Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Net sales	$ 898,500	$ 811,311	$ 2,617,283	$ 2,455,015
Cost of sales	640,569	576,308	1,854,408	1,745,283
Gross profit	257,931	235,003	762,875	709,732
Selling and administrative expenses	153,391	142,666	447,427	421,812
Operating income	104,540	92,337	315,448	287,920
Interest and other non-operating expenses, net	5,498	4,931	18,538	14,449
Income before income taxes and equity earnings	99,042	87,406	296,910	273,471
Provision for income taxes	19,593	18,206	53,569	55,989
Equity earnings in unconsolidated investments, net	76	61	210	167
Net income	$ 79,525	$ 69,261	$ 243,551	$ 217,649
Earnings per share:
Basic (in dollars per share)	$ 1.99	$ 1.71	$ 6.13	$ 5.39
Diluted (in dollars per share)	$ 1.95	$ 1.66	$ 5.97	$ 5.20
Weighted average shares outstanding: [Abstract]
Basic (in shares)	39,933	40,422	39,750	40,416
Diluted (in shares)	40,865	41,797	40,811	41,831
Cash dividends declared per common share	$ 0.55	$ 0.45	$ 1.55	$ 1.27