Note 20 - Quarterly Data (Unaudited) - Summary of Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Net sales	$ 39,179		$ 41,088		$ 42,061		$ 33,928		$ 45,562		$ 52,335		$ 53,846		$ 84,865		$ 156,256		$ 236,608		$ 403,298
Gross profit (loss)	2,251		2,123		(2,162)		(5,437)		(11,412)		(2,511)		(2,593)		3,891		(3,225)		(12,625)		40,576
Operating income (loss)	4,819		(2,063)		(6,253)		(10,036)		(16,516)		(7,284)		(13,327)		(3,083)		(13,533)		(40,210)		194
Net income (loss)	$ 5,834		$ 727		$ (6,242)		$ (9,583)		$ (13,693)		$ (1,515)		$ (12,079)		$ (2,101)		$ (9,263)		$ (29,388)		$ (17,887)
Basic (in dollars per share)	$ 0.61		$ 0.08		$ (0.65)		$ (1)										$ (0.97)
Diluted (in dollars per share)	$ 0.60		$ 0.08		$ (0.65)		$ (1)										(0.97)
Total (in dollars per share)									$ (1.43)		$ (0.16)		$ (1.26)		$ (0.22)		$ (0.97)		$ (3.07)		$ (1.88)
Operating Segments [Member]
Operating income (loss)																	$ (2,287)		$ (27,291)		$ 14,813
Corporate, Non-Segment [Member]
Operating income (loss)	$ (3,135)		$ (2,624)		$ (2,603)		$ (2,884)		$ (2,960)		$ (2,602)		$ (3,258)		$ (4,099)		(11,246)		(12,919)
Water Transmission Group [Member] | Operating Segments [Member]
Net sales	39,179		41,075		39,775		29,358		38,681		39,792		38,445		56,242		149,387		173,160		238,545
Gross profit (loss)	3,767		2,939		(1,272)		(5,750)		(7,443)		(725)		1,255		7,519		(317)		606		39,601
Operating income (loss)	9,590	[1]	1,363	[1]	(2,648)	[1]	(7,256)	[1]	(9,026)	[2]	(2,384)	[2]	(5,815)	[2]	5,633	[2]	1,049	[1],[3]	(11,592)	[2],[3]	31,490	[3]
Tubular Products [Member] | Operating Segments [Member]
Net sales			13		2,286		4,570		6,881		12,543		15,401		28,623		6,869		63,448		164,753
Gross profit (loss)	(1,516)		(816)		(890)		313		(3,969)		(1,786)		(3,848)		(3,628)		(2,908)		(13,231)		975
Operating income (loss)	$ (1,636)		$ (802)		$ (1,002)		$ 104		$ (4,530)		$ (2,298)		$ (4,254)		$ (4,617)		$ (3,336)	[4]	$ (15,699)	[4]	$ (16,677)	[4]

[1] Operating income for Water Transmission for the fourth quarter of 2016 includes the gain on sale of facility of $7.9 million.

[2] Operating loss for Water Transmission for the second quarter of 2015 includes the write-off of goodwill of $5.3 million.

[3] Operating income for Water Transmission for 2016 includes restructuring expenses of $1.0 million and gain on sale of facility of $7.9 million. Operating loss for Water Transmission for 2015 includes the write-off of goodwill of $5.3 million.

[4] Operating loss for Tubular Products for 2014 includes the write-off of goodwill of $16.1 million.