SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Investments in Unconsolidated Affiliates (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	$ 2,302,880	$ 2,176,080
Offshore Wind Business - North East Offshore
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	50.00%
Investments in unconsolidated affiliates	$ 2,159,200	1,947,100
Natural Gas Pipeline - Algonquin Gas Transmission, LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	15.00%
Investments in unconsolidated affiliates	$ 117,500	118,800
Renewable Energy Investment Fund
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	90.00%
Investments in unconsolidated affiliates	$ 0	84,100
Other
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	$ 26,200	$ 26,100