Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Royalties	$ 121,533	$ 72,401
Deferred Revenue	17,472	10,986
Transportation Charges	15,607	15,969
Accrued Other Taxes	12,404	10,580
Accrued Interest	12,215	26,549
Short-Term Incentive Compensation	7,974	20,340
Litigation Contingency	7,215	2,025
Accrued Payroll & Benefits	6,504	5,009
Purchased Gas Payable	1,229	1,528
Other	11,413	23,144
Current Portion of Long-Term Liabilities:
Asset Retirement Obligations	8,455	8,455
Salary Retirement	1,831	1,787
Total Other Accrued Liabilities	$ 223,852	$ 198,773

Accrued Transportation Charges

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Carrying value as of the balance sheet date of obligations incurred and payable for real and property taxes. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Carrying value as of the balance sheet date of obligations incurred and payable for incentive compensation awarded to employees and directors or earned by them based on the terms of one or more relevant arrangements. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Carrying value as of the balance sheet date of obligations incurred through that date and payable for royalties.

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Current portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

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Amount of liability, recognized in statement of financial position, for defined benefit pension plan, classified as current. Excludes other postretirement benefit plan.

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Carrying value as of the balance sheet date of obligations incurred and payable for purchases of natural gas. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Carrying amount of reserve for known or estimated probable loss from litigation, which may include attorneys' fees and other litigation costs, which is expected to be paid within one year of the date of the statement of financial position.

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