Investments in Real Estate Funds - Schedule of carrying amount and maximum exposure to loss relating to VIEs (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
Carrying Amount	$ 35,011.0	$ 31,276.4
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Carrying Amount	893.3
Maximum Exposure to Loss	$ 1,202.3
Variable Interest Entity, Not Primary Beneficiary | LCS SHIP Venture I, LLC
Variable Interest Entity [Line Items]
Account Interest	90.00%
Carrying Amount	$ 234.7
Maximum Exposure to Loss	$ 234.7
Variable Interest Entity, Not Primary Beneficiary | Veritas Trophy VI, LLC
Variable Interest Entity [Line Items]
Account Interest	90.40%
Carrying Amount	$ 83.5
Maximum Exposure to Loss	$ 99.5
Variable Interest Entity, Not Primary Beneficiary | SP V - II, LLC
Variable Interest Entity [Line Items]
Account Interest	61.80%
Carrying Amount	$ 107.3
Maximum Exposure to Loss	$ 117.3
Variable Interest Entity, Not Primary Beneficiary | Taconic New York City GP Fund, LP
Variable Interest Entity [Line Items]
Account Interest	60.00%
Carrying Amount	$ 27.4
Maximum Exposure to Loss	$ 31.6
Variable Interest Entity, Not Primary Beneficiary | Silverpeak NRE FundCo LLC
Variable Interest Entity [Line Items]
Account Interest	90.00%
Carrying Amount	$ 36.8
Maximum Exposure to Loss	$ 66.4
Variable Interest Entity, Not Primary Beneficiary | IDR - Core Property Index Fund, LLC
Variable Interest Entity [Line Items]
Account Interest	1.60%
Carrying Amount	$ 45.2
Maximum Exposure to Loss	$ 45.2
Variable Interest Entity, Not Primary Beneficiary | Townsend Group Value-Add Fund
Variable Interest Entity [Line Items]
Account Interest	99.00%
Carrying Amount	$ 160.5
Maximum Exposure to Loss	$ 250.2
Variable Interest Entity, Not Primary Beneficiary | Flagler - REA Healthcare Properties Partnership
Variable Interest Entity [Line Items]
Account Interest	90.00%
Carrying Amount	$ 23.4
Maximum Exposure to Loss	$ 24.7
Variable Interest Entity, Not Primary Beneficiary | Grubb Southeast Real Estate Fund VI, LLC
Variable Interest Entity [Line Items]
Account Interest	66.70%
Carrying Amount	$ 18.4
Maximum Exposure to Loss	$ 18.4
Variable Interest Entity, Not Primary Beneficiary | Silverpeak NRE FundCo 2 LLC
Variable Interest Entity [Line Items]
Account Interest	90.00%
Carrying Amount	$ 81.4
Maximum Exposure to Loss	$ 113.5
Variable Interest Entity, Not Primary Beneficiary | JCR Capital - REA Preferred Equity Parallel Fund
Variable Interest Entity [Line Items]
Account Interest	31.10%
Carrying Amount	$ 44.7
Maximum Exposure to Loss	$ 100.8
Variable Interest Entity, Not Primary Beneficiary | Silverpeak NRE FundCo 3 LLC
Variable Interest Entity [Line Items]
Account Interest	90.00%
Carrying Amount	$ 30.0
Maximum Exposure to Loss	$ 100.0