Real Estate - Schedule of Property Dispositions (Details) (Parenthetical) $ in Millions	9 Months Ended
Sep. 30, 2021 USD ($)
Fund IV \| 110 University Place
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on termination of lease	$ 0.7

Amount of gain (loss) on termination of lease before expiration of lease term.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 40
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=123386189&loc=SL77918607-209975

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration