Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Premiums, fees and reimbursements received	$ 23	$ 17
Investment income received	113	90
Insured derivative commutations and losses paid	(15)	(13)
Financial guarantee losses and loss adjustment expenses paid	(17)	(17)
Proceeds from recoveries and reinsurance	24	23
Operating and employee related expenses paid	(52)	(55)
Interest paid, net of interest converted to principal	(37)	(54)
Net cash provided (used) by operating activities	39	(9)
Cash flows from investing activities:
Purchases of available-for-sale investments	(452)	(478)
Sales of available-for-sale investments	281	192
Paydowns and maturities of available-for-sale investments	122	113
Purchases of investments at fair value	(24)	(166)
Sales, paydowns and maturities of investments at fair value	92	170
Sales, paydowns and maturities (purchases) of short-term investments, net	(32)	232
Sales, paydowns and maturities of held-to-maturity investments	1,799	15
Paydowns and maturities of loans receivable	56	52
Consolidation of variable interest entities	9	7
(Payments) proceeds for derivative settlements	(20)	70
Collateral (to) from swap counterparty	(13)	(110)
Capital expenditures	0	(1)
Other investing	(4)	24
Net cash provided (used) by investing activities	1,814	120
Cash flows from financing activities:
Proceeds from investment agreements	5	7
Principal paydowns of investment agreements	(15)	(17)
Principal paydowns of medium-term notes	0	(28)
Principal paydowns of variable interest entity notes	(1,939)	(132)
Principal paydowns of long-term debt	0	(11)
Purchases of treasury stock	(97)	(75)
Net cash provided (used) by financing activities	(2,046)	(256)
Effect of exchange rate changes on cash and cash equivalents	3	(10)
Net increase (decrease) in cash and cash equivalents	(190)	(155)
Cash and cash equivalents - beginning of period	522	782
Cash and cash equivalents - end of period	332	627
Reconciliation of net income (loss) to net cash provided (used) by operating activities: [Abstract]
Net income (loss)	(78)	69
Change in: [Abstract]
Premiums receivable	53	4
Deferred acquisition costs	10	13
Unearned premium revenue	(81)	(83)
Loss and loss adjustment expense reserves	9	(6)
Insurance loss recoverable	21	5
Accrued interest payable	28	25
Accrued expenses	(21)	(11)
Unrealized (gains) losses on insured derivatives	14	(37)
Net (gains) losses on financial instruments at fair value and foreign exchange	70	(20)
Other net realized (gains) losses	1	(20)
Deferred income tax provision (benefit)	(23)	44
Interest on variable interest entities, net	22	14
Other operating	14	(6)
Total adjustments to net income (loss)	117	(78)
Net cash provided (used) by operating activities	$ 39	$ (9)