Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Assumptions Used for Estimating Fair Value of Employee Stock Options (Detail)

v3.6.0.2
Stock-Based Compensation - Assumptions Used for Estimating Fair Value of Employee Stock Options (Detail) - Employee Stock Options [Member]
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Expected dividend yield of stock 0.00% 0.00% 0.00%
Minimum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Risk-free interest rate 1.13% 1.46% 1.60%
Expected life of option (in years) 5 years 3 months 11 days 5 years 3 months 5 years 3 months 11 days
Expected volatility 0.68% 0.66% 0.66%
Maximum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Risk-free interest rate 1.61% 1.58% 1.70%
Expected life of option (in years) 5 years 3 months 15 days 5 years 3 months 22 days 5 years 3 months 29 days
Expected volatility 0.70% 0.67% 0.69%