Fair Value Measurement and Fair Value of Financial Instruments (Details 1) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Trading account liabilities [Member]
Total gains (losses) (realized/unrealized):
Purchases/additions, liabilities	$ (2)
Fair Value Measurements Recurring [Member] | Trading account assets [Member]
Reconciliation of the assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs
Reconciliation of asset balance at fair value on a recurring basis using significant unobservable inputs, beginning of period	153
Total gains (losses) (realized/unrealized):
Included in income before taxes	(34)		(34)
Included in other comprehensive income
Purchases/additions , assets	2		2
Sales	(3)		(3)
Transfers into Level 3, Assets			153
Reconciliation of asset balance at fair value on a recurring basis using significant unobservable inputs, end of period	118		118
Changes in unrealized (gains) included in income before taxes for assets and liabilities still held at end of period	(34)		(34)
Fair Value Measurements Recurring [Member] | Available for sale Securities [Member]
Reconciliation of the assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs
Reconciliation of asset balance at fair value on a recurring basis using significant unobservable inputs, beginning of period	43	49	48	8
Total gains (losses) (realized/unrealized):
Included in other comprehensive income	1	(1)	(4)	(1)
Purchases/additions , assets	1,090		1,090
Purchases/additions, liabilities				42
Sales		(1)		(1)
Transfers into Level 3, Assets
Reconciliation of asset balance at fair value on a recurring basis using significant unobservable inputs, end of period	1,134	48	1,134	48
Fair Value Measurements Recurring [Member] | Trading account liabilities [Member]
Reconciliation of the assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs
Reconciliation of liability balance at fair value on a recurring basis using significant unobservable inputs, beginning of period	(153)	(10)
Reconciliation of asset balance at fair value on a recurring basis using significant unobservable inputs, beginning of period				(14)
Total gains (losses) (realized/unrealized):
Included in income before taxes	34	2	34	6
Included in other comprehensive income
Purchases/additions, liabilities			(2)
Sales	3		3
Transfers into Level 3, Liability
Transfers into Level 3, Assets			(153)
Reconciliation of liability balance at fair value on a recurring basis using significant unobservable inputs, ending of period	(118)	(8)	(118)	(8)
Changes in unrealized (gains) included in income before taxes for assets and liabilities still held at end of period	34	2	34	6
Fair Value Measurements Recurring [Member] | Other liabilities [Member]
Reconciliation of the assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs
Reconciliation of liability balance at fair value on a recurring basis using significant unobservable inputs, beginning of period	(63)	(47)
Reconciliation of asset balance at fair value on a recurring basis using significant unobservable inputs, beginning of period			(51)	(36)
Total gains (losses) (realized/unrealized):
Included in income before taxes	(9)	6	(21)	(5)
Included in other comprehensive income
Transfers into Level 3, Liability
Transfers into Level 3, Assets
Reconciliation of liability balance at fair value on a recurring basis using significant unobservable inputs, ending of period	(72)	(41)	(72)	(41)
Changes in unrealized (gains) included in income before taxes for assets and liabilities still held at end of period	$ (9)	$ 6	$ (21)	$ (5)