Debt Obligations (Details Textual) - USD ($) $ / shares in Units, $ in Millions			1 Months Ended	3 Months Ended		9 Months Ended
	Mar. 18, 2019	Oct. 17, 2018	May 31, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	May 22, 2019
Debt Instrument [Line Items]
Increased in credit facility			$ 30.0
Senior notes				$ 694.9		$ 694.9
Conversion price	$ 188.73
Debt instrument, convertible, carrying amount of equity component				99.7		99.7
Contractual interest expense				1.0	$ 1.0	$ 3.0	$ 3.0
Debt instrument, interest rate during period	100.00%					4.40%
Line of credit facility, expiration date		Oct. 17, 2023
Line of credit, current				1.1		$ 1.1		$ 0.9
Accretion Expense				4.0	$ 3.8	11.9	$ 11.4
Line of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				200.0		$ 200.0
Due 2049 [Member]
Debt Instrument [Line Items]
Sale of convertible senior notes	$ 525.0
Debt instrument, interest rate during period						0.75%
Debt instrument, unamortized discount				$ 60.8		$ 60.8
Senior Notes, 1.375 Percent due 2026 [Member]
Debt Instrument [Line Items]
Senior notes									$ 669.9
Debt instrument, interest rate during period						1.375%
Long-term debt, percentage bearing fixed interest, percentage rate				1.375%		1.375%
Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt instrument, applicable margin						1.125%
Minimum [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Debt instrument, applicable margin						0.175%
Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt instrument, applicable margin						2.00%
Maximum [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Debt instrument, applicable margin						1.00%
Swingline loans [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 50.0		$ 50.0
Foreign Swingline Loans [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				90.0		90.0
Unsecured Debt [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 1,000.0
Euro Member Countries, Euro
Debt Instrument [Line Items]
Senior notes				$ 600.0		$ 600.0
Euro Member Countries, Euro | Senior Notes, 1.375 Percent due 2026 [Member]
Debt Instrument [Line Items]
Senior notes									$ 600.0