Condensed Consolidating Statements of Income (Details) - 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
Condensed Financial Statements, Captions [Line Items]
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)
Intercompany interest (income) expense, net									0	0	0
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
Income (Loss) from Subsidiaries, Net of Tax									0	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
Parent
Condensed Financial Statements, Captions [Line Items]
Revenue									0	0	0
Cost of goods sold									0	0	0
Gross margin									0	0	0
Facility and warehouse expenses									0	0	0
Distribution expenses									0	0	0
Selling, general and administrative expenses									32,946	25,770	26,778
Restructuring and acquisition related expenses									0	0	0
Depreciation and amortization									154	218	250
Operating income									(33,100)	(25,988)	(27,028)
Other expense (income):
Interest expense									(47,626)	(50,636)	(42,442)
Intercompany interest (income) expense, net									(41,904)	(48,556)	(45,459)
Loss on debt extinguishment										324	2,795
Change in fair value of contingent consideration liabilities									0	0	0
Interest and other income, net									99	230	252
Total other expense, net									5,821	2,634	30
Income before provision for income taxes									(38,921)	(28,622)	(27,058)
Provision for income taxes									(16,054)	(10,536)	(7,193)
Equity in earnings of unconsolidated subsidiaries									(1,000)	0	331,488
Income (Loss) from Subsidiaries, Net of Tax									447,090	399,605
Net income									423,223	381,519	311,623
Guarantors
Condensed Financial Statements, Captions [Line Items]
Revenue									4,965,355	4,649,391	3,576,269
Cost of goods sold									3,010,820	2,813,427	2,100,804
Gross margin									1,954,535	1,835,964	1,475,465
Facility and warehouse expenses									408,828	382,937	323,042
Distribution expenses									408,112	389,430	297,908
Selling, general and administrative expenses									490,530	460,516	377,481
Restructuring and acquisition related expenses									13,962	8,628	1,406
Depreciation and amortization									82,058	81,253	55,802
Operating income									551,045	513,200	419,826
Other expense (income):
Interest expense									(669)	(635)	(640)
Intercompany interest (income) expense, net									28,944	23,865	21,978
Loss on debt extinguishment										0	0
Change in fair value of contingent consideration liabilities									(230)	2,081	744
Interest and other income, net									(7,644)	(6,278)	(2,858)
Total other expense, net									22,199	16,141	19,016
Income before provision for income taxes									528,846	497,059	400,810
Provision for income taxes									205,176	190,456	151,369
Equity in earnings of unconsolidated subsidiaries									59	40	22,050
Income (Loss) from Subsidiaries, Net of Tax									24,632	28,846
Net income									348,361	335,489	271,491
Non-Guarantors
Condensed Financial Statements, Captions [Line Items]
Revenue									2,357,655	2,221,831	1,598,832
Cost of goods sold									1,478,661	1,405,882	998,895
Gross margin									878,994	815,949	599,937
Facility and warehouse expenses									147,213	143,354	102,039
Distribution expenses									194,785	187,911	134,039
Selling, general and administrative expenses									304,857	276,602	192,793
Restructuring and acquisition related expenses									5,549	6,178	8,767
Depreciation and amortization									39,908	39,248	24,917
Operating income									186,682	162,656	137,382
Other expense (income):
Interest expense									(9,565)	(13,271)	(8,102)
Intercompany interest (income) expense, net									12,960	24,691	23,481
Loss on debt extinguishment										0	0
Change in fair value of contingent consideration liabilities									(224)	(230)	(3,248)
Interest and other income, net									4,828	5,013	476
Total other expense, net									27,577	43,205	35,307
Income before provision for income taxes									159,105	119,451	102,075
Provision for income taxes									30,581	24,344	20,028
Equity in earnings of unconsolidated subsidiaries									(5,163)	(2,145)	0
Income (Loss) from Subsidiaries, Net of Tax									0	0
Net income									123,361	92,962	82,047
Eliminations
Condensed Financial Statements, Captions [Line Items]
Revenue									(130,377)	(131,158)	(112,573)
Cost of goods sold									(130,377)	(131,158)	(112,573)
Gross margin									0	0	0
Facility and warehouse expenses									0	0	0
Distribution expenses									0	0	0
Selling, general and administrative expenses									0	0	0
Restructuring and acquisition related expenses									0	0	0
Depreciation and amortization									0	0	0
Operating income									0	0	0
Other expense (income):
Interest expense									0	0	0
Intercompany interest (income) expense, net									0	0	0
Loss on debt extinguishment										0	0
Change in fair value of contingent consideration liabilities									0	0	0
Interest and other income, net									0	0	0
Total other expense, net									0	0	0
Income before provision for income taxes									0	0	0
Provision for income taxes									0	0	0
Equity in earnings of unconsolidated subsidiaries									0	0	(353,538)
Income (Loss) from Subsidiaries, Net of Tax									(471,722)	(428,451)
Net income									$ (471,722)	$ (428,451)	$ (353,538)