Financial Risk Factors - Schedule of Assets (Liabilities) Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) - Fair Value, Inputs, Level 3 [Member] $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	$ (12)
Contingent consideration on business combination	12
Amount of total losses for the period included in earnings attributable to assets still held at the reporting date	$ 0