Investments in Real Estate Funds (Details) - Variable Interest Entity, Not Primary Beneficiary $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Variable Interest Entity [Line Items]
Carrying Amount	$ 354.1
Maximum Exposure to Loss	$ 354.1
LCS SHIP Venture I, LLC
Variable Interest Entity [Line Items]
Account Interest	90.00%
Carrying Amount	$ 212.8
Maximum Exposure to Loss	$ 212.8
SP V - II, LLC
Variable Interest Entity [Line Items]
Account Interest	79.20%
Carrying Amount	$ 28.2
Maximum Exposure to Loss	$ 28.2
Taconic New York City GP Fund, LP
Variable Interest Entity [Line Items]
Account Interest	60.00%
Carrying Amount	$ 29.8
Maximum Exposure to Loss	$ 29.8
Veritas Trophy VI, LLC
Variable Interest Entity [Line Items]
Account Interest	92.10%
Carrying Amount	$ 42.7
Maximum Exposure to Loss	$ 42.7
IDR - Core Property Index Fund, LLC
Variable Interest Entity [Line Items]
Account Interest	2.00%
Carrying Amount	$ 25.0
Maximum Exposure to Loss	$ 25.0
Grubb Southeast Real Estate Fund VI, LLC
Variable Interest Entity [Line Items]
Account Interest	66.70%
Carrying Amount	$ 13.4
Maximum Exposure to Loss	$ 13.4
JCR Capital - REA Preferred Equity Parallel Fund
Variable Interest Entity [Line Items]
Account Interest	49.20%
Carrying Amount	$ 2.2
Maximum Exposure to Loss	$ 2.2