Summary of Significant Accounting Policies - Revenue by Product (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue by product
Total Revenue	$ 83,412	$ 82,837
Product, accessories and parts
Revenue by product
Total Revenue	66,303	66,754
Total from Micro turbine Products
Revenue by product
Total Revenue	51,417	50,813
C30
Revenue by product
Total Revenue	1,810	1,694
C65
Revenue by product
Total Revenue	11,719	12,740
C200
Revenue by product
Total Revenue	5,218	2,832
C600
Revenue by product
Total Revenue	6,286	9,057
C800
Revenue by product
Total Revenue	5,846	6,461
C1000
Revenue by product
Total Revenue	20,538	17,886
Unit upgrades
Revenue by product
Total Revenue		143
Accessories and parts
Revenue by product
Total Revenue	14,886	15,941
Service
Revenue by product
Total Revenue	$ 17,109	$ 16,083