Note 3 - Revenue from Contracts with Customers - Summary of Unbilled Receivables and Deferred Revenue (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)
Unbilled receivables	$ 4,085
Unbilled receivables	11,262
Recognition of unbilled receivables (a)	13,612	[1]
Revenues billed to customers (a)	(20,789)	[1]
Deferred revenue	4,454
Deferred revenue	3,648
Cash collected in excess of revenue recognized	1,230
Recognition of deferred revenue	(424)	[2]
New Venture [Member]
Unbilled receivables	1,212
Unbilled receivables	9,158
Deferred revenue	2,158
Deferred revenue	2,169
Imaging and Resevoir Services [Member]
Unbilled receivables	1,287
Unbilled receivables	680
Deferred revenue	672
Deferred revenue	665
Devices [Member]
Unbilled receivables	1,586
Unbilled receivables	1,424
Deferred revenue	622
Deferred revenue	48
Optimization Software and Services [Member]
Deferred revenue	1,002
Deferred revenue	$ 766

[1] Includes all gross revenue recognition and related billing activity of the Company. As a matter of process, all net revenue recognized is initially reflected as an unbilled receivable and subsequently billed to customers, as applicable, including net revenue for all of software and a portion of devices within the Operations Optimization segment, although they are billed at the time of recognition.

[2] The majority of deferred revenue recognized relates to Company’s Ventures group.