Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Sales	$ 8,977,726	$ 8,593,096	$ 7,966,674
Cost of goods sold, including warehouse and distribution expenses	4,257,043	4,084,085	3,804,031
Gross profit	4,720,683	4,509,011	4,162,643
Selling, general and administrative expenses	2,995,283	2,809,805	2,648,622
Operating income	1,725,400	1,699,206	1,514,021
Other income (expense):
Interest expense	(91,349)	(70,931)	(57,129)
Interest income	2,347	4,224	2,340
Other, net	1,406	4,692	1,134
Total other expense	(87,596)	(62,015)	(53,655)
Income before income taxes	1,637,804	1,637,191	1,460,366
Provision for income taxes	504,000	599,500	529,150
Net income	$ 1,133,804	$ 1,037,691	$ 931,216
Earnings per share-basic:
Earnings per share - basic	$ 12.82	$ 10.87	$ 9.32
Weighted-average common shares outstanding - basic	88,426	95,447	99,965
Earnings per share-assuming dilution:
Earnings per share - assuming dilution	$ 12.67	$ 10.73	$ 9.17
Weighted-average common shares outstanding - assuming dilution	89,502	96,720	101,514