Consolidated Statements Of Operations (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Change in fair value of insured derivatives:
Unrealized gains (losses) on insured derivatives	$ 838		$ (73)
Net change in fair value of insured derivatives	469		(61)
Net gains (losses) on financial instruments at fair value and foreign exchange	(55)		63
Investment losses related to other-than-temporary impairments:
Net investment losses related to other-than-temporary impairments	0		0
Net gains (losses) on extinguishment of debt	1		4
Other net realized gains (losses)	1		0
Total revenues	577		219
Expenses:
Losses and loss adjustment	50		(194)
Interest	54		60
Total expenses	173		4
Income (loss) before income taxes	404		215
Provision (benefit) for income taxes	148		51
Net income (loss)	256		164
Net income (loss) per common share:
Net income (loss) per basic common share	$ 1.33		$ 0.84
Net income (loss) per diluted common share	$ 1.32		$ 0.84
Weighted average number of common shares outstanding:
Basic	189,033,982	[1]	189,111,170	[1]
Diluted	190,263,748		190,219,197
Non Variable Interest Entity [Member]
Premiums earned:
Scheduled premiums earned	69		79
Refunding premiums earned	19		41
Premiums earned (net of ceded premiums of $2 and $2)	88		120
Net investment income	50		38
Fees and reimbursements	4		6
Change in fair value of insured derivatives:
Realized gains (losses) and other settlements on insured derivatives	(369)		12
Unrealized gains (losses) on insured derivatives	838		(73)
Net change in fair value of insured derivatives	469		(61)
Net gains (losses) on financial instruments at fair value and foreign exchange	(55)		63
Investment losses related to other-than-temporary impairments:
Net gains (losses) on extinguishment of debt	1		4
Other net realized gains (losses)	1		0
Expenses:
Losses and loss adjustment	50		(194)
Amortization of deferred acquisition costs	10		16
Operating	46		106
Interest	54		60
Variable Interest Entity Primary Beneficiary [Member]
Premiums earned:
Net investment income	12		16
Change in fair value of insured derivatives:
Net gains (losses) on financial instruments at fair value and foreign exchange	3		33
Investment losses related to other-than-temporary impairments:
Net gains (losses) on extinguishment of debt	4		0
Expenses:
Operating	3		4
Interest	$ 10		$ 12

[1] Includes 405,961 and 712,836 of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for the three months ended March 31, 2014 and 2013, respectively.