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Share-Based Compensation - Summary of Weighted Average Assumptions Used for Options Granted (Detail) - Stock Option Plan [Member]
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected life (in years) 6 years 6 years 6 years 4 months 24 days
Expected volatility 28.30% 30.90% 32.40%
Risk-free interest rate 1.70% 1.80% 1.40%
Expected forfeiture rate 1.70% 3.00% 3.00%