Financial Guaranty Insurance Premiums (Details 2) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Financial Guaranty Insurance Premiums [Line Items]
Deferred premium revenue, gross	$ 4,793		$ 5,356
Deferred premium revenue, ceded	503		586
Deferred premium revenue, net	4,290	[1]	4,770	[1]
Unearned premium reserve	4,676		5,207
Prepaid Reinsurance Premiums	480		561
Unearned Premiums, Net	4,196	[1]	4,646	[1]
Total net unearned premium reserve related to FG VIE	197		262
Contra-paid related to FG and VIEs	64		98
Financial guaranty
Financial Guaranty Insurance Premiums [Line Items]
Deferred premium revenue, gross	4,787		5,349
Deferred premium revenue, ceded	503		586
Deferred premium revenue, net	4,284	[1]	4,763	[1]
Contra-paid, gross	(117)		(149)
Contra-paid, ceded	(23)		(25)
Contra-paid, net	(94)	[1]	(124)	[1]
Other
Financial Guaranty Insurance Premiums [Line Items]
Unearned premium reserve	6		7
Prepaid Reinsurance Premiums	0		0
Unearned Premiums, Net	$ 6	[1]	$ 7	[1]

[1] Excludes $197 million and $262 million of deferred premium revenue, and $64 million and $98 million of contra-paid related to FG VIEs as of September 30, 2013 and December 31, 2012, respectively.