Reconciliation of Net Income and Weighted-Average Shares of Common Stock Outstanding for Purposes of Calculating Basic and Diluted Earnings Per Share (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Numerator:        
Net income $ 8,777 $ 4,072 $ 18,929 $ 15,070
Denominator:        
Weighted average shares outstanding - basic 43,944 44,132 44,026 44,175
Dilutive effect of share-based awards 81 373 157 245
Weighted average shares outstanding - diluted 44,025 44,505 44,183 44,420
Earnings per share:        
Basic $ 0.20 $ 0.09 $ 0.43 $ 0.34
Diluted $ 0.20 $ 0.09 $ 0.43 $ 0.34