Summary of Significant Accounting Policies - Segment Reporting - Revenue by Product (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue by product
Total Revenue	$ 67,636	$ 68,926
Product and accessories
Revenue by product
Total Revenue	36,517	35,338
Total from Micro turbine Products
Revenue by product
Total Revenue	34,121	33,790
C30
Revenue by product
Total Revenue	1,607	1,518
C65
Revenue by product
Total Revenue	10,756	9,366
C200
Revenue by product
Total Revenue	3,603	3,880
C600
Revenue by product
Total Revenue	7,913	7,204
C800
Revenue by product
Total Revenue	3,069	3,253
C1000
Revenue by product
Total Revenue	7,173	8,340
Unit upgrades
Revenue by product
Total Revenue		229
Accessories and parts
Revenue by product
Total Revenue	2,396	1,548
Parts and service
Revenue by product
Total Revenue	$ 31,119	$ 33,588