Other Accrued Expenses Other Accrued Expenses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Schedule of Other Liabilities [Line Items]
Amortization of Other Deferred Charges	$ 500	$ 1,000
Production Tax Liability	29,585	29,585	$ 68,020
Deferred Midstream gathering credits	173,006	173,006	175,897
Operating and Finance Lease Liability, Noncurrent		14,354	15,779
Other Accrued Liabilities, Noncurrent	238,695	$ 238,695	283,133
Document Period End Date		Jun. 30, 2020
Non Current Liabilities
Schedule of Other Liabilities [Line Items]
Increase (Decrease) in Accrued Cost of Oil and Gas Reclamation		$ 19,095	20,100
Other Accrued Liabilities	2,655	2,655	3,337
Current Liabilities
Schedule of Other Liabilities [Line Items]
Other Accrued Liabilities	13,355	13,355	$ 8,469
Midstream Oil Gathering [Member]
Schedule of Other Liabilities [Line Items]
Amortization of Other Deferred Charges	900	1,700
MIdstream Water Gathering [Member]
Schedule of Other Liabilities [Line Items]
Amortization of Other Deferred Charges	400	800
Midstream Gas Gathering [Member]
Schedule of Other Liabilities [Line Items]
Amortization of Other Deferred Charges	$ 300	$ 400