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Convertible Senior Notes - Additional Information (Detail) $ / shares in Units, shares in Millions |  | 1 Months Ended | 3 Months Ended | 6 Months Ended |
--- | --- | --- | --- | --- | ---
May 02, 2017 USD ($) d $ / shares | Nov. 30, 2020 USD ($) | Jun. 30, 2021 USD ($) shares | Jun. 30, 2021 USD ($) $ / shares shares | Dec. 31, 2020 USD ($)
Debt Instrument [Line Items] |  |  |  |  |
Principal amount |  |  | $ 381,200,000 | $ 381,200,000 | $ 381,300,000
2.25% Convertible Senior Notes due 2024 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Principal amount | $ 517,500,000 |  | $ 381,200,000 | $ 381,200,000 |
Interest rate percentage | 2.25% |  |  |  |
Maturity date | May 15, 2024 |  |  |  |
Aggregate principal amount repurchased |  | $ 136,200,000 |  |  |
Aggregate repurchase price paid in cash |  | $ 186,900,000 |  |  |
Threshold percentage of common stock price trigger | 130.00% |  |  |  |
Common stock price trigger (in USD per share) | $ / shares |  |  |  | $ 98.70 |
Threshold common stock trading days | d | 20 |  |  |  |
Threshold consecutive common stock trading days | d | 30 |  |  |  |
Convertible senior notes redemption rate | 100.00% |  |  |  |
Number of consecutive business days | 5 days |  |  |  |
Principal amount on conversion rate | $ 1,000 |  |  |  |
Minimum percentage of common stock price trigger | 98.00% |  |  |  |
Conversion observation period | 25 days |  |  |  |
Convertible senior notes convertible in to shares | 0.0131711 |  |  |  |
Convertible senior notes conversion price (in USD per share) | $ / shares | $ 75.92 |  |  |  |
Shares issued to settle notes at initial conversion rate (in shares) | shares |  |  | 5.0 | 5.0 |
Convertible senior note premium | 42.50% |  |  |  |
Market price of common stock (in USD per share) | $ / shares | $ 53.28 |  |  |  |
Convertible senior note carrying value of the liability component | $ 368,300,000 |  |  |  |
Convertible senior note assumed borrowing rate | 7.50% |  |  |  |
Convertible senior note carrying value of the equity component | $ 149,200,000 |  |  |  |
Convertible senior notes term | 7 years |  |  |  |
Discount on liability component, remaining amortization period |  |  |  | 2 years 10 months 24 days |
Transaction cost related to issuance of convertible senior notes | $ 14,700,000 |  |  |  |
Debt instrument events of default percentage of principal and accrued and unpaid interest due and payable upon default | 100.00% |  |  |  |
Convertible senior notes fair value |  |  | $ 506,600,000 | $ 506,600,000 | $ 514,300,000

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