Revenue Recognition - Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenue	$ 18,030	$ 22,761	$ 61,393	$ 61,776
Product, accessories and parts
Disaggregation of Revenue [Line Items]
Total revenue	13,310	18,876	49,022	50,373
Total from Micro turbine Products
Disaggregation of Revenue [Line Items]
Total revenue	10,120		38,630
Accessories and parts
Disaggregation of Revenue [Line Items]
Total revenue	3,190		10,392
Service
Disaggregation of Revenue [Line Items]
Total revenue	4,720	$ 3,885	12,371	$ 11,403
Total North America
Disaggregation of Revenue [Line Items]
Total revenue	12,066		35,940
United States
Disaggregation of Revenue [Line Items]
Total revenue	9,396		31,208
Mexico
Disaggregation of Revenue [Line Items]
Total revenue	2,422		4,217
All other North America
Disaggregation of Revenue [Line Items]
Total revenue	248		515
Europe
Disaggregation of Revenue [Line Items]
Total revenue	2,822		9,473
United Kingdom
Disaggregation of Revenue [Line Items]
Total revenue	158		2,717
Columbia
Disaggregation of Revenue [Line Items]
Total revenue	196		2,855
Asia
Disaggregation of Revenue [Line Items]
Total revenue	1,175		4,241
Australia
Disaggregation of Revenue [Line Items]
Total revenue	1,386		2,751
Kuwait
Disaggregation of Revenue [Line Items]
Total revenue			2,161
All other
Disaggregation of Revenue [Line Items]
Total revenue	$ 227		$ 1,255