Outstanding Exposure - Debt Service Outstanding (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	$ 646,722	$ 737,380
Net Debt Service Outstanding	609,622	690,535
Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	587,245	650,924
Net Debt Service Outstanding	553,612	610,011
Structured Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	59,477	86,456
Net Debt Service Outstanding	$ 56,010	$ 80,524