Note 1 - Summary of Significant Accounting Policies (Details Textual)		6 Months Ended		12 Months Ended
	Apr. 20, 2021 USD ($) $ / shares shares	Jun. 30, 2021 USD ($) $ / shares	Jun. 30, 2020 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) $ / shares	Dec. 30, 2020 USD ($)
Restructuring Plan, Cost Eliminated					$ 40,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share) | $ / shares	$ 0.01	$ 0.01			$ 0.01
Debt Conversion, Converted Instrument, Amount		$ 11,755,000	$ 0
Stock Issued During Period, Shares, New Issues (in shares) | shares	10,900,000
Proceeds from Restructuring Transactions	$ 14,000,000
Long-term Debt, Total		$ 133,837,000			$ 143,731,000
Loss Contingency, Decrease in Expense From Scaling Down Operations						$ 40,000,000
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) | shares	6,100,000
Exchange Offer, Early Participation [Member]
Debt Conversion, Converted Instrument, Shares Issued (in shares) | shares	1,500,000
Exchange Offer, Stock in Lieu of Notes [Member]
Debt Conversion, Converted Instrument, Shares Issued (in shares) | shares	4,600,000
Rights Offering [Member]
Rights Offering, Common Stock Amount Per Right (in shares) | shares	1.08
Shares Issued, Price Per Share (in dollars per share) | $ / shares	$ 2.57
Rights Offering, Value of Rights Issued	$ 41,800,000
Stock Issued During Period, Value, New Issues	$ 11,700,000
Stock Issued During Period, Shares, New Issues (in shares) | shares	4,600,000
Rights Offering, Maximum Offering Without Proration	$ 50,000,000.0
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%
INOVA Geophysical Equipment Limited [Member]
Equity Method Investment, Ownership Percentage		49.00%
Forecast [Member] | Minimum [Member]
Restructuring Plan, Cost Eliminated				$ 15,000,000
Forecast [Member] | Maximum [Member]
Restructuring Plan, Cost Eliminated				$ 20,000,000
Second Lien Notes [Member] | Senior Notes [Member]
Debt Instrument, Term (Year)	4 years
Debt Instrument, Percent of Note Holders Supporting Restructuring	94.10%
Long-term Debt, Gross	$ 120,600,000	$ 116,193,000			0
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	7,100,000			120,600,000
New Second Lien Notes [Member] | Senior Notes [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, Convertible, Conversion Price (in dollars per share) | $ / shares	$ 3.00
Debt Instrument, Convertible, Number of Equity Instruments	38,700,000
Debt Instrument, Convertible, Number of Additional Equity Instruments (in shares) | shares	6,500,000
Long-term Debt, Gross	$ 116,200,000	7,097,000			$ 120,569,000
Debt Instrument, Face Amount	116,200,000
Long-term Debt, Total		$ 116,200,000
New Second Lien Notes [Member] | Senior Notes [Member] | Rights Offering [Member]
Proceeds from Issuance of Long-term Debt, Total	30,100,000
New Second Lien Notes [Member] | Senior Notes [Member] | Rights Offering [Member] | Backstop Parties [Member]
Debt Instrument, Face Amount	$ 1,500,000