Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ (4,558)	$ (4,206)
Other comprehensive gain (loss) before reclassifications	(114)	(419)
Amounts reclassified from accumulated other comprehensive loss	304	467
Income taxes	(20)	(35)
Net other comprehensive (loss) income	170	13
Ending Balance	(4,388)	(4,193)
Currency Translation Adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(2,053)	(1,531)
Other comprehensive gain (loss) before reclassifications	(26)	(260)
Net other comprehensive (loss) income	(26)	(260)
Ending Balance	(2,079)	(1,791)
Unrealized Gain/(Loss) on Marketable Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		10
Other comprehensive gain (loss) before reclassifications	(2)	(36)
Net other comprehensive (loss) income	(2)	(36)
Ending Balance	(2)	(26)
Cash Flow Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(39)	(96)
Other comprehensive gain (loss) before reclassifications	(86)	(123)
Amounts reclassified from accumulated other comprehensive loss	109	161
Net other comprehensive (loss) income	23	38
Ending Balance	(16)	(58)
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	195	306
Income taxes	(20)	(35)
Net other comprehensive (loss) income	175	271
Ending Balance	$ (2,291)	$ (2,318)