Consolidated Statements Of Operations - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Change in fair value of insured derivatives:
Unrealized gains (losses) on insured derivatives		$ 14	$ 14
Net change in fair value of insured derivatives		14	(5)
Net gains (losses) on financial instruments at fair value and foreign exchange		22	(9)
Net investment losses related to other-than-temporary impairments:
Net investment losses related to other-than-temporary impairments		(28)	(1)
Net gains (losses) on extinguishment of debt		0	0
Other net realized gains (losses)		1	(1)
Total revenues		50	73
Expenses:
Losses and loss adjustment		(38)	72
Interest		52	51
Total expenses		69	169
Income (loss) before income taxes		(19)	(96)
Provision (benefit) for income taxes		(2)	2
Net income (loss)		$ (17)	$ (98)
Net income (loss) per common share:
Basic		$ (0.2)	$ (1.12)
Diluted		$ (0.2)	$ (1.12)
Weighted average number of common shares outstanding:
Basic	[1]	85,554,236	88,131,373
Diluted	[1]	85,554,236	88,131,373
Non Variable Interest Entity [Member]
Premiums earned:
Scheduled premiums earned		$ 18	$ 23
Refunding premiums earned		5	17
Premiums earned (net of ceded premiums of $1 and $1)		23	40
Net investment income		32	31
Fees and reimbursements		0	6
Change in fair value of insured derivatives:
Realized gains (losses) and other settlements on insured derivatives		0	(19)
Unrealized gains (losses) on insured derivatives		14	14
Net change in fair value of insured derivatives		14	(5)
Net gains (losses) on financial instruments at fair value and foreign exchange		22	(9)
Net investment losses related to other-than-temporary impairments:
Investment losses related to other-than-temporary impairments		0	0
Other-than-temporary impairments recognized in accumulated other comprehensive income (loss)		(28)	(1)
Net investment losses related to other-than-temporary impairments		(28)	(1)
Net gains (losses) on extinguishment of debt		0	0
Other net realized gains (losses)		1	(1)
Expenses:
Losses and loss adjustment		(38)	72
Amortization of deferred acquisition costs		4	4
Operating		26	20
Interest		52	51
Variable Interest Entity Primary Beneficiary [Member]
Premiums earned:
Net investment income		10	8
Change in fair value of insured derivatives:
Net gains (losses) on financial instruments at fair value and foreign exchange		18	4
Net investment losses related to other-than-temporary impairments:
Other net realized gains (losses)		(42)	0
Expenses:
Operating		3	2
Interest		$ 22	$ 20

[1] Includes 0.9 million and 0.3 million of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for the three months ended March 31, 2019 and 2018, respectively.