Note 4 - Restructuring - Recognized Cost Restructuring Activities (Details) - Restructuring 2017 [Member] - USD ($) $ in Thousands	3 Months Ended				6 Months Ended				35 Months Ended
	Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020
Restructuring reserve, balance					$ 8,088		$ 2,412
Restructuring charges	$ 4,833	[1]	$ 6,516	[2]	8,456	[3]	9,382	[4]
Restructuring reserve, foreign currency translation					(50)		(27)
Restructuring reserve, settled with cash					9,681	[5]	5,942	[6]	$ 51,100
Restructuring reserve, settled without cash					2,718		1,409
Restructuring reserve, balance	4,095		4,416		4,095		4,416		4,095
Employee Severance [Member]
Restructuring reserve, balance					4,389		1,742
Restructuring charges	350		2,132		1,488		2,627
Restructuring reserve, foreign currency translation					(21)		(10)
Restructuring reserve, settled with cash					4,104	[5]	1,860	[6]
Restructuring reserve, settled without cash					0		0
Restructuring reserve, balance	1,752		2,499		1,752		2,499		1,752
Contract Termination [Member]
Restructuring reserve, balance					953		359
Restructuring charges	211		698		327		1,238
Restructuring reserve, foreign currency translation					(7)		(13)
Restructuring reserve, settled with cash					575	[5]	606	[6]
Restructuring reserve, settled without cash					0		0
Restructuring reserve, balance	698		978		698		978		698
Employee Relocation [Member]
Restructuring reserve, balance					367		0
Restructuring charges	103		144		137		195
Restructuring reserve, foreign currency translation					0		(1)
Restructuring reserve, settled with cash					211	[5]	26	[6]
Restructuring reserve, settled without cash					0		0
Restructuring reserve, balance	293		168		293		168		293
Other Restructuring [Member]
Restructuring reserve, balance					2,379		311
Restructuring charges	4,169	[7]	3,542	[7]	6,504	[8]	5,322	[8]
Restructuring reserve, foreign currency translation					(22)		(3)
Restructuring reserve, settled with cash					4,791	[5]	3,450	[6]
Restructuring reserve, settled without cash					2,718		1,409
Restructuring reserve, balance	$ 1,352		$ 771		$ 1,352		$ 771		$ 1,352

[1] Total pre-tax restructuring charges for the quarter ended June 30, 2020, include cash charges of $2.6 million and non-cash charges of $2.2 million. Cash charges consist of charges incurred during the quarter that will be settled in cash, either during the current period or future periods.

[2] Total pre-tax restructuring charges for the quarter ended June 30, 2019, include cash charges of $5.4 million and non-cash charges of $1.1 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] Total pre-tax restructuring charges for the six months ended June 30, 2020, include cash charges of $5.8 million and non-cash charges of $2.7 million. Cash charges consist of charges incurred during the quarter that will be settled in cash, either during the current period or future periods.

[4] Total pre-tax restructuring charges for the six months ended June 30, 2019, include cash charges of $8.5 million and non-cash charges of $0.9 million. Cash charges consist of charges incurred during the quarter that will be settled in cash, either during the current period or future periods.

[5] Refers to cash utilized to settle charges during the first six months of 2020.

[6] Refers to cash utilized to settle charges during the first six months of 2019.

[7] For the quarter ended June 30, 2020, charges primarily related to certain wind-down costs, allowances for accounts receivable, 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. Amounts also include goodwill and definite-lived intangible asset impairments related to the exiting P2S. For the quarter ended June 30, 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 Europe, exiting the cathodic protection operations in the Middle East and other cost savings initiatives.

[8] For the six months ended June 30, 2020, charges primarily related to certain wind-down costs, allowances for accounts receivable, 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. Amounts also include goodwill and definite-lived intangible asset impairments related to the exiting P2S. For the six months ended June 30, 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 Europe, exiting the cathodic protection operations in the Middle East and other cost savings initiatives.