Fair Value Measurements (Additional Fair Value Information Relating To Company's Financial Instruments Outstanding) (Detail) - USD ($) $ in Millions	Jun. 29, 2018	Dec. 29, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, Notes, Credit Facilities	$ 1,286.6	$ 913.9
Uncommitted Facilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, Notes, Credit Facilities	0.0	128.0
Long-term Debt, Fair Value	0.0	128.0
Promissory Notes And Other Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Note Payable Fair Value	1.3	1.2
Promissory Notes and Other Debt, Current and Noncurrent	1.3	1.2
2023 Senior Notes | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, Notes, Credit Facilities	300.0	0.0
Note Payable Fair Value	300.4	0.0
2024 Senior Notes | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, Notes, Credit Facilities	400.0	400.0
Note Payable Fair Value	408.1	430.4
2028 Senior Notes | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, Notes, Credit Facilities	600.0	0.0
Note Payable Fair Value	600.1	0.0
2014 Credit Facility, retired | Revolving Credit Facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, Notes, Credit Facilities	0.0	389.0
Line of Credit Facility, Fair Value of Amount Outstanding	$ 0.0	$ 389.0