Financial Guaranty Insurance - Gross Premium Receivable Net of Commissions on Assumed Business Roll Forward (Details) - USD ($) $ in Millions	6 Months Ended				12 Months Ended
	Jun. 30, 2016		Jun. 30, 2015		Dec. 31, 2015
Gross Premium Receivable Net of Ceding Commissions [Roll Forward]
Beginning of period	$ 693		$ 729		$ 729
Premiums receivable acquired in Radian Asset Acquisition on April 1, 2015	0		2
Gross written premiums, net of commissions on assumed business	83		61
Gross premiums received, net of commissions on assumed business	(107)		(79)
Adjustments:
Changes in the expected term	(27)		(9)
Accretion of discount, net of commissions on assumed business	3		10
Foreign exchange translation	(22)		(8)
Consolidation/deconsolidation of FG VIEs	0		(4)
End of period	623	[1]	702	[1]	693
Premiums receivable, net of commissions payable	623				$ 693
Variable Interest Entity, Primary Beneficiary [Member]
Adjustments:
End of period	$ 11		23
Non-financial Guaranty Line of business [Member]
Adjustments:
Premiums receivable, net of commissions payable			$ 1
Premiums Receivable [Member] | Foreign Currency Concentration Risk [Member]
Adjustments:
Percentage of installment premiums denominated in currencies other than the U.S. dollar	55.00%		50.00%		52.00%

[1] Excludes $11 million and $23 million as of June 30, 2016 and June 30, 2015, respectively, related to consolidated FG VIEs. Excludes $1 million related to non-financial guaranty line of business as of June 30, 2015