Long Term Debt - Components of Convertible Senior Notes (Details) - 1.50% Convertible Senior Notes - USD ($) $ in Thousands	Sep. 30, 2020	May 31, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Principal	$ 500,000		$ 0
Unamortized debt discount	(84,127)		0
Unamortized issuance costs	(9,123)	$ (10,100)	0
Long-term Debt, Total	406,750		0
Equity component, net of issuance costs	$ 88,672		$ 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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The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.

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