UNCONSOLIDATED INVESTMENTS - Schedule of Joint Ventures (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	$ 2,238.1	$ 1,947.6
Multifamily
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	1,235.7	981.6
Commercial
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	404.6	391.4
Hotel
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	195.9	131.0
Funds
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	202.6	235.2
Residential and Other
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	199.3	208.4
Western U.S.
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	1,470.1	1,172.9
Western U.S. | Multifamily
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	857.6	592.1
Western U.S. | Commercial
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	89.2	81.0
Western U.S. | Hotel
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	195.9	131.0
Western U.S. | Funds
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	158.3	189.2
Western U.S. | Residential and Other
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	169.1	179.6
Ireland
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	562.8	533.7
Ireland | Multifamily
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	378.1	389.5
Ireland | Commercial
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	176.7	141.1
Ireland | Hotel
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	0.0	0.0
Ireland | Funds
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	8.0	3.1
Ireland | Residential and Other
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	0.0	0.0
United Kingdom
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	205.2	241.0
United Kingdom | Multifamily
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	0.0	0.0
United Kingdom | Commercial
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	138.7	169.3
United Kingdom | Hotel
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	0.0	0.0
United Kingdom | Funds
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	36.3	42.9
United Kingdom | Residential and Other
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	$ 30.2	$ 28.8