| Standard label: | Financial Guarantee Insurance Contracts, Premium Received over Contract Period, Unearned Premium Revenue |
| Name: | us-gaap:FinancialGuaranteeInsuranceContractsPremiumReceivedOverContractPeriodUnearnedPremiumRevenue |
| Documentation: | Amount of unearned premium revenue in the statement of financial position for financial guarantee insurance contracts where the premium is received over the contract period. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | As Of (instant) |
| Balance type: | Credit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:FinancialGuaranteeInsuranceContractsPremiumReceivedOverContractPeriodUnearnedPremiumRevenue |
| Label | Role | Language |
| Financial Guarantee Insurance Contracts, Premium Received over Contract Period, Unearned Premium Revenue | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 944 310 50 3 (a)(2) | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |