Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ (4,558)	$ (4,206)
Other comprehensive gain (loss) before reclassifications	(116)	(214)
Amounts reclassified from accumulated other comprehensive loss	210	334
Income taxes	(14)	(22)
Net other comprehensive (loss) income	80	98
Ending Balance	(4,478)	(4,108)
Currency Translation Adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(2,053)	(1,531)
Other comprehensive gain (loss) before reclassifications	(51)	(94)
Net other comprehensive (loss) income	(51)	(94)
Ending Balance	(2,104)	(1,625)
Unrealized Gain/(Loss) on Marketable Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		10
Other comprehensive gain (loss) before reclassifications	3	(10)
Net other comprehensive (loss) income	3	(10)
Ending Balance	3
Cash Flow Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(39)	(96)
Other comprehensive gain (loss) before reclassifications	(68)	(110)
Amounts reclassified from accumulated other comprehensive loss	80	140
Net other comprehensive (loss) income	12	30
Ending Balance	(27)	(66)
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	130	194
Income taxes	(14)	(22)
Net other comprehensive (loss) income	116	172
Ending Balance	$ (2,350)	$ (2,417)