Financial Guaranty Insurance Premiums - Selected Information for Policies Paid in Installments (Details) - Policies Paid in Installments [Member] - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Financial Guarantee Insurance Premiums [Line Items]
Premiums receivable, net of commission payable	$ 702	$ 729
Gross deferred premium revenue	$ 1,302	$ 1,370
Weighted-average risk-free rate used to discount premiums	3.40%	3.50%
Weighted-average period of premiums receivable (in years)	9 years 4 months 24 days	9 years 4 months 24 days