Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Disaggregation of Revenue [Abstract]
Net sales		$ 2,508,767	$ 2,355,565	$ 7,316,862	$ 6,945,047
Total excluding Corporate TSA revenues [Member]
Disaggregation of Revenue [Abstract]
Net sales		2,487,024	2,355,565	7,256,621	6,945,047
Corporate TSA revenues [Member]
Disaggregation of Revenue [Abstract]
Net sales	[1]	21,743	0	60,241	0
North America [Member]
Disaggregation of Revenue [Abstract]
Net sales		1,857,419	1,757,912	5,307,480	4,992,089
North America [Member] | Total excluding Corporate TSA revenues [Member]
Disaggregation of Revenue [Abstract]
Net sales		1,856,342	1,757,912	5,303,382	4,992,089
North America [Member] | Corporate TSA revenues [Member]
Disaggregation of Revenue [Abstract]
Net sales		1,077	0	4,098	0
International [Member]
Disaggregation of Revenue [Abstract]
Net sales		651,348	597,653	2,009,382	1,952,958
International [Member] | Total excluding Corporate TSA revenues [Member]
Disaggregation of Revenue [Abstract]
Net sales		630,682	597,653	1,953,239	1,952,958
International [Member] | Corporate TSA revenues [Member]
Disaggregation of Revenue [Abstract]
Net sales		20,666	0	56,143	0
Healthcare Distribution [Member] | Total excluding Corporate TSA revenues [Member]
Disaggregation of Revenue [Abstract]
Net sales	[2]	2,349,693	2,236,267	6,878,730	6,650,901
Healthcare Distribution [Member] | Total excluding Corporate TSA revenues [Member] | Reportable Subsegments [Member]
Disaggregation of Revenue [Abstract]
Net sales	[2]	2,349,693	2,236,267	6,878,730	6,650,901
Healthcare Distribution [Member] | North America [Member] | Total excluding Corporate TSA revenues [Member] | Reportable Subsegments [Member]
Disaggregation of Revenue [Abstract]
Net sales		1,736,145	1,653,957	4,975,764	4,746,328
Healthcare Distribution [Member] | International [Member] | Total excluding Corporate TSA revenues [Member] | Reportable Subsegments [Member]
Disaggregation of Revenue [Abstract]
Net sales		613,548	582,310	1,902,966	1,904,573
Healthcare Distribution [Member] | Dental [Member] | Total excluding Corporate TSA revenues [Member] | Reportable Subsegments [Member]
Disaggregation of Revenue [Abstract]
Net sales	[2]	1,545,984	1,514,325	4,693,803	4,674,534
Healthcare Distribution [Member] | Dental [Member] | North America [Member] | Total excluding Corporate TSA revenues [Member] | Reportable Subsegments [Member]
Disaggregation of Revenue [Abstract]
Net sales		951,796	951,199	2,850,762	2,830,384
Healthcare Distribution [Member] | Dental [Member] | International [Member] | Total excluding Corporate TSA revenues [Member] | Reportable Subsegments [Member]
Disaggregation of Revenue [Abstract]
Net sales		594,188	563,126	1,843,041	1,844,150
Healthcare Distribution [Member] | Medical [Member] | Total excluding Corporate TSA revenues [Member] | Reportable Subsegments [Member]
Disaggregation of Revenue [Abstract]
Net sales	[2]	803,709	721,942	2,184,927	1,976,367
Healthcare Distribution [Member] | Medical [Member] | North America [Member] | Total excluding Corporate TSA revenues [Member] | Reportable Subsegments [Member]
Disaggregation of Revenue [Abstract]
Net sales		784,349	702,758	2,125,002	1,915,944
Healthcare Distribution [Member] | Medical [Member] | International [Member] | Total excluding Corporate TSA revenues [Member] | Reportable Subsegments [Member]
Disaggregation of Revenue [Abstract]
Net sales		19,360	19,184	59,925	60,423
Technology [Member] | Total excluding Corporate TSA revenues [Member]
Disaggregation of Revenue [Abstract]
Net sales	[3]	137,331	119,298	377,891	294,146
Technology [Member] | North America [Member] | Total excluding Corporate TSA revenues [Member]
Disaggregation of Revenue [Abstract]
Net sales		120,197	103,955	327,618	245,761
Technology [Member] | International [Member] | Total excluding Corporate TSA revenues [Member]
Disaggregation of Revenue [Abstract]
Net sales		$ 17,134	$ 15,343	$ 50,273	$ 48,385

[1] Corporate TSA revenues represents sales of certain products to Covetrus under the transition services agreement entered into in connection with the Animal Health Spin-off, which we expect to continue through August 2020.

[2] Consists of consumable products, small equipment, laboratory products, large equipment, equipment repair services, branded and generic pharmaceuticals, vaccines, surgical products, diagnostic tests, infection-control products and vitamins.

[3] Consists of practice management software and other value-added products, which are distributed primarily to health care providers, and financial services on a non-recourse basis, e-services, continuing education services for practitioners, consulting and other services.