Annual report pursuant to Section 13 and 15(d)

Stock-based Expense - Awards Granted Assumptions (Detail)

v3.6.0.2
Stock-based Expense - Awards Granted Assumptions (Detail) - $ / shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate   1.50% 1.30%
Expected option life (in years)   4 years 7 months 6 days 4 years 4 months 24 days
Forfeiture rate   0.00%  
Expected volatility   42.30% 42.80%
Weighted-average grant date fair value (in dollars per share)   $ 7.42 $ 6.44
Market Based Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate 1.10% 1.10% 1.10%
Expected volatility 41.50% 38.70% 43.60%