Securities (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
Roll-forward of credit losses on debt securities that were other-than-temporarily impaired
Credit losses at the beginning of the period		$ 1	$ 1	$ 1	$ 36
Reduction of credit losses previously recognized on sold securities			(4)
Reduction of credit losses previously recognized on held to maturity securities due to deconsolidation of VIE			(31)
Ending balance of credit losses on debt securities held for which a portion of an other-than-temporary impairment may have been recognized in other comprehensive income (loss)		$ 1	$ 1	$ 1	$ 36