| Standard label: | Insured Financial Obligations with Credit Deterioration, Remaining Weighted Average Contract Period |
| Name: | us-gaap:InsuredFinancialObligationsWithCreditDeteriorationRemainingWeightedAverageContractPeriod |
| Documentation: | Remaining weighted average contract period of financial guarantee insurance contracts, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. |
| Object type: | cm:Concept |
| Data type: | xbrli:durationItemType |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:InsuredFinancialObligationsWithCreditDeteriorationRemainingWeightedAverageContractPeriod |
| Label | Role | Language |
| Insured Financial Obligations with Credit Deterioration, Remaining Weighted Average Contract Period | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 944 40 50 9 (a)(5)(ii) | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |
| FASB Accounting Standards Codification 944 40 55 32 | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |