Quarterly Results (unaudited) (Unaudited Operating Data) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Data [Abstract]
Sales	$ 1,621,234		$ 1,728,025		$ 1,714,969		$ 1,585,009		$ 1,488,385		$ 1,601,558		$ 1,562,849		$ 1,529,392		$ 6,649,237	$ 6,182,184	$ 5,788,816
Gross profit	819,300		879,163		871,875		798,663		750,384		805,493		779,861		761,680		3,369,001	3,097,418	2,837,349
Operating income	255,760		300,380		296,261		251,084		222,971		263,318		243,603		247,501		1,103,485	977,393	866,766
Net income	$ 152,347		$ 186,489		$ 177,127		$ 154,329		$ 132,802		$ 159,332		$ 146,120		$ 147,492		$ 670,292	$ 585,746	$ 507,673
Earnings per share - basic	$ 1.43	[1]	$ 1.72	[1]	$ 1.61	[1]	$ 1.38	[1]	$ 1.16	[1]	$ 1.34	[1]	$ 1.17	[1]	$ 1.16	[1]	$ 6.14	$ 4.83	$ 3.77
Earnings per share - assuming dilution	$ 1.40	[1]	$ 1.69	[1]	$ 1.58	[1]	$ 1.36	[1]	$ 1.14	[1]	$ 1.32	[1]	$ 1.15	[1]	$ 1.14	[1]	$ 6.03	$ 4.75	$ 3.71

[1] Earnings per share amounts are computed independently for each quarter and annual period. The quarterly earnings per share amounts may not sum to equal the full-year earnings per share.