Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ 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	$ 604,244	$ 554,814	$ 1,939,191	$ 1,600,633
Cost of sales	478,343	433,594	1,522,101	1,224,312
Gross profit	125,901	121,220	417,090	376,321
Selling, general and administrative expenses	80,548	73,293	247,829	206,225
Operating profit	45,353	47,927	169,261	170,096
Interest expense, net	1,720	311	4,481	1,162
Income before income taxes	43,633	47,616	164,780	168,934
Provision for income taxes	9,821	15,478	36,408	53,514
Net income	$ 33,812	$ 32,138	$ 128,372	$ 115,420
Net income per common share:
Basic (in usd per share)	$ 1.34	$ 1.28	$ 5.09	$ 4.62
Diluted (in usd per share)	$ 1.33	$ 1.26	$ 5.03	$ 4.56
Weighted average common shares outstanding:
Basic (in shares)	25,235	25,060	25,208	24,993
Diluted (in shares)	25,504	25,459	25,509	25,332