Note 6 - Leases (Details Textual) - USD ($) $ in Thousands	Mar. 31, 2020		Dec. 31, 2019
Lessee, Operating Lease, Renewal Term (Year)	5 years
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Disposal Group, Including Discontinued Operation, Operating Lease, Right-of-Use Asset	$ 55	[1]	$ 326	[2]
Disposal Group, Including Discontinued Operation, Other Liabilities	100
Disposal Group Including Discontinued Operation, Operating Lease Liability Current			200
Disposal Group, Including Discontinued Operation, Operating Lease, Liability, Noncurrent	$ 12	[1]	$ 174	[2]
Minimum [Member]
Lessee, Operating Lease, Remaining Lease Term (Year)	1 year
Maximum [Member]
Lessee, Operating Lease, Remaining Lease Term (Year)	20 years

[1] Includes Environmental Techniques and land held at Corporate.

[2] Includes Insituform Australia, Insituform Spain, Environmental Techniques and land held at Corporate.