GOODWILL AND INTANGIBLE ASSETS - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Acquired Finite-Lived Intangible Assets [Line Items]
Fully-amortized intangibles, amount removed during the period	$ 3,400,000
Purchase price to goodwill	213,216,000
Reallocation	0
Goodwill impairment	0	$ 0
Real Assets Group
Acquired Finite-Lived Intangible Assets [Line Items]
Purchase price to goodwill	213,313,000
Reallocation	10,530,000
From Private Equity Group To Real Assets Group
Acquired Finite-Lived Intangible Assets [Line Items]
Reallocation	10,500,000
From Real Estate Group To Real Assets Group
Acquired Finite-Lived Intangible Assets [Line Items]
Reallocation	53,300,000
Infrastructure Debt Acquisition | Real Assets Group
Acquired Finite-Lived Intangible Assets [Line Items]
Purchase price to goodwill	213,300,000
Infrastructure Debt Acquisition | Management contracts
Acquired Finite-Lived Intangible Assets [Line Items]
Acquisition and merger-related expense	$ 68,700,000
Estimated useful lives, intangible assets	5 years 2 months 12 days
Infrastructure Debt Acquisition | Client relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Acquisition and merger-related expense	$ 32,800,000
Estimated useful lives, intangible assets	8 years 4 months 24 days
General, administrative and other expense
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 33,200,000	$ 10,600,000