Outstanding Exposure - Net Direct Economic Exposure to Selected European Countries (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014
Financial guarantee obligations
Net economic exposure to selected european countries	$ 2,473	[1]
Hungary
Financial guarantee obligations
Net economic exposure to selected european countries	524	[1]
Italy
Financial guarantee obligations
Net economic exposure to selected european countries	1,453	[1]
Portugal
Financial guarantee obligations
Net economic exposure to selected european countries	106	[1]
Spain
Financial guarantee obligations
Net economic exposure to selected european countries	390	[1]
Sovereign and sub-sovereign exposure
Financial guarantee obligations
Net economic exposure to selected european countries	1,767	[1]
Sovereign and sub-sovereign exposure | Non-infrastructure public finance
Financial guarantee obligations
Net economic exposure to selected european countries	1,274	[1],[2]
Sovereign and sub-sovereign exposure | Infrastructure finance
Financial guarantee obligations
Net economic exposure to selected european countries	493	[1]
Sovereign and sub-sovereign exposure | Hungary
Financial guarantee obligations
Net economic exposure to selected european countries	327	[1]
Sovereign and sub-sovereign exposure | Hungary | Non-infrastructure public finance
Financial guarantee obligations
Net economic exposure to selected european countries	0	[1],[2]
Sovereign and sub-sovereign exposure | Hungary | Infrastructure finance
Financial guarantee obligations
Net economic exposure to selected european countries	327	[1]
Sovereign and sub-sovereign exposure | Italy
Financial guarantee obligations
Net economic exposure to selected european countries	944	[1]
Sovereign and sub-sovereign exposure | Italy | Non-infrastructure public finance
Financial guarantee obligations
Net economic exposure to selected european countries	929	[1],[2]
Sovereign and sub-sovereign exposure | Italy | Infrastructure finance
Financial guarantee obligations
Net economic exposure to selected european countries	15	[1]
Sovereign and sub-sovereign exposure | Portugal
Financial guarantee obligations
Net economic exposure to selected european countries	106	[1]
Sovereign and sub-sovereign exposure | Portugal | Non-infrastructure public finance
Financial guarantee obligations
Net economic exposure to selected european countries	95	[1],[2]
Sovereign and sub-sovereign exposure | Portugal | Infrastructure finance
Financial guarantee obligations
Net economic exposure to selected european countries	11	[1]
Sovereign and sub-sovereign exposure | Spain
Financial guarantee obligations
Net economic exposure to selected european countries	390	[1]
Sovereign and sub-sovereign exposure | Spain | Non-infrastructure public finance
Financial guarantee obligations
Net economic exposure to selected european countries	250	[1],[2]
Sovereign and sub-sovereign exposure | Spain | Infrastructure finance
Financial guarantee obligations
Net economic exposure to selected european countries	140	[1]
Non-sovereign exposure
Financial guarantee obligations
Net economic exposure to selected european countries	706	[1]
Non-sovereign exposure | Regulated utilities
Financial guarantee obligations
Net economic exposure to selected european countries	229	[1]
Non-sovereign exposure | RMBS
Financial guarantee obligations
Net economic exposure to selected european countries	477	[1]
Non-sovereign exposure | Hungary
Financial guarantee obligations
Net economic exposure to selected european countries	197	[1]
Non-sovereign exposure | Hungary | Regulated utilities
Financial guarantee obligations
Net economic exposure to selected european countries	0	[1]
Non-sovereign exposure | Hungary | RMBS
Financial guarantee obligations
Net economic exposure to selected european countries	197	[1]
Non-sovereign exposure | Italy
Financial guarantee obligations
Net economic exposure to selected european countries	509	[1]
Non-sovereign exposure | Italy | Regulated utilities
Financial guarantee obligations
Net economic exposure to selected european countries	229	[1]
Non-sovereign exposure | Italy | RMBS
Financial guarantee obligations
Net economic exposure to selected european countries	280	[1]
Non-sovereign exposure | Portugal
Financial guarantee obligations
Net economic exposure to selected european countries	0	[1]
Non-sovereign exposure | Portugal | Regulated utilities
Financial guarantee obligations
Net economic exposure to selected european countries	0	[1]
Non-sovereign exposure | Portugal | RMBS
Financial guarantee obligations
Net economic exposure to selected european countries	0	[1]
Non-sovereign exposure | Spain
Financial guarantee obligations
Net economic exposure to selected european countries	0	[1]
Non-sovereign exposure | Spain | Regulated utilities
Financial guarantee obligations
Net economic exposure to selected european countries	0	[1]
Non-sovereign exposure | Spain | RMBS
Financial guarantee obligations
Net economic exposure to selected european countries	0	[1]
Below investment grade (BIG)
Financial guarantee obligations
Net economic exposure to selected european countries	1,020	[1]
Below investment grade (BIG) | Hungary
Financial guarantee obligations
Net economic exposure to selected european countries	524	[1]
Below investment grade (BIG) | Italy
Financial guarantee obligations
Net economic exposure to selected european countries	0	[1]
Below investment grade (BIG) | Portugal
Financial guarantee obligations
Net economic exposure to selected european countries	106	[1]
Below investment grade (BIG) | Spain
Financial guarantee obligations
Net economic exposure to selected european countries	390	[1]
Europe | Pooled corporate obligations
Financial guarantee obligations
Net economic exposure to selected european countries	425
Europe | Commercial receivable
Financial guarantee obligations
Net economic exposure to selected european countries	$ 68

[1] While the Company’s exposures are shown in U.S. dollars, the obligations the Company insures are in various currencies, primarily Euros. 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] The exposure shown in the “Non-infrastructure public finance” category is from transactions backed by receivable payments from sub-sovereigns in Italy, Spain and Portugal. Sub-sovereign debt is debt issued by a governmental entity or government backed entity, or supported by such an entity, that is other than direct sovereign debt of the ultimate governing body of the country.