Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Premiums, fees and reimbursements received	$ 3	$ 10
Investment income received	44	59
Insured derivative commutations and losses paid	0	(19)
Financial guarantee losses and loss adjustment expenses paid	(95)	(86)
Proceeds from recoveries and reinsurance	60	16
Operating and employee related expenses paid	(34)	(38)
Interest paid, net of interest converted to principal	(46)	(42)
Income taxes (paid) received	(2)	(1)
Net cash provided (used) by operating activities	(70)	(101)
Cash flows from investing activities:
Purchases of available-for-sale investments	(747)	(819)
Sales of available-for-sale investments	683	651
Paydowns and maturities of available-for-sale investments	234	94
Purchases of investments at fair value	(69)	(53)
Sales, paydowns, maturities and other proceeds of investments at fair value	122	57
Sales, paydowns and maturities (purchases) of short-term investments, net	(154)	222
Paydowns and maturities of loans receivable and other instruments at fair value	7	48
Consolidation of variable interest entities	72	0
(Payments) proceeds for derivative settlements	(11)	(9)
Collateral (to) from counterparties	(9)	0
Net cash provided (used) by investing activities	128	191
Cash flows from financing activities:
Proceeds from investment agreements	3	3
Principal paydowns of investment agreements	0	(8)
Principal paydowns of medium-term notes	0	(20)
Principal paydowns of variable interest entity notes	(168)	(55)
Purchases of treasury stock	(10)	(15)
Other financing	0	0
Net cash provided (used) by financing activities	(175)	(95)
Net increase (decrease) in cash and cash equivalents	(117)	(5)
Cash and cash equivalents - beginning of period	280	146
Cash and cash equivalents - end of period	163	141
Reconciliation of net income (loss) to net cash provided (used) by operating activities: [Abstract]
Net income (loss)	(17)	(98)
Change in: [Abstract]
Premiums receivable	22	5
Deferred acquisition costs	3	4
Unearned premium revenue	(43)	(39)
Loss and loss adjustment expense reserves	(58)	21
Insurance loss recoverable	(20)	(19)
Accrued interest payable	30	33
Accrued expenses	(11)	(18)
Net investment losses related to other-than-temporary impairments	28	1
Unrealized (gains) losses on insured derivatives	(14)	(14)
Net (gains) losses on financial instruments at fair value and foreign exchange	(40)	5
Other net realized (gains) losses	41	1
Deferred income tax provision (benefit)	(4)	1
Interest on variable interest entities, net	(2)	5
Other operating	15	11
Total adjustments to net income (loss)	(53)	(3)
Net cash provided (used) by operating activities	$ (70)	$ (101)