v3.21.2

Summary of Significant Accounting Policies - Convertible Notes (Details) - Convertible Debt - USD ($) | 1 Months Ended |  |  |  |
--- | --- | --- | --- | --- | ---
Nov. 30, 2020 | Sep. 30, 2021 | May 31, 2021 | Jun. 30, 2019 | Feb. 28, 2018
Convertible Senior Notes Due February 2023 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Principal amount |  | $ 10,900,000 |  |  | $ 230,000,000
Extinguishment of debt | $ 181,900,000 |  |  |  |
Repurchased principal amount |  |  | $ 37,100,000 |  |
Convertible Senior Notes Due June 2026 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Principal amount |  |  |  | $ 316,300,000 |
Convertible Notes Due 2025 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Principal amount | 350,000,000 |  |  |  |
Principal amount received | 210,700,000 |  |  |  |
Principal amount, additional | $ 139,300,000 |  |  |  |

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