Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Net sales	$ 171,207	$ 144,806
Cost of sales	94,494	79,637
Gross profit	76,713	65,169
Selling, general and administrative expenses	28,959	23,269
Income from operations	47,754	41,900
Interest expense, net	229	204
Income before income taxes	47,525	41,696
Provision for income taxes	10,415	13,747
Net income	$ 37,110	$ 27,949
Basic earnings per common share	$ 1.26	$ 0.95
Basic weighted average common shares outstanding	29,427,578	29,363,210
Diluted earnings per common share	$ 1.25	$ 0.95
Diluted weighted average common shares outstanding	29,599,811	29,561,406
Comprehensive income	$ 37,110	$ 27,949