Share-Based Compensation - Summary of Outstanding and Exercisable Options and SARs (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of SARs outstanding
Fair value of SARs vested	$ 8,000,000	$ 3,000,000	$ 8,000,000
Income tax benefit	$ 11,000,000	9,000,000	11,000,000
Vesting period for SARs (years)	2 years 2 months 12 days
SARs
Summary of SARs outstanding
Aggregate intrinsic value, Outstanding	$ 70,000,000
Aggregate intrinsic value, Exercisable	$ 47,000,000
Weighted-average remaining contractual term, Outstanding	6 years 1 month 6 days
Weighted-average remaining contractual term, Exercisable	4 years 8 months 12 days
Intrinsic value of SARs exercised	$ 14,000,000	6,000,000	$ 11,000,000
Cash received from the exercise of SARs	12,000,000	6,000,000
Income tax benefit	$ 3,000,000	$ 1,000,000
Maximum
Summary of SARs outstanding
Vesting period for SARs (years)	4 years