Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net sales	$ 684,455	$ 547,483	$ 1,334,947	$ 1,045,819
Cost of sales	533,999	416,396	1,043,758	790,718
Gross profit	150,456	131,087	291,189	255,101
Selling, general and administrative expenses	86,368	68,047	167,281	132,932
Operating profit	64,088	63,040	123,908	122,169
Interest expense, net	1,660	414	2,761	851
Income before income taxes	62,428	62,626	121,147	121,318
Provision for income taxes	15,204	22,489	26,587	38,036
Net income	$ 47,224	$ 40,137	$ 94,560	$ 83,282
Net income per common share:
Basic (in usd per share)	$ 1.87	$ 1.61	$ 3.75	$ 3.34
Diluted (in usd per share)	$ 1.86	$ 1.59	$ 3.70	$ 3.29
Weighted average common shares outstanding:
Basic (in shares)	25,233	24,992	25,195	24,959
Diluted (in shares)	25,454	25,305	25,527	25,296