Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Premiums, fees and reimbursements received	$ 17	$ 30
Investment income received	90	110
Insured derivative commutations and losses paid	(13)	(343)
Financial guarantee losses and loss adjustment expenses paid	(17)	(86)
Proceeds from recoveries and reinsurance	23	20
Operating and employee related expenses paid	(55)	(111)
Interest paid, net of interest converted to principal	(54)	(48)
Income taxes (paid) received	0	4
Net cash provided (used) by operating activities	(9)	(424)
Cash flows from investing activities:
Purchases of available-for-sale investments	(478)	(325)
Sales of available-for-sale investments	192	16
Paydowns and maturities of available-for-sale investments	113	135
Purchases of investments at fair value	(166)	(386)
Sales, paydowns and maturities of investments at fair value	170	452
Sales, paydowns and maturities (purchases) of short-term investments, net	232	219
Sales, paydowns and maturities of held-to-maturity investments	15	8
Paydowns and maturities of loans receivable	52	55
Consolidation of variable interest entities including cash acquired	7	0
Deconsolidation of variable interest entities	0	(1)
(Payments) proceeds for derivative settlements	70	(8)
Collateral (to) from swap counterparty	(110)	46
Capital expenditures	(1)	(1)
Other investing	24	0
Net cash provided (used) by investing activities	120	210
Cash flows from financing activities:
Proceeds from investment agreements	7	6
Principal paydowns of investment agreements	(17)	(20)
Principal paydowns of medium-term notes	(28)	(28)
Principal paydowns of variable interest entity notes	(132)	(270)
Principal paydowns of long-term debt	(11)	0
Purchases of treasury stock	(75)	0
Net cash provided (used) by financing activities	(256)	(312)
Effect of exchange rate changes on cash and cash equivalents	(10)	1
Net increase (decrease) in cash and cash equivalents	(155)	(525)
Cash and cash equivalents - beginning of period	782	1,258
Cash and cash equivalents - end of period	627	733
Reconciliation of net income (loss) to net cash provided (used) by operating activities: [Abstract]
Net income (loss)	69	256
Change in: [Abstract]
Premiums receivable	4	41
Deferred acquisition costs	13	10
Unearned premium revenue	(83)	(107)
Loss and loss adjustment expense reserves	(6)	(39)
Insurance loss recoverable	5	23
Accrued interest payable	25	27
Accrued expenses	(11)	(63)
Realized (gains) losses and other settlements on insured derivatives	0	30
Unrealized (gains) losses on insured derivatives	(37)	(838)
Net (gains) losses on financial instruments at fair value and foreign exchange	(20)	52
Other net realized (gains) losses	(20)	(1)
Deferred income tax provision (benefit)	44	148
Interest on variable interest entities, net	14	18
Other operating	(6)	19
Total adjustments to net income (loss)	(78)	(680)
Net cash provided (used) by operating activities	$ (9)	$ (424)