Financial Instruments (Cash flow hedges) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Cash Flow Hedge [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	$ 292	$ (397)	$ 247	$ 261
Gain (loss) reclassified from AOCI into earnings	72	(389)	(75)	88
Pre-tax gain (loss) included in AOCI related to cash flow hedges of forecasted transactions	515		515
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	330
Gain Loss Related To Hedge Forecasted Transactions And Firm Commitments That Did Not Occur By End Of Originally Specified Period			insignificant gains and losses insignificant gains and losses	insignificant gains and losses insignificant gains and losses
Maximum term of hedged forecasted transactions			19	20
Hedge ineffectiveness gain (loss)	0	(1)	1	3
Cash Flow Hedge [Member] | Interest Rate Contract [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	20	(52)	9	(79)
Gain (loss) reclassified from AOCI into earnings	(92)	(124)	(194)	(264)
Cash Flow Hedge [Member] | Foreign Exchange Contract [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	272	(345)	238	340
Gain (loss) reclassified from AOCI into earnings	164	(265)	119	352
Cash Flow Hedge [Member] | Commodity Contract [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	0	0
Gain (loss) reclassified from AOCI into earnings	0	0
Net Investment Hedge [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Hedge ineffectiveness gain (loss)	(187)	(260)	(353)	(480)
Net Investment Hedge [Member] | Foreign Exchange Contract [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	412	1,853	2,517	351
Gain (loss) reclassified from AOCI into earnings	15	(2)	(109)	(12)
Fair Value Hedges [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Hedge ineffectiveness gain (loss)	$ 14	$ (82)	$ (15)	$ (187)