Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Premiums, fees and reimbursements received	$ 9	$ 23
Investment income received	64	113
Insured derivative commutations and losses paid	(31)	(15)
Financial guarantee losses and loss adjustment expenses paid	(469)	(17)
Proceeds from recoveries and reinsurance	44	24
Operating and employee related expenses paid	(53)	(51)
Interest paid, net of interest converted to principal	(35)	(37)
Net cash provided (used) by operating activities	(471)	40
Cash flows from investing activities:
Purchases of available-for-sale investments	(394)	(452)
Sales of available-for-sale investments	271	281
Paydowns and maturities of available-for-sale investments	169	122
Purchases of investments at fair value	(69)	(24)
Sales, paydowns and maturities of investments at fair value	75	92
Sales, paydowns and maturities (purchases) of short-term investments, net	206	(32)
Sales, paydowns and maturities of held-to-maturity investments	0	1,799
Paydowns and maturities of loans receivable	70	56
Consolidation of variable interest entities	18	9
(Payments) proceeds for derivative settlements	(7)	(20)
Collateral (to) from swap counterparty	(5)	(13)
Other investing	(23)	(4)
Net cash provided (used) by investing activities	311	1,814
Cash flows from financing activities:
Proceeds from investment agreements	2	5
Principal paydowns of investment agreements	(13)	(15)
Principal paydowns of medium-term notes	(67)	0
Proceeds from the MBIA Corp. Financing Facility	328	0
Principal paydowns of variable interest entity notes	(93)	(1,939)
Purchases of treasury stock	(31)	(98)
Other financing	(2)	0
Net cash provided (used) by financing activities	124	(2,047)
Effect of exchange rate changes on cash and cash equivalents	1	3
Net increase (decrease) in cash and cash equivalents	(35)	(190)
Cash and cash equivalents - beginning of period	187	522
Cash and cash equivalents - end of period	152	332
Reconciliation of net income (loss) to net cash provided (used) by operating activities: [Abstract]
Net income (loss)	(72)	(78)
Change in: [Abstract]
Premiums receivable	3	53
Deferred acquisition costs	6	10
Unearned premium revenue	(45)	(81)
Loss and loss adjustment expense reserves	359	9
Insurance loss recoverable	(691)	21
Accrued interest payable	37	28
Accrued expenses	(28)	(21)
Unrealized (gains) losses on insured derivatives	22	14
Net (gains) losses on financial instruments at fair value and foreign exchange	16	70
Other net realized (gains) losses	(31)	1
Deferred income tax provision (benefit)	(49)	(23)
Interest on variable interest entities, net	10	22
Other operating	(8)	15
Total adjustments to net income (loss)	(399)	118
Net cash provided (used) by operating activities	(471)	40
Supplementary Disclosure of Consolidated Cash Flow Information
Non-cash consideration received from the sale of MBIA UK Insurance Limited	$ 332	$ 0