Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Net sales	$ 650,492	$ 498,336
Cost of sales	509,759	374,322
Gross profit	140,733	124,014
Selling, general and administrative expenses	80,913	64,885
Operating profit	59,820	59,129
Interest expense, net	1,101	437
Income before income taxes	58,719	58,692
Provision for income taxes	11,383	15,547
Net income	$ 47,336	$ 43,145
Net income per common share:
Basic (in usd per share)	$ 1.88	$ 1.73
Diluted (in usd per share)	$ 1.86	$ 1.71
Weighted average common shares outstanding:
Basic (in shares)	25,149	24,906
Diluted (in shares)	25,465	25,255