Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ (4,558)	$ (4,206)
Other comprehensive gain (loss) before reclassifications	(65)	(283)
Amounts reclassified from accumulated other comprehensive loss	164	219
Income taxes	(7)	(15)
Net other comprehensive (loss) income	92	(79)
Ending Balance	(4,466)	(4,285)
Currency Translation Adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(2,053)	(1,531)
Other comprehensive gain (loss) before reclassifications	17	(113)
Net other comprehensive (loss) income	17	(113)
Ending Balance	(2,036)	(1,644)
Unrealized Gain/(Loss) on Marketable Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		10
Other comprehensive gain (loss) before reclassifications	3	(18)
Net other comprehensive (loss) income	3	(18)
Ending Balance	3	(8)
Cash Flow Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(39)	(96)
Other comprehensive gain (loss) before reclassifications	(85)	(152)
Amounts reclassified from accumulated other comprehensive loss	94	118
Net other comprehensive (loss) income	9	(34)
Ending Balance	(30)	(130)
Pension and Other Postretirement Benefit Plans
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(2,466)	(2,589)
Amounts reclassified from accumulated other comprehensive loss	70	101
Income taxes	(7)	(15)
Net other comprehensive (loss) income	63	86
Ending Balance	$ (2,403)	$ (2,503)