Convertible Notes Convertible Notes (Interest Expense for December 2021 Notes) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Debt Instrument [Line Items]
Debt Instrument, Convertible, Beneficial Conversion Feature	$ 234	$ 1,766
December 2021 Notes [Member]
Debt Instrument [Line Items]
Contractual coupon interest	123	1,031
Amortization of debt issuance costs	2	20
Amortization of debt discount	17	138
Interest Expense, Debt	$ 376	$ 2,955

Amortization of debt issuance costs

No definition available.

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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.

+ References

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- Definition

Amount of a favorable spread to a debt holder between the amount of debt being converted and the value of the securities received upon conversion. This is an embedded conversion feature of convertible debt issued that is in-the-money at the commitment date.

+ References

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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.

+ References

No definition available.

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- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

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-Topic 470
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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.

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