Outstanding Exposure - Expected Amortization of Net Par Outstanding (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Estimated Net Par Amortization [Abstract]
0 to 5 years	$ 161,006
5 to 10 years	88,437
10 to 15 years	77,740
15 to 20 years	58,751
20 years and above	73,173
Net Par Outstanding (excluding loss mitigation bonds)	459,107	[1]	518,772	[1]
Public Finance
Estimated Net Par Amortization [Abstract]
0 to 5 years	104,223
5 to 10 years	81,176
10 to 15 years	74,775
15 to 20 years	56,734
20 years and above	69,271
Net Par Outstanding (excluding loss mitigation bonds)	386,179		425,469
Structured Finance
Estimated Net Par Amortization [Abstract]
0 to 5 years	56,783
5 to 10 years	7,261
10 to 15 years	2,965
15 to 20 years	2,017
20 years and above	3,902
Net Par Outstanding (excluding loss mitigation bonds)	$ 72,928		$ 93,303

[1] In the third quarter of 2013, the Company adjusted its approach to assigning internal ratings. See "Refinement of Approach to Internal Credit Ratings and Surveillance Categories" above. This approach is reflected in the "Financial Guaranty Portfolio by Internal Rating" tables as of both December 31, 2013 and December 31, 2012.