Acquisition - Summary of Unaudited Pro Forma Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Business Combinations [Abstract]
Net sales	$ 166,380	$ 140,194	$ 544,279	$ 442,941
Net income	$ 29,471	$ 20,098	$ 109,401	$ 76,829
Basic earnings per common share	$ 0.50	$ 0.34	$ 1.86	$ 1.31
Diluted earnings per common share	$ 0.50	$ 0.34	$ 1.85	$ 1.30
Pro Forma Net sales				$ 475,076
Pro Forma Net income				$ 77,570
Pro Forma Basic earnings per common share				$ 1.32
Pro Forma Diluted earnings per common share				$ 1.31