Computation of Earnings Per Share - Summary of Calculation of Basic Earnings Per Common Share and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Net income	$ 11,387	$ 10,575
Denominator:
Denominator for basic earnings per share–weighted average common shares	25,225	24,998
Effect of dilutive stock options	118	48
Effect of other common stock equivalents	628	399
Denominator for diluted earnings per share–adjusted weighted average common shares	25,971	25,445
Basic Earnings Per Share	$ 0.45	$ 0.42
Diluted Earnings Per Share	$ 0.44	$ 0.42