Note 13 - Related Party Transactions (Details Textual) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015	Dec. 12, 2014
Equity Method Investments	$ 11,589	$ 10,977
Powersem GmbH [Member]
Related Party Transaction, Expenses from Transactions with Related Party	3,900	3,400	$ 4,000
Accounts Receivable, Related Parties	96	99
Accounts Payable, Related Parties	72	63
Equity Method Investments	$ 2,500	2,500
Equity Method Investment, Ownership Percentage	45.00%
Revenue from Related Parties	$ 1,600	1,500	1,800
EB Tech Ltd [Member]
Related Party Transaction, Expenses from Transactions with Related Party	347	378	$ 278
Accounts Payable, Related Parties	35	26
Equity Method Investments	$ 2,600	2,700
Equity Method Investment, Ownership Percentage	20.00%
ATEC [Member]
Related Party Transaction, Expenses from Transactions with Related Party	$ 7,800	8,000
Accounts Payable, Related Parties	996	737
Equity Method Investments	$ 6,500	$ 5,700
Equity Method Investment, Ownership Percentage				24.00%

Amount for accounts payable to related parties.

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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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