Financial Instruments (Free-standing derivatives) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Free Standing Derivatives [Member]
Free standing derivatives
Gain (loss) on derivatives	$ (2,708)	$ 1,078
Interest Rate Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	(43)	0
Foreign Exchange Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	(2,660)	1,090
Other Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	$ (5)	$ (12)