Note 3 - Revenues (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Disaggregation of Revenue [Table Text Block]

	Year Ended December 31, 2019
	Infrastructure Solutions		Corrosion Protection		Energy Services		Total
Geographic region:
United States	$	427,220	$	159,408	$	328,048	$	914,676
Canada		65,370		57,663		—		123,033
Europe		49,157		15,121		—		64,278
Other foreign		49,050		62,898		—		111,948
Total revenues	$	590,797	$	295,090	$	328,048	$	1,213,935

	Year Ended December 31, 2018
	Infrastructure Solutions		Corrosion Protection		Energy Services		Total
Geographic region:
United States	$	430,187	$	200,397	$	335,707	$	966,291
Canada		62,292		71,320		—		133,612
Europe		54,567		12,227		—		66,794
Other foreign		57,075		109,796		—		166,871
Total revenues	$	604,121	$	393,740	$	335,707	$	1,333,568

	Year Ended December 31, 2017
	Infrastructure Solutions		Corrosion Protection		Energy Services		Total
Geographic region:
United States	$	437,944	$	299,643	$	290,726		$ 1,028,313
Canada		60,675		79,059		—		139,734
Europe		58,520		13,319		—		71,839
Other foreign		55,015		64,118		—		119,133
Total revenues	$	612,154	$	456,139	$	290,726	$	1,359,019

	Year Ended December 31, 2019
	Infrastructure Solutions		Corrosion Protection		Energy Services		Total
Contract type:
Fixed fee	$	523,042	$	203,887	$	704	$	727,633
Time and materials		—		65,084		327,344		392,428
Product sales		67,512		26,119		—		93,631
License fees		243		—		—		243
Total revenues	$	590,797	$	295,090	$	328,048	$	1,213,935

	Year Ended December 31, 2018
	Infrastructure Solutions		Corrosion Protection		Energy Services		Total
Contract type:
Fixed fee	$	556,642	$	296,217	$	16,134	$	868,993
Time and materials		—		58,372		319,573		377,945
Product sales		45,030		39,151		—		84,181
License fees		2,449		—		—		2,449
Total revenues	$	604,121	$	393,740	$	335,707	$	1,333,568

	Year Ended December 31, 2017
	Infrastructure Solutions		Corrosion Protection		Energy Services		Total
Contract type:
Fixed fee	$	569,701	$	353,480	$	9,225	$	932,406
Time and materials		—		56,288		281,501		337,789
Product sales		41,878		46,371		—		88,249
License fees		575		—		—		575
Total revenues	$	612,154	$	456,139	$	290,726	$	1,359,019

Contract Asset and Liability [Table Text Block]

	December 31,
	2019 (1)			2018 (2)
Contract assets – current	$	51,092		$	62,467
Contract liabilities – current		(37,562	)		(32,339	)
Net contract assets	$	13,530		$	30,128