| Amount of premium receivables under financial guarantee insurance contracts. | en-US | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |
| Financial Guarantee Insurance Contracts, Premium Receivable, Premium Expected to be Collected | en-US | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Financial Guarantee Insurance Contracts, Premium Receivable, Premium Expected to be Collected, Total | en-US | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |