Consolidated Statements of Operations (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net sales:
Total net sales	$ 1,936,478	$ 1,912,547	$ 6,049,264	$ 5,434,034
Costs of goods sold:
Total costs of goods sold	1,628,915	1,636,352	5,091,976	4,633,918
Gross profit	307,563	276,195	957,288	800,116
Operating expenses:
Selling and administrative expenses	245,155	223,215	756,598	613,767
Severance and restructuring expenses	808	2,662	9,962	3,712
Acquisition and integration related expenses	118	5,896	2,195	9,059
Earnings from operations	61,482	44,422	188,533	173,578
Non-operating (income) expense:
Interest expense, net	9,115	7,694	31,160	16,581
Other (income) expense, net	1,301	(538)	836	858
Earnings before income taxes	51,066	37,266	156,537	156,139
Income tax expense	12,160	10,134	37,285	39,682
Net earnings	$ 38,906	$ 27,132	$ 119,252	$ 116,457
Net earnings per share:
Basic	$ 1.11	$ 0.76	$ 3.40	$ 3.27
Diluted	$ 1.10	$ 0.76	$ 3.37	$ 3.23
Shares used in per share calculations:
Basic	35,077	35,512	35,123	35,631
Diluted	35,348	35,868	35,418	36,027
Products [Member]
Net sales:
Total net sales	$ 1,661,568	$ 1,668,880	$ 5,182,817	$ 4,729,887
Costs of goods sold:
Total costs of goods sold	1,500,312	1,519,240	4,688,497	4,315,464
Services [Member]
Net sales:
Total net sales	274,910	243,667	866,447	704,147
Costs of goods sold:
Total costs of goods sold	$ 128,603	$ 117,112	$ 403,479	$ 318,454