Note 2 - Revenue Recognition - Impact of Adoption of Topic 606 (Details) - USD ($) $ in Thousands		3 Months Ended
		Jun. 30, 2018	Jul. 01, 2017
Net Sales		$ 343,392	$ 280,662
Cost of Product Sold		337,494	266,372
Gross profit			14,290
Operating income		(7,837)	(632)
Loss before income taxes		(11,266)	(2,361)
Net Loss		$ (8,755)	(842)
Previously Reported [Member]
Net Sales	[1]		288,927
Cost of Product Sold	[1]		273,392
Gross profit	[1]		15,535
Operating income	[1]		613
Loss before income taxes	[1]		(2,583)
Net Loss	[1]		(980)
Restatement Adjustment [Member] | Accounting Standards Update 2014-09 [Member]
Net Sales			(8,265)
Cost of Product Sold			(7,020)
Gross profit			(1,245)
Operating income			(1,245)
Loss before income taxes			222
Net Loss			$ 138

[1] These reported amounts for the three months ended July 1, 2017 are restated amounts. See the Company's Annual Report on Form 10-K for the year ended March 31, 2018 which was filed on June 29, 2018 for more information on the restatement.