Fair Value Measurement and Fair Value of Financial Instruments (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Trading Assets
Reconciliation of assets measured using significant unobservable inputs
Reconciliation of asset balance at fair value on a recurring basis using significant unobservable inputs, beginning of period	$ 136
Total gains (losses) (realized/unrealized) included in income before taxes	119	(18)
Purchases/additions, assets	24	8
Settlements	(8)	(7)
Transfers into Level 3, assets		153
Reconciliation of asset balance at fair value on a recurring basis using significant unobservable inputs, end of period	271	136
Changes in unrealized gains (losses) included in income before taxes for assets still held at end of period	119	(18)
Securities Available for Sale
Reconciliation of assets measured using significant unobservable inputs
Reconciliation of asset balance at fair value on a recurring basis using significant unobservable inputs, beginning of period	1,499	48
Total gains (losses) (realized/unrealized) included in other comprehensive income	28	(35)
Purchases/additions, assets	700	1,619
Sales	(14)
Settlements	(195)	(133)
Reconciliation of asset balance at fair value on a recurring basis using significant unobservable inputs, end of period	2,018	1,499
Other assets
Reconciliation of assets measured using significant unobservable inputs
Purchases/additions, assets	1
Reconciliation of asset balance at fair value on a recurring basis using significant unobservable inputs, end of period	$ 1