Outstanding Exposure (Details 3) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	$ 4,184	[1]
Greece
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	22	[1],[2]
Hungary
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	615	[1]
Ireland
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	348	[1]
Italy
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	2,039	[1]
Portugal
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	230	[1]
Spain
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	930	[1],[2]
Sovereign and sub-sovereign exposure
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	2,115	[1]
Sovereign and sub-sovereign exposure | Public finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	1,341	[1]
Sovereign and sub-sovereign exposure | Infrastructure finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	774	[1]
Sovereign and sub-sovereign exposure | Greece
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1],[2]
Sovereign and sub-sovereign exposure | Greece | Public finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1],[2]
Sovereign and sub-sovereign exposure | Greece | Infrastructure finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1],[2]
Sovereign and sub-sovereign exposure | Hungary
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	408	[1]
Sovereign and sub-sovereign exposure | Hungary | Public finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Sovereign and sub-sovereign exposure | Hungary | Infrastructure finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	408	[1]
Sovereign and sub-sovereign exposure | Ireland
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	23	[1]
Sovereign and sub-sovereign exposure | Ireland | Public finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Sovereign and sub-sovereign exposure | Ireland | Infrastructure finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	23	[1]
Sovereign and sub-sovereign exposure | Italy
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	1,061	[1]
Sovereign and sub-sovereign exposure | Italy | Public finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	978	[1]
Sovereign and sub-sovereign exposure | Italy | Infrastructure finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	83	[1]
Sovereign and sub-sovereign exposure | Portugal
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	201	[1]
Sovereign and sub-sovereign exposure | Portugal | Public finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	105	[1]
Sovereign and sub-sovereign exposure | Portugal | Infrastructure finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	96	[1]
Sovereign and sub-sovereign exposure | Spain
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	422	[1],[2]
Sovereign and sub-sovereign exposure | Spain | Public finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	258	[1],[2]
Sovereign and sub-sovereign exposure | Spain | Infrastructure finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	164	[1],[2]
Non Sovereign Debt
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	2,069	[1]
Non Sovereign Debt | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	223	[1]
Non Sovereign Debt | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	816	[1]
Non Sovereign Debt | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	92	[1]
Non Sovereign Debt | Pooled corporate
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	938	[1]
Non Sovereign Debt | Greece
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	22	[1],[2]
Non Sovereign Debt | Greece | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1],[2]
Non Sovereign Debt | Greece | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1],[2]
Non Sovereign Debt | Greece | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1],[2]
Non Sovereign Debt | Greece | Pooled corporate
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	22	[1],[2]
Non Sovereign Debt | Hungary
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	207	[1]
Non Sovereign Debt | Hungary | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Non Sovereign Debt | Hungary | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	205	[1]
Non Sovereign Debt | Hungary | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	2	[1]
Non Sovereign Debt | Hungary | Pooled corporate
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Non Sovereign Debt | Ireland
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	325	[1]
Non Sovereign Debt | Ireland | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Non Sovereign Debt | Ireland | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	135	[1]
Non Sovereign Debt | Ireland | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	13	[1]
Non Sovereign Debt | Ireland | Pooled corporate
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	177	[1]
Non Sovereign Debt | Italy
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	978	[1]
Non Sovereign Debt | Italy | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	215	[1]
Non Sovereign Debt | Italy | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	476	[1]
Non Sovereign Debt | Italy | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	61	[1]
Non Sovereign Debt | Italy | Pooled corporate
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	226	[1]
Non Sovereign Debt | Portugal
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	29	[1]
Non Sovereign Debt | Portugal | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Non Sovereign Debt | Portugal | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Non Sovereign Debt | Portugal | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	14	[1]
Non Sovereign Debt | Portugal | Pooled corporate
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	15	[1]
Non Sovereign Debt | Spain
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	508	[1],[2]
Non Sovereign Debt | Spain | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	8	[1],[2]
Non Sovereign Debt | Spain | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1],[2]
Non Sovereign Debt | Spain | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	2	[1],[2]
Non Sovereign Debt | Spain | Pooled corporate
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	498	[1],[2]
Below investment grade (BIG)
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	1,112	[1]
Below investment grade (BIG) | Greece
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1],[2]
Below investment grade (BIG) | Hungary
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	576	[1]
Below investment grade (BIG) | Ireland
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	7	[1]
Below investment grade (BIG) | Italy
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	2	[1]
Below investment grade (BIG) | Portugal
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	121	[1]
Below investment grade (BIG) | Spain
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	$ 406	[1],[2]

[1] While the Company’s exposures are shown in U.S. dollars, the obligations the Company insures are in various currencies, including U.S. dollars, Euros and British pounds sterling. Included in the table above is $135 million of reinsurance assumed on a 2004 - 2006 pool of Irish residential mortgages that is part of the Company’s remaining legacy mortgage reinsurance business. One of the residential mortgage-backed securities included in the table above includes residential mortgages in both Italy and Germany, and only the portion of the transaction equal to the portion of the original mortgage pool in Italian mortgages is shown in the table.

[2] See Note 5, Expected Loss to be Paid.