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v3.20.4

Debt (Tables) | 12 Months Ended
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Dec. 31, 2020
Debt |
Schedule of carrying value of Convertible Senior Notes | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | December 31, 2020 | ​ | ​ | December 31, 2019
​ | ​ | ​ | 2023 Notes | ​ | ​ | 2025 Notes | ​ | ​ | 2027 Notes | ​ | ​ | Total | ​ | ​ | 2023 Notes
​ | ​ | ​ | (in thousands)
Principal amount | ​ | $ | 131,695 | ​ | $ | 132,500 | ​ | $ | 125,000 | ​ | $ | 389,195 | ​ | $ | 345,000
Unamortized debt discount/transaction costs | ​ |  | (11,925) | ​ |  | (22,097) | ​ |  | (34,058) | ​ |  | (68,080) | ​ |  | (44,932)
Net carrying value | ​ | $ | 119,770 | ​ | $ | 110,403 | ​ | $ | 90,942 | ​ | $ | 321,115 | ​ | $ | 300,068
Schedule of interest expense related to Convertible Senior Notes | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | For the year ended December 31,
​ | ​ | 2020 | ​ | 2019 | ​ | 2018
​ | ​ | (in thousands)
Cash Interest Expense | ​ | ​ |  | ​ | ​ |  | ​ | ​ | ​
Coupon interest expense - 2023 Notes | ​ | $ | 7,390 | ​ | $ | 9,315 | ​ | $ | 9,315
Coupon interest expense - 2025 Notes | ​ | ​ | 554 | ​ | ​ | — | ​ | ​ | —
Coupon interest expense - 2027 Notes | ​ | ​ | 2,904 | ​ | ​ | — | ​ | ​ | —
Non-cash Interest Expense | ​ |  | ​ | ​ |  | ​ | ​ |  |
Amortization of debt discount/transaction costs- 2023 Notes | ​ |  | 10,887 | ​ |  | 12,676 | ​ |  | 11,762
Amortization of debt discount/transaction costs- 2025 Notes | ​ | ​ | 546 | ​ | ​ | — | ​ | ​ | —
Amortization of debt discount/transaction costs- 2027 Notes | ​ | ​ | 2,359 | ​ | ​ | — | ​ | ​ | —
Total Interest Expense | ​ | $ | 24,640 | ​ | $ | 21,991 | ​ | $ | 21,077

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- Definition Tabular disclosure of borrowings which can be exchanged for a specified number of another security at the option of the issuer or the holder. Disclosures include, but are not limited to, principal amount, amortized premium or discount, and amount of liability and equity components. + References No definition available. + Details
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- Definition Tabular disclosure of interest income and expense, including, but not limited to, interest income and expense from investments, loans, and securities. + References No definition available. + Details
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