SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Investments in Unconsolidated Affiliates (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	$ 741,697	$ 660,473
Offshore Wind Business
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	50.00%
Investments in unconsolidated affiliates	$ 596,400	515,500
Offshore Wind Business | Maximum
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	100.00%
Offshore Wind Business | Minimum
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	50.00%
Natural Gas Pipeline - Algonquin Gas Transmission, LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)	15.00%
Investments in unconsolidated affiliates	$ 115,900	116,000
Other
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	$ 29,400	$ 29,000