Outstanding Exposure - Debt Service Outstanding (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	$ 508,805	$ 559,470
Net Debt Service Outstanding	488,362	536,341
Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	473,991	515,494
Net Debt Service Outstanding	455,056	494,426
Structured Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	34,814	43,976
Net Debt Service Outstanding	$ 33,306	$ 41,915