Convertible Senior Notes - Schedule of Convertible Debt (Details) - Initial Notes - Convertible Notes - USD ($)	Sep. 30, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Principal amount of Convertible Senior Notes	$ 200,000,000
Less: Unamortized debt discount and issuance costs	(72,040,000)
Net carrying amount	$ 127,960,000	$ 0

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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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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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.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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