| Standard label: | Financial Guarantee Insurance Contracts, Premium Received over Contract Period, Premium Receivable, Weighted Average Collection Period |
| Name: | us-gaap:FinancialGuaranteeInsuranceContractsPremiumReceivedOverContractPeriodPremiumReceivableWeightedAverageCollectionPeriod1 |
| Documentation: | Weighted average period over which premium receivable for financial guarantee insurance contracts is collected where premium is received over the contract period, 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:FinancialGuaranteeInsuranceContractsPremiumReceivedOverContractPeriodPremiumReceivableWeightedAverageCollectionPeriod1 |
| Label | Role | Language |
| Financial Guarantee Insurance Contracts, Premium Received over Contract Period, Premium Receivable, Weighted Average Collection Period | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 944 310 50 3 (a)(5) | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |