Acquisition and Related Goodwill - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Sep. 25, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Consideration
Equity (884,890 shares of common stock at $4.02 per share)		$ 3,498	$ 0	$ 0
Recognized amounts of identifiable assets acquired and liabilities assumed
Goodwill		1,719	$ 0
Infinia Technology Corporation (ITC)
Consideration
Cash	$ 100
Equity (884,890 shares of common stock at $4.02 per share)	$ 3,600
Business combination, stock issued (in shares)	884,890
Fair value per acquiree share (in dollars per share)	$ 4.02
Contingent consideration	$ 600
Total Consideration	4,300
Recognized amounts of identifiable assets acquired and liabilities assumed
Core technology and know-how	3,400
Working capital	200
Property, plant and equipment	0
Total identifiable net assets	3,600
Long-term deferred tax liability	1,100	1,100
Goodwill	$ 1,700	$ 1,700