| Standard label: | Certain Loans Acquired in Transfer Accounted for as Debt Securities, Other-than-Temporary Impairment Charges, Credit Loss |
| Name: | us-gaap:CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesOtherthanTemporaryImpairmentChargesCreditLoss |
| Documentation: | Amount of expense to write-down the amortized cost basis of loans, after acquisition, to fair value when the decline in the fair value is determined to be other than temporary (OTTI) for loans accounted for as debt securities. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | For Period (duration) |
| Balance type: | Debit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesOtherthanTemporaryImpairmentChargesCreditLoss |
| Label | Role | Language |
| Certain Loans Acquired in Transfer Accounted for as Debt Securities, Other-than-Temporary Impairment Charges, Credit Loss | http://www.xbrl.org/2003/role/label | en-US |
| Certain Loans Acquired in Transfer Accounted for as Debt Securities, Other-than-Temporary Impairment Charges, Credit Loss, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 310 30 35 8 (a) | http://fasb.org/us-gaap/role/ref/legacyRef | 310 |
| FASB Accounting Standards Codification 320 10 35 34D | http://fasb.org/us-gaap/role/ref/legacyRef | 320 |