Derivative Instruments and Hedging Activities - Effect of Derivative Instruments Designated as Fair Value and Cash Flow Hedges and Not Designated as Hedges on Consolidated Statement of Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Derivatives not designated as hedges | Foreign exchange contracts | Cost of services/sales
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Recognized in Income	$ (9)	$ 6
Cash Flow Hedging | Derivatives designated as hedges
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Recognized in Income	57	(18)
Cash Flow Hedging | Derivatives designated as hedges | Foreign exchange contracts | Cost of services/sales
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Recognized in Income	(1)	(2)
Cash Flow Hedging | Derivatives designated as hedges | Cross currency swaps | Interest expense
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Recognized in Income	$ 58	$ (16)