Financial Instruments (Free-standing derivatives) (Details) (Free Standing Derivatives [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Free standing derivatives
Gain (loss) on derivatives	$ 1,108	$ (686)
Interest Rate Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	11	(62)
Foreign Exchange Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	1,126	(720)
Other Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	$ (29)	$ 96