Revenue Recognition - Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue:
Total revenue	$ 20,740	$ 22,174	$ 39,984	$ 43,363
Product, accessories and parts
Revenue:
Total revenue	15,988	18,627	30,061	35,712
Total from Micro turbine Products
Revenue:
Total revenue	12,016		22,102
Accessories and parts
Revenue:
Total revenue	3,972		7,959
Service
Revenue:
Total revenue	4,752	$ 3,547	9,923	$ 7,651
Total North America
Revenue:
Total revenue	10,159		19,702
United States
Revenue:
Total revenue	9,838		17,467
Mexico
Revenue:
Total revenue	242		1,483
All other North America
Revenue:
Total revenue	79		752
All other Europe
Revenue:
Total revenue	4,468		7,017
Total Europe
Revenue:
Total revenue	5,298		9,302
Asia
Revenue:
Total revenue	921		2,449
Australia
Revenue:
Total revenue	468		2,138
Russia
Revenue:
Total revenue	830		2,285
All other
Revenue:
Total revenue	$ 3,894		$ 6,393