Note 14 - Segment and Geographic Information - Summary of Revenues (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues	[1]	$ 807,764	$ 885,887	$ 997,861
Gross profit	[1]	196,459	205,001	225,379
Total operating income (loss)	[1]	40,988	1,233	20,009
Interest expense	[2]	(12,483)	(11,358)	(14,709)
Interest income		1,125	1,038	516
Other	[3]	437	(10,893)	(9,881)
Total other expense		(10,921)	(21,213)	(24,074)
Income (loss) before taxes (benefit) on income (loss)		30,067	(19,980)	(4,065)
Total assets		901,447	995,513	992,417
Assets held for sale		92,850	168,799	162,236
Capital expenditures	[4]	16,559	25,335	27,461
Depreciation and amortization	[5]	28,702	28,673	30,744
Operating income (loss)	[1]	40,988	1,233	20,009
Long-lived assets	[1],[6]	101,790	104,215	128,660
UNITED STATES
Revenues	[1]	572,729	586,628	630,584
Gross profit	[1]	139,308	134,471	136,477
Total operating income (loss)	[1]	18,817	(3,528)	(9,464)
Operating income (loss)	[1]	18,817	(3,528)	(9,464)
Long-lived assets	[1],[6]	89,487	83,225	105,978
CANADA
Revenues	[1]	118,253	123,033	133,612
Gross profit	[1]	24,360	22,183	22,823
Total operating income (loss)	[1]	11,849	7,460	9,482
Operating income (loss)	[1]	11,849	7,460	9,482
Long-lived assets	[1],[6]	7,817	7,462	7,725
Europe [Member]
Revenues	[1]	37,251	64,278	66,794
Gross profit	[1]	11,437	14,849	8,379
Total operating income (loss)	[1]	6,230	(11,363)	(10,599)
Operating income (loss)	[1]	6,230	(11,363)	(10,599)
Long-lived assets	[1],[6]	3,073	3,336	8,295
Other Foreign Countries [Member]
Revenues	[1]	79,531	111,948	166,871
Gross profit	[1]	21,354	33,498	57,700
Total operating income (loss)	[1]	4,092	8,664	30,590
Operating income (loss)	[1]	4,092	8,664	30,590
Long-lived assets	[1],[6]	1,413	10,192	6,662
Infrastructure Solutions [Member]
Revenues		562,571	590,797	604,121
Infrastructure Solutions [Member] | UNITED STATES
Revenues		443,196	427,220	430,187
Infrastructure Solutions [Member] | CANADA
Revenues		69,190	65,370	62,292
Infrastructure Solutions [Member] | Europe [Member]
Revenues		23,782	49,157	54,567
Infrastructure Solutions [Member] | Other Foreign Countries [Member]
Revenues		26,403	49,050	57,075
Corrosion Protection [Member]
Revenues		245,193	295,090	393,740
Corrosion Protection [Member] | UNITED STATES
Revenues		129,533	159,408	200,397
Corrosion Protection [Member] | CANADA
Revenues		49,063	57,663	71,320
Corrosion Protection [Member] | Europe [Member]
Revenues		13,469	15,121	12,227
Corrosion Protection [Member] | Other Foreign Countries [Member]
Revenues		53,128	62,898	109,796
Operating Segments [Member] | Infrastructure Solutions [Member]
Revenues		562,571	590,797	604,121
Gross profit		144,213	144,074	132,411
Total operating income (loss)	[7]	78,098	42,079	37,509
Total assets		511,606	508,226	500,977
Capital expenditures	[4]	10,103	10,679	12,730
Depreciation and amortization	[5]	14,174	13,773	16,758
Operating income (loss)	[7]	78,098	42,079	37,509
Operating Segments [Member] | Corrosion Protection [Member]
Revenues		245,193	295,090	393,740
Gross profit		52,246	60,927	92,968
Total operating income (loss)	[8]	(6,133)	(5,635)	16,283
Total assets		238,566	278,694	279,106
Capital expenditures	[4]	5,654	11,437	9,754
Depreciation and amortization	[5]	12,007	12,487	11,874
Operating income (loss)	[8]	(6,133)	(5,635)	16,283
Corporate, Non-Segment [Member]
Total operating income (loss)	[9]	(30,977)	(35,211)	(33,783)
Total assets		58,425	39,794	50,098
Capital expenditures	[4]	802	3,219	4,977
Depreciation and amortization	[5]	2,521	2,413	2,112
Operating income (loss)	[9]	$ (30,977)	$ (35,211)	$ (33,783)

[1] Attributed to the country of origin.

[2] Interest expense for 2020 includes $0.7 million of third-party arranging fees, expenses and the write-off of unamortized loan costs associated with the amended Credit Facility (see Note 9). Interest expense for 2018 includes $2.3 million of third-party arranging fees, expenses and the write-off of unamortized loan costs associated with the amended Credit Facility (see Note 9).

[3] Other expense for 2020 includes gains of $0.9 million related to restructuring (see Note 4). Other expense for 2019 includes $10.2 million of restructuring charges (see Note 4). Other expense for 2018 includes charges of $7.0 million related to the loss on the sale of Bayou (see Note 1) and $4.0 million of restructuring charges (see Note 4).

[4] Capital expenditures from our discontinued operations were $3.0 million, $3.4 million and $3.1 million in 2020, 2019 and 2018, respectively.

[5] Depreciation and amortization from our discontinued operations were $6.8 million, $7.5 million and $7.1 million in 2020, 2019 and 2018, respectively.

[6] Long-lived assets do not include goodwill, intangible assets, operating lease assets or deferred tax assets.

[7] Operating income for 2020 includes: (i) $0.1 million of restructuring reversals (see Note 4); (ii) $0.4 million of costs primarily related to the planned divestiture of certain international operations; and (iii) $1.1 million of impairment reversals related to assets held for sale. Operating income for 2019 includes: (i) $7.5 million of restructuring charges (see Note 4); (ii) $1.0 million of costs primarily related to the planned divestiture of certain international operations; and (iii) $17.6 million of impairment charges to assets held for sale (see Note 6). Operating income for 2018 includes: (i) $16.1 million of restructuring charges (see Note 4); and (ii) $0.4 million of cost incurred related to the disposition of Denmark.

[8] Operating loss for 2020 includes $9.5 million of restructuring charges (see Note 4). Operating loss for 2019 includes: (i) $7.7 million of restructuring charges (see Note 4); (ii) $0.1 million of divestiture costs; and (iii) $2.9 million of impairment charges to assets held for sale (see Note 6). Operating income for 2018 includes: (i) $7.6 million of restructuring charges (see Note 4); and (ii) $2.5 million of costs incurred related to the divestiture of Bayou.

[9] Operating loss for 2020 includes: (i) $2.7 million of restructuring charges (see Note 4); (ii) $3.2 million of divestiture costs; and (iii) $1.3 million of impairment charges related to assets held for sale (see Note 6). Operating loss for 2019 includes: (i) $5.2 million of restructuring charges (see Note 4); (ii) $2.2 million of costs primarily related to the planned divestiture of certain international operations; and (iii) $2.9 million of impairment charges to assets held for sale (see Note 6). Operating loss for 2018 includes $1.6 million of restructuring charges (see Note 4) and $4.1 million of divestiture costs.