Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified			3 Months Ended
	Mar. 31, 2014 Level 2 Financial Products Nonrecurring basis	Dec. 31, 2013 Level 2 Financial Products Nonrecurring basis	Mar. 31, 2014 Level 3 Guarantees Recurring basis	Mar. 31, 2013 Level 3 Guarantees Recurring basis
Roll-forward of liabilities measured at fair value using Level 3 inputs
Balance at beginning of period			$ 13	$ 14
Issuance of guarantees			0	5
Expiration of guarantees			0	(3)
Balance at end of period			13	16
Fair value of impaired loans
Impaired loans	$ 75	$ 81