Financial Instruments (Free-standing derivatives) (Details) (Free Standing Derivatives [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Free standing derivatives
Gain (loss) on derivatives	$ (1,127)	$ (644)
Interest Rate Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	(82)	(211)
Foreign Exchange Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	(1,065)	(428)
Other Contract [Member]
Free standing derivatives
Gain (loss) on derivatives	$ 20	$ (5)