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Convertible Senior Notes - Additional Information (Details) $ / shares in Units, shares in Millions |  | 1 Months Ended | 12 Months Ended
--- | --- | --- | ---
May 02, 2017 USD ($) d $ / shares | Dec. 31, 2020 USD ($) shares | Nov. 30, 2020 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |
Principal amount |  | $ 381,300,000 |  | $ 381,300,000 | $ 517,500,000 |
Equity component of repurchased convertible senior notes |  |  |  | 47,500,000 |  |
Loss on extinguishment of convertible senior notes |  |  |  | $ 18,400,000 | 0 | $ 0
2.25% Convertible senior notes due 2024 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Principal amount | $ 517,500,000 |  |  |  |  |
Stated interest rate percentage | 2.25% |  |  |  |  |
Proceeds from issuance | $ 502,800,000 |  |  |  |  |
Threshold common stock trading days | d | 20 |  |  |  |  |
Threshold consecutive common stock trading days | d | 30 |  |  |  |  |
Threshold percentage of common stock price trigger | 130.00% |  |  |  |  |
Principal amount on conversion rate | $ 1,000 |  |  |  |  |
Trading days during observation period | 30 days |  |  |  |  |
Conversion observation period | 25 days |  |  |  |  |
Conversion ratio | 0.00131711 |  |  |  |  |
Conversion price (in USD per share) | $ / shares | $ 75.92 |  |  |  |  |
Shares issued to settle notes at initial conversion rate (in shares) | shares |  | 5.0 |  |  |  |
Conversion premium | 42.50% |  |  |  |  |
Market price of common stock (in USD per share) | $ / shares | $ 53.28 |  |  |  |  |
Redemption rate | 100.00% |  |  |  |  |
Carrying amount of the liability component upon issuance | $ 368,300,000 |  |  |  |  |
Assumed borrowing rate | 7.50% |  |  |  |  |
Carrying amount of the equity component upon issuance | $ 149,200,000 |  |  |  |  |
Term | 7 years |  |  |  |  |
Remaining discount amortization period |  |  |  | 3 years 4 months 24 days |  |
Transaction cost related to issuance of convertible senior note | $ 14,700,000 |  |  |  |  |
Events of default percentage of principal and accrued and unpaid interest due and payable upon default | 100.00% |  |  |  |  |
Aggregate principal amount repurchased |  |  | $ 136,200,000 |  |  |
Aggregate repurchase price paid in cash |  |  | 186,900,000 |  |  |
Fair value of the liability component immediately before extinguishment |  |  | 130,700,000 |  |  |
Equity component of repurchased convertible senior notes |  |  | 56,300,000 |  |  |
Carrying amount of the liability component at settlement |  |  | 112,400,000 |  |  |
Loss on extinguishment of convertible senior notes |  |  | $ 18,400,000 |  |  |
Fair value |  | $ 514,300,000 |  | $ 514,300,000 | $ 596,800,000 |
2.25% Convertible senior notes due 2024 | Conversion Period One |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Threshold common stock trading days | d | 20 |  |  |  |  |
Threshold consecutive common stock trading days | d | 30 |  |  |  |  |
Threshold percentage of common stock price trigger | 130.00% |  |  |  |  |
2.25% Convertible senior notes due 2024 | Conversion Period Two |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Threshold common stock trading days | d | 5 |  |  |  |  |
Threshold consecutive common stock trading days | d | 5 |  |  |  |  |
Principal amount on conversion rate | $ 1,000 |  |  |  |  |
Minimum percentage of common stock price trigger | 98.00% |  |  |  |  |
2.25% Convertible senior notes due 2024 | Discount rate |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Discount rate |  |  | 0.0337 |  |  |

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