Percentage increase in interest applied to the outstanding debt balance in the event of default.

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Contractual interest rate base for funds borrowed under the debt agreement.

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Premium rate owed to lender for prepayments of any borrowings under the debt agreement.

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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.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount of the fee that accompanies borrowing money under the debt instrument.

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Net increase or decrease in the carrying amount of the debt instrument for the period.

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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.

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Amount, after accumulated amortization, of debt discount.

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Amount, after accumulated amortization, of debt discount (premium).

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

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

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The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings.

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Fair value of the amount outstanding under the credit facility.

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Increase for accrued, but unpaid interest on the credit facility for the period.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Carrying value as of the balance sheet date of all notes and loans payable (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

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Per share or per unit amount of equity securities issued.

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Debt (Details) - USD ($) $ / shares in Units, $ in Thousands					1 Months Ended	3 Months Ended		55 Months Ended
	Apr. 29, 2019	Dec. 31, 2018	Aug. 14, 2017	Aug. 08, 2017	Apr. 30, 2019	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Dec. 31, 2019	Aug. 31, 2017	Sep. 30, 2015
Debt Instrument [Line Items]
Issuance of common stock to Orbimed (in shares)	25,000
Common stock, shares issued						78,652,000		78,652,000	78,005,000
Amortization of debt discount						$ 121	$ 98
Interest expense						2,464	2,724
Debt principal balance						75,000		$ 75,000	$ 75,000
Less: unamortized debt discount						(2,119)		(2,119)	(1,344)
Net carrying amount at end of period						72,881		72,881	$ 73,656
Line Of Credit-UBS
Debt Instrument [Line Items]
Maximum borrowing capacity											$ 50,000
Outstanding balance						49,000		49,000
Accrued interest								1,100
Interest expense						$ 300	400
Line Of Credit-UBS \| LIBOR
Debt Instrument [Line Items]
Spread on interest rate (as a percent)						1.10%
Noncurrent assets
Debt Instrument [Line Items]
Debt discount						$ 0		0
Long-term Debt
Debt Instrument [Line Items]
Debt discount						900		900
2017 Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity										$ 100,000
Remaining borrowing capacity		$ 50,000		$ 25,000	$ 50,000					$ 50,000
Outstanding balance				$ 75,000
Interest expense						2,100	$ 2,300
Additional interest in the event of default (as a percent)				3.00%
Common stock, shares issued			300,000		25,000					300,000
Debt instrument, fee amount			$ 2,400
Stock issued (in dollars per share)			$ 8.16
Legal fees			$ 300
Debt discount			2,700
Debt, increase (decrease)			(2,100)
Debt principal balance			$ 75,000
Net carrying amount at end of period						$ 72,900		$ 72,900
2017 Term Loan \| Minimum
Debt Instrument [Line Items]
Remaining borrowing capacity					$ 25,000
Prepayment premium (as a percent)				2.50%
2017 Term Loan \| Maximum
Debt Instrument [Line Items]
Prepayment premium (as a percent)				12.50%
2017 Term Loan \| LIBOR
Debt Instrument [Line Items]
Spread on interest rate (as a percent)		8.75%		8.75%	8.75%
Base interest rate (as a percent)		1.00%		1.00%	1.00%
2017 Term Loan \| LIBOR \| Scenario of minimum borrowing capacity of drawn
Debt Instrument [Line Items]
Spread on interest rate (as a percent)		8.25%			8.25%
Base interest rate (as a percent)		1.00%			1.00%
2017 Term Loan \| Noncurrent assets
Debt Instrument [Line Items]
Debt instrument, fee amount										$ 1,200