Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash Flows from Operating Activities:
Net Loss	$ (83,213)	$ (27,948)
Adjustments to Reconcile Net Loss to Net Cash Provided by Operating Activities:
Depreciation, Depletion and Amortization	168,073	156,057
Gain on Sale of Assets	(10,563)	(15,241)
Stock/Unit-Based Compensation	4,607	9,462
Amortization of Debt Issuance Costs	6,472	5,301
Loss (Gain) on Debt Extinguishment	(657)	(17,911)
Unrealized Loss on Commodity Derivative Instruments	167,743	0
Deferred Income Taxes	(43,966)	143
Equity in Earnings of Affiliates	507	1,147
Changes in Operating Assets:
Accounts and Notes Receivable	53,970	25,197
Inventories	185	(2,446)
Prepaid Expenses and Other Assets	446	5,880
Changes in Other Assets	4,952	(16,902)
Changes in Operating Liabilities:
Accounts Payable	6,247	(29,746)
Other Operating Liabilities	14,368	(1,645)
Changes in Other Liabilities	(36,028)	(28,960)
Net Cash Provided by Operating Activities	253,143	62,388
Cash Flows from Investing Activities:
Capital Expenditures	(103,318)	(65,955)
Proceeds from Sales of Assets	12,053	8,779
Other Investing Activity	(338)	(229)
Net Cash Used in Investing Activities	(91,603)	(57,405)
Cash Flows from Financing Activities:
Proceeds from Finance Lease Obligations	0	16,293
Payments on Finance Lease Obligations	(20,864)	(18,732)
Proceeds from Long-Term Debt	75,000	0
Distributions to Noncontrolling Interest	0	(5,575)
Shares/Units Withheld for Taxes	(2,303)	(772)
Debt-Related Financing Fees	(2,368)	(9,002)
Net Cash Used in Financing Activities	(84)	(62,992)
Net Increase (Decrease) in Cash and Cash Equivalents and Restricted Cash	161,456	(58,009)
Cash and Cash Equivalents and Restricted Cash at Beginning of Period	50,850	80,293
Cash and Cash Equivalents and Restricted Cash at End of Period	212,306	22,284
Non-Cash Investing and Financing Activities:
Finance Lease	12,298	17,335
Other Equipment Financing	0	13,123
Term Loan A Facility [Member]
Cash Flows from Financing Activities:
Payments on Debt	(25,000)	(16,250)
Term Loan B Facility [Member]
Cash Flows from Financing Activities:
Payments on Debt	(6,911)	(2,063)
Senior Secured Second Lien Notes due 2025 [Member]
Cash Flows from Financing Activities:
Payments on Debt	(17,092)	(26,365)
Other Asset Backed Financing [Member]
Cash Flows from Financing Activities:
Payments on Debt	$ (546)	$ (526)