Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Cash Flows from Operating Activities:
Net Income (Loss)	$ (19,951)	$ (305,976)	$ 8,429	$ (311,834)
Adjustments to reconcile net income to net cash provided by operating activities -
Depreciation, depletion, and amortization	16,039	13,716	29,431	37,156
Write-down of oil and gas properties	0	260,342	0	355,948
Accretion of asset retirement obligation	74	88	148	173	$ 354
Deferred income taxes			0	21,087
Stock-based compensation expenses			2,260	2,437
Loss (gain) on derivatives			64,326	(79,829)
Cash settlements on derivatives			(10,708)	67,496
Settlements of asset retirement obligations			(166)	(15)
Write off of Deferred Debt Issuance Cost			229	459
Other Noncash Income (Expense)			1,202	1,814
(Increase) decrease in accounts receivable and other current assets			(1,387)	14,293
Increase (decrease) in accounts payable and accrued liabilities			(502)	(10,137)
Increase (Decrease) in Income Taxes Payable			0	92
Increase (decrease) in accrued interest			(28)	(140)
Net Cash Provided by (Used in) Operating Activities			93,234	99,000
Cash Flows from Investing Activities:
Additions to property and equipment			(56,995)	(85,594)
Acquisition of oil and gas properties			(207)	(3,394)
Proceeds from Sale of Property, Plant, and Equipment			0	(4,752)
Payments on property sale obligations			(1,084)	(426)
Net Cash Provided by (Used in) Investing Activities			(58,286)	(84,662)
Cash Flows from Financing Activities:
Proceeds from bank borrowings			123,000	50,000
Payments of bank borrowings			(155,000)	(59,000)
Purchase of treasury shares			(603)	(86)
Payments of Debt Issuance Costs			(2,400)	0
Net Cash Provided by (Used in) Financing Activities			(35,003)	(9,086)
Net increase (decrease) in Cash, Cash Equivalents and Restricted Cash			(55)	5,252
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 2,063	$ 6,610	2,063	6,610	$ 2,118	$ 1,358
Supplemental Disclosures of Cash Flows Information:
Cash paid during period for interest, net of amounts capitalized			13,282	15,006
Changes in capital accounts payable and capital accruals			$ 1,307	$ (28,618)