Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Net sales	$ 2,475,807	$ 2,147,770	$ 1,678,898
Cost of sales	1,955,463	1,654,656	1,249,995
Gross profit	520,344	493,114	428,903
Selling, general and administrative expenses	321,556	278,833	228,053
Operating profit	198,788	214,281	200,850
Interest expense, net	6,436	1,437	1,678
Income before income taxes	192,352	212,844	199,172
Provision for income taxes	43,801	79,960	69,501
Net income	$ 148,551	$ 132,884	$ 129,671
Net income per common share:
Basic (in usd per share)	$ 5.90	$ 5.31	$ 5.26
Diluted (in usd per share)	$ 5.83	$ 5.24	$ 5.20
Weighted average common shares outstanding:
Basic (in shares)	25,178	25,020	24,631
Diluted (in shares)	25,463	25,375	24,933