Condensed Consolidated Statements of Income and Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Net sales	$ 4,095,906	$ 3,941,743	$ 12,101,725	$ 11,559,648
Cost of goods sold	2,869,016	2,743,142	8,479,402	8,091,124
Gross profit	1,226,890	1,198,601	3,622,323	3,468,524
Operating expenses:
Selling, administrative and other expenses	940,259	869,562	2,717,416	2,522,223
Depreciation and amortization	40,276	37,682	117,640	108,247
Total operating expenses	980,535	907,244	2,835,056	2,630,470
Income before income taxes	246,355	291,357	787,267	838,054
Income taxes	87,913	106,031	278,693	303,334
Net income	$ 158,442	$ 185,326	$ 508,574	$ 534,720
Basic net income per common share (usd per share)	$ 1.08	$ 1.24	$ 3.45	$ 3.58
Diluted net income per common share (usd per share)	1.08	1.24	3.44	3.56
Dividends declared per common share (usd per share)	$ 0.675	$ 0.6575	$ 2.025	$ 1.9725
Weighted average common shares outstanding (in shares)	146,720	148,899	147,312	149,243
Dilutive effect of stock options and non-vested restricted stock awards (in shares)	502	828	561	781
Weighted average common shares outstanding - assuming dilution (in shares)	147,222	149,727	147,873	150,024
Comprehensive income	$ 202,897	$ 201,981	$ 644,661	$ 599,828