Consolidated Statements Of Operations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in fair value of insured derivatives:
Unrealized gains (losses) on insured derivatives	$ 31	$ 0	$ 21
Net change in fair value of insured derivatives	(25)	(51)	(19)
Net gains (losses) on financial instruments at fair value and foreign exchange	(17)	(24)	84
Net investment losses related to other-than-temporary impairments:
Net investment losses related to other-than-temporary impairments	(5)	(106)	(5)
Net gains (losses) on extinguishment of debt	3	28	5
Other net realized gains (losses)	0	31	(282)
Total revenues	162	433	294
Expenses:
Losses and loss adjustment	63	683	220
Interest	206	197	197
Total expenses	458	1,094	633
Income (loss) before income taxes	(296)	(661)	(339)
Provision (benefit) for income taxes	0	944	(1)
Net income (loss)	$ (296)	$ (1,605)	$ (338)
Net income (loss) per common share:
Basic	$ (3.33)	$ (13.5)	$ (2.54)
Diluted	$ (3.33)	$ (13.5)	$ (2.54)
Weighted average number of common shares outstanding:
Basic	89,013,711	118,930,282	133,001,088
Diluted	89,013,711	118,930,282	133,001,088
Non Variable Interest Entity [Member]
Premiums earned:
Scheduled premiums earned	$ 114	$ 107	$ 168
Refunding premiums earned	48	94	132
Premiums earned (net of ceded premiums of $5, $6 and $7)	162	201	300
Net investment income	130	154	152
Fees and reimbursements	25	15	28
Change in fair value of insured derivatives:
Realized gains (losses) and other settlements on insured derivatives	(56)	(51)	(40)
Unrealized gains (losses) on insured derivatives	31	0	21
Net change in fair value of insured derivatives	(25)	(51)	(19)
Net gains (losses) on financial instruments at fair value and foreign exchange	(17)	(24)	84
Net investment losses related to other-than-temporary impairments:
Investment losses related to other-than-temporary impairments	0	(101)	(1)
Other-than-temporary impairments recognized in accumulated other comprehensive income (loss)	(5)	(5)	(4)
Net investment losses related to other-than-temporary impairments	(5)	(106)	(5)
Net gains (losses) on extinguishment of debt	3	28	5
Other net realized gains (losses)	0	31	(282)
Expenses:
Losses and loss adjustment	63	683	220
Amortization of deferred acquisition costs	20	23	40
Operating	71	106	137
Interest	206	197	197
Variable Interest Entity Primary Beneficiary [Member]
Premiums earned:
Net investment income	35	27	31
Change in fair value of insured derivatives:
Net gains (losses) on financial instruments at fair value and foreign exchange	25	130	0
Net investment losses related to other-than-temporary impairments:
Other net realized gains (losses)	(171)	28	0
Expenses:
Operating	11	10	14
Interest	$ 87	$ 75	$ 25