Convertible Senior Notes - Summary of Information about the Equity and Liability Components of Notes (Details) - USD ($)	Jun. 30, 2019	Apr. 15, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt	$ 59,255,000		$ 0
Less: Deferred tax liability	(4,065,000)
Less: Issuance costs	1,100,000
Convertible Notes \| Convertible Senior Notes due 2024
Debt Instrument [Line Items]
Principal amount of 2024 Notes outstanding	80,000,000	$ 80,000,000.0
Unamortized discount (including unamortized debt issuance cost)	(20,745,000)
Long-term debt	59,255,000
Equity component of notes	17,624,000	$ 17,600,000
Less: Issuance costs	1,094,000
Capital in excess of Par Value	$ 12,465,000

Debt Instrument, Convertible, Amount Of Equity Component, Recognized In Additional Paid-In Capital

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- Definition

Debt Issuance Costs, Net, Allocated To Equity Component

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- Definition

The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.

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Face (par) amount of debt instrument at time of issuance.

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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 of unamortized debt discount (premium) and debt issuance costs.

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- Definition

Amount of deferred tax liability attributable to taxable temporary differences from debt issuance costs.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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