Outstanding Exposure (Details 3) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	$ 4,780	[1]
Mortgage Guaranty Insured Obligations Outstanding Principal Amount	148
Net Par Amount Outstanding	552,934		558,048
Greece
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	307	[1],[2]
Greece | Public finance
Financial Guaranty Portfolio
Net Par Amount Outstanding	276
Hungary
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	646	[1]
Ireland
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	383	[1]
Italy
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	2,263	[1]
Portugal
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	237	[1]
Spain
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	944	[1]
Sovereign and sub-sovereign exposure
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	2,659	[1]
Sovereign and sub-sovereign exposure | Public finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	1,620	[1]
Sovereign and sub-sovereign exposure | Infrastructure finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	1,039	[1]
Sovereign and sub-sovereign exposure | Greece
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	276	[1],[2]
Sovereign and sub-sovereign exposure | Greece | Public finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	276	[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	430	[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	430	[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	1,299	[1]
Sovereign and sub-sovereign exposure | Italy | Public finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	977	[1]
Sovereign and sub-sovereign exposure | Italy | Infrastructure finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	322	[1]
Sovereign and sub-sovereign exposure | Portugal
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	209	[1]
Sovereign and sub-sovereign exposure | Portugal | Public finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	110	[1]
Sovereign and sub-sovereign exposure | Portugal | Infrastructure finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	99	[1]
Sovereign and sub-sovereign exposure | Spain
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	422	[1]
Sovereign and sub-sovereign exposure | Spain | Public finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	257	[1]
Sovereign and sub-sovereign exposure | Spain | Infrastructure finance
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	165	[1]
Non-sovereign
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	2,121	[1]
Non-sovereign | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	234	[1]
Non-sovereign | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	837	[1]
Non-sovereign | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	78	[1]
Non-sovereign | Pooled corporate obligations
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	972	[1]
Non-sovereign | Greece
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	31	[1],[2]
Non-sovereign | Greece | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1],[2]
Non-sovereign | Greece | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1],[2]
Non-sovereign | Greece | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1],[2]
Non-sovereign | Greece | Pooled corporate obligations
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	31	[1],[2]
Non-sovereign | Hungary
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	216	[1]
Non-sovereign | Hungary | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Non-sovereign | Hungary | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	215	[1]
Non-sovereign | Hungary | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	1	[1]
Non-sovereign | Hungary | Pooled corporate obligations
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Non-sovereign | Ireland
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	360	[1]
Non-sovereign | Ireland | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Non-sovereign | Ireland | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	133	[1]
Non-sovereign | Ireland | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	19	[1]
Non-sovereign | Ireland | Pooled corporate obligations
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	208	[1]
Non-sovereign | Italy
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	964	[1]
Non-sovereign | Italy | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	222	[1]
Non-sovereign | Italy | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	489	[1]
Non-sovereign | Italy | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	26	[1]
Non-sovereign | Italy | Pooled corporate obligations
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	227	[1]
Non-sovereign | Portugal
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	28	[1]
Non-sovereign | Portugal | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Non-sovereign | Portugal | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Non-sovereign | Portugal | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	14	[1]
Non-sovereign | Portugal | Pooled corporate obligations
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	14	[1]
Non-sovereign | Spain
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	522	[1]
Non-sovereign | Spain | Regulated utilities
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	12	[1]
Non-sovereign | Spain | RMBS
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	0	[1]
Non-sovereign | Spain | Commercial receivable
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	18	[1]
Non-sovereign | Spain | Pooled corporate obligations
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	492	[1]
BIG
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	1,556	[1]
BIG | Greece
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	276	[1],[2]
BIG | Hungary
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	516	[1]
BIG | Ireland
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	8	[1]
BIG | Italy
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	238	[1]
BIG | Portugal
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	127	[1]
BIG | Spain
Financial Guaranty Portfolio
Net Economic Exposure to Selected European Countries	$ 391	[1]

[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 $133 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] As of June 30, 2012, the Company had established a full limit loss on this exposure. The Company accelerated claims under its financial guaranty on the July payment date with respect to the 2057 bonds and intends to accelerate claims on or after the September payment date with respect to the 2037 bonds.