Financial Instruments (Cash flow hedges) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash Flow Hedge [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	$ 186	$ (45)
Gain (loss) reclassified from AOCI into earnings	65	(147)
Pre-tax gain (loss) included in AOCI related to cash flow hedges of forecasted transactions	(157)
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	191
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	19	20
Cash Flow Hedge [Member] | Interest Rate Contract [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	3	(11)
Gain (loss) reclassified from AOCI into earnings	(69)	(102)
Cash Flow Hedge [Member] | Foreign Exchange Contract [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	183	(34)
Gain (loss) reclassified from AOCI into earnings	134	(45)
Net Investment Hedge [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Hedge ineffectiveness gain (loss)	(142)	(166)
Net Investment Hedge [Member] | Foreign Exchange Contract [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	(1,033)	2,105
Gain (loss) reclassified from AOCI into earnings	10	(124)
Fair Value Hedges [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Hedge ineffectiveness gain (loss)	$ (16)	$ (29)