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 |