Note 4 - Restructuring (Details Textual) $ in Thousands	3 Months Ended					12 Months Ended		32 Months Ended
	Mar. 31, 2020 USD ($)		Dec. 31, 2019	Mar. 31, 2019 USD ($)		Dec. 31, 2019	Dec. 31, 2017 USD ($)	Mar. 31, 2020 USD ($)
Restructuring Charges, Non-Cash	$ 463			$ (151)
Restructuring 2017 [Member]
Restructuring Charges Pre Tax								$ 158,900
Payments for Restructuring	5,262	[1]		3,264	[2]			48,500
Restructuring Reserve, Settled without Cash								$ 127,100
Restructuring and Related Cost, Number of Positions Eliminated							650
Restructuring Charges, Cash	3,100			3,100
Restructuring Charges, Non-Cash	463			(151)
Downsize Operation in US [Member]
Restructuring and Related Cost, Number of Office Closed			3
Restructuring and Related Cost, Number of Offices Exiting Capital Intensive Drilling Activities			4
Restructuring and Related Cost, Number of Positions Eliminated, Period Percent						20.00%
Restructuring and Related Cost, Contributed To Cathodic Protection Domestic Revenue, Percentage						20.00%
Restructuring Charges Related to Goodwill and Long-lived Asset Impairment Charges [Member] | Restructuring 2017 [Member]
Restructuring Reserve, Settled without Cash							$ 86,400
Allowance, Write-offs and Long-lived Assets, Impairment of Intangible Assets and Net Losses On Disposal of Entities [Member] | Restructuring 2017 [Member]
Restructuring Reserve, Settled without Cash							$ 40,700
Severance, Other Termination Benefit Costs and Contract Termination Costs [Member] | Restructuring 2017 [Member]
Restructuring and Related Costs, Incurred Cost, Total	$ 1,300			$ 1,100

[1] Refers to cash utilized to settle charges during the first quarter of 2020.

[2] Refers to cash utilized to settle charges during the first quarter of 2019.