Investments in Real Estate Funds (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
Carrying Amount	$ 35,124.7	$ 31,276.4
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Carrying Amount	907.0
Maximum Exposure to Loss	$ 1,225.8
Variable Interest Entity, Not Primary Beneficiary | LCS SHIP Venture I, LLC
Variable Interest Entity [Line Items]
Account Interest	90.00%
Carrying Amount	$ 223.7
Maximum Exposure to Loss	$ 223.7
Variable Interest Entity, Not Primary Beneficiary | Veritas Trophy VI, LLC
Variable Interest Entity [Line Items]
Account Interest	90.40%
Carrying Amount	$ 81.3
Maximum Exposure to Loss	$ 99.9
Variable Interest Entity, Not Primary Beneficiary | SP V - II, LLC
Variable Interest Entity [Line Items]
Account Interest	61.80%
Carrying Amount	$ 104.6
Maximum Exposure to Loss	$ 115.0
Variable Interest Entity, Not Primary Beneficiary | Taconic New York City GP Fund, LP
Variable Interest Entity [Line Items]
Account Interest	60.00%
Carrying Amount	$ 27.5
Maximum Exposure to Loss	$ 31.7
Variable Interest Entity, Not Primary Beneficiary | Silverpeak NRE FundCo LLC
Variable Interest Entity [Line Items]
Account Interest	90.00%
Carrying Amount	$ 74.3
Maximum Exposure to Loss	$ 104.0
Variable Interest Entity, Not Primary Beneficiary | IDR - Core Property Index Fund, LLC
Variable Interest Entity [Line Items]
Account Interest	1.40%
Carrying Amount	$ 43.4
Maximum Exposure to Loss	$ 43.4
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	$ 23.5
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	$ 19.1
Maximum Exposure to Loss	$ 19.1
Variable Interest Entity, Not Primary Beneficiary | Silverpeak NRE FundCo 2 LLC
Variable Interest Entity [Line Items]
Account Interest	90.00%
Carrying Amount	$ 81.7
Maximum Exposure to Loss	$ 113.8
Variable Interest Entity, Not Primary Beneficiary | JCR Capital - REA Preferred Equity Parallel Fund
Variable Interest Entity [Line Items]
Account Interest	31.10%
Carrying Amount	$ 44.2
Maximum Exposure to Loss	$ 100.3
Variable Interest Entity, Not Primary Beneficiary | Silverpeak NRE FundCo 3 LLC
Variable Interest Entity [Line Items]
Account Interest	90.00%
Carrying Amount	$ 23.2
Maximum Exposure to Loss	$ 100.0