Fair Value Measurements (Additional Fair Value Information Relating To The Company's Financial Instruments Outstanding) (Details) - USD ($) $ in Millions	Dec. 28, 2018	Dec. 29, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Outstanding	$ 1,968.5	$ 913.9
Uncommitted Facilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Outstanding	255.9	128.0
Long-term Debt, Fair Value	255.9	128.0
Promissory Notes And Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Promissory notes and other debt	1.0	1.2
Notes Payable, Fair Value Disclosure	1.0	1.2
Two Thousand Twenty Four Senior Notes [Member] | Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Outstanding	400.0	400.0
Notes Payable, Fair Value Disclosure	406.5	430.4
Two Thousand Twenty Eight Senior Notes [Member] | Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Outstanding	600.0	0.0
Notes Payable, Fair Value Disclosure	598.5	0.0
2014 Credit Facility [Member] | Revolving Credit Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Outstanding	0.0	389.0
Line of Credit Facility, Fair Value of Amount Outstanding	0.0	389.0
Two Thousand Twenty Three Senior Notes [Member] | Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Outstanding	300.0	0.0
Notes Payable, Fair Value Disclosure	300.8	$ 0.0
Term Loan [Member] | Term Loan, due May 2021 [Member] | Revolving Credit Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Outstanding	425.0
Long-term Debt, Fair Value	$ 425.0