Note 15 - Segment Reporting - Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Revenues from external customers									$ 145,619	$ 198,496
Revenue from Contract with Customer, Including Assessed Tax	$ 26,011	$ 40,389	$ 46,491	$ 32,728	$ 40,322	$ 54,614	$ 54,926	$ 48,634	145,619	198,496
Operating loss	(3,975)	$ (1,997)	$ (2,311)	$ (4,311)	(1,818)	$ (475)	$ 1,035	$ 1,680	(12,594)	422
Depreciation and amortization									6,336	6,279
Capital expenditures									1,707	1,547
Total assets	118,047				119,682				118,047	119,682
Consolidation, Eliminations [Member]
Revenues from external customers									0	0
Revenue from Contract with Customer, Including Assessed Tax									(360)	(137)
Operating loss									0	(8)
Depreciation and amortization									0	0
Capital expenditures									0	0
Total assets	(204,347)				(194,747)				(204,347)	(194,747)
Intersegment Eliminations [Member]
Revenue from Contract with Customer, Including Assessed Tax									0	0
Heavy Fabrications [Member]
Total assets	37,131				40,438				37,131	40,438
Heavy Fabrications [Member] | Operating Segments [Member]
Revenues from external customers									101,989	155,096
Revenue from Contract with Customer, Including Assessed Tax									101,994	155,198
Operating loss									(3,214)	10,385
Depreciation and amortization									3,844	3,736
Capital expenditures									1,038	1,049
Heavy Fabrications [Member] | Intersegment Eliminations [Member]
Revenue from Contract with Customer, Including Assessed Tax									5	102
Gearing [Member]
Total assets	46,219				43,319				46,219	43,319
Gearing [Member] | Operating Segments [Member]
Revenues from external customers									28,583	25,104
Revenue from Contract with Customer, Including Assessed Tax									28,583	25,136
Operating loss									(2,593)	(3,883)
Depreciation and amortization									1,855	1,961
Capital expenditures									328	283
Gearing [Member] | Intersegment Eliminations [Member]
Revenue from Contract with Customer, Including Assessed Tax									0	32
Industrial Solutions [Member]
Total assets	10,825				10,244				10,825	10,244
Industrial Solutions [Member] | Operating Segments [Member]
Revenues from external customers									15,047	18,296
Revenue from Contract with Customer, Including Assessed Tax									15,402	18,299
Operating loss									(386)	881
Depreciation and amortization									425	430
Capital expenditures									261	159
Industrial Solutions [Member] | Intersegment Eliminations [Member]
Revenue from Contract with Customer, Including Assessed Tax									355	3
Corporate Segment [Member]
Total assets	$ 228,219				$ 220,428				228,219	220,428
Corporate Segment [Member] | Operating Segments [Member]
Revenues from external customers									0	0
Revenue from Contract with Customer, Including Assessed Tax									0	0
Operating loss									(6,401)	(6,953)
Depreciation and amortization									212	152
Capital expenditures									80	56
Corporate Segment [Member] | Intersegment Eliminations [Member]
Revenue from Contract with Customer, Including Assessed Tax									$ 0	$ 0