Financial Instruments (Fair value hedges) (Details) (Fair Value Hedges [Member], USD $) In Millions, unless otherwise specified	3 Months Ended			12 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Interest Rate Contract [Member]	Dec. 31, 2013 Interest Rate Contract [Member]	Mar. 31, 2014 Foreign Exchange Contract [Member]	Dec. 31, 2013 Foreign Exchange Contract [Member]
Fair value hedges
Gain (loss) on derivatives			$ 990	$ (914)	$ 2	$ (9)
Hedge ineffectiveness gain (loss)	$ (16)	$ (34)	$ (1,005)	$ 881	$ (3)	$ 8
Hedge Amounts Excluded From Assessment Of Effectiveness Insignificant Amounts	insignificant amounts	insignificant amounts