Financial Guaranty Insurance Premiums - Selected Information for Policies Paid in Installments (Details) (USD $) In Millions, unless otherwise specified							9 Months Ended	12 Months Ended
	Sep. 30, 2014		Dec. 31, 2013	Sep. 30, 2013		Dec. 31, 2012	Sep. 30, 2014 Policies Paid in Installments	Dec. 31, 2013 Policies Paid in Installments
Financial Guaranty Insurance Premiums [Line Items]
Premiums receivable, net of commissions payable	$ 801	[1]	$ 876	$ 906	[1]	$ 1,005	$ 801	$ 876
Gross deferred premium revenue	$ 4,326		$ 4,652				$ 1,442	$ 1,576
Weighted-average risk-free rate used to discount premiums (as a percent)							3.40%	3.40%
Weighted-average period of premiums receivable (in years)							9 years 3 months 24 days	9 years 4 months 24 days

[1] Excludes $18 million and $19 million as of September 30, 2014 and September 30, 2013, respectively, related to consolidated FG VIEs.