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, 2020	Mar. 31, 2019
Numerator:
Net income	$ 28,111	$ 22,259
Denominator:
Denominator for basic earnings per share–weighted average common shares	26,070	25,873
Effect of dilutive stock options	96	125
Effect of other common stock equivalents	326	324
Denominator for diluted earnings per share–adjusted weighted average common shares	26,492	26,322
Basic Earnings Per Share	$ 1.08	$ 0.86
Diluted Earnings Per Share	$ 1.06	$ 0.85