Derivative Financial Instruments - Schedule of Total Value by Underlying Risk Recognized in Other Comprehensive Income and Reclassified from AOCI to Statement of Operations (Detail) - USD ($) $ in Millions		3 Months Ended						9 Months Ended
		Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments Gain Loss [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss)		$ (41)	$ (16)	$ (58)	$ (9)	$ (23)	$ (1)
Revenues	[1]	2,121			2,289			$ 6,469	$ 4,632
Cost of operations		2,173			1,986			6,140	3,948
Interest expense, net		(108)			(86)			(300)	(169)
Designated as Hedging Instrument [Member] | Foreign Exchange Hedges [Member]
Derivative Instruments Gain Loss [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss)		(25)			(11)			(29)	(16)
Revenues		(2)						(7)
Cost of operations		(3)			(2)			(2)	(2)
Designated as Hedging Instrument [Member] | Interest Rate Hedges [Member]
Derivative Instruments Gain Loss [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss)		(9)			10			(52)
Interest expense, net		$ (1)			(1)			(4)	(1)
Derivatives not Designated as Hedges [Member] | Foreign Exchange Hedges [Member]
Derivative Instruments Gain Loss [Line Items]
Revenues								$ 2
Cost of operations					$ (2)				$ (12)

[1] Intercompany amounts have been eliminated in consolidation.