Debt and Credit Facilities (Narrative) (Details) $ / shares in Units, shares in Millions				3 Months Ended	9 Months Ended
	May 21, 2020 USD ($) Trading_day $ / shares shares	May 06, 2020 USD ($)	Sep. 20, 2019 USD ($)	Oct. 02, 2020 USD ($) $ / shares	Oct. 02, 2020 USD ($) $ / shares	Sep. 27, 2019 USD ($)	Oct. 02, 2020 EUR (€)	Dec. 31, 2019 USD ($)	Sep. 20, 2019 EUR (€)
Debt Instrument [Line Items]
Unamortized debt issuance costs				$ 115,000,000.0	$ 115,000,000.0
Total borrowings under term loan			$ 1,300,000,000
Senior unsecured revolving credit facility			$ 250,000,000.0
Payments of debt restructuring		$ 2,800,000
Deferred debt restructuring costs		$ 2,300,000
Proceeds from convertible debt					$ 517,500,000	$ 0
Conversion price (in USD per share) | $ / shares				$ 21.01	$ 21.01
Long-term debt				$ 1,759,300,000	$ 1,759,300,000			$ 1,324,900,000
US term loan due 2022
Debt Instrument [Line Items]
Debt instrument, term			3 years
Term loan			$ 650,000,000.0
Loan facility interest rates				4.30%	4.00%
Long-term debt			$ 650,000,000.0	$ 647,900,000	$ 647,900,000			648,700,000
Debt issuance costs				$ 2,100,000	$ 2,100,000			1,300,000
Euro term loan due 2022
Debt Instrument [Line Items]
Debt instrument, term			3 years
Term loan | €							€ 600,000,000.0		€ 600,000,000.0
Loan facility interest rates				3.40%	3.00%
Long-term debt				$ 701,500,000	$ 701,500,000			672,000,000.0
Debt issuance costs				1,500,000	1,500,000			900,000
Senior multi-currency revolving credit facility ($250.0 million borrowing capacity) (the “Revolving Credit Facility”)
Debt Instrument [Line Items]
Revolving credit facility maximum borrowing capacity				250,000,000.0	250,000,000.0
Revolving credit facility increase				$ 200,000,000.0	$ 200,000,000.0
Loan facility interest rates				3.80%	3.50%
Senior multi-currency revolving credit facility ($250.0 million borrowing capacity) (the “Revolving Credit Facility”) | Standby letters of credit
Debt Instrument [Line Items]
Revolving credit facility maximum borrowing capacity				$ 20,000,000.0	$ 20,000,000.0
Outstanding borrowings				$ 0	$ 0
Convertible Debt | 2.375% convertible senior notes over allotment option
Debt Instrument [Line Items]
Term loan	$ 67,500,000
Convertible Debt | Convertible senior notes, net of deferred debt issuance costs of $11.3 million and unamortized discount of $100.1 million
Debt Instrument [Line Items]
Term loan	517,500,000
Proceeds from convertible debt	$ 502,600,000
Interest rate	2.375%
Conversion ratio	0.0475862
Conversion price (in USD per share) | $ / shares	$ 21.01			$ 23.79	$ 23.79
Repurchase price (as a percentage of principal)	100.00%
Percentage stock price trigger	130.00%
Threshold of trading days | Trading_day	20
Threshold of consecutive trading days | Trading_day	30
Long-term debt	$ 410,900,000			$ 406,100,000	$ 406,100,000			$ 0
Fair value of convertible debt				717,200,000	717,200,000
Equity component	106,600,000
Debt issuance costs	11,900,000			$ 11,300,000	$ 11,300,000
Debt issuance costs	3,100,000
Net deferred tax liability	$ 20,500,000
Effective interest rate				7.30%	7.30%		7.30%
If-converted value in excess of principal					$ 87,600,000
Convertible Debt | 2.375% convertible senior notes, capped calls
Debt Instrument [Line Items]
Conversion price (in USD per share) | $ / shares	$ 23.79
Convertible note hedge, price per common share (in USD per share) | $ / shares	$ 21.01
Convertible note hedge (in shares) | shares	2.9
Convertible note hedge	$ 20,700,000
Line of Credit | Senior multi-currency revolving credit facility ($250.0 million borrowing capacity) (the “Revolving Credit Facility”)
Debt Instrument [Line Items]
Debt instrument, term			5 years