Fair Value Measurements (Additional Fair Value Information Relating To Company's Financial Instruments Outstanding) (Detail) - USD ($) $ in Millions	Sep. 29, 2017	Dec. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total debt	$ 695.8	$ 619.9
Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes Payable, Noncurrent	400.0	400.0
Note Payable Fair Value	427.1	410.6
Uncommitted Facilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total debt	135.0	130.0
Long-term Debt, Fair Value	135.0	130.0
Promissory Notes And Other Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes Payable, Noncurrent	0.9	0.5
Note Payable Fair Value	1.3	0.8
Total debt	1.3	0.8
Two Thousand Fourteen Credit Facility [Member] | Revolving Credit Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total debt	164.0	94.0
Line of Credit Facility, Fair Value of Amount Outstanding	$ 164.0	$ 94.0