Investments in Real Estate Funds (Details) - Variable Interest Entity, Not Primary Beneficiary $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Variable Interest Entity [Line Items]
Carrying Amount	$ 311.8
Maximum Exposure to Loss	$ 311.8
LCS SHIP Venture I, LLC
Variable Interest Entity [Line Items]
Account Interest	90.00%
Carrying Amount	$ 216.1
Maximum Exposure to Loss	$ 216.1
SP V - II, LLC
Variable Interest Entity [Line Items]
Account Interest	75.00%
Carrying Amount	$ 23.3
Maximum Exposure to Loss	$ 23.3
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	90.00%
Carrying Amount	$ 4.2
Maximum Exposure to Loss	$ 4.2
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	67.00%
Carrying Amount	$ 13.4
Maximum Exposure to Loss	$ 13.4

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118582676&loc=d3e5747-111685

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=118582676&loc=d3e5728-111685

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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Carrying amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
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-URI http://asc.fasb.org/extlink&oid=118582676&loc=d3e5728-111685

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Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 5A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=118582676&loc=SL6759159-111685

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