Revenue Recognition - Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Revenue:
Total revenue	$ 16,082	$ 14,193
Product and accessories
Revenue:
Total revenue	8,389	6,606
Total from Micro turbine Products
Revenue:
Total revenue	8,312	6,126
Accessories and parts
Revenue:
Total revenue	77	480
Parts and service
Revenue:
Total revenue	7,693	7,587
Total North America
Revenue:
Total revenue	7,823	9,007
United States
Revenue:
Total revenue	7,343	7,924
Mexico
Revenue:
Total revenue	441	1,033
All other North America
Revenue:
Total revenue	39	50
Russia
Revenue:
Total revenue	1,257	467
All other Europe
Revenue:
Total revenue	2,785	2,625
Total Europe
Revenue:
Total revenue	4,042	3,092
Asia
Revenue:
Total revenue	364	944
Australia
Revenue:
Total revenue	1,411	637
All other
Revenue:
Total revenue	$ 2,442	$ 513