REVENUE - Narrative (Details) - USD ($)	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 revenue	$ 22,058,000	$ 30,714,000	$ 36,510,000	$ 35,101,000	$ 35,497,000	$ 44,251,000	$ 26,281,000	$ 10,811,000	$ 124,383,000	$ 116,840,000	$ 150,841,000
Percentage of contract for sale equal monthly progress payments									90.00%
Long-term accounts receivable	0								$ 0
Proceeds from sale of revenue earned but not billed									2,800,000	5,100,000	4,400,000
Gain (loss) on sale of revenue earned but not billed									$ (13,000)	(100,000)	$ (100,000)
Revenue, Practical Expedient, Initial Application and Transition, Nondisclosure of Transaction Price Allocation to Remaining Performance Obligation [true false]									true
Revenue, Practical Expedient, Financing Component [true false]									true
Unbilled accounts receivable	$ 500,000				$ 600,000				$ 500,000	$ 600,000
Contract liabilities									0
Light fixture sales-type lease
Disaggregation Of Revenue [Line Items]
Total revenue									1,200,000
Sale of tax credits
Disaggregation Of Revenue [Line Items]
Total revenue									200,000
Legacy solar facilities
Disaggregation Of Revenue [Line Items]
Total revenue									$ 100,000