Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($)		3 Months Ended	12 Months Ended
	Apr. 20, 2021	Mar. 31, 2021	Dec. 30, 2020	Apr. 30, 2021	Dec. 31, 2020
Common Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.01			$ 0.01
Stock Issued During Period, Value, New Issues		$ 9,802,000
Common Stock, Shares, Outstanding, Ending Balance (in shares)		17,344,187			14,333,101
Loss Contingency, Decrease in Expense From Scaling Down Operations			$ 40,000,000
Subsequent Event [Member]
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01
Stock Issued During Period, Shares, New Issues (in shares)	10,900,000
Proceeds from Restructuring Transactions	$ 14,000,000
Common Stock, Shares, Outstanding, Ending Balance (in shares)	28,800,000
Crude Oil Price				$ 66
Subsequent Event [Member] | Rights Offering [Member]
Rights Offering, Common Stock Amount Per Right (in shares)	1.08
Shares Issued, Price Per Share (in dollars per share)	$ 2.57
Rights Offering, Value of Rights Issued	$ 41,800,000
Stock Issued During Period, Value, New Issues	$ 11,800,000
Stock Issued During Period, Shares, New Issues (in shares)	4,600,000
Rights Offering, Maximum Offering Without Proration	$ 50,000,000.0
Subsequent Event [Member] | Rights Offering [Member] | Backstop Parties [Member]
Stock Issued During Period, Value, New Issues	$ 200,000
Debt Instrument, Maximum Backstop Fee Percent of the Backstop Commitment Amount	5.00%
Subsequent Event [Member] | Exchange Offer [Member]
Debt Conversion, Original Debt, Amount	$ 113,500,000
Debt Conversion, Converted Instrument, Amount	$ 84,700,000
Debt Conversion, Converted Instrument, Shares Issued (in shares)	6,100,000
Subsequent Event [Member] | Exchange Offer, Early Participation [Member]
Debt Conversion, Converted Instrument, Shares Issued (in shares)	1,500,000
Subsequent Event [Member] | Exchange Offer, Stock in Lieu of Notes [Member]
Debt Conversion, Converted Instrument, Shares Issued (in shares)	4,600,000
Second Lien Notes [Member] | Senior Notes [Member]
Long-term Debt, Gross		$ 120,569,000			$ 120,569,000
Second Lien Notes [Member] | Senior Notes [Member] | Subsequent Event [Member]
Debt Instrument, Term (Year)	4 years
Debt Instrument, Interest Rate, Stated Percentage	9.125%
Debt Instrument, Percent of Note Holders Supporting Restructuring	94.10%
Long-term Debt, Gross	$ 120,600,000
Repayments of Long-term Debt, Total	20,700,000
Interest Paid, Including Capitalized Interest, Operating and Investing Activities, Total	$ 3,600,000
Debt Instrument, Repurchase Offer, Percentage of Proceeds in Excess of 35 Million	50.00%
Debt Instrument, Repurchase Offer, Value	$ 3,400,000
Long-term Debt, Total	$ 7,100,000
New Second Lien Notes [Member] | Senior Notes [Member] | Subsequent Event [Member]
Debt Instrument, Interest Rate, Stated Percentage	8.00%
Rights Offering, Principal Amount of Debt Instrument Per Right	$ 2.78
Rights Offering, Debt Instrument, Purchase Price, Percentage of Principal	100.00%
Debt Instrument, Face Amount	$ 116,200,000
New Second Lien Notes [Member] | Senior Notes [Member] | Subsequent Event [Member] | Rights Offering [Member]
Proceeds from Issuance of Long-term Debt, Total	30,100,000
New Second Lien Notes [Member] | Senior Notes [Member] | Subsequent Event [Member] | Rights Offering [Member] | Backstop Parties [Member]
Debt Instrument, Face Amount	$ 1,500,000