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

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

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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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The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

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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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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	Jun. 23, 2021	Aug. 20, 2018	Sep. 12, 2016	May 21, 2015	Nov. 17, 2014	May 20, 2013	Dec. 31, 2021	Dec. 31, 2020
Senior Notes [Line Items]
Unsecured Long-term Debt, Noncurrent							$ 1,673,452	$ 1,660,663
6.125% Senior Unsecured Notes Due 2022 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage					6.125%		6.125%	6.125%
Senior Notes, Principal amount					$ 600,000		$ 0	$ 212,403
Unamortized Debt Issuance Expense							0	855
Unsecured Long-term Debt, Noncurrent							$ 0	$ 211,548
Proceeds from Senior Unsecured Notes, Net of debt issuance costs					590,000
Senior Notes Debt Issuance Costs					$ 10,000
5.0% Senior Unsecured Notes Due 2024 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage						5.00%	5.00%	5.00%
Senior Notes, Principal amount						$ 500,000	$ 104,769	$ 277,034
Unamortized Debt Issuance Expense							403	1,576
Unsecured Long-term Debt, Noncurrent							$ 104,366	$ 275,458
Proceeds from Senior Unsecured Notes, Net of debt issuance costs						490,200
Senior Notes Debt Issuance Costs						$ 9,800
5.625% Senior Unsecured Notes Due 2025 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage				5.625%			5.625%	5.625%
Senior Notes, Principal amount				$ 500,000			$ 349,118	$ 349,118
Unamortized Debt Issuance Expense							2,160	2,792
Unsecured Long-term Debt, Noncurrent							$ 346,958	$ 346,326
Proceeds from Senior Unsecured Notes, Net of debt issuance costs				491,000
Senior Notes Debt Issuance Costs				$ 9,000
6.75% Senior Unsecured Notes Due 2026 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage			6.75%				6.75%	6.75%
Senior Notes, Principal amount			$ 500,000				$ 419,235	$ 419,235
Unamortized Debt Issuance Expense							3,270	3,970
Unsecured Long-term Debt, Noncurrent							$ 415,965	$ 415,265
Proceeds from Senior Unsecured Notes, Net of debt issuance costs			491,600
Senior Notes Debt Issuance Costs			$ 8,400
6.625% Senior Unsecured Notes Due 2027 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage		6.625%					6.625%	6.625%
Senior Notes, Principal amount		$ 500,000					$ 416,791	$ 416,791
Unamortized Debt Issuance Expense							3,949	4,725
Unsecured Long-term Debt, Noncurrent							$ 412,842	$ 412,066
Proceeds from Senior Unsecured Notes, Net of debt issuance costs		492,100
Senior Notes Debt Issuance Costs		$ 7,900
6.5% Senior Unsecured Notes Due 2028 [Member]
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
Unamortized Debt Issuance Expense							6,679	0
Unsecured Long-term Debt, Noncurrent							393,321	0
Proceeds from Senior Unsecured Notes, Net of debt issuance costs	392,800
Senior Notes Debt Issuance Costs	$ 7,200
Senior Unsecured Notes [Member]
Senior Notes [Line Items]
Senior Notes, Principal amount							1,689,913	1,674,581
Unamortized Debt Issuance Expense							$ 16,461	$ 13,918