Commitments and Contingencies (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2014	Sep. 30, 2017
Schedule of Equity Method Investments [Line Items]
Purchase obligation	$ 19,300			$ 34,400
Price of an ion implanter	686	$ 210
Environmental Clean-up | BTU International, Inc (BTU) Merger
Schedule of Equity Method Investments [Line Items]
Loss contingency accrual, less than	100			100
Letter of credit	$ 200			$ 200
Tempress Systems and Energy Research Centre Agreement
Schedule of Equity Method Investments [Line Items]
Price of an ion implanter			$ 1,400
Ownership rights to results of projects developed separately by individual parties			100.00%
Required contribution in form of labor and assets			$ 1,400
Period from agreement start for contribution for project support			2 years
Minimum
Schedule of Equity Method Investments [Line Items]
Severance payment term	12 months
Maximum
Schedule of Equity Method Investments [Line Items]
Severance payment term	36 months