Condensed Consolidated Statements of Income and Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Net sales	$ 3,905,641	$ 3,718,267
Cost of goods sold	2,749,920	2,613,796
Gross profit	1,155,721	1,104,471
Operating expenses:
Selling, administrative and other expenses	873,814	823,172
Depreciation and amortization	38,132	34,654
Total operating expenses	911,946	857,826
Income before income taxes	243,775	246,645
Income taxes	83,615	88,620
Net income	$ 160,160	$ 158,025
Basic net income per common share (usd per share)	$ 1.08	$ 1.06
Diluted net income per common share (usd per share)	1.08	1.05
Dividends declared per common share (usd per share)	$ 0.675	$ 0.658
Weighted average common shares outstanding (in shares)	148,154	149,593
Dilutive effect of stock options and non-vested restricted stock awards (in shares)	634	749
Weighted average common shares outstanding - assuming dilution (in shares)	148,788	150,342
Comprehensive income	$ 222,912	$ 226,124