Consolidated Statements Of Operations - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Change in fair value of insured derivatives:
Unrealized gains (losses) on insured derivatives			$ (10)	$ 0
Net change in fair value of insured derivatives	$ (1)	$ 16	(51)	(20)
Net gains (losses) on financial instruments at fair value and foreign exchange	(11)	38	(55)	(17)
Net investment losses related to other-than-temporary impairments:
Net investment losses related to other-than-temporary impairments	(71)	0	(84)	(1)
Net gains (losses) on extinguishment of debt	1	0	9	5
Other net realized gains (losses)	(1)	(2)	36	(3)
Total revenues	33	203	182	353
Expenses:
Losses and loss adjustment	205	50	469	149
Interest	50	49	148	148
Total expenses	306	148	785	454
Income (loss) before income taxes	(273)	55	(603)	(101)
Provision (benefit) for income taxes	(6)	24	965	(28)
Net income (loss)	$ (267)	$ 31	$ (1,568)	$ (73)
Net income (loss) per common share:
Basic	$ (2.17)	$ 0.23	$ (12.38)	$ (0.55)
Diluted	$ (2.17)	$ 0.23	$ (12.38)	$ (0.55)
Weighted average number of common shares outstanding:
Basic	122,967,924	131,633,411	126,643,642	133,368,752
Diluted	122,967,924	132,042,067	126,643,642	133,368,752
Non Variable Interest Entity [Member]
Premiums earned:
Scheduled premiums earned	$ 26	$ 42	$ 82	$ 131
Refunding premiums earned	27	35	64	94
Premiums earned (net of ceded premiums of $1, $2, $4 and $5)	53	77	146	225
Net investment income	33	39	122	115
Fees and reimbursements	1	22	9	24
Change in fair value of insured derivatives:
Realized gains (losses) and other settlements on insured derivatives	(7)	(4)	(41)	(20)
Unrealized gains (losses) on insured derivatives	6	20	(10)	0
Net change in fair value of insured derivatives	(1)	16	(51)	(20)
Net gains (losses) on financial instruments at fair value and foreign exchange	(11)	38	(55)	(17)
Net investment losses related to other-than-temporary impairments:
Investment losses related to other-than-temporary impairments	(26)	0	(80)	(1)
Other-than-temporary impairments recognized in accumulated other comprehensive income (loss)	(45)	0	(4)	0
Net investment losses related to other-than-temporary impairments	(71)	0	(84)	(1)
Net gains (losses) on extinguishment of debt	1	0	9	5
Other net realized gains (losses)	(1)	(2)	36	(3)
Expenses:
Losses and loss adjustment	205	50	469	149
Amortization of deferred acquisition costs	8	10	23	30
Operating	21	32	82	97
Interest	50	49	148	148
Variable Interest Entity Primary Beneficiary [Member]
Premiums earned:
Net investment income	8	5	20	25
Change in fair value of insured derivatives:
Net gains (losses) on financial instruments at fair value and foreign exchange	21	8	2	0
Net investment losses related to other-than-temporary impairments:
Other net realized gains (losses)	0	0	28	0
Expenses:
Operating	3	3	8	10
Interest	$ 19	$ 4	$ 55	$ 20