Face (par) amount of debt instrument at time of issuance.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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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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- 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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Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

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Senior Unsecured Notes (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jun. 23, 2021	Dec. 31, 2020	Sep. 30, 2020
Senior Notes [Line Items]
Unsecured Long-term Debt, Noncurrent	$ 1,672,623		$ 1,660,663
6.125% Senior Unsecured Notes due 2022
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage	6.125%		6.125%
Senior Notes, Principal amount	$ 0		$ 212,403
Senior Notes, unamortized deferred financing costs	0		855
Unsecured Long-term Debt, Noncurrent	$ 0		$ 211,548
5.0% Senior Unsecured Notes due 2024
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage	5.00%		5.00%
Senior Notes, Principal amount	$ 104,769		$ 277,034
Senior Notes, unamortized deferred financing costs	451		1,576
Unsecured Long-term Debt, Noncurrent	$ 104,318		$ 275,458
5.625% Senior Unsecured Notes due 2025
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage	5.625%		5.625%
Senior Notes, Principal amount	$ 349,118		$ 349,118
Senior Notes, unamortized deferred financing costs	2,318		2,792
Unsecured Long-term Debt, Noncurrent	$ 346,800		$ 346,326
6.75% Senior Unsecured Notes due 2026
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage	6.75%		6.75%
Senior Notes, Principal amount	$ 419,235		$ 419,235
Senior Notes, unamortized deferred financing costs	3,445		3,970
Unsecured Long-term Debt, Noncurrent	$ 415,790		$ 415,265
6.625% Senior Unsecured Notes due 2027
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage	6.625%		6.625%
Senior Notes, Principal amount	$ 416,791		$ 416,791
Senior Notes, unamortized deferred financing costs	4,143		4,725
Unsecured Long-term Debt, Noncurrent	$ 412,648		$ 412,066
6.5% Senior Unsecured Notes Due 2028
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage	6.50%	6.50%	6.50%
Senior Notes, Principal amount	$ 400,000	$ 400,000	$ 0
Senior Notes, unamortized deferred financing costs	6,933		0
Unsecured Long-term Debt, Noncurrent	393,067		0
Senior Unsecured Notes [Member]
Senior Notes [Line Items]
Senior Notes, Principal amount	1,689,913		1,674,581
Senior Notes, unamortized deferred financing costs	$ 17,290		$ 13,918
1.50% Senior Unsecured Convertible Notes Due 2021 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage				1.50%