Balance Sheet Accounts - Schedule of Estimated Fair Value and Principal Amount of Outstanding Debt (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Fair Value	$ 528.3	$ 916.0
Principal Amount	434.7	608.5
Term loan
Debt Instrument [Line Items]
Fair Value	281.9	306.5
Principal Amount	288.8	308.5
2 1/4% Notes
Debt Instrument [Line Items]
Fair Value	246.4	609.5
Principal Amount	$ 145.9	$ 300.0
Convertible Debt | 2 1/4% Notes
Debt Instrument [Line Items]
Debt instrument interest rate stated percentage	2.25%