Derivative Financial Instruments - Schedule of Total Value by Underlying Risk Recognized in Other Comprehensive Income and Reclassified from AOCI to Cost of Operations and Interest Expense, Net in Statement of Operations (Detail) - Designated as Hedging Instrument [Member] - Cash Flow Hedging [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Foreign Currency Hedges [Member]
Derivative Instruments Gain Loss [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss)	$ (11)	$ 5	$ (16)	$ 15
Foreign Currency Hedges [Member] | Cost of operations [Member]
Derivative Instruments Gain Loss [Line Items]
Loss (gain) reclassified from AOCI	(2)	$ 4	(2)	1
Foreign Currency Hedges [Member] | Other non-operating expense [Member]
Derivative Instruments Gain Loss [Line Items]
Ineffective portion and amount excluded from effectiveness testing: gain (loss) recognized in Other non-operating income (expense)	(1)		(3)	$ (1)
Interest Rate Hedges [Member]
Derivative Instruments Gain Loss [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss)	10
Interest Rate Hedges [Member] | Interest Expense [Member]
Derivative Instruments Gain Loss [Line Items]
Loss (gain) reclassified from AOCI	$ (1)		$ (1)