Note E - Segment Information - Segment Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2016
Operating Segments [Member] | Coil [Member]
Net sales	$ 15,451,000	$ 18,288,000	$ 34,450,000	$ 37,635,000
Total net sales	15,451,000	18,288,000	34,450,000	37,635,000
Operating profit (loss)	118,000	885,000	(1,396,000)	3,040,000
Coil	19,208,000		19,208,000		$ 25,317,000
Operating Segments [Member] | Tubular [Member]
Net sales	2,867,000	4,878,000	6,261,000	9,499,000
Total net sales	2,867,000	4,878,000	6,261,000	9,499,000
Operating profit (loss)	(649,000)	(710,000)	(923,000)	(1,347,000)
Coil	35,896,000		35,896,000		37,543,000
Operating Segments [Member]
Operating profit (loss)	(531,000)	175,000	(2,319,000)	1,693,000
Coil	55,104,000		55,104,000		62,860,000
Corporate, Non-Segment [Member]
Corporate expenses	431,000	480,000	988,000	1,210,000
Coil	9,559,000		9,559,000		4,030,000
Net sales	18,317,506	23,165,705	40,711,270	47,134,273
Total net sales	18,317,506	23,165,705	40,711,270	47,134,273
Interest & other income	(14,750)	(17,250)	(29,500)	(34,500)
Total earnings (loss) before taxes	(946,790)	$ (287,883)	(3,277,778)	$ 517,804
Coil	$ 64,662,854		$ 64,662,854		$ 66,890,397