Financial Instruments (Fair value hedges) (Details) (Fair Value Hedges [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Fair value hedges
Hedge ineffectiveness gain (loss)	$ (74)	$ (303)
Hedge amount excluded from assessment of effectiveness	insignificant amounts	insignificant amounts
Interest Rate Contract [Member]
Fair value hedges
Gain (loss) on derivatives	(5,253)	708
Gain (loss) on hedged items	5,180	(1,041)
Foreign Exchange Contract [Member]
Fair value hedges
Gain (loss) on derivatives	(7)	(68)
Gain (loss) on hedged items	$ 6	$ 98