CONSOLIDATED STATEMENTS OF ASSETS AND LIABILITIES (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Real estate properties at cost	$ 13,864.0	$ 14,682.0
Real estate joint ventures at cost	5,989.6	5,645.7
Real estate funds at cost	778.2	821.0
Real estate operating business at cost	462.1	390.8
Marketable securities at cost	383.9	147.3
Loans receivable at cost	1,361.0	1,483.7
Loans receivable with related parties at cost	69.3	102.0
Total investments at cost	22,908.1	23,272.5
Loans payable principal outstanding	1,787.5	1,922.6
Line of credit principal outstanding	72.0	463.0
Other unsecured debt principal outstanding	$ 900.0	$ 900.0