Investment in Joint Venture - Summarized financial information (Details) - USD ($) $ in Thousands	3 Months Ended		4 Months Ended	9 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Jul. 30, 2021	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2022
Variable Interest Entity [Line Items]
Current assets	$ 36,399			$ 36,399		$ 44,794
Variable Interest Entity, Measure of Activity [Abstract]
Gross loss	(2,669)	$ 669		(1,125)	$ 10,382
Variable Interest Entity, Not Primary Beneficiary | AFSW
Variable Interest Entity, Measure of Activity [Abstract]
Sales			$ 2,200
Gross loss			(3,200)
Net loss			$ (4,300)
Variable Interest Entity, Not Primary Beneficiary | GaNovation
Variable Interest Entity [Line Items]
Current assets	3,678			3,678		4,259
Long-term assets	5,870			5,870		3,690
Other current liabilities	4,282			4,282		3,799
Due to related parties	4			4		(1)
Net surplus	5,149			5,149		4,151
Variable Interest Entity, Measure of Activity [Abstract]
Sales	3,926	2,262		9,958	5,957
Gross loss	(2,716)	(2,338)		(6,964)	(7,094)
Net loss	(3,197)	$ (2,848)		(8,351)	$ (9,085)
Variable Interest Entity, Not Primary Beneficiary | Transphorm, Inc.
Variable Interest Entity [Line Items]
Due to related parties	$ 113			$ 113		$ 0