Financial Instruments (Fair value hedges) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair value hedges
Hedge ineffectiveness gain (loss)			$ (74)	$ (55)
Interest Rate Contract [Member]
Fair value hedges
Gain (loss) on derivatives			(24)	(82)
Interest Rate Contract [Member] | Fair Value Hedges [Member]
Fair value hedges
Gain (loss) on derivatives	341	(449)	2,056	(4,290)
Gain (loss) on hedged items	(350)	410	(2,129)	4,236
Foreign Exchange Contract [Member]
Fair value hedges
Gain (loss) on derivatives			(569)	(1,065)
Foreign Exchange Contract [Member] | Fair Value Hedges [Member]
Fair value hedges
Gain (loss) on derivatives	(8)	(4)	(11)	(11)
Gain (loss) on hedged items	$ 8	$ 3	$ 10	$ 10