FRESH-START ACCOUNTING - Balance sheet effects (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Oct. 02, 2019	Oct. 01, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 938	$ 5,701	$ 15,546	$ 15,546
Accounts receivable, net	30,260	48,504	37,826
Assets from derivative contracts	71,353	4,995	15,310
Restricted cash			13,839
Prepaids and other	6,341	7,379	10,290
Total current assets	108,892	71,153	92,811
Oil and natural gas properties (full cost method):
Evaluated	485,813	420,609	380,364
Unevaluated	104,923	105,009	108,954
Gross oil and natural gas properties	590,736	525,618	489,318
Less - accumulated depletion	(37,075)	(19,474)
Net oil and natural gas properties	553,661	506,144	489,318
Other operating property and equipment:
Other operating property and equipment	3,655	3,655	3,655
Less - accumulated depreciation	(659)	(378)
Net other operating property and equipment	2,996	3,277	3,655
Other noncurrent assets:
Assets from derivative contracts	37,766	224	4,120
Operating lease right of use assets	2,932	3,165	3,394
Funds in escrow and other			1,138
Total assets	712,395	584,666	594,436
Current liabilities:
Accounts payable and accrued liabilities	92,585	97,333	115,305
Liabilities from derivative contracts	3,972	8,069	6,829
Operating lease liabilities	935	923	913
Asset retirement obligations	225	109
Total current liabilities	97,717	106,434	123,047
Long-term debt, net	170,000	144,000	130,000
Liabilities subject to compromise				625,005
Other noncurrent liabilities:
Liabilities from derivative contracts	473	4,854	1,625
Asset retirement obligations	10,619	10,481	10,153
Operating lease liabilities	2,009	2,247	2,482
Commitments and contingencies
Stockholders' equity:
Common stock: 100,000,000 shares of $0.0001 par value authorized;16,203,967 and 16,203,940 shares issued and outstanding as of March 31, 2020 and December 31, 2019, respectively	2	2	2
Additional paid-in capital	327,544	327,108	327,127
Retained earnings (accumulated deficit)	104,031	(10,460)
Total stockholders' equity	431,577	316,650	327,129	30,477	$ 148,431	$ 214,157	$ 853,663	$ 1,197,044
Total liabilities and stockholders' equity	$ 712,395	$ 584,666	594,436
Reorganization Adjustments
Current assets:
Cash and cash equivalents				(1,463)
Restricted cash				13,839
Prepaids and other				7,110
Total current assets				19,486
Other noncurrent assets:
Total assets				19,486
Current liabilities:
Accounts payable and accrued liabilities				2,727
Current portion of long-term debt, net				(258,234)
Total current liabilities				(255,507)
Long-term debt, net				130,000
Liabilities subject to compromise				(625,005)
Stockholders' equity:
Common stock: 100,000,000 shares of $0.0001 par value authorized;16,203,967 and 16,203,940 shares issued and outstanding as of March 31, 2020 and December 31, 2019, respectively			2	(16)
Additional paid-in capital			$ 327,127	(1,087,441)
Retained earnings (accumulated deficit)				1,530,326
Total stockholders' equity				769,998
Total liabilities and stockholders' equity				19,486
Fresh Start Adjustments
Current assets:
Prepaids and other				(11,462)
Total current assets				(11,462)
Oil and natural gas properties (full cost method):
Evaluated				(1,774,924)
Unevaluated				(329,411)
Gross oil and natural gas properties				(2,104,335)
Less - accumulated depletion				1,709,719
Net oil and natural gas properties				(394,616)
Other operating property and equipment:
Other operating property and equipment				(199,718)
Less - accumulated depreciation				14,416
Net other operating property and equipment				(185,302)
Other noncurrent assets:
Operating lease right of use assets				(300)
Total assets				(591,680)
Current liabilities:
Operating lease liabilities				(424)
Total current liabilities				(424)
Other noncurrent liabilities:
Operating lease liabilities				44
Stockholders' equity:
Retained earnings (accumulated deficit)				(591,300)
Total stockholders' equity				(591,300)
Total liabilities and stockholders' equity				(591,680)
Predecessor
Current assets:
Cash and cash equivalents				17,009
Accounts receivable, net				37,826
Assets from derivative contracts				15,310
Prepaids and other				14,642
Total current assets				84,787
Oil and natural gas properties (full cost method):
Evaluated				2,155,288
Unevaluated				438,365
Gross oil and natural gas properties				2,593,653
Less - accumulated depletion				(1,709,719)
Net oil and natural gas properties				883,934
Other operating property and equipment:
Other operating property and equipment				203,373
Less - accumulated depreciation				(14,416)
Net other operating property and equipment				188,957
Other noncurrent assets:
Assets from derivative contracts				4,120
Operating lease right of use assets				3,694
Funds in escrow and other				1,138
Total assets				1,166,630
Current liabilities:
Accounts payable and accrued liabilities				112,578
Liabilities from derivative contracts				6,829
Current portion of long-term debt, net				258,234
Operating lease liabilities				1,337
Total current liabilities				378,978
Liabilities subject to compromise				625,005
Other noncurrent liabilities:
Liabilities from derivative contracts				1,625
Asset retirement obligations				10,153
Operating lease liabilities				2,438
Stockholders' equity:
Common stock: 100,000,000 shares of $0.0001 par value authorized;16,203,967 and 16,203,940 shares issued and outstanding as of March 31, 2020 and December 31, 2019, respectively				16
Additional paid-in capital				1,087,441
Retained earnings (accumulated deficit)				(939,026)
Total stockholders' equity				148,431
Total liabilities and stockholders' equity				$ 1,166,630