Financial Instruments (Free-standing derivatives) (Details) (Free Standing Derivatives [Member], Nondesignated as Hedges, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Free standing derivatives
Gain (loss) on derivatives	$ (2,045)	$ (449)
Interest Rate Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	(58)	(111)
Foreign Exchange Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	(2,034)	(595)
Other Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	$ 47	$ 257