Restructuring and Integration Costs - Additional Information (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018		Sep. 30, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring And Related Activities [Abstract]
Restructuring and integration costs	$ 28,000,000	[1]	$ 31,000,000		$ 63,000,000		$ 12,000,000		$ 134,000,000	$ 0	$ 11,000,000
Restructuring and related cost, anticipated cost	$ 56,000,000								$ 56,000,000

[1] Restructuring and integration costs primarily relate to costs to achieve our CPI. See Note 12, Restructuring and Integration Costs, for further discussion.