Financial Instruments (Cash flow hedges) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Summary Of Cash Flow Hedge Activity [Line Items]
Pre-tax gain (loss) included in AOCI related to cash flow hedges of forecasted transactions			$ 213
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months			$ (189)
Maximum term of hedged forecasted transactions			P17Y	P18Y
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	$ (126)	$ (293)	$ (794)	$ (267)
Gain (loss) reclassified from AOCI into earnings	(113)	(430)	(699)	(569)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Interest Rate Contract
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	10	9	0	0
Gain (loss) reclassified from AOCI into earnings	(39)	(53)	(100)	(182)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Foreign Exchange Contract
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	(136)	(302)	(794)	(267)
Gain (loss) reclassified from AOCI into earnings	$ (75)	$ (377)	$ (600)	$ (387)