Financial Guaranty Contracts Accounted for as Credit Derivatives - Net Change in Fair Value of Credit Derivatives Gain (Loss) and Net Par and Accelerations of Credit Derivative Revenues from Termination of CDS Contracts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net credit derivative premiums received and receivable	$ 119		$ 127		$ 185
Net ceding commissions (paid and payable) received and receivable	2		1		3
Realized gains on credit derivatives	121		128		188
Terminations	0		(1)		(23)
Net credit derivative losses (paid and payable) recovered and recoverable	(163)		(235)		(159)
Realized gains (losses) and other settlements on credit derivatives	(42)		(108)		6
Net change in unrealized gains (losses) on credit derivatives	107	[1]	(477)	[1]	554	[1]
Net par of terminated CDS contracts	4,054		2,264		11,543
Accelerations of credit derivative revenues	$ 21		$ 3		$ 25

[1] Except for net estimated credit impairments (i.e., net expected loss to be paid as discussed in Note 6), the unrealized gains and losses on credit derivatives are expected to reduce to zero as the exposure approaches its maturity date. With considerable volatility continuing in the market, unrealized gains (losses) on credit derivatives may fluctuate significantly in future periods.