Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Premiums, fees and reimbursements received	$ 28	$ 47	$ 86
Investment income received	118	176	205
Insured derivative commutations and losses paid	(1)	(11)	(56)
Financial guarantee losses and loss adjustment expenses paid	(475)	(489)	(385)
Proceeds from recoveries and reinsurance	84	155	61
Operating and employee related expenses paid	(73)	(77)	(83)
Interest paid, net of interest converted to principal	(84)	(180)	(146)
Income taxes (paid) received	13	11	(1)
Net cash provided (used) by operating activities	(390)	(368)	(319)
Cash flows from investing activities:
Purchases of available-for-sale investments	(1,133)	(2,140)	(2,265)
Sales of available-for-sale investments	1,095	2,195	2,117
Paydowns and maturities of available-for-sale investments	724	857	329
Purchases of investments at fair value	(179)	(151)	(189)
Sales, paydowns and maturities of investments at fair value	198	617	212
Sales, paydowns and maturities (purchases) of short-term investments, net	143	(157)	420
Sales, paydowns and maturities of held-to-maturity investments	890	0	0
Paydowns and maturities of loans receivable and other instruments at fair value	16	74	614
Consolidation of variable interest entities	0	72	0
Deconsolidation of variable interest entities	0	(2)	(7)
(Payments) proceeds for derivative settlements	(16)	(98)	(24)
Capital expenditures	0	0	(1)
Net cash provided (used) by investing activities	1,738	1,267	1,206
Cash flows from financing activities:
Proceeds from investment agreements	12	15	12
Principal paydowns of investment agreements	(48)	(25)	(37)
Principal paydowns of medium-term notes	0	(57)	(85)
Principal paydowns of variable interest entity notes	(914)	(765)	(598)
Principal paydowns of long-term debt	(115)	(150)	0
Purchases of treasury stock	(200)	(106)	(44)
Other financing	0	(8)	0
Net cash provided (used) by financing activities	(1,265)	(1,096)	(752)
Effect of exchange rate changes on cash and cash equivalents	1	0	(1)
Net increase (decrease) in cash and cash equivalents	84	(197)	134
Cash and cash equivalents—beginning of year	83	280	146
Cash and cash equivalents—end of year	167	83	280
Reconciliation of net income (loss) to net cash provided (used) by operating activities:
Net income (loss)	(578)	(359)	(296)
Change in:
Premiums receivable	29	62	60
Deferred acquisition costs	10	12	21
Accrued investment income	6	20	8
Unearned premium revenue	(77)	(105)	(165)
Loss and loss adjustment expense reserves	86	0	(46)
Insurance loss recoverable	16	(99)	(213)
Accrued interest payable	133	106	157
Accrued expenses	34	12	(9)
Net investment losses related to other-than-temporary impairments	0	67	5
Unrealized (gains) losses on insured derivatives	(7)	(25)	(31)
Net (gains) losses on financial instruments at fair value and foreign exchange	(70)	(157)	(8)
Other net realized (gains) losses	(37)	58	171
Deferred income tax provision (benefit)	12	13	0
Interest on variable interest entities, net	6	(3)	17
Other operating	47	30	10
Total adjustments to net income (loss)	188	(9)	(23)
Net cash provided (used) by operating activities	$ (390)	$ (368)	$ (319)