Unconsolidated Investments - Schedule of Joint Ventures (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	$ 2,320.9	$ 2,238.1
Multifamily
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	1,290.6	1,235.7
Commercial
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	424.5	404.6
Hotel
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	245.6	195.9
Funds
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	173.1	202.6
Residential and Other
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	187.1	199.3
Western U.S.
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	1,499.6	1,470.1
Western U.S. | Multifamily
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	893.0	857.6
Western U.S. | Commercial
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	84.0	89.2
Western U.S. | Hotel
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	245.6	195.9
Western U.S. | Funds
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	119.1	158.3
Western U.S. | Residential and Other
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	157.9	169.1
Ireland
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	594.1	562.8
Ireland | Multifamily
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	397.6	378.1
Ireland | Commercial
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	190.2	176.7
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	6.3	8.0
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	227.2	205.2
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	150.3	138.7
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	47.7	36.3
United Kingdom | Residential and Other
Schedule of Equity Method Investments [Line Items]
Investments in joint ventures	$ 29.2	$ 30.2