Cash and Cash Equivalents, and Investments and Fair Value Measurements - Debt (Details) - Estimate of Fair Value Measurement - Senior Notes - Fair Value, Measurements, Nonrecurring - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
2026 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	$ 818.8	$ 840.0
2025 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	$ 708.8	$ 682.2