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	$ 1,089	$ (902)
Interest Rate Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	11	(61)
Foreign Exchange Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	1,090	(853)
Other Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	$ (12)	$ 12