Long-Term Debt - Schedule of Convertible Debt (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Debt Instrument [Line Items]
Unamortized Issuance Costs		$ (18,526)		$ (26,852)
Total Debt		2,435,406		2,424,001
Equity Component, net of Purchase Discounts and Issuance Costs	$ 10	(33)	$ 78,317
Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Total Debt		249,463		237,265
Convertible Debt \| Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Principal		345,000		345,000
Unamortized Discount		(89,938)		(101,367)
Unamortized Issuance Costs		(5,599)		(6,368)
Total Debt		249,463		237,265
Equity Component, net of Purchase Discounts and Issuance Costs		$ 78,284		$ 78,317

Adjustment to additional paid in capital resulting from the recognition of convertible debt instruments as two separate components - a debt component and an equity component. This bifurcation may result in a basis difference associated with the liability component that represents a temporary difference for purposes of applying accounting for income taxes. The initial recognition of deferred taxes for the tax effect of that temporary difference is as an adjustment to additional paid in capital.

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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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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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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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