Consolidated Statements Of Operations - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Change in fair value of insured derivatives:
Unrealized gains (losses) on insured derivatives			$ 121	$ 863
Net change in fair value of insured derivatives	$ 3	$ 24	91	446
Net gains (losses) on financial instruments at fair value and foreign exchange	(55)	57	20	63
Investment losses related to other-than-temporary impairments:
Net investment losses related to other-than-temporary impairments	(3)	(14)	(10)	(14)
Net gains (losses) on extinguishment of debt	0		(1)	3
Other net realized gains (losses)	(1)	30	18	31
Total revenues	92	291	556	1,055
Expenses:
Losses and loss adjustment	39	20	79	82
Interest	49	52	149	158
Total expenses	147	143	406	448
Income (loss) before income taxes	(55)	148	150	607
Provision (benefit) for income taxes	(20)	(25)	52	58
Net income (loss)	$ (35)	$ 173	$ 98	$ 549
Net income (loss) per common share:
Net income (loss) per basic common share	$ (0.23)	$ 0.9	$ 0.56	$ 2.83
Net income (loss) per diluted common share	$ (0.23)	$ 0.8	$ 0.55	$ 2.62
Weighted average number of common shares outstanding:
Basic	155,239,723	187,104,785	169,610,370	188,428,870
Diluted	155,239,723	188,424,318	170,566,386	191,616,723
Non Variable Interest Entity [Member]
Premiums earned:
Scheduled premiums earned	$ 47	$ 64	$ 153	$ 196
Refunding premiums earned	37	52	123	97
Premiums earned (net of ceded premiums of $2, $4, $7 and $8)	84	116	276	293
Net investment income	38	44	112	136
Fees and reimbursements	1	17	4	25
Change in fair value of insured derivatives:
Realized gains (losses) and other settlements on insured derivatives	(18)	(24)	(30)	(417)
Unrealized gains (losses) on insured derivatives	21	48	121	863
Net change in fair value of insured derivatives	3	24	91	446
Net gains (losses) on financial instruments at fair value and foreign exchange	(55)	57	20	63
Investment losses related to other-than-temporary impairments:
Investment losses related to other-than-temporary impairments	(1)	(93)	(10)	(93)
Other-than-temporary impairments recognized in accumulated other comprehensive income (loss)	(2)	79	0	79
Net investment losses related to other-than-temporary impairments	(3)	(14)	(10)	(14)
Net gains (losses) on extinguishment of debt	0	0	(1)	3
Other net realized gains (losses)	(1)	30	18	31
Expenses:
Losses and loss adjustment	39	20	79	82
Amortization of deferred acquisition costs	11	13	37	31
Operating	35	46	102	141
Interest	49	52	149	158
Variable Interest Entity Primary Beneficiary [Member]
Premiums earned:
Net investment income	12	12	37	37
Change in fair value of insured derivatives:
Net gains (losses) on financial instruments at fair value and foreign exchange	13	8	9	34
Investment losses related to other-than-temporary impairments:
Net gains (losses) on extinguishment of debt	0	0	0	4
Other net realized gains (losses)	0	(3)	0	(3)
Expenses:
Operating	3	2	10	6
Interest	$ 10	$ 10	$ 29	$ 30