Fair Value Measurements (Details) - USD ($) $ in Millions	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Fair value of assets and liabilities measured on recurring basis
Contingent consideration		$ (75.0)
Recurring basis
Fair value of assets and liabilities measured on recurring basis
Short-term investments	$ 35.7		$ 17.4
Forward contracts	(7.7)		(1.3)
Contingent consideration			(75.0)
Total liability			(58.9)
Total asset	28.0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value of assets and liabilities measured on recurring basis
Short-term investments	35.7		17.4
Forward contracts	0.0		0.0
Contingent consideration			0.0
Total asset	35.7		17.4
Recurring basis | Significant Observable Inputs (Level 2)
Fair value of assets and liabilities measured on recurring basis
Short-term investments	0.0		0.0
Forward contracts	(7.7)		(1.3)
Contingent consideration			0.0
Total liability	(7.7)		(1.3)
Recurring basis | Significant Unobservable Inputs (Level 3)
Fair value of assets and liabilities measured on recurring basis
Short-term investments	0.0		0.0
Forward contracts	0.0		0.0
Contingent consideration			(75.0)
Total liability			$ (75.0)
Total asset	$ 0.0