Note 9 - Details of Selected Balance Sheet Accounts (Tables)

3 Months Ended

Mar. 31, 2021

Notes Tables

Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]

	March 31,			December 31,
	2021			2020
Accounts receivable, principally trade	$	11,186		$	10,458
Less: allowance for expected credit losses		(2,729	)		(2,413	)
Accounts receivable, net	$	8,457		$	8,045

Schedule of Inventory, Current [Table Text Block]

	March 31,			December 31,
	2021			2020
Raw materials and purchased subassemblies	$	18,215		$	18,638
Work-in-process		1,363			1,218
Finished goods		4,372			4,417
Less: reserve for excess and obsolete inventories		(12,919	)		(13,006	)
Inventories, net	$	11,031		$	11,267

Property, Plant and Equipment [Table Text Block]

	March 31,			December 31,
	2021			2020
Buildings	$	15,675		$	15,675
Machinery and equipment		120,979			120,949
Seismic rental equipment		2,030			2,003
Furniture and fixtures		3,172			3,172
Other (a)		30,666			30,287
Total		172,522			172,086
Less: accumulated depreciation		(126,906	)		(126,022	)
Less: impairment of long-lived assets		(36,553	)		(36,553	)
Property, plant, equipment and seismic rental equipment, net	$	9,063		$	9,511

Schedule of Multi-client Data Library [Table Text Block]

	March 31,			December 31,
	2021			2020
Gross costs of multi-client data creation	$	1,024,429		$	1,021,758
Less: accumulated amortization		(841,985	)		(838,700	)
Less: impairments to multi-client data library		(132,144	)		(132,144	)
Multi-client data library, net	$	50,300		$	50,914

Schedule of Goodwill [Table Text Block]

	E&P Technology & Services		Optimization Software & Services			Total
Balance at January 1, 2020	$	2,943	$	20,642		$	23,585
Impairment of goodwill		—		(4,150	)		(4,150	)
Impact of foreign currency translation adjustments		—		130			130
Balance at December 31, 2020		2,943		16,622			19,565
Impact of foreign currency translation adjustments		—		208			208
Balance at March 31, 2021	$	2,943	$	16,830		$	19,773