Note 13 - Related Party Transactions (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014	Dec. 12, 2014
Powersem GmbH [Member]
Equity Method Investment, Ownership Percentage	45.00%
Revenue from Related Parties	$ 1,500	$ 1,800	$ 2,100
Related Party Transaction, Expenses from Transactions with Related Party	3,400	4,000	5,200
Accounts Receivable, Related Parties	99	82
Accounts Payable, Related Parties	63	115
Equity Method Investments	$ 2,500	2,600
EB Tech Ltd [Member]
Equity Method Investment, Ownership Percentage	20.00%
Related Party Transaction, Expenses from Transactions with Related Party	$ 378	278	211
Accounts Payable, Related Parties	26	23	$ 0
Equity Method Investments	2,700	2,700
ATEC [Member]
Equity Method Investment, Ownership Percentage				24.30%
Related Party Transaction, Expenses from Transactions with Related Party	8,000	2,000
Accounts Payable, Related Parties	737	632
Equity Method Investments	5,700	5,700
Equity Method Investments	$ 10,977	$ 11,041