Earnings Per Share - Computation of Basic and Diluted Net Earnings (Loss) Per Share (Detail) - USD ($)
shares in Thousands, $ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Numerator:        
Net income $ 5,999 $ 14,511 $ 22,437 $ 36,652
Denominator:        
Denominator for basic earnings per share – weighted average shares (in shares) 20,704 20,716 20,696 20,726
Effect of dilutive securities:        
Employee stock options (in shares) 71 58 67 71
Denominator for diluted earnings per share - weighted average shares (in shares) 20,775 20,774 20,763 20,797