Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net sales	$ 166,380	$ 140,194	$ 544,279	$ 442,941
Cost of sales	99,170	84,910	309,241	250,473
Gross profit	67,210	55,284	235,038	192,468
Selling, general and administrative expenses	28,132	24,919	90,603	75,409
Income from operations	39,078	30,365	144,435	117,059
Interest (income) expense, net	(222)	59	377	515
Income before income taxes	39,300	30,306	144,058	116,544
Provision for income taxes	9,829	10,208	34,657	39,715
Net income	$ 29,471	$ 20,098	$ 109,401	$ 76,829
Basic earnings per common share	$ 0.50	$ 0.34	$ 1.86	$ 1.31
Basic weighted average common shares outstanding	58,741,973	58,808,098	58,785,546	58,771,444
Diluted earnings per common share	$ 0.50	$ 0.34	$ 1.85	$ 1.30
Diluted weighted average common shares outstanding	59,084,117	59,156,432	59,111,303	59,126,994
Comprehensive income	$ 29,471	$ 20,098	$ 109,401	$ 76,829