Consolidated Statements of Income - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Revenue		$ 1,748,919	$ 1,831,732	$ 1,838,070	$ 1,773,912	$ 1,684,131	$ 1,721,024	$ 1,709,132	$ 1,625,777	$ 7,192,633	$ 6,740,064	$ 5,062,528
Cost of goods sold										4,359,104	4,088,151	2,987,126
Gross margin		697,327	712,779	723,944	699,479	664,559	664,411	671,059	651,884	2,833,529	2,651,913	2,075,402
Facility and warehouse expenses										556,041	526,291	425,081
Distribution expenses										602,897	577,341	431,947
Selling, general and administrative expenses										828,333	762,888	597,052
Restructuring and acquisition related expenses										(19,511)	(14,806)	(10,173)
Depreciation and amortization										122,120	120,719	80,969
Operating income		151,671	166,745	200,285	185,926	146,250	156,188	173,596	173,834	704,627	649,868	530,180
Other expense (income):
Interest expense										(57,860)	(64,542)	(51,184)
Loss on debt extinguishment										0	324	2,795
Change in fair value of contingent consideration liabilities										(454)	1,851	(2,504)
Interest and other income, net										(2,717)	(1,035)	(2,130)
Total other expense, net										55,597	61,980	54,353
Income before provision for income taxes										649,030	587,888	475,827
Provision for income taxes										219,703	204,264	164,204
Equity in earnings of unconsolidated subsidiaries										(6,104)	(2,105)	0
Net income		$ 95,060	$ 101,346	$ 119,722	$ 107,095	$ 80,469	$ 91,515	$ 104,882	$ 104,653	$ 423,223	$ 381,519	$ 311,623
Earnings per share:
Basic	[1]									$ 1.39	$ 1.26	$ 1.04
Diluted	[1]									$ 1.38	$ 1.25	$ 1.02

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