Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Premiums, fees and reimbursements received	$ 95	$ 193	$ 185
Investment income received	353	419	426
Errors and omissions insurance recoveries received	0	30	0
Insured derivative commutations and losses paid	(42)	(432)	(458)
Financial guarantee losses and loss adjustment expenses paid	(238)	(240)	(443)
Proceeds from recoveries and reinsurance	85	131	2,621
Operating and employee related expenses paid	(130)	(238)	(277)
Interest paid, net of interest converted to principal	(169)	(179)	(224)
Income taxes (paid) received	(9)	(17)	(1)
Net cash provided (used) by operating activities	(55)	(333)	1,829
Cash flows from investing activities:
Purchases of available-for-sale investments	(2,146)	(1,494)	(2,397)
Sales of available-for-sale investments	1,145	757	1,726
Paydowns and maturities of available-for-sale investments	800	484	452
Purchases of investments at fair value	(390)	(631)	(371)
Sales, paydowns and maturities of investments at fair value	551	789	595
Sales, paydowns and maturities (purchases) of short-term investments, net	525	515	(358)
Sales, paydowns and maturities of held-to-maturity investments	67	44	28
Sales, paydowns and maturities of other investments	0	1	0
Purchases of loans at fair value	0	(310)	0
Paydowns and maturities of loans at fair value	232	313	280
Consolidation of variable interest entities including cash acquired	7	221	0
Deconsolidation of variable interest entities	0	18	(26)
(Payments) proceeds for derivative settlements	13	(26)	(54)
Collateral (to) from swap counterparty	(31)	144	122
Capital expenditures	(3)	(13)	(3)
Other investing	47	0	0
Net cash provided (used) by investing activities	817	812	(6)
Cash flows from financing activities:
Proceeds from investment agreements	24	30	31
Principal paydowns of investment agreements	(116)	(192)	(285)
Principal paydowns of medium-term notes	(118)	(168)	(197)
Principal paydowns of variable interest entity notes	(490)	(609)	(1,112)
Proceeds from issuance of variable interest entity notes	0	79	0
Principal paydowns of long-term debt	(11)	0	(3)
Purchases of treasury stock	(303)	(32)	0
Net cash provided (used) by financing activities	(1,014)	(892)	(1,566)
Effect of exchange rate changes on cash and cash equivalents	(8)	(8)	11
Net increase (decrease) in cash and cash equivalents	(260)	(421)	268
Cash and cash equivalents - beginning of year	782	1,258	990
Reclassification to assets held for sale	0	(55)	0
Cash and cash equivalents - end of year	522	782	1,258
Reconciliation of net income (loss) to net cash provided (used) by operating activities: [Abstract]
Net income (loss)	180	569	250
Change in: [Abstract]
Premiums receivable	50	138	176
Deferred acquisition costs	49	43	43
Unearned premium revenue	(371)	(412)	(506)
Loss and loss adjustment expense reserves	12	(133)	(216)
Insurance loss recoverable	(44)	162	3,637
Accrued interest payable	105	106	106
Accrued expenses	14	(36)	43
Net investment losses related to other-than-temporary impairments	13	15	0
Realized (gains) losses and other settlements on insured derivatives	0	30	0
Unrealized (gains) losses on insured derivatives	(157)	(903)	(1,777)
Net (gains) losses on financial instruments at fair value and foreign exchange	(105)	(128)	(244)
Other net realized (gains) losses	(17)	(25)	28
Deferred income tax provision (benefit)	107	50	157
(Gains) losses on extinguishment of debt	0	0	(61)
Interest on variable interest entities, net	71	77	90
Other operating	38	114	103
Total adjustments to net income (loss)	(235)	(902)	1,579
Net cash provided (used) by operating activities	$ (55)	$ (333)	$ 1,829