| Name | ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability |
|---|---|
| Namespace | http://fasb.org/us-gaap/2020-01-31 |
| Prefix | us-gaap |
| Data type | xbrli:monetaryItemType |
| Period type | instant |
| Substitution Group | xbrli:item |
| Balance | credit |
| Nillable | True |
| Abstract | False |
| Text | Lang | Role | Container role |
|---|---|---|---|
| This element represents the net claim liability related to financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. | en-US | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |
| Schedule of Insured Financial Obligations with Credit Deterioration, Net Claim Liability | en-US | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Schedule of Insured Financial Obligations with Credit Deterioration, Net Claim Liability, Total | en-US | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |
| Name | Value | Role |
|---|---|---|
| Publisher | FASB | http://fasb.org/us-gaap/role/ref/legacyRef |
| Name | Accounting Standards Codification | http://fasb.org/us-gaap/role/ref/legacyRef |
| Topic | 944 | http://fasb.org/us-gaap/role/ref/legacyRef |
| SubTopic | 40 | http://fasb.org/us-gaap/role/ref/legacyRef |
| Section | 50 | http://fasb.org/us-gaap/role/ref/legacyRef |
| Paragraph | 9 | http://fasb.org/us-gaap/role/ref/legacyRef |
| Subparagraph | (a)(5)(vii) | http://fasb.org/us-gaap/role/ref/legacyRef |
| URI | http://asc.fasb.org/extlink&oid=99382878&loc=SL5749324-161292 | http://fasb.org/us-gaap/role/ref/legacyRef |
| Publisher | FASB | http://fasb.org/us-gaap/role/ref/legacyRef |
| Name | Accounting Standards Codification | http://fasb.org/us-gaap/role/ref/legacyRef |
| Topic | 944 | http://fasb.org/us-gaap/role/ref/legacyRef |
| SubTopic | 40 | http://fasb.org/us-gaap/role/ref/legacyRef |
| Section | 55 | http://fasb.org/us-gaap/role/ref/legacyRef |
| Paragraph | 32 | http://fasb.org/us-gaap/role/ref/legacyRef |
| URI | http://asc.fasb.org/extlink&oid=99379334&loc=SL5751133-161288 | http://fasb.org/us-gaap/role/ref/legacyRef |