Derivative Instruments and Hedging Activities - Effect of Derivative Instruments Designated as Fair Value Hedges and Not Designated as Hedges on Consolidated Statement of Income (Loss) (Detail) - Cash Flow Hedging - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivatives designated as hedges | Cross currency swap | Interest
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Recognized in Income	$ 73	$ (31)	$ (64)
Not Designated as Hedging Instrument
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Recognized in Income	(34)	(246)	(154)
Not Designated as Hedging Instrument | Cross currency swap | Interest
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Recognized in Income	(8)
Not Designated as Hedging Instrument | Foreign exchange contracts | Cost of services/sales
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Recognized in Income	$ (26)	$ (246)	$ (154)