Debt - Schedule of Net Carrying Value of Liability Component of Convertible Notes (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Principal	$ 231,040	$ 231,174
Less: unamortized debt discount	42,070	46,820
Less: unamortized debt issuance costs	5,105	5,686
Convertible Senior Notes Due in 2024 [Member]
Debt Instrument [Line Items]
Principal	230,000	230,000
Less: unamortized debt discount	42,070	46,820
Less: unamortized debt issuance costs	5,105	5,686
Net carrying amount	$ 182,825	$ 177,494

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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- 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.

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Amount, after accumulated amortization, of debt discount.

+ References

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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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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
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