Financial Instruments and Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Fair Value Measurements
Liabilities at fair value	$ 0	$ 0
Transfers between level 1 and level 2, assets	0	0
Transfers between level 2 and level 1, assets	0	0
Transfers between level 1 and level 2, liabilities	0	0
Transfers between level 2 and level 1, liabilities	0	0
Transfer of assets into level 3	0	0
Transfer of assets out of level 3	0	0
Transfer of liabilities into level 3	0	0
Transfer of liabilities out of level 3	0	0
Convertible senior notes	504,680	504,680	$ 644,751
Convertible Senior Unsecured Notes 2021 Notes
Fair Value Measurements
Convertible senior notes	64,000	64,000
Convertible Senior Unsecured Notes 2021 Notes \| Fair Value, Inputs, Level 2
Fair Value Measurements
Convertible senior notes, fair value	58,200	58,200
Convertible Senior Unsecured Notes 2024 Notes
Fair Value Measurements
Convertible senior notes	147,000	147,000
Convertible senior notes, fair value	152,800	152,800
Convertible Senior Unsecured Notes 2025 Notes
Fair Value Measurements
Convertible senior notes	293,600	293,600
Convertible senior notes, fair value	$ 180,800	$ 180,800

Carrying amount of long-term convertible debt as of the balance sheet date, net of the amount due in the next twelve months or greater than the normal operating cycle, if longer. The debt is convertible into another form of financial instrument, typically the entity's common stock.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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Fair value of financial and nonfinancial obligations.

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