Convertible Senior Notes - Convertible Debt Balances (Details) - Convertible Debt - Convertible Senior Notes - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Sep. 25, 2020
Liability:
Principal amount	$ 575,000	$ 575,000
Unamortized discount	(77,136)	(95,744)
Unamortized debt issuance costs	(9,712)	(12,055)
Convertible senior notes, liability component	488,152	467,201	$ 461,800
Equity component of convertible senior notes	$ 72,732	$ 72,732	$ 72,700

Debt Instrument, Convertible, Liability Component

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- Definition

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

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

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- Definition

Amount, after accumulated amortization, of debt discount.

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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.

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- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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