| Standard label: | Premiums Earned, Net, Financial Guarantee Insurance Contracts |
| Name: | us-gaap:PremiumsEarnedNetFinancialGuaranteeInsuranceContracts |
| Documentation: | Amount, after premiums ceded to other entities and premiums assumed by the entity, of financial guarantee premiums earned. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | For Period (duration) |
| Balance type: | Credit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:PremiumsEarnedNetFinancialGuaranteeInsuranceContracts |
| Label | Role | Language |
| Premiums Earned, Net, Financial Guarantee Insurance Contracts | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 944 20 50 3 | http://fasb.org/us-gaap/role/ref/otherTransitionRef | 944 |
| FASB Accounting Standards Codification 944 20 50 4 | http://fasb.org/us-gaap/role/ref/otherTransitionRef | 944 |
| FASB Accounting Standards Codification 944 20 50 7 | http://fasb.org/us-gaap/role/ref/otherTransitionRef | 944 |
| FASB Accounting Standards Codification 944 220 S99 1 (SX 210.7-04(1)) | http://fasb.org/us-gaap/role/ref/otherTransitionRef | 944 |
| FASB Accounting Standards Codification 944 605 50 1 (a)(2) | http://fasb.org/us-gaap/role/ref/otherTransitionRef | 944 |
| FASB Accounting Standards Codification 944 605 45 1 | http://fasb.org/us-gaap/role/ref/otherTransitionRef | 944 |
| FASB Accounting Standards Codification 944 605 50 1 (c)(3) | http://fasb.org/us-gaap/role/ref/otherTransitionRef | 944 |
| FASB Accounting Standards Codification 944 605 50 1 | http://fasb.org/us-gaap/role/ref/otherTransitionRef | 944 |