Note 4 - Restructuring - Recognized Cost Restructuring Activities (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended				26 Months Ended
	Sep. 30, 2019		Sep. 30, 2018		Sep. 30, 2019		Sep. 30, 2018		Sep. 30, 2019
Restructuring charges	$ 1,400		$ 1,200		$ 5,500		$ 4,500
Restructing reserve, settled without cash					6,419		5,891
Restructuring 2017 [Member]
Restructing reserve, balance					2,412		5,189
Restructuring charges	8,607	[1]	7,423	[2]	17,989	[3]	15,580	[4]
Restructing reserve, foreign currency translation					(69)		(34)
Restructing reserve, settled with cash					9,739	[5]	9,424	[6]	$ 37,300
Restructing reserve, settled without cash	5,500		5,100		6,419		8,150
Restructing reserve, balance	4,174		3,161		4,174		3,161		4,174
Employee Severance [Member] | Restructuring 2017 [Member]
Restructing reserve, balance					1,742		3,864
Restructuring charges	1,147		949		3,774		3,217
Restructing reserve, foreign currency translation					(26)		(30)
Restructing reserve, settled with cash					2,434	[5]	4,754	[6]
Restructing reserve, settled without cash					0		0
Restructing reserve, balance	3,056		2,297		3,056		2,297		3,056
Contract Termination [Member] | Restructuring 2017 [Member]
Restructing reserve, balance					359		650
Restructuring charges	209		215		1,447		1,202
Restructing reserve, foreign currency translation					(30)		(4)
Restructing reserve, settled with cash					1,153	[5]	1,337	[6]
Restructing reserve, settled without cash					0		0
Restructing reserve, balance	623		511		623		511		623
Employee Relocation [Member] | Restructuring 2017 [Member]
Restructing reserve, balance					0		0
Restructuring charges	79		55		274		129
Restructing reserve, foreign currency translation					(4)		0
Restructing reserve, settled with cash					198	[5]	129	[6]
Restructing reserve, settled without cash					0		0
Restructing reserve, balance	72		0		72		0		72
Other Restructuring [Member] | Restructuring 2017 [Member]
Restructing reserve, balance					311		675
Restructuring charges	7,172	[7]	6,204	[7]	12,494	[8]	11,032	[8]
Restructing reserve, foreign currency translation					(9)		0
Restructing reserve, settled with cash					5,954	[5]	3,204	[6]
Restructing reserve, settled without cash					6,419		8,150
Restructing reserve, balance	$ 423		$ 353		$ 423		$ 353		$ 423

[1] 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.

[2] Total pre-tax restructuring charges for the quarter ended September 30, 2018, include cash charges of $2.3 million and non-cash charges of $5.1 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 include cash charges of $11.6 million and non-cash charges of $6.4 million. Cash charges consist of charges incurred during the period that will be settled in cash, either during the current period or future periods.

[4] Total pre-tax restructuring charges include cash charges of $7.4 million and non-cash charges of $8.2 million. Cash charges consist of charges incurred during the period 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 2019.

[6] Refers to cash utilized to settle charges during the first nine months of 2018.

[7] For the quarter ended September 30, 2019, 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 exiting the CIPP operations in Europe, exiting the cathodic protection operations in the Middle East, disposing of certain international businesses and other cost savings initiatives. For the quarter ended September 30, 2018, charges primarily related to certain wind-down costs, allowances for accounts receivable, fixed asset disposals, and other restructuring-related costs in connection with exiting non-pipe-related applications for the Tyfo systems in North America and right-sizing the CIPP operations in Australia and Denmark.

[8] For the nine months ended September 30, 2019, 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 exiting the CIPP operations in Europe, exiting the cathodic protection operations in the Middle East, disposing of certain international businesses and other cost savings initiatives. For the nine months ended September 30, 2018, charges primarily related to certain wind-down costs, allowances for accounts receivable, fixed asset disposals, and other restructuring-related costs in connection with exiting non-pipe-related applications for the Tyfo® systems in North America and right-sizing the CIPP operations in Australia and Denmark.