Note 4 - Restructuring - Recognized Cost Restructuring Activities (Details) - USD ($) $ in Thousands		3 Months Ended				32 Months Ended
		Mar. 31, 2020		Mar. 31, 2019		Mar. 31, 2020
Restructuring reserve, settled without cash		$ 463		$ (151)
Restructuring 2017 [Member]
Restructuring reserve, balance		8,088		2,412
Restructuring charges		3,623	[1]	2,866	[2]
Restructuring reserve, foreign currency translation		(40)		(4)
Restructuring reserve, settled with cash		5,262	[3]	3,264	[4]	$ 48,500
Restructuring reserve, settled without cash		463		(151)
Restructuring reserve, balance		5,946		2,161		5,946
Employee Severance [Member] | Restructuring 2017 [Member]
Restructuring reserve, balance		4,389		1,742
Restructuring charges		1,138		495
Restructuring reserve, foreign currency translation		(16)		(5)
Restructuring reserve, settled with cash		1,973	[3]	1,102	[4]
Restructuring reserve, settled without cash		0		0
Restructuring reserve, balance		3,538		1,130		3,538
Contract Termination [Member] | Restructuring 2017 [Member]
Restructuring reserve, balance		953		359
Restructuring charges		116		540
Restructuring reserve, foreign currency translation		(6)		3
Restructuring reserve, settled with cash		177	[3]	310	[4]
Restructuring reserve, settled without cash		0		0
Restructuring reserve, balance		886		592		886
Employee Relocation [Member] | Restructuring 2017 [Member]
Restructuring reserve, balance		367		0
Restructuring charges		34		51
Restructuring reserve, foreign currency translation		3		0
Restructuring reserve, settled with cash		70	[3]	0	[4]
Restructuring reserve, settled without cash		0		0
Restructuring reserve, balance		334		51		334
Other Restructuring [Member] | Restructuring 2017 [Member]
Restructuring reserve, balance		2,379		311
Restructuring charges	[5]	2,335		1,780
Restructuring reserve, foreign currency translation		(21)		(2)
Restructuring reserve, settled with cash		3,042	[3]	1,852	[4]
Restructuring reserve, settled without cash		463		(151)
Restructuring reserve, balance		$ 1,188		$ 388		$ 1,188

[1] Total pre-tax restructuring charges for the quarter ended March 31, 2020, include cash charges of $3.1 million and non-cash charges of $0.5 million. Cash charges consist of charges incurred during the quarter that will be settled in cash, either during the current period or future periods.

[2] Total pre-tax restructuring charges for the quarter ended March 31, 2019, include cash charges of $3.1 million and non-cash charges of (0.2) million. Cash charges consist of charges incurred during the quarter that will be settled in cash, either during the current period or future periods.

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

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

[5] For the quarter ended March 31, 2020, charges primarily related to certain wind-down costs, fixed asset disposals, release of cumulative currency translation adjustments and other restructuring-related costs in connection with optimizing the cathodic protection operations in North America, exiting the CIPP operations in Europe, disposing of certain international businesses and other cost savings initiatives. For the quarter ended March 31, 2019, charges primarily related to certain wind-down costs, allowances for accounts receivable, fixed asset disposals, and other restructuring-related costs in connection with exiting the CIPP operations in the UK, exiting the cathodic protection operations in the Middle East and other cost savings initiatives.