedPaymentTransactions2011
1140	042501 - Disclosure - Pension and other post-retirement benefits - Defined benefit plans (Details)	Network	*	*	http://www.cameco.com/role/PensionAndOtherPostretirementBenefitsDefinedBenefitPlansDetails
1141	Disclosure of net defined benefit liability (asset) [table]	Table	*	*	ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetTable
1142	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
1143	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
1144	Pension plans [member]	Member			ifrs-full:PensionDefinedBenefitPlansMember
1145	Other Benefit Plans [Member]	Member			ccj:OtherBenefitPlansMember
1146	Net defined benefit liability (asset) [axis]	Axis			ifrs-full:NetDefinedBenefitLiabilityAssetAxis
1147	Net defined benefit liability (asset) [member]	Member			ifrs-full:NetDefinedBenefitLiabilityAssetMember
1148	Plan assets [member]	Member			ifrs-full:PlanAssetsMember
1149	Defined benefit obligations [member]	Member			ifrs-full:PresentValueOfDefinedBenefitObligationMember
1150	Disclosure of benefit plans [line items]	LineItems			ifrs-full:DisclosureOfDefinedBenefitPlansLineItems
1151	Fair value of plan assets, beginning of year	Concept (Monetary)	As Of	Debit	ifrs-full:PlanAssetsAtFairValue
1152	Defined benefit obligation, beginning of year	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilityAssetOfDefinedBenefitPlans
1153	Current service cost	Concept (Monetary)	For Period	Credit	ifrs-full:CurrentServiceCostNetDefinedBenefitLiabilityAsset
1154	Interest income or cost	Concept (Monetary)	For Period	Credit	ifrs-full:InterestExpenseIncomeNetDefinedBenefitLiabilityAsset
1155	Return on assets excluding interest income	Concept (Monetary)	For Period	Debit	ifrs-full:ReturnOnPlanAssetsNetDefinedBenefitLiabilityAsset
1156	Employer contributions	Concept (Monetary)	For Period	Debit	ifrs-full:ContributionsToPlanByEmployerNetDefinedBenefitLiabilityAsset
1157	Actuarial loss (gain) arising from:	Abstract			ifrs-full:GainLossOnRemeasurementOfNetDefinedBenefitLiabilityAssetAbstract
1158	- demographic assumptions	Concept (Monetary)	For Period	Debit	ifrs-full:ActuarialGainsLossesArisingFromChangesInDemographicAssumptionsNetDefinedBenefitLiabilityAsset
1159	- financial assumptions	Concept (Monetary)	For Period	Debit	ifrs-full:ActuarialGainsLossesArisingFromChangesInFinancialAssumptionsNetDefinedBenefitLiabilityAsset
1160	- experience adjustment	Concept (Monetary)	For Period	Debit	ifrs-full:ActuarialGainsLossesArisingFromExperienceAdjustmentsNetDefinedBenefitLiabilityAsset
1161	Past service cost	Concept (Monetary)	For Period	Credit	ifrs-full:PastServiceCostNetDefinedBenefitLiabilityAsset
1162	Benefits paid	Concept (Monetary)	For Period	Debit	ifrs-full:PaymentsFromPlanNetDefinedBenefitLiabilityAsset
1163	Benefits paid	Concept (Monetary)	For Period	Debit	ccj:PaymentsInRespectOfSettlementNetDefinedBenefitLiabilityAsset
1164	Administration	Concept (Monetary)	For Period	Debit	ifrs-full:AdministrativeExpense
1165	Foreign exchange	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughChangesInForeignExchangeRatesNetDefinedBenefitLiabilityAsset
1166	Fair value of plan assets, end of year	Concept (Monetary)	As Of	Debit	ifrs-full:PlanAssetsAtFairValue
1167	Defined benefit obligation, end of year	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilityAssetOfDefinedBenefitPlans
1168	Defined benefit liability	Concept (Monetary)	As Of	Debit	ifrs-full:SurplusDeficitInPlan
1169	042502 - Disclosure - Pension and other post-retirement benefits - percentages of the total fair value of assets (Details)	Network	*	*	http://www.cameco.com/role/PensionAndOtherPostretirementBenefitsPercentagesOfTheTotalFairValueOfAssetsDetails
1170	Disclosure of fair value of plan [table]	Table	*	*	ifrs-full:DisclosureOfDefinedBenefitPlansTable
1171	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
1172	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
1173	Pension plans [member]	Member			ifrs-full:PensionDefinedBenefitPlansMember
1174	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
1175	Asset Category [member]	Member			ifrs-full:ClassesOfAssetsMember
1176	Canadian Equity Securities [member]	Member			ccj:CanadianEquitySecuritiesMember
1177	Global Equity Securities [member]	Member			ccj:GlobalEquitySecuritiesMember
1178	Canadian Fixed Income [member]	Member			ccj:CanadianFixedIncomeMember
1179	Other [member]	Member			ifrs-full:OtherAssetsMember
1180	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
1181	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
1182	Related Parties [member]	Member			ifrs-full:RelatedPartiesMember
1183	Disclosure of benefit plans [line items]	LineItems			ifrs-full:DisclosureOfDefinedBenefitPlansLineItems
1184	The percentages of the total fair value of assets	Concept (Percent)	As Of		ccj:PercentageOfTotalFairValueOfAssets
1185	Defined benefit plan assets	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilityAssetOfDefinedBenefitPlans
1186	Description of the refundable tax account held by CRA	Concept (Text/String)	For Period		ccj:DescriptionOfRefundableTaxAccountHeldByCanadaRevenueAgency
1187	042503 - Disclosure - Pension and other post-retirement benefits - components of net pension and other benefit expense (Details)	Network	*	*	http://www.cameco.com/role/PensionAndOtherPostretirementBenefitsComponentsOfNetPensionAndOtherBenefitExpenseDetails
1188	Disclosure of net defined benefit liability (asset) [table]	Table	*	*	ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetTable
1189	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
1190	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
1191	Pension plans [member]	Member			ifrs-full:PensionDefinedBenefitPlansMember
1192	Other Benefit Plans [Member]	Member			ccj:OtherBenefitPlansMember
1193	Disclosure of benefit plans [line items]	LineItems			ifrs-full:DisclosureOfDefinedBenefitPlansLineItems
1194	Current service cost	Concept (Monetary)	For Period	Credit	ifrs-full:CurrentServiceCostNetDefinedBenefitLiabilityAsset
1195	Interest income or cost	Concept (Monetary)	For Period	Credit	ifrs-full:InterestExpenseIncomeNetDefinedBenefitLiabilityAsset
1196	Past service cost	Concept (Monetary)	For Period	Credit	ifrs-full:PastServiceCostNetDefinedBenefitLiabilityAsset
1197	Administration cost	Concept (Monetary)	For Period	Debit	ccj:AdministrativeCostsPostemploymentBenefitPlan
1198	Defined benefit expense	Concept (Monetary)	For Period	Debit	ifrs-full:PostemploymentBenefitExpenseDefinedBenefitPlans
1199	Defined contribution pension expense	Concept (Monetary)	For Period	Debit	ifrs-full:PostemploymentBenefitExpenseDefinedContributionPlans
1200	Employee benefit expense	Concept (Monetary)	For Period	Debit	ifrs-full:EmployeeBenefitsExpense
1201	Amount of actuarial losses (gains) recognized in other comprehensive income	Abstract			ifrs-full:GainLossOnRemeasurementOfNetDefinedBenefitLiabilityAssetAbstract
1202	Actuarial loss (gain)	Concept (Monetary)	For Period	Debit	ccj:GainLossRelatedActuarialChangesFromAssumptionsAndAdjustments
1203	Return on assets excluding interest income	Concept (Monetary)	For Period	Debit	ifrs-full:ReturnOnPlanAssetsNetDefinedBenefitLiabilityAsset
1204	Total actuarial losses (gains) recognized in other comprehensive income	Concept (Monetary)	For Period	Debit	ifrs-full:GainLossOnRemeasurementOfNetDefinedBenefitLiabilityAsset
1205	042504 - Disclosure - Pension and other post-retirement benefits - Assumptions and 1% change (Details)	Network	*	*	http://www.cameco.com/role/PensionAndOtherPostretirementBenefitsAssumptionsAnd1ChangeDetails
1206	Disclosure of net defined benefit liability (asset) [table]	Table	*	*	ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetTable
1207	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
1208	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
1209	Pension plans [member]	Member			ifrs-full:PensionDefinedBenefitPlansMember
1210	Other Benefit Plans [Member]	Member			ccj:OtherBenefitPlansMember
1211	Actuarial assumptions [axis]	Axis			ifrs-full:ActuarialAssumptionsAxis
1212	Actuarial assumptions [member]	Member			ifrs-full:ActuarialAssumptionsMember
1213	Discount rate [member]	Member			ifrs-full:ActuarialAssumptionOfDiscountRatesMember
1214	Rate of compensation increase [member]	Member			ifrs-full:ActuarialAssumptionOfExpectedRatesOfSalaryIncreasesMember
1215	Increase of one year in the expected lifetime [member]	Member			ifrs-full:ActuarialAssumptionOfLifeExpectancyAfterRetirementMember
1216	Disclosure of benefit plans [line items]	LineItems			ifrs-full:DisclosureOfDefinedBenefitPlansLineItems
1217	Assumptions defined benefit obligation and net pension and other benefit expense	Abstract			ccj:AssumptionsDefinedBenefitObligationNetPensionOtherBenefitExpenseAbstract
1218	Discount rate - obligation	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfDiscountRates
1219	Discount rate - expense	Concept (Percent)	As Of		ccj:ActuarialAssumptionOfDiscountRatesPriorYearObligations
1220	Rate of compensation increase	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfExpectedRatesOfSalaryIncreases
1221	Initial health care cost trend rate	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfMedicalCostTrendRates
1222	Cost trend rate declines to	Concept (Percent)	As Of		ccj:ActuarialAssumptionOfDecliningMedicalCostTrendRate
1223	Year the rate reaches its final level	Concept (Year)	For Period		ccj:ActuarialAssumptionOfYearRateReachesFinalLevel
1224	Dental care cost trend rate	Concept (Percent)	As Of		ccj:ActuarialAssumptionOfDentalCostTrendRates
1225	Sensitivity analysis of actuarial assumptions	Abstract			ifrs-full:DisclosureOfSensitivityAnalysisForActuarialAssumptionsAbstract
1226	Increase in actuarial assumption by	Concept (Percent)	As Of		ifrs-full:PercentageOfReasonablyPossibleIncreaseInActuarialAssumption
1227	Increase in defined benefit obligation	Concept (Monetary)	As Of	Credit	ifrs-full:IncreaseDecreaseInDefinedBenefitObligationDueToReasonablyPossibleIncreaseInActuarialAssumption
1228	Decrease in actuarial assumption by	Concept (Percent)	As Of		ifrs-full:PercentageOfReasonablyPossibleDecreaseInActuarialAssumption
1229	Decrease in defined benefit obligation	Concept (Monetary)	As Of	Credit	ifrs-full:IncreaseDecreaseInDefinedBenefitObligationDueToReasonablyPossibleDecreaseInActuarialAssumption
1230	042505 - Disclosure - Pension and other post-retirement benefits - Narrative (Details)	Network	*	*	http://www.cameco.com/role/PensionAndOtherPostretirementBenefitsNarrativeDetails
1231	Disclosure of net defined benefit liability (asset) [table]	Table	*	*	ifrs-full:DisclosureOfNetDefinedBenefitLiabilityAssetTable
1232	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
1233	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
1234	Pension plans [member]	Member			ifrs-full:PensionDefinedBenefitPlansMember
1235	Other Benefit Plans [Member]	Member			ccj:OtherBenefitPlansMember
1236	Actuarial assumptions [axis]	Axis			ifrs-full:ActuarialAssumptionsAxis
1237	Actuarial assumptions [member]	Member			ifrs-full:ActuarialAssumptionsMember
1238	Increase of one year in the expected lifetime [member]	Member			ifrs-full:ActuarialAssumptionOfLifeExpectancyAfterRetirementMember
1239	Maturity [Axis]	Axis			ifrs-full:MaturityAxis
1240	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
1241	2019 [Member]	Member			ifrs-full:NotLaterThanOneYearMember
1242	Disclosure of benefit plans [line items]	LineItems			ifrs-full:DisclosureOfDefinedBenefitPlansLineItems
1243	Description of Retirement benefit plan	Concept (Text/String)	For Period		ifrs-full:DescriptionOfRetirementBenefitsPromisedToParticipants
1244	Description of Retirement benefits promised to participants	Concept (Text/String)	For Period		ifrs-full:DescriptionOfRetirementBenefitPlan
1245	Contributions and fees payable	Concept (Monetary)	For Period	Credit	ifrs-full:EstimateOfContributionsExpectedToBePaidToPlan
1246	Defined benefit plan assets	Concept (Monetary)	As Of	Credit	ifrs-full:LiabilityAssetOfDefinedBenefitPlans
1247	Description of the refundable tax account held by CRA	Concept (Text/String)	For Period		ccj:DescriptionOfRefundableTaxAccountHeldByCanadaRevenueAgency
1248	Change in defined benefit obligations due to increase in actuarial assumption	Concept (Monetary)	As Of	Credit	ifrs-full:IncreaseDecreaseInDefinedBenefitObligationDueToReasonablyPossibleIncreaseInActuarialAssumption
1249	Weighted Average Length Of Time Of Defined Benefit Obligation	Concept (xbrli:durationItemType)	For Period		ccj:WeightedAverageLengthOfTimeOfDefinedBenefitObligation
1250	042601 - Disclosure - Financial instruments - related risk management (Details)	Network	*	*	http://www.cameco.com/role/FinancialInstrumentsRelatedRiskManagementDetails
1251	Disclosure of detailed information about hedging instruments [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutHedgingInstrumentsTable
1252	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
1253	Risks [member]	Member			ifrs-full:TypesOfRisksMember
1254	Currency risk [member]	Member			ifrs-full:CurrencyRiskMember
1255	Interest rate risk [member]	Member			ifrs-full:InterestRateRiskMember
1256	Credit risk [member]	Member			ifrs-full:CreditRiskMember
1257	Hedging instruments [axis]	Axis			ifrs-full:ClassesOfFinancialInstrumentsAxis
1258	Financial instruments, class [member]	Member			ifrs-full:ClassesOfFinancialInstrumentsMember
1259	Cash and cash equivalents [member]	Member			ccj:CashAndCashEquivalentsMember
1260	Accounts receivable [Member]	Member			ifrs-full:TradeReceivablesMember
1261	Long-term receivables, investments and other [Member]	Member			ccj:LongTermReceivablesInvestmentsOtherMember
1262	Accounts Payable and Accrued Liabilities [Member]	Member			ccj:AccountsPayableAndAccruedLiabilitiesMember
1263	Net foreign currency derivatives [Member]	Member			ccj:NetForeignCurrencyDerivativesMember
1264	Interest rate contracts [member]	Member			ifrs-full:InterestRateSwapContractMember
1265	Advances receivable from Inkai [Member]	Member			ccj:AdvancesReceivableFromInkaiMember
1266	Currency [Axis]	Axis			srt:CurrencyAxis
1267	All currencies [Domain]	Member			currency:AllCurrenciesDomain
1268	USD [Member]	Member			currency:USD
1269	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
1270	Financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
1271	Financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilities
1272	Gain (loss), foreign exchange	Concept (Monetary)	For Period	Credit	ccj:ForeignExchagneGainLossOnFinancialInstruments
1273	Gain (loss) on derivatives	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnChangeInFairValueOfDerivatives
1274	Finance income	Concept (Monetary)	For Period	Credit	ifrs-full:FinanceIncome
1275	Percentage increase or decrease in CAD$	Concept (Percent)	For Period		ccj:PercentageIncreaseDecreaseCurrencyRate
1276	Percentage increase or decrease in the interest rate	Concept (Percent)	For Period		ccj:PercentageIncreaseDecreaseInterestRate
1277	Disclosure of credit risk exposure [abstract]	Abstract			ifrs-full:DisclosureOfCreditRiskExposureAbstract
1278	Cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
1279	Short-term investments	Concept (Monetary)	As Of	Debit	ifrs-full:ShorttermDepositsNotClassifiedAsCashEquivalents
1280	Accounts receivable	Concept (Monetary)	As Of	Debit	ifrs-full:TradeReceivables
1281	Advances receivable from JV Inkai LLP	Concept (Monetary)	As Of	Debit	ifrs-full:AmountsReceivableRelatedPartyTransactions
1282	Derivative assets	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
1283	Other	Concept (Monetary)	As Of	Debit	ifrs-full:OtherFinancialAssets
1284	042602 - Disclosure - Financial Instruments - Exposure to credit risk receivables (Details)	Network	*	*	http://www.cameco.com/role/FinancialInstrumentsExposureToCreditRiskReceivablesDetails
1285	Disclosure of credit risk exposure [table]	Table	*	*	ifrs-full:DisclosureOfCreditRiskExposureTable
1286	External credit grades [Axis]	Axis			ifrs-full:ExternalCreditGradesAxis
1287	Entity's total for external credit grades [Member]	Member			ifrs-full:EntitysTotalForExternalCreditGradesMember
1288	Investment grade rating [Member]	Member			ccj:InvestmentGradeRatingMember
1289	Non-investment grade rating [Member]	Member			ccj:NonInvestmentGradeRatingMember
1290	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
1291	Trade receivables	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentTradeReceivables
1292	Loss allowance	Concept (Monetary)	As Of	Credit	ifrs-full:AllowanceAccountForCreditLossesOfFinancialAssets
1293	Net	Concept (Monetary)	As Of	Debit	ccj:Nettradereceivables
1294	042603 - Disclosure - Financial Instruments - Aging of trade receivables (Details)	Network	*	*	http://www.cameco.com/role/FinancialInstrumentsAgingOfTradeReceivablesDetails
1295	Disclosure of financial assets that are either past due or impaired [Table]	Table	*	*	ifrs-full:DisclosureOfFinancialAssetsThatAreEitherPastDueOrImpairedTable
1296	Past due status [Axis]	Axis			ifrs-full:PastDueStatusAxis
1297	Past due status [Member]	Member			ifrs-full:PastDueStatusMember
1298	Current (not past due)	Member			ifrs-full:CurrentMember
1299	1-30 days past due	Member			ccj:LaterThanOneDayAndNotLaterThanThirtyDaysMember
1300	More than 30 days past due	Member			ccj:LaterThanOneMonthMember
1301	Type of customer axis [Axis]	Axis			ccj:TypeOfCustomerAxis
1302	Type of customer [Member]	Member			ccj:TypeOfCustomerMember
1303	Corporate customers [Member]	Member			ccj:CorporateCustomersMember
1304	Other customers [Member]	Member			ccj:OtherCustomersMember
1305	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
1306	Trade receivables	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentTradeReceivables
1307	042604 - Disclosure - Financial instruments - Liquidity Risk Tables (Details)	Network	*	*	http://www.cameco.com/role/FinancialInstrumentsLiquidityRiskTablesDetails
1308	Disclosure of detailed information about borrowings [table]	Table	*	*	ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsTable
1309	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
1310	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
1311	Unsecured revolving credit facility [Member]	Member			ccj:UnsecuredRevolvingCreditFacilityMember
1312	Letter of credit facilities [Member]	Member			ccj:LetterOfCreditFacilitiesMember
1313	NUKEM multicurrency revolving loan facility [Member]	Member			ccj:NukemMulticurrencyRevolvingLoanFacilityMember
1314	Classes of financial liabilities [axis]	Axis			ifrs-full:ClassesOfFinancialLiabilitiesAxis
1315	Financial Liabilities [Member]	Member			ifrs-full:FinancialLiabilitiesMember
1316	Accounts Payable and Accrued Liabilities [Member]	Member			ccj:AccountsPayableAndAccruedLiabilitiesMember
1317	Dividends Payable [Member]	Member			ccj:DividendsPayableMember
1318	Long-Term Debt [Member]	Member			ccj:LongtermDebtMember
1319	Foreign currency contracts [Member]	Member			ccj:ForeignCurrencyContractsMember
1320	Other Derivative Liabilities [Member]	Member			ccj:OtherDerivativeLiabilitiesMember
1321	Maturity [Axis]	Axis			ifrs-full:MaturityAxis
1322	Aggregated time bands [member]	Member			ifrs-full:AggregatedTimeBandsMember
1323	Due in less than one year [Member]	Member			ifrs-full:LaterThanThreeMonthsAndNotLaterThanOneYearMember
1324	Due in one to three years [Member]	Member			ifrs-full:LaterThanOneYearAndNotLaterThanThreeYearsMember
1325	Due in three to five years [Member]	Member			ifrs-full:LaterThanThreeYearsAndNotLaterThanFiveYearsMember
1326	Due after five years [member]	Member			ifrs-full:LaterThanFiveYearsMember
1327	Disclosure of detailed information about borrowings [line items]	LineItems			ifrs-full:DisclosureOfDetailedInformationAboutBorrowingsLineItems
1328	Maximum borrowing capacity	Concept (Monetary)	As Of	Credit	ccj:MaximumBorrowingCapacity
1329	Committed and outstanding	Concept (Monetary)	As Of	Credit	ifrs-full:Borrowings
1330	Available borrowing facility	Concept (Monetary)	As Of	Credit	ifrs-full:UndrawnBorrowingFacilities
1331	Disclosure of maturity analysis for financial liabilities [abstract]	Abstract			ifrs-full:DisclosureOfMaturityAnalysisForNonderivativeFinancialLiabilitiesAbstract
1332	Carrying amount	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilities
1333	Contractual cash flows	Concept (Monetary)	As Of	Credit	ifrs-full:NonderivativeFinancialLiabilitiesUndiscountedCashFlows
1334	Total interest payments on long-term debt	Concept (Monetary)	As Of	Credit	ifrs-full:InterestPayable
1335	042605 - Disclosure - Financial instruments - Measurement of fair values (Details)	Network	*	*	http://www.cameco.com/role/FinancialInstrumentsMeasurementOfFairValuesDetails
1336	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
1337	Categories of financial assets [axis]	Axis			ifrs-full:CategoriesOfFinancialAssetsAxis
1338	Financial assets, category [member]	Member			ifrs-full:FinancialAssetsCategoryMember
1339	Fair value through profit or loss [member]	Member			ifrs-full:FinancialAssetsAtFairValueThroughProfitOrLossCategoryMember
1340	Financial assets at amortised cost category [Member]	Member			ifrs-full:FinancialAssetsAtAmortisedCostCategoryMember
1341	Investments in equity instruments measured at FVOCI [Member]	Member			ifrs-full:InvestmentsInEquityInstrumentsMeasuredAtFairValueThroughOtherComprehensiveIncomeMember
1342	Loans and receivables [member]	Member			ifrs-full:LoansAndReceivablesCategoryMember
1343	Available for sale [member]	Member			ifrs-full:FinancialAssetsAvailableforsaleCategoryMember
1344	Other financial assets [member]	Member			ccj:FinancialAssetsOtherCategoryMember
1345	Financial liabilities, category [axis]	Axis			ifrs-full:CategoriesOfFinancialLiabilitiesAxis
1346	Financial liabilities, category member	Member			ifrs-full:FinancialLiabilitiesCategoryMember
1347	Fair value through profit or loss [member]	Member			ifrs-full:FinancialLiabilitiesAtFairValueThroughProfitOrLossDesignatedUponInitialRecognitionCategoryMember
1348	Financial liabilities at amortised cost category [Member]	Member			ifrs-full:FinancialLiabilitiesAtAmortisedCostCategoryMember
1349	Other financial liabilities [member]	Member			ccj:FinancialliabilitiesothercategorymemberMember
1350	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
1351	Financial assets, class member	Member			ifrs-full:FinancialAssetsMember
1352	Derivatives [member]	Member			ifrs-full:DerivativesMember
1353	Foreign currency contracts [Member]	Member			ccj:ForeignCurrencyContractsMember
1354	Interest rate contracts [member]	Member			ifrs-full:InterestRateSwapContractMember
1355	Uranium contracts [Member]	Member			ccj:UraniumContractsMember
1356	Other derivative contracts [Member]	Member			ccj:OtherDerivativeContractsMember
1357	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
1358	Financial assets [Abstract]	Abstract			ifrs-full:CategoriesOfFinancialAssetsAbstract
1359	Cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
1360	Short-term investments	Concept (Monetary)	As Of	Debit	ifrs-full:ShorttermDepositsNotClassifiedAsCashEquivalents
1361	Derivative assets	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
1362	Accounts receivable	Concept (Monetary)	As Of	Debit	ifrs-full:TradeAndOtherCurrentReceivables
1363	Investments in equity securities	Concept (Monetary)	As Of	Debit	ifrs-full:FairValueOfInvestmentsInEquityInstrumentsDesignatedAsMeasuredAtFairValueThroughOtherComprehensiveIncome
1364	Advances receivable from JV Inkai LLP	Concept (Monetary)	As Of	Debit	ifrs-full:AmountsReceivableRelatedPartyTransactions
1365	Other	Concept (Monetary)	As Of	Debit	ifrs-full:OtherFinancialAssets
1366	Financial assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssets
1367	Financial liabilities [Abstract]	Abstract			ifrs-full:CategoriesOfFinancialLiabilitiesAbstract
1368	Accounts payable and accrued liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:TradeAndOtherCurrentPayables
1369	Current portion of long-term debt	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentPortionOfLongtermBorrowings
1370	Dividends payable	Concept (Monetary)	As Of	Credit	ifrs-full:DividendPayables
1371	Derivative liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
1372	Long-term debt	Concept (Monetary)	As Of	Credit	ifrs-full:LongtermBorrowings
1373	Financial liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:FinancialLiabilities
1374	Net	Concept (Monetary)	As Of	Debit	ccj:NetFinancialAssetsLiabilies
1375	042606 - Disclosure - Financial instruments - Measurement of fair values hierarchy levels (Details)	Network	*	*	http://www.cameco.com/role/FinancialInstrumentsMeasurementOfFairValuesHierarchyLevelsDetails
1376	Disclosure of fair value measurement of assets [table]	Table	*	*	ifrs-full:DisclosureOfFairValueMeasurementOfAssetsTable
1377	Levels Of Fair Value Hierarchy [Axis]	Axis			ifrs-full:LevelsOfFairValueHierarchyAxis
1378	All Levels Of Fair Value Hierarchy [member]	Member			ifrs-full:AllLevelsOfFairValueHierarchyMember
1379	Level 1 of fair value hierarchy [member]	Member			ifrs-full:Level1OfFairValueHierarchyMember
1380	Level 2 of fair value hierarchy [member]	Member			ifrs-full:Level2OfFairValueHierarchyMember
1381	Fair value [member]	Member			ifrs-full:AtFairValueMember
1382	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
1383	Financial assets, class member	Member			ifrs-full:FinancialAssetsMember
1384	Derivatives [member]	Member			ifrs-full:DerivativesMember
1385	Foreign currency contracts [Member]	Member			ccj:ForeignCurrencyContractsMember
1386	Interest rate contracts [member]	Member			ifrs-full:InterestRateSwapContractMember
1387	Uranium contracts [Member]	Member			ccj:UraniumContractsMember
1388	Share purchase options [Member]	Member			ccj:SharePurchaseOptionsMember
1389	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
1390	Derivative assets	Concept (Monetary)	As Of	Debit	ifrs-full:DerivativeFinancialAssets
1391	Investments in equity securities	Concept (Monetary)	As Of	Debit	ifrs-full:FairValueOfInvestmentsInEquityInstrumentsDesignatedAsMeasuredAtFairValueThroughOtherComprehensiveIncome
1392	Current portion of long-term debt	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentPortionOfLongtermBorrowings
1393	Derivative liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:DerivativeFinancialLiabilities
1394	Long-term debt	Concept (Monetary)	As Of	Credit	ifrs-full:LongtermBorrowings
1395	Net financial instruments	Concept (Monetary)	As Of	Credit	ccj:NetFinancialInstruments
1396	042607 - Disclosure - Financial instruments - Derivatives (Details)	Network	*	*	http://www.cameco.com/role/FinancialInstrumentsDerivativesDetails
1397	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
1398	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
1399	Financial assets, class member	Member			ifrs-full:FinancialAssetsMember
1400	Derivatives [member]	Member			ifrs-full:DerivativesMember
1401	Foreign currency contracts [Member]	Member			ccj:ForeignCurrencyContractsMember
1402	Interest rate swap contracts [member]	Member			ifrs-full:InterestRateSwapContractMember
1403	Uranium contracts [Member]	Member			ccj:UraniumContractsMember
1404	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
1405	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
1406	Current portion of long-term receivables, investments and other [member]	Member			ccj:CurrentPortionOfLongtermReceivablesInvestmentsAndOtherMember
1407	Long-term receivables, investments and other [Member]	Member			ccj:LongTermReceivablesInvestmentsAndOtherMember
1408	Classes of liabilities [axis]	Axis			ifrs-full:ClassesOfLiabilitiesAxis
1409	Liabilities [member]	Member			ifrs-full:LiabilitiesMember
1410	Current portion of other liabilities [member]	Member			ccj:CurrentPortionOfOtherLiabilitiesMember
1411	Other liabilities [Member]	Member			ccj:OtherLiabilitiesMember
1412	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
1413	Net	Concept (Monetary)	For Period	Debit	ccj:FairValueOfNonhedgeDerivatives
1414	Gain (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnChangeInFairValueOfDerivatives
1415	042608 - Disclosure - Financial instruments - Narrative (Details)	Network	*	*	http://www.cameco.com/role/FinancialInstrumentsNarrativeDetails
1416	Disclosure of detailed information about financial instruments [table]	Table	*	*	ifrs-full:DisclosureOfFinancialInstrumentsTable
1417	Types of risks [axis]	Axis			ifrs-full:TypesOfRisksAxis
1418	Risks [member]	Member			ifrs-full:TypesOfRisksMember
1419	Currency risk [member]	Member			ifrs-full:CurrencyRiskMember
1420	Credit risk [member]	Member			ifrs-full:CreditRiskMember
1421	Interest rate risk [member]	Member			ifrs-full:InterestRateRiskMember
1422	Commodity price risk [member]	Member			ifrs-full:CommodityPriceRiskMember
1423	Classes of financial assets [axis]	Axis			ifrs-full:ClassesOfFinancialAssetsAxis
1424	Financial assets, class member	Member			ifrs-full:FinancialAssetsMember
1425	Derivatives [member]	Member			ifrs-full:DerivativesMember
1426	Interest rate swap contracts [member]	Member			ifrs-full:InterestRateSwapContractMember
1427	Range [axis]	Axis			ifrs-full:RangeAxis
1428	Ranges [member]	Member			ifrs-full:RangesMember
1429	Bottom of range [member]	Member			ifrs-full:BottomOfRangeMember
1430	Top of range [member]	Member			ifrs-full:TopOfRangeMember
1431	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
1432	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
1433	Series D senior unsecured debenture [member]	Member			ccj:SeriesDSeniorUnsecuredDebentureMember
1434	Series E senior unsecured debenture [Member]	Member			ccj:SeriesESeniorUnsecuredDebentureMember
1435	Types of interest rates [Axis]	Axis			ifrs-full:TypesOfInterestRatesAxis
1436	Interest rate types [member]	Member			ifrs-full:InterestRateTypesMember
1437	Floating interest rate [member]	Member			ifrs-full:FloatingInterestRateMember
1438	Fixed interest rate [member]	Member			ifrs-full:FixedInterestRateMember
1439	Disclosure of detailed information about financial instruments [line items]	LineItems			ifrs-full:DisclosureOfFinancialInstrumentsLineItems
1440	Percentage increase (decrease) in commodity price	Concept (Percent)	For Period		ccj:PercentageIncreaseDecreaseInCommodityPrices
1441	Gain (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnChangeInFairValueOfDerivatives
1442	Proportion of outstanding debt that carries fixed rate	Concept (Percent)	For Period		ccj:ProportionOfOutstandingDebtWithFixedRate
1443	Notional amount	Concept (Monetary)	As Of		ifrs-full:NotionalAmount
1444	Interest rate basis	Concept (Text/String)	For Period		ifrs-full:BorrowingsInterestRateBasis
1445	Margin rate	Concept (Percent)	As Of		ifrs-full:BorrowingsAdjustmentToInterestRateBasis
1446	Interest rate	Concept (Percent)	As Of		ifrs-full:BorrowingsInterestRate
1447	Fair value of Cameco's interest rate swap assets	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsAtFairValue
1448	Cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
1449	Short-term investments	Concept (Monetary)	As Of	Debit	ifrs-full:ShorttermDepositsNotClassifiedAsCashEquivalents
1450	Amount of receivables sold	Concept (Monetary)	For Period	Debit	ccj:DerecognisedAccountsReceivable
1451	Pledged cash as security	Concept (Monetary)	As Of	Debit	ifrs-full:FinancialAssetsPledgedAsCollateralForLiabilitiesOrContingentLiabilities
1452	Quoted market yields	Concept (Percent)	For Period		ccj:QuotedMarktYields
1453	042701 - Disclosure - Capital management (Details)	Network	*	*	http://www.cameco.com/role/CapitalManagementDetails
1454	Implied Table	Table	*	*	implied:Table
1455	Disclosure of objectives policies and processes for managing capital abstract	Abstract			ifrs-full:DisclosureOfObjectivesPoliciesAndProcessesForManagingCapitalAbstract
1456	Current portion of long-term debt	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentPortionOfLongtermBorrowings
1457	Long-term debt	Concept (Monetary)	As Of	Credit	ifrs-full:LongtermBorrowings
1458	Cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
1459	Short-term investments	Concept (Monetary)	As Of	Debit	ifrs-full:ShorttermDepositsNotClassifiedAsCashEquivalents
1460	Net debt	Concept (Monetary)	As Of	Credit	ccj:LongtermBorrowingsNetOfCashAndCashEquivalent
1461	Non-controlling interest	Concept (Monetary)	As Of	Credit	ifrs-full:NoncontrollingInterests
1462	Shareholders' equity	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAttributableToOwnersOfParent
1463	Total shareholders' equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
1464	Total capital	Concept (Monetary)	As Of	Credit	ccj:NetDebtAndEquity
1465	042801 - Disclosure - Segmented information - Narrative (Details)	Network	*	*	http://www.cameco.com/role/SegmentedInformationNarrativeDetails
1466	Implied Table	Table	*	*	implied:Table
1467	Disclosure Of Operating Segments [Abstract]	Abstract			ifrs-full:DisclosureOfOperatingSegmentsAbstract
1468	Segment information	Concept (Text/String)	For Period		ifrs-full:FactorsUsedToIdentifyEntitysReportableSegments
1469	Care and maintenance	Concept (Monetary)	For Period	Debit	ccj:CareAndMaintenanceCosts
1470	Severance costs	Concept (Monetary)	For Period	Debit	ccj:SeveranceCosts
1471	042802 - Disclosure - Segmented information - Business segments (Details)	Network	*	*	http://www.cameco.com/role/SegmentedInformationBusinessSegmentsDetails
1472	Disclosure of operating segments [table]	Table	*	*	ifrs-full:DisclosureOfOperatingSegmentsTable
1473	Segments [axis]	Axis			ifrs-full:SegmentsAxis
1474	Segments [member]	Member			ifrs-full:SegmentsMember
1475	Uranium [Member]	Member			ccj:UraniumMember
1476	Fuel Service [Member]	Member			ccj:FuelServiceMember
1477	Other Segment [Member]	Member			ccj:OtherSegmentMember
1478	NUKEM [Member]	Member			ccj:NukemMember
1479	Disclosure Of Operating Segments [Line Items]	LineItems			ifrs-full:DisclosureOfOperatingSegmentsLineItems
1480	Revenue	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
1481	Cost of products and services sold	Concept (Monetary)	For Period	Debit	ccj:Costofgoodssoldexcludingdepreciationdepletionandamortization
1482	Depreciation and amortization	Concept (Monetary)	For Period	Debit	ifrs-full:DepreciationAndAmortisationExpense
1483	Cost of sales	Concept (Monetary)	For Period	Debit	ifrs-full:CostOfSales
1484	Gross profit	Concept (Monetary)	For Period	Credit	ifrs-full:GrossProfit
1485	Administration	Concept (Monetary)	For Period	Debit	ifrs-full:AdministrativeExpense
1486	Impairment charges	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossPropertyPlantAndEquipment
1487	Exploration	Concept (Monetary)	For Period	Debit	ifrs-full:ExpenseArisingFromExplorationForAndEvaluationOfMineralResources
1488	Research and development	Concept (Monetary)	For Period	Debit	ifrs-full:ResearchAndDevelopmentExpense
1489	Other operating expense	Concept (Monetary)	For Period	Credit	ifrs-full:OtherOperatingIncomeExpense
1490	Loss on disposal of assets	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnDisposalsOfPropertyPlantAndEquipment
1491	Finance costs	Concept (Monetary)	For Period	Debit	ifrs-full:FinanceCosts
1492	Gain on derivatives	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnChangeInFairValueOfDerivatives
1493	Finance income	Concept (Monetary)	For Period	Credit	ifrs-full:FinanceIncome
1494	Share of earnings from equity-accounted investee	Concept (Monetary)	For Period	Credit	ifrs-full:ShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
1495	Other income	Concept (Monetary)	For Period	Credit	ifrs-full:OtherIncome
1496	Earnings (loss) before income taxes	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
1497	Income tax recovery	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
1498	Net earnings (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
1499	Capital expenditures for the year	Concept (Monetary)	For Period	Credit	ccj:CapitalExpenditures
1500	042803 - Disclosure - Segmented information - Geographical segment (Details)	Network	*	*	http://www.cameco.com/role/SegmentedInformationGeographicalSegmentDetails
1501	Disclosure of geographical areas [table]	Table	*	*	ifrs-full:DisclosureOfGeographicalAreasTable
1502	Geographical areas [axis]	Axis			ifrs-full:GeographicalAreasAxis
1503	Geographical areas [member]	Member			ifrs-full:GeographicalAreasMember
1504	Canada [member]	Member			country:CA
1505	Australia [Member]	Member			country:AU
1506	United States [Member]	Member			country:US
1507	Kazakhstan [Member]	Member			country:KZ
1508	Germany [Member]	Member			country:DE
1509	Switzerland [Member]	Member			country:CH
1510	Disclosure of geographical areas [line items]	LineItems			ifrs-full:DisclosureOfGeographicalAreasLineItems
1511	Revenue	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
1512	Non-current assets, excluding deferred tax assets and financial instruments	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssetsOtherThanFinancialInstrumentsDeferredTaxAssetsPostemploymentBenefitAssetsAndRightsArisingUnderInsuranceContracts
1513	042804 - Disclosure - Segmented information - Major customers (Details)	Network	*	*	http://www.cameco.com/role/SegmentedInformationMajorCustomersDetails
1514	Disclosure of major customers [table]	Table	*	*	ifrs-full:DisclosureOfMajorCustomersTable
1515	Major customers [axis]	Axis			ifrs-full:MajorCustomersAxis
1516	Major Customers [member]	Member			ifrs-full:MajorCustomersMember
1517	One customer of Cameco's uranium and fuel services segments [member]	Member			ccj:OneMajorCustomerOfCamecoAllSegmentsMember
1518	Disclosure of major customers [line items]	LineItems			ifrs-full:DisclosureOfMajorCustomersLineItems
1519	Revenue	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
1520	Percentage of entity's revenue	Concept (Percent)	For Period		ifrs-full:PercentageOfEntitysRevenue
1521	Information about major customers	Concept (Text/String)	For Period		ifrs-full:InformationAboutMajorCustomers
1522	042901 - Disclosure - Group entities (Details)	Network	*	*	http://www.cameco.com/role/GroupEntitiesDetails
1523	Disclosure of subsidiaries [table]	Table	*	*	ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesTable
1524	Subsidiaries [axis]	Axis			ifrs-full:SignificantInvestmentsInSubsidiariesAxis
1525	Entity's total for subsidiaries [member]	Member			ifrs-full:EntitysTotalForSubsidiariesMember
1526	Cameco Fuel Manufacturing Inc. [member]	Member			ccj:CamecoFuelManufacturingIncMember
1527	Cameco Marketing Inc. [member]	Member			ccj:CamecoMarketingIncMember
1528	Cameco Inc. [member]	Member			ccj:CamecoIncMember
1529	Power Resources, Inc. [member]	Member			ccj:PowerResourcesIncMember
1530	Crow Butte Resources, Inc. [member]	Member			ccj:CrowButteResourcesIncMember
1531	NUKEM, Inc. [member]	Member			ccj:NukemIncMember
1532	NUKEM Investments GmbH [member]	Member			ccj:NukemInvestmentsGmbhMember
1533	Cameco Australia Pty. Ltd. [member]	Member			ccj:CamecoAustraliaPtyLtdMember
1534	Cameco Europe Ltd. [member]	Member			ccj:CamecoEuropeLtdMember
1535	Associates [Axis]	Axis			ifrs-full:SignificantInvestmentsInAssociatesAxis
1536	Entity's total for associates [Member]	Member			ifrs-full:EntitysTotalForAssociatesMember
1537	GE-Hitachi Global Laser Enrichment LLC [Member]	Member			ccj:GEHitachiGlobalLaserEnrichmentLLCMember
1538	JV Inkai Associate [Member]	Member			ccj:JvInkaiAssociateMember
1539	Disclosure of subsidiaries [line items]	LineItems			ifrs-full:DisclosureOfSignificantInvestmentsInSubsidiariesLineItems
1540	Ownership interest in subsidiaries	Concept (Percent)	For Period		ifrs-full:ProportionOfOwnershipInterestInSubsidiary
1541	Ownership interest in associates	Concept (Percent)	For Period		ifrs-full:ProportionOfOwnershipInterestInAssociate
1542	Principal place of business of subsidiary	Concept (Text/String)	For Period		ifrs-full:PrincipalPlaceOfBusinessOfSubsidiary
1543	Principal place of business of associate	Concept (Text/String)	For Period		ifrs-full:PrincipalPlaceOfBusinessOfAssociate
1544	043001 - Disclosure - Joint operations (Details)	Network	*	*	http://www.cameco.com/role/JointOperationsDetails
1545	Disclosure of joint operations [table]	Table	*	*	ifrs-full:DisclosureOfJointOperationsTable
1546	Joint operations [axis]	Axis			ifrs-full:JointOperationsAxis
1547	Entity's total for joint operations [member]	Member			ifrs-full:EntitysTotalForJointOperationsMember
1548	Joint operations [member]	Member			ifrs-full:JointOperationsMember
1549	McArthur River [Member]	Member			ccj:McarthurRiverMember
1550	Key Lake [Member]	Member			ccj:KeyLakeMember
1551	Cigar Lake [Member]	Member			ccj:CigarLakeMember
1552	Inkai [Member]	Member			ccj:InkaiMember
1553	Disclosure of joint operations [line items]	LineItems			ifrs-full:DisclosureOfJointOperationsLineItems
1554	Ownership	Concept (Percent)	For Period		ifrs-full:ProportionOfOwnershipInterestInJointOperation
1555	Principal place of business	Concept (Text/String)	For Period		ifrs-full:PrincipalPlaceOfBusinessOfJointOperation
1556	Total assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
1557	Total liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:Liabilities
1558	Percentage of interest in advances receivable	Concept (Percent)	For Period		ccj:PercentageOfInterestInAdvancesReceivable
1559	043101 - Disclosure - Related parties (Details)	Network	*	*	http://www.cameco.com/role/RelatedPartiesDetails
1560	Disclosure of transactions between related parties [table]	Table	*	*	ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesTable
1561	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
1562	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
1563	Cameco [member]	Member			ifrs-full:ParentMember
1564	Key management personnel of entity or parent [member]	Member			ifrs-full:KeyManagementPersonnelOfEntityOrParentMember
1565	Inkai [Member]	Member			ccj:InkaiMember
1566	Key management personnel resident [member]	Member			ccj:KeyManagementPersonnelOfEntityOrParentResidentMember
1567	Key management personnel non-resident [member]	Member			ccj:KeyManagementPersonnelOfEntityOrParentNonResidentMember
1568	Disclosure of transactions between related parties [line items]	LineItems			ifrs-full:DisclosureOfTransactionsBetweenRelatedPartiesLineItems
1569	Short-term employee benefits	Concept (Monetary)	For Period	Debit	ifrs-full:KeyManagementPersonnelCompensationShorttermEmployeeBenefits
1570	Share-based compensation	Concept (Monetary)	For Period	Debit	ifrs-full:KeyManagementPersonnelCompensationSharebasedPayment
1571	Post-employment benefits	Concept (Monetary)	For Period	Debit	ifrs-full:KeyManagementPersonnelCompensationPostemploymentBenefits
1572	Termination benefits	Concept (Monetary)	For Period	Debit	ifrs-full:KeyManagementPersonnelCompensationTerminationBenefits
1573	Total compensation	Concept (Monetary)	For Period	Debit	ifrs-full:KeyManagementPersonnelCompensation
1574	Loan facilities	Concept (Monetary)	As Of	Credit	ifrs-full:UndrawnBorrowingFacilities
1575	Interest rate basis	Concept (Text/String)	For Period		ifrs-full:BorrowingsInterestRateBasis
1576	Advances receivable from JV Inkai LLP	Concept (Monetary)	As Of	Debit	ifrs-full:AmountsReceivableRelatedPartyTransactions
1577	Percentage of related party amounts receivable	Concept (Percent)	As Of		ccj:PercentageOfRelatedPartyAmountsReceivable
1578	Interest income	Concept (Monetary)	For Period	Credit	ifrs-full:InterestIncomeOnLoansAndReceivables
1579	Description of any retirement benefit plan termination terms	Concept (Text/String)	For Period		ifrs-full:DescriptionOfAnyRetirementBenefitPlanTerminationTerms
1580	Loan oustanding	Concept (Monetary)	As Of	Credit	ifrs-full:Borrowings
1581	Purchases	Concept (Monetary)	For Period	Debit	ifrs-full:PurchasesOfGoodsRelatedPartyTransactions