CONSOLIDATED STATEMENTS OF ASSETS AND LIABILITIES (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Real estate properties at cost	$ 14,503.4	$ 14,323.2
Real estate joint ventures at cost	5,789.6	5,738.1
Real estate funds at cost	815.8	787.7
Real estate operating business at cost	371.4	355.0
Marketable securities at cost	639.0	2,077.1
Loans receivable at cost	1,551.1	1,546.0
Loans receivable with related parties at cost	101.0	69.9
Total investments at cost	23,771.3	24,897.0
Loans payable principal outstanding	1,923.5	2,168.7
Other unsecured debt principal outstanding	$ 1,400.0	$ 1,000.0