Fair Value Measurements (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013	Dec. 31, 2013
Derivative assets	$ 517			$ 517			$ 500
Fair value of derivative liability	286			286			249
Commitments to fund additional investments in nonmarketable equity securities	5			5
Underlying assets of funds, estimated liquidation period, years, maximum				16 years
Federal Home Loan Bank stock	7			7			48
Federal Reserve Bank stock	85			85			85
Recurring [Member]
Derivative assets	521			521			503
Transfers into or out of Level 1 or Level 2 or Level 3	0		0	0		0
Total liabilities at fair value	384			384			347
Nonrecurring
Commitments to fund additional investments in nonmarketable equity securities	0			0			0
Total liabilities at fair value	0			0			0
Carrying Amount
Carrying value of nonmarketable equity securities	12	[1]		12	[1]		12	[1]
Warrants | Recurring [Member]
Derivative assets	4			4			3
Visa derivative contract
Fair value of derivative liability	$ 2			$ 2			$ 2

[1] Included $1 million and $2 million of nonmarketable equity securities recorded at fair value on a nonrecurring basis at June 30, 2014 and December 31, 2013, respectively.