Consolidated Statements Of Operations (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Change in fair value of insured derivatives:
Unrealized gains (losses) on insured derivatives			$ 815	$ 1,277
Net change in fair value of insured derivatives	(47)	(182)	422	(243)
Net gains (losses) on financial instruments at fair value and foreign exchange	61	(6)	6	57
Investment losses related to other-than-temporary impairments:
Net investment losses related to other-than-temporary impairments	0	0	0	0
Net gains (losses) on extinguishment of debt	2	39	3	43
Other net realized gains (losses)	0	0	1	0
Total revenues	187	112	764	331
Expenses:
Losses and loss adjustment	12	188	62	(6)
Interest	52	60	106	120
Total expenses	132	376	305	380
Income (loss) before income taxes	55	(264)	459	(49)
Provision (benefit) for income taxes	(65)	(86)	83	(35)
Net income (loss)	120	(178)	376	(14)
Net income (loss) per common share:
Net income (loss) per basic common share	$ 0.61	$ (0.94)	$ 1.93	$ (0.07)
Net income (loss) per diluted common share	$ 0.45	$ (0.94)	$ 1.83	$ (0.07)
Weighted average number of common shares outstanding:
Basic	189,169,042	189,163,527	189,101,884	189,135,587
Diluted	192,906,871	189,163,527	193,051,436	189,135,587
Non Variable Interest Entity [Member]
Premiums earned:
Scheduled premiums earned	63	77	132	156
Refunding premiums earned	26	47	45	88
Premiums earned (net of ceded premiums of $2, $2, $5 and $5)	89	124	177	244
Net investment income	42	38	92	76
Fees and reimbursements	4	6	8	12
Change in fair value of insured derivatives:
Realized gains (losses) and other settlements on insured derivatives	(24)	(1,532)	(393)	(1,520)
Unrealized gains (losses) on insured derivatives	(23)	1,350	815	1,277
Net change in fair value of insured derivatives	(47)	(182)	422	(243)
Net gains (losses) on financial instruments at fair value and foreign exchange	61	(6)	6	57
Investment losses related to other-than-temporary impairments:
Investment losses related to other-than-temporary impairments	0	0	0	0
Other-than-temporary impairments recognized in accumulated other comprehensive income (loss)	0	0	0	0
Net investment losses related to other-than-temporary impairments	0	0	0	0
Net gains (losses) on extinguishment of debt	2	39	3	43
Other net realized gains (losses)	0	0	1	0
Expenses:
Losses and loss adjustment	12	188	62	(6)
Amortization of deferred acquisition costs	8	11	18	27
Operating	49	103	95	209
Interest	52	60	106	120
Variable Interest Entity Primary Beneficiary [Member]
Premiums earned:
Net investment income	13	14	25	30
Change in fair value of insured derivatives:
Net gains (losses) on financial instruments at fair value and foreign exchange	23	78	26	111
Investment losses related to other-than-temporary impairments:
Net gains (losses) on extinguishment of debt	0	0	4	0
Other net realized gains (losses)	0	1	0	1
Expenses:
Operating	1	2	4	6
Interest	$ 10	$ 12	$ 20	$ 24