| Amount of premium revenue under financial guarantee insurance contract to be recognized in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). | en-US | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |
| Financial Guarantee Insurance Contract, Premium Revenue to be Recognized, Year One | en-US | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Financial Guarantee Insurance Contract, Premium Revenue to be Recognized, Year One, Total | en-US | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |