Consolidated Statements Of Operations - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Premiums earned:
Premiums earned (net of ceded premiums of $7, $9 and $12)		$ 300	$ 372	$ 397
Change in fair value of insured derivatives:
Unrealized gains (losses) on insured derivatives		21	157	903
Net change in fair value of insured derivatives		(19)	129	459
Net gains (losses) on financial instruments at fair value and foreign exchange		84	63	78
Net investment losses related to other-than-temporary impairments:
Net investment losses related to other-than-temporary impairments		(5)	(13)	(15)
Net gains (losses) on extinguishment of debt		5	(1)	3
Other net realized gains (losses)		(282)	17	28
Total revenues		294	853	1,270
Expenses:
Losses and loss adjustment		220	123	133
Interest		197	199	210
Total expenses		633	564	629
Income (loss) before income taxes		(339)	289	641
Provision (benefit) for income taxes		(1)	109	72
Net income (loss)		$ (338)	$ 180	$ 569
Net income (loss) per common share:
Basic		$ (2.54)	$ 1.06	$ 2.94
Diluted		$ (2.54)	$ 1.06	$ 2.76
Weighted average number of common shares outstanding:
Basic	[1]	133,001,088	163,936,318	188,171,503
Diluted		133,001,088	164,869,788	190,898,627
Non Variable Interest Entity [Member]
Premiums earned:
Scheduled premiums earned		$ 168	$ 199	$ 258
Refunding premiums earned		132	173	139
Premiums earned (net of ceded premiums of $7, $9 and $12)		300	372	397
Net investment income		152	152	179
Fees and reimbursements		28	6	40
Change in fair value of insured derivatives:
Realized gains (losses) and other settlements on insured derivatives		(40)	(28)	(444)
Unrealized gains (losses) on insured derivatives		21	157	903
Net change in fair value of insured derivatives		(19)	129	459
Net gains (losses) on financial instruments at fair value and foreign exchange		84	63	78
Net investment losses related to other-than-temporary impairments:
Investment losses related to other-than-temporary impairments		(1)	(12)	(99)
Other-than-temporary impairments recognized in accumulated other comprehensive income (loss)		(4)	(1)	84
Net investment losses related to other-than-temporary impairments		(5)	(13)	(15)
Net gains (losses) on extinguishment of debt		5	(1)	3
Other net realized gains (losses)		(282)	17	28
Expenses:
Losses and loss adjustment		220	123	133
Amortization of deferred acquisition costs		40	50	44
Operating		137	140	195
Interest		197	199	210
Variable Interest Entity Primary Beneficiary [Member]
Premiums earned:
Net investment income		31	86	50
Change in fair value of insured derivatives:
Net gains (losses) on financial instruments at fair value and foreign exchange		0	42	50
Net investment losses related to other-than-temporary impairments:
Net gains (losses) on extinguishment of debt		0	0	4
Other net realized gains (losses)		0	0	(3)
Expenses:
Operating		14	13	8
Interest		$ 25	$ 39	$ 39

[1] Includes 930,406, 617,909 and 412,769 of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for the years ended December 31, 2016, 2015 and 2014, respectively.