Revenue Recognition - Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue:
Total revenue	$ 17,196	$ 14,906	$ 33,278	$ 29,099
Product and accessories
Revenue:
Total revenue	8,465	7,206	16,854	13,812
Total from Micro turbine Products
Revenue:
Total revenue			16,664	13,173
Accessories and parts
Revenue:
Total revenue			190	639
Parts and service
Revenue:
Total revenue	$ 8,731	$ 7,700	16,424	15,287
Total North America
Revenue:
Total revenue			17,205	15,623
United States
Revenue:
Total revenue			15,174	13,597
Mexico
Revenue:
Total revenue			1,584	1,926
All other North America
Revenue:
Total revenue			447	100
Russia
Revenue:
Total revenue			2,206	2,098
All other Europe
Revenue:
Total revenue			5,612	7,001
Total Europe
Revenue:
Total revenue			7,818	9,099
Asia
Revenue:
Total revenue			823	2,216
Australia
Revenue:
Total revenue			3,342	1,225
All other
Revenue:
Total revenue			$ 4,090	$ 936