INVESTMENTS IN UNCONSOLIDATED AFFILIATES - Summary of Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affilitates	$ 1,436,293	$ 1,107,143
Offshore Wind Business - North East Offshore
Schedule of Equity Method Investments [Line Items]
Ownership interest	50.00%
Investments in unconsolidated affilitates	$ 1,213,600	887,100
Natural Gas Pipeline - Algonquin Gas Transmission, LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest	15.00%
Investments in unconsolidated affilitates	$ 121,900	125,200
Renewable Energy Investment Fund
Schedule of Equity Method Investments [Line Items]
Ownership interest	90.00%
Investments in unconsolidated affilitates	$ 76,500	71,600
Other
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affilitates	$ 24,300	$ 23,200