Outstanding Exposure - Debt Service Outstanding (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	$ 559,470	$ 646,722
Net Debt Service Outstanding	536,341	609,622
Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	515,494	587,245
Net Debt Service Outstanding	494,426	553,612
Structured Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	43,976	59,477
Net Debt Service Outstanding	$ 41,915	$ 56,010