INCOME TAXES (Details) - USD ($) $ in Thousands					12 Months Ended
		Dec. 31, 2019	May 22, 2018	Dec. 31, 2016	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2024	Dec. 31, 2021	Dec. 31, 2020
Income Tax Contingency [Line Items]
Federal statutory rate						24.50%	35.00%
Change in tax rate, deferred tax liability, provisional income tax (expense) benefit						$ 228,400
Change in tax rate, deferred income taxes						164,300
Change in tax rate, provisional income tax expense (benefit)						64,100
Initial revaluation of excess deferred income taxes			$ 20,100
Overcollection of taxes			9,000
Deferred income tax expense (benefit), remeasurement						14,300
Amortization of excess deferred income taxes						1,800
Revaluation of deferred income taxes not included in base rates						880
Regulatory liability, excess deferred income taxes						205,400
Tax estimate adjustment						(2,100)
Deferred Tax Assets, Operating Loss Carryforwards, Domestic, Refundable and Receivables						$ 23,000	$ 15,400
Net operating losses, life						20 years
Federal net operating losses	[1]					$ 24,500	28,487
Valuation allowance						4,000	1,000
Investment tax credit, project phase out				3 years
Domestic Tax Authority
Income Tax Contingency [Line Items]
Net operating losses						136,800	125,300
State and Local Jurisdiction
Income Tax Contingency [Line Items]
Net operating losses						578,800	471,700
Forecast
Income Tax Contingency [Line Items]
Federal statutory rate					21.00%
Investment tax credit, solar property, percentage		30.00%						10.00%	22.00%	26.00%
Investment tax credit, project phase out		5 years
March 2018 BGSS/CIP Filing
Income Tax Contingency [Line Items]
Approved customer refunds			$ 31,000
Clean Energy Ventures
Income Tax Contingency [Line Items]
Tax credit carryforward						121,100	109,300
Natural Gas Distribution
Income Tax Contingency [Line Items]
Income tax expense (benefit) provision						17,000
Tax credit carryforward						$ 2,200	$ 2,300
Minimum | State and Local Jurisdiction
Income Tax Contingency [Line Items]
Net operating losses, life						7 years
Maximum
Income Tax Contingency [Line Items]
Net operating losses, life						20 years

[1] See discussion of federal net operating loss utilization in the Other Tax Items section of this note.