REVENUE - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 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	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									$ 122,936	$ 113,892	$ 149,209
Revenue accounted for under other guidance									1,447	2,948	1,632
Total revenue	$ 22,058	$ 30,714	$ 36,510	$ 35,101	$ 35,497	$ 44,251	$ 26,281	$ 10,811	124,383	116,840	150,841
Product revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									90,442	84,716	111,720
Revenue accounted for under other guidance									1,447	2,948	1,632
Total revenue									91,889	87,664	113,352
Service revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									32,494	29,176	37,489
Revenue accounted for under other guidance									0	0	0
Total revenue									32,494	29,176	37,489
Federal government
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									2,290	1,661	1,301
Federal government | Product revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									920	696	922
Federal government | Service revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									1,370	965	379
Commercial and industrial
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									120,604	112,174	147,852
Commercial and industrial | Product revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									89,480	83,963	110,742
Commercial and industrial | Service revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									31,124	28,211	37,110
Total lighting
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									122,894	113,835	149,153
Total lighting | Product revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									90,400	84,659	111,664
Total lighting | Service revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									32,494	29,176	37,489
Solar energy related revenues
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									42	57	56
Solar energy related revenues | Product revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									42	57	56
Solar energy related revenues | Service revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers									$ 0	$ 0	$ 0