| Standard label: | Financial Guarantee Insurance Contracts, Premiums Receivable, Period Increase (Decrease) |
| Name: | us-gaap:FinancialGuaranteeInsuranceContractsPremiumsReceivablePeriodIncreaseDecrease |
| Documentation: | Amount of increase (decrease) in the premiums receivable on financial guarantee insurance contracts. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:FinancialGuaranteeInsuranceContractsPremiumsReceivablePeriodIncreaseDecrease |
| Label | Role | Language |
| Financial Guarantee Insurance Contracts, Premiums Receivable, Period Increase (Decrease) | http://www.xbrl.org/2003/role/label | en-US |
| Financial Guarantee Insurance Contracts, Premiums Receivable, Period Increase (Decrease), Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 944 310 50 3 (c) | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |