Debt Instruments - Summary of the Effective Interest Rate, Contractually Stated Interest Expense and Costs Related to Amortization of Discount for the Notes (Details) - Convertible debt - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2017 |
Jun. 30, 2018 |
Jun. 30, 2017 |
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| Convertible senior notes due 2020 | ||||
| Debt Instrument [Line Items] | ||||
| Effective interest rate | 10.18% | 10.18% | 10.18% | 10.18% |
| Contractually stated interest expense | $ 1,119 | $ 1,493 | $ 2,629 | $ 3,002 |
| Amortization of discount | $ 4,043 | $ 4,912 | $ 9,438 | $ 9,799 |
| Convertible senior notes due 2023 | ||||
| Debt Instrument [Line Items] | ||||
| Effective interest rate | 10.38% | 10.38% | ||
| Contractually stated interest expense | $ 347 | $ 347 | ||
| Amortization of discount | $ 979 | $ 979 | ||
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- Definition Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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