Consolidated Statements Of Operations (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Change in fair value of insured derivatives:
Unrealized gains (losses) on insured derivatives	$ 37	$ 838
Net change in fair value of insured derivatives	28	469
Net gains (losses) on financial instruments at fair value and foreign exchange	30	(55)
Net gains (losses) on extinguishment of debt		1
Other net realized gains (losses)	20	1
Total revenues	219	577
Expenses:
Losses and loss adjustment	(6)	50
Interest	50	54
Total expenses	106	173
Income (loss) before income taxes	113	404
Provision (benefit) for income taxes	44	148
Net income (loss)	69	256
Net income (loss) per common share:
Net income (loss) per basic common share	$ 0.37	$ 1.33
Net income (loss) per diluted common share	$ 0.37	$ 1.32
Weighted average number of common shares outstanding:
Basic	181,735,876	189,033,982
Diluted	182,736,415	190,263,748
Non Variable Interest Entity [Member]
Premiums earned:
Scheduled premiums earned	55	69
Refunding premiums earned	46	19
Premiums earned (net of ceded premiums of $4 and $2)	101	88
Net investment income	37	50
Fees and reimbursements	1	4
Change in fair value of insured derivatives:
Realized gains (losses) and other settlements on insured derivatives	(9)	(369)
Unrealized gains (losses) on insured derivatives	37	838
Net change in fair value of insured derivatives	28	469
Net gains (losses) on financial instruments at fair value and foreign exchange	30	(55)
Net gains (losses) on extinguishment of debt	0	1
Other net realized gains (losses)	20	1
Expenses:
Losses and loss adjustment	(6)	50
Amortization of deferred acquisition costs	13	10
Operating	35	46
Interest	50	54
Variable Interest Entity Primary Beneficiary [Member]
Premiums earned:
Net investment income	12	12
Change in fair value of insured derivatives:
Net gains (losses) on financial instruments at fair value and foreign exchange	(10)	3
Net gains (losses) on extinguishment of debt	0	4
Expenses:
Operating	4	3
Interest	$ 10	$ 10