Indebtedness (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017	Jan. 29, 2015
Debt Instrument [Line Items]
Line of Credit Facility, Description	In May 2019 and November 2019, we entered into amendments to our Third Amended and Restated Credit Agreement (as amended, the "Credit Agreement") with a syndicate of lenders. The Credit Agreement provides for an unsecured revolving credit facility expiring in May 2024, and includes: (a) a revolving credit loan facility of up to $1.00 billion at any time outstanding, and (b) a letter of credit facility of up to $100 million at any time outstanding (which is a sub-facility of the $1.00 billion revolving credit loan facility). The Credit Agreement also includes an accordion feature allowing an increase of the credit facility of up to an additional $200 million ($1.20 billion in the aggregate) at any time outstanding, subject to lender participation and the satisfaction of specified conditions. Borrowings outstanding under the Credit Agreement are due in May 2024, with prepayment permitted at any time. Proceeds may be used for working capital and general corporate purposes, including but not limited to certain business acquisitions and purchases under our share repurchase programs. The Credit Agreement provides certain restrictions on our ability to borrow, incur liens, sell assets and pay dividends, and contains certain leverage and interest coverage covenants
Repayment of long-term debt	$ 0	$ 75,000	$ 0
Description of Lessee Leasing Arrangements, Capital Leases	Capital lease obligations primarily related to the procurement of hardware and health care devices
Line of Credit Facility, Interest Rate Description	Generally, interest on revolving credit loans is payable at a variable rate based on LIBOR, prime, or the U.S. federal funds rate, plus a spread that varies depending on leverage ratios maintained. Unused commitment, letter of credit, and other fees are also payable under the Credit Agreement
Line of Credit Facility, Interest Rate at Period End	2.54%
Long-term Debt	$ 1,039,162	444,076
Letters of Credit Outstanding, Amount	30,000
Line of Credit Facility, Remaining Borrowing Capacity	$ 370,000
Debt Instrument, Covenant Compliance	As of December 28, 2019, we were in compliance with all debt covenants
General Discussion of Derivative Instruments and Hedging Activities	We are exposed to market risk from fluctuations in the variable interest rates on outstanding indebtedness under our Credit Agreement. In order to manage this exposure, we have entered into an interest rate swap agreement, with an initial notional amount of $600 million, to hedge the variability of cash flows associated with such interest obligations through May 2024. The interest rate swap has an effective start date of May 13, 2019, and is designated as a cash flow hedge, which effectively fixes the interest rate on the hedged indebtedness under our Credit Agreement at 3.06%
Derivative, Fair Value, Net	$ 17,000
Derivatives, Methods of Accounting, Hedging Derivatives [Policy Text Block]	Our interest rate swap agreement is accounted for in accordance with ASC Topic 815, Derivatives and Hedging. Such agreement is designated as a cash flow hedge and considered to be highly effective under hedge accounting principles. Therefore, the swap agreement is recognized in our consolidated balance sheets as either an asset or liability, measured at fair value. Changes in the fair value of the swap agreement are initially recorded in accumulated other comprehensive loss, net and then subsequently recognized in our consolidated statements of operations in the periods in which earnings are affected by the hedged item. All cash flows associated with the swap agreement are classified as operating activities in our consolidated statements of cash flows
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 500,000
Debt Instrument, Restrictive Covenants	The Master Note Purchase Agreement contains certain leverage and interest coverage ratio covenants and provides certain restrictions on our ability to borrow, incur liens, sell assets, and other customary terms
Long-term Debt	$ 425,000	425,000
Series 2015-A [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 225,000
Debt Instrument, Interest Rate, Stated Percentage				3.18%
Debt Instrument, Frequency of Periodic Payment	payable semiannually
Debt Instrument, Date of First Required Payment	Aug. 15, 2015
Debt Instrument, Maturity Date	Feb. 15, 2022
Series 2015-B [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 200,000
Debt Instrument, Interest Rate, Stated Percentage				3.58%
Debt Instrument, Maturity Date	Feb. 14, 2025
Series 2015-C [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 75,000
Debt Instrument, Maturity Date	Feb. 15, 2022
Repayment of long-term debt		75,000
Line of Credit [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 600,000	0
2014 Shelf Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument, Aggregate Principle Amount	1,500,000
Debt Instrument, Amount Uncommitted and Available for Sale	$ 1,000,000
Other [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Sep. 01, 2025
Long-term Debt	$ 14,162	$ 14,162
2019 Shelf Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument, Aggregate Principle Amount	1,050,000
Debt Instrument, Amount Uncommitted and Available for Sale	$ 1,050,000