Note 4 - Restructuring - Recognized Cost Restructuring Activities (Details) - Restructuring 2017 [Member] - USD ($) $ in Thousands	3 Months Ended				9 Months Ended				38 Months Ended
	Sep. 30, 2020		Sep. 30, 2019		Sep. 30, 2020		Sep. 30, 2019		Sep. 30, 2020
Restructuring reserve, balance					$ 8,088		$ 2,412
Restructuring charges	$ 4,243	[1]	$ 8,607	[2]	12,699	[3]	17,989	[4]
Restructuring reserve, foreign currency translation					(36)		(69)
Restructuring reserve, settled with cash					13,955	[5]	9,739	[6]	$ 54,800
Restructuring reserve, settled without cash					3,282		6,419
Restructuring reserve, balance	3,514		4,174		3,514		4,174		3,514
Employee Severance [Member]
Restructuring reserve, balance					4,389		1,742
Restructuring charges	2,038		1,147		3,526		3,774
Restructuring reserve, foreign currency translation					(18)		(26)
Restructuring reserve, settled with cash					6,567	[5]	2,434	[6]
Restructuring reserve, settled without cash					0		0
Restructuring reserve, balance	1,330		3,056		1,330		3,056		1,330
Contract Termination [Member]
Restructuring reserve, balance					953		359
Restructuring charges	274		209		601		1,447
Restructuring reserve, foreign currency translation					(7)		(30)
Restructuring reserve, settled with cash					961	[5]	1,153	[6]
Restructuring reserve, settled without cash					0		0
Restructuring reserve, balance	586		623		586		623		586
Employee Relocation [Member]
Restructuring reserve, balance					367		0
Restructuring charges	23		79		160		274
Restructuring reserve, foreign currency translation					1		(4)
Restructuring reserve, settled with cash					288	[5]	198	[6]
Restructuring reserve, settled without cash					0		0
Restructuring reserve, balance	240		72		240		72		240
Other Restructuring [Member]
Restructuring reserve, balance					2,379		311
Restructuring charges	1,908	[7]	7,172	[7]	8,412	[8]	12,494	[8]
Restructuring reserve, foreign currency translation					(12)		(9)
Restructuring reserve, settled with cash					6,139	[5]	5,954	[6]
Restructuring reserve, settled without cash					3,282		6,419
Restructuring reserve, balance	$ 1,358		$ 423		$ 1,358		$ 423		$ 1,358

[1] Total pre-tax restructuring charges for the quarter ended September 30, 2020 include cash charges of $3.7 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 September 30, 2019 include cash charges of $3.1 million and non-cash charges of $5.5 million. Cash charges consist of charges incurred during the quarter that will be settled in cash, either during the current period or future periods.

[3] Total pre-tax restructuring charges for the nine months ended September 30, 2020 include cash charges of $9.5 million and non-cash charges of $3.2 million. Cash charges consist of charges incurred during the quarter that will be settled in cash, either during the current period or future periods.

[4] Total pre-tax restructuring charges for the nine months ended September 30, 2019 include cash charges of $11.6 million and non-cash charges of $6.4 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 nine months of 2020.

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

[7] For the quarter ended September 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, disposing of certain international businesses and other cost savings initiatives. For the quarter ended September 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 nine months ended September 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 nine months ended September 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.