Revenue Recognition - Revenues (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Mar. 31, 2022	Mar. 31, 2021
Revenue:
Total revenue	$ 16,049	$ 17,808	$ 17,640	$ 12,467	$ 18,135	$ 16,697	$ 13,710	$ 19,065	$ 30,107	$ 32,775	$ 47,915	$ 49,472	$ 63,964	$ 67,607
Product and accessories
Revenue:
Total revenue	8,236	9,901	9,344	5,239	$ 10,495	$ 8,848	$ 6,099	$ 11,209	14,583	$ 17,308	24,484	$ 26,156	32,720	36,651
Total from Micro turbine Products
Revenue:
Total revenue													31,367	34,367
Accessories and parts
Revenue:
Total revenue													1,353	2,284
Parts and service
Revenue:
Total revenue	$ 7,813	$ 7,907	$ 8,296	$ 7,228					$ 15,524		$ 23,431		31,244	30,956
Labor reimbursement of Factory Protection Plan contracts.
Revenue:
Non revenue, Parts and service													300	100
Total North America
Revenue:
Total revenue													34,575	37,472
United States
Revenue:
Total revenue													30,269	33,332
Mexico
Revenue:
Total revenue													3,706	3,836
All other North America
Revenue:
Total revenue													600	304
Russia
Revenue:
Total revenue													3,381	3,107
All other Europe
Revenue:
Total revenue													10,872	13,026
Total Europe
Revenue:
Total revenue													14,253	16,133
Asia
Revenue:
Total revenue													5,978	6,342
Australia
Revenue:
Total revenue													4,195	3,297
All other
Revenue:
Total revenue													$ 4,963	$ 4,363