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Stock-based Compensation - Summary of Weighted-Average Assumptions Using Black-Scholes Option-Pricing Model (Detail) - Time-Based Options and SARs [Member]
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term to exercise (years), Time-Based awards 4 years 4 years 4 years
Expected volatility, Time-Based awards 25.61% 27.64% 26.63%
Risk-free interest rate, Time-Based awards 1.92% 1.30% 1.42%
Expected dividend yield, Time-Based awards 0.73% 0.82% 0.74%