Supplemental Information (Derivatives and Hedging - Cash Flow Hedges) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	$ 12	$ 446	$ (45)	$ (637)
Gain (loss) reclassified from AOCI into earnings	14	415	(71)	(582)
Interest Rate Contracts
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	12	(7)	31	(10)
Gain (loss) reclassified from AOCI into earnings	(26)	(22)	(55)	(61)
Currency Exchange Contracts
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	1	452	(77)	(625)
Gain (loss) reclassified from AOCI into earnings	40	437	(13)	(520)
Commodity Contracts
Summary Of Cash Flow Hedge Activity [Line Items]
Gain (loss) recognized in AOCI	(1)	1	0	(2)
Gain (loss) reclassified from AOCI into earnings	$ (1)	$ 0	$ (3)	$ (1)