Revenue Recognition - Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue:
Total revenue	$ 14,906	$ 20,740	$ 29,099	$ 39,984
Product, accessories and parts
Revenue:
Total revenue	9,344	15,988	18,280	30,061
Total from Micro turbine Products
Revenue:
Total revenue	7,047		13,173
Accessories and parts
Revenue:
Total revenue	2,297		5,107
Service
Revenue:
Total revenue	5,562	$ 4,752	10,819	$ 9,923
Total North America
Revenue:
Total revenue	6,616		15,623
United States
Revenue:
Total revenue	5,673		13,597
Mexico
Revenue:
Total revenue	893		1,926
All other North America
Revenue:
Total revenue	50		100
Russia
Revenue:
Total revenue	1,631		2,098
All other Europe
Revenue:
Total revenue	4,376		7,001
Total Europe
Revenue:
Total revenue	6,007		9,099
Asia
Revenue:
Total revenue	1,272		2,216
Australia
Revenue:
Total revenue	588		1,225
All other
Revenue:
Total revenue	$ 423		$ 936