Debt (Narrative) (Detail) € in Millions, £ in Millions, $ in Millions	May 04, 2020 USD ($)	Apr. 03, 2020 GBP (£) loan	Apr. 03, 2020 USD ($) loan	Apr. 03, 2020 EUR (€) loan	Feb. 24, 2020 GBP (£)	Jan. 03, 2020 USD ($)
Debt Instrument [Line Items]
Long-term Debt			$ 1,975.4			$ 1,843.2
Uncommitted Revolving Credit Facilities $75 million
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity			$ 75.0
Number Of Revolving Loan Facilities | loan		2	2	2
Uncommitted Revolving Credit Facilities 100 million euros
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity | €				€ 100.0
Number Of Revolving Loan Facilities | loan		1	1	1
Uncommitted Revolving Credit Facilities 55 million GBP
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity | £		£ 55.0			£ 55.0
Number Of Revolving Loan Facilities | loan		1	1	1
JPMorgan Chase Bank, N.A. [Member] | Revolving Credit Facility | Unsecured Debt [Member] | 2018 Credit Facility
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity			$ 1,750.0
JPMorgan Chase Bank, N.A. [Member] | Revolving Credit Facility, due May 2023 [Member] | Unsecured Debt [Member] | 2018 Credit Facility
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity			1,250.0
JPMorgan Chase Bank, N.A. [Member] | Delayed Draw Term Loan [Member] | Unsecured Debt [Member] | 2018 Credit Facility
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity			500.0
JPMorgan Chase Bank, N.A. [Member] | Additional Loan Facility [Member] | Unsecured Debt [Member] | 2018 Credit Facility
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity			$ 500.0
Subsequent Event [Member] | JPMorgan Chase Bank, N.A. [Member] | Term Loan, due July 2022 | Revolving Credit Facility | 2018 Credit Facility
Debt Instrument [Line Items]
Long-term Debt	$ 225.0