Consolidated Statements Of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Premiums, fees and reimbursements received	$ 26	$ 32
Investment income received	112	127
Insured derivative commutations and losses paid	(44)	(34)
Financial guarantee losses and loss adjustment expenses paid	(116)	(497)
Proceeds from recoveries and reinsurance	32	91
Operating and employee related expenses paid	(52)	(77)
Interest paid, net of interest converted to principal	(83)	(101)
Income taxes (paid) received	(1)	0
Net cash provided (used) by operating activities	(126)	(459)
Cash flows from investing activities:
Purchases of available-for-sale investments	(1,158)	(738)
Sales of available-for-sale investments	1,064	987
Paydowns and maturities of available-for-sale investments	181	277
Purchases of investments at fair value	(96)	(118)
Sales, paydowns and maturities of investments at fair value	108	138
Sales, paydowns and maturities (purchases) of short-term investments, net	185	(177)
Paydowns and maturities of loans receivable	88	137
Consolidation of variable interest entities	0	18
Deconsolidation of variable interest entities	(7)	0
(Payments) proceeds for derivative settlements	(14)	(48)
Collateral (to) from counterparties	0	4
Other investing	0	(23)
Net cash provided (used) by investing activities	351	457
Cash flows from financing activities:
Proceeds from investment agreements	5	4
Principal paydowns of investment agreements	(28)	(33)
Principal paydowns of medium-term notes	(36)	(55)
Proceeds from the MBIA Corp. Financing Facility	0	328
Principal paydowns of variable interest entity notes	(100)	(183)
Purchases of treasury stock	(15)	(79)
Other financing	0	(3)
Net cash provided (used) by financing activities	(174)	(21)
Net increase (decrease) in cash and cash equivalents	51	(23)
Cash and cash equivalents - beginning of year	146	187
Cash and cash equivalents - end of year	197	164
Reconciliation of net income (loss) to net cash provided (used) by operating activities: [Abstract]
Net income (loss)	(244)	(1,301)
Change in: [Abstract]
Premiums receivable	16	27
Deferred acquisition costs	9	14
Unearned premium revenue	(74)	(97)
Loss and loss adjustment expense reserves	57	512
Insurance loss recoverable	(9)	(653)
Accrued interest payable	70	45
Accrued expenses	(14)	(19)
Unrealized (gains) losses on insured derivatives	(32)	16
Net (gains) losses on financial instruments at fair value and foreign exchange	(30)	63
Other net realized (gains) losses	94	(65)
Deferred income tax provision (benefit)	1	970
Interest on variable interest entities, net	12	19
Other operating	18	10
Total adjustments to net income (loss)	118	842
Net cash provided (used) by operating activities	(126)	(459)
Supplementary Disclosure of Consolidated Cash Flow Information
Non-cash consideration received from the sale of MBIA UK Insurance Limited	$ 0	$ 332