Deferred Royalty Obligation (Details) - USD ($)		12 Months Ended
May 10, 2018	Dec. 31, 2018
Debt Instrument [Line Items]
Royalty obligation payable		$ 400,000
HealthCare Royalty Partners
Debt Instrument [Line Items]
Proceeds from royalty agreement	$ 125,000,000
Maximum potential royalty payout	180.00%
Required payment for breach of agreement, payment one	$ 125,000,000.0
Required payment for breach of agreement, payment two	225,000,000.0
HealthCare Royalty Partners \| Loans Payable \| Royalty Financing Agreement
Debt Instrument [Line Items]
Deferred royalty obligation, net	125,000,000	124,300,000
Debt issuance costs	$ 700,000
Interest expense		7,300,000
Unamortized debt discount		700,000
Accrued interest expense		6,800,000
Royalty payments		$ 500,000
HealthCare Royalty Partners \| Period One
Debt Instrument [Line Items]
Maximum potential royalty payout	10.00%
HealthCare Royalty Partners \| Period Two
Debt Instrument [Line Items]
Increase in maximum potential payout percent	4.00%
HealthCare Royalty Partners \| Payout Period
Debt Instrument [Line Items]
Increase in maximum potential payout percent	4.00%

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- Definition

Royalty Agreement, Amount Funded

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Royalty Agreement, Increase In Maximum Potential Payout, Percent

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Royalty Agreement, Required Payment For Breach Of Agreement, Payment One

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Royalty Obligation Payable

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Amount, after accumulated amortization, of debt discount.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Sum of the carrying values as of the balance sheet date of (a) interest payable on all forms of debt, including trade payables, that has been incurred, and (b) dividends declared but unpaid on equity securities issued by the entity and outstanding (also includes dividends collected on behalf of another owner of securities that are being held by the entity).

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