Consolidated Statements Of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Premiums, fees and reimbursements received	$ 41	$ 87
Investment income received	193	249
Insured derivative commutations and losses paid	(41)	(24)
Financial guarantee losses and loss adjustment expenses paid	(744)	(324)
Proceeds from recoveries and reinsurance	100	88
Operating and employee related expenses paid	(103)	(98)
Interest paid, net of interest converted to principal	(119)	(102)
Income taxes (paid) received	0	(4)
Net cash provided (used) by operating activities	(673)	(128)
Cash flows from investing activities:
Purchases of available-for-sale investments	(1,146)	(2,112)
Sales of available-for-sale investments	1,300	1,785
Paydowns and maturities of available-for-sale investments	392	410
Purchases of investments at fair value	(199)	(88)
Sales, paydowns and maturities of investments at fair value	270	197
Sales, paydowns and maturities (purchases) of short-term investments, net	67	90
Sales, paydowns and maturities of held-to-maturity investments	0	1,799
Sales, paydowns and maturities of other investments	0	1
Paydowns and maturities of loans receivable	202	188
Consolidation of variable interest entities	18	1
(Payments) proceeds for derivative settlements	(58)	(36)
Collateral (to) from counterparties	4	10
Capital expenditures	(1)	(1)
Other investing	(23)	(8)
Net cash provided (used) by investing activities	826	2,236
Cash flows from financing activities:
Proceeds from investment agreements	13	17
Principal paydowns of investment agreements	(66)	(63)
Principal paydowns of medium-term notes	(67)	(122)
Proceeds from the MBIA Corp. Financing Facility	328	0
Principal paydowns of variable interest entity notes	(311)	(2,136)
Purchases of treasury stock	(98)	(109)
Other financing	(3)	0
Net cash provided (used) by financing activities	(204)	(2,413)
Effect of exchange rate changes on cash and cash equivalents	0	(1)
Net increase (decrease) in cash and cash equivalents	(51)	(306)
Cash and cash equivalents - beginning of year	187	522
Cash and cash equivalents - end of year	136	216
Reconciliation of net income (loss) to net cash provided (used) by operating activities: [Abstract]
Net income (loss)	(1,568)	(73)
Change in: [Abstract]
Premiums receivable	34	61
Deferred acquisition costs	22	31
Unearned premium revenue	(149)	(197)
Loss and loss adjustment expense reserves	615	(1)
Insurance loss recoverable	(781)	(98)
Accrued interest payable	101	82
Accrued expenses	(26)	4
Unrealized (gains) losses on insured derivatives	10	0
Net (gains) losses on financial instruments at fair value and foreign exchange	53	17
Other net realized (gains) losses	(64)	3
Deferred income tax provision (benefit)	961	(33)
Interest on variable interest entities, net	26	45
Other operating	93	31
Total adjustments to net income (loss)	895	(55)
Net cash provided (used) by operating activities	(673)	(128)
Supplementary Disclosure of Consolidated Cash Flow Information
Non-cash consideration received from the sale of MBIA UK Insurance Limited	$ 332	$ 0