Earnings Per Share - Computation of Basic and Diluted Earnings Per Share for Continuing Operations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Income from continuing operations	$ 20,096	$ 18,006	$ 78,437	$ 72,185
Basic
Weighted average common shares outstanding	54,403	54,268	54,372	54,215
Diluted
Stock options	738	1,279	825	1,267
Restricted stock awards	135	185	192	212
Contingent shares	84	84	84	84
Diluted weighted average common shares outstanding	55,360	55,816	55,473	55,778
Basic earnings per share from continuing operations	$ 0.37	$ 0.33	$ 1.44	$ 1.33
Diluted earnings per share from continuing operations	$ 0.36	$ 0.32	$ 1.41	$ 1.29