Financial Instruments (Cash flow hedges) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Cash Flow Hedge [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	$ (541)	$ 344	$ (426)	$ 545
Gain (loss) reclassified from AOCI into earnings	(534)	236	(600)	388
Pre-tax gain (loss) included in AOCI related to cash flow hedges of forecasted transactions	1,187		1,187
Expected gain (loss) to be recorded in the next 12 months	487
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
Maximum term of hedged forecasted transactions	20	21
Hedge ineffectiveness gain (loss)	(1)	(17)	3	12
Cash Flow Hedge [Member] | Interest Rate Contract [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	(52)	(141)	(79)	(117)
Gain (loss) reclassified from AOCI into earnings	(124)	(220)	(264)	(476)
Cash Flow Hedge [Member] | Foreign Exchange Contract [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	(489)	485	(347)	662
Gain (loss) reclassified from AOCI into earnings	(410)	445	(336)	864
Cash Flow Hedge [Member] | Commodity Contract [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	0	0	0	0
Gain (loss) reclassified from AOCI into earnings	0	11	0	0
Net Investment Hedge [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Hedge ineffectiveness gain (loss)	(260)	(377)	(480)	(655)
Net Investment Hedge [Member] | Foreign Exchange Contract [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	1,853	(2,605)	351	(3,406)
Gain (loss) reclassified from AOCI into earnings	(2)	(360)	(12)	(698)
Fair Value Hedges [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Hedge ineffectiveness gain (loss)	$ (82)	$ (130)	$ (187)	$ (203)