Consolidated Statements Of Operations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Premiums earned:
Premiums earned (net of ceded premiums of $9, $12 and $10)	$ 372	$ 397	$ 457
Change in fair value of insured derivatives:
Unrealized gains (losses) on insured derivatives	157	903	1,777
Net change in fair value of insured derivatives	129	459	232
Net gains (losses) on financial instruments at fair value and foreign exchange	63	78	69
Investment losses related to other-than-temporary impairments:
Net investment losses related to other-than-temporary impairments	(13)	(15)
Net gains (losses) on extinguishment of debt	(1)	3	60
Other net realized gains (losses)	17	28	(29)
Total revenues	853	1,270	1,209
Expenses:
Losses and loss adjustment	123	133	117
Interest	199	210	236
Total expenses	564	629	793
Income (loss) before income taxes	289	641	416
Provision (benefit) for income taxes	109	72	166
Net income (loss)	$ 180	$ 569	$ 250
Net income (loss) per common share:
Basic	$ 1.06	$ 2.94	$ 1.3
Diluted	$ 1.06	$ 2.76	$ 1.29
Weighted average number of common shares outstanding:
Basic	163,936,318	188,171,503	189,071,011
Diluted	164,869,788	190,898,627	190,312,913
Non Variable Interest Entity [Member]
Premiums earned:
Scheduled premiums earned	$ 199	$ 258	$ 304
Refunding premiums earned	173	139	153
Premiums earned (net of ceded premiums of $9, $12 and $10)	372	397	457
Net investment income	152	179	166
Fees and reimbursements	6	40	21
Change in fair value of insured derivatives:
Realized gains (losses) and other settlements on insured derivatives	(28)	(444)	(1,545)
Unrealized gains (losses) on insured derivatives	157	903	1,777
Net change in fair value of insured derivatives	129	459	232
Net gains (losses) on financial instruments at fair value and foreign exchange	63	78	69
Investment losses related to other-than-temporary impairments:
Investment losses related to other-than-temporary impairments	(12)	(99)	0
Other-than-temporary impairments recognized in accumulated other comprehensive income (loss)	(1)	84	0
Net investment losses related to other-than-temporary impairments	(13)	(15)	0
Net gains (losses) on extinguishment of debt	(1)	3	60
Other net realized gains (losses)	17	28	(29)
Expenses:
Losses and loss adjustment	123	133	117
Amortization of deferred acquisition costs	50	44	46
Operating	140	195	338
Interest	199	210	236
Variable Interest Entity Primary Beneficiary [Member]
Premiums earned:
Net investment income	86	50	56
Change in fair value of insured derivatives:
Net gains (losses) on financial instruments at fair value and foreign exchange	42	50	175
Investment losses related to other-than-temporary impairments:
Net gains (losses) on extinguishment of debt	0	4	1
Other net realized gains (losses)	0	(3)	1
Expenses:
Operating	13	8	11
Interest	$ 39	$ 39	$ 45