Real Estate - Schedule of Acquisitions and Conversions (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Purchase Price	$ 0	$ 172,152
Core Portfolio
Business Acquisition [Line Items]
Purchase Price		$ 158,143
Core Portfolio | 917 W. Armitage - Chicago, IL
Business Acquisition [Line Items]
Percent Acquired		100.00%
Purchase Price		$ 3,515
Core Portfolio | Soho Acquisitions | 37 Greene Street - New York, NY
Business Acquisition [Line Items]
Percent Acquired		100.00%
Purchase Price		$ 15,689
Core Portfolio | Town Center | Wilmington, DE
Business Acquisition [Line Items]
Percent Acquired		100.00%
Purchase Price		$ 138,939
Fund IV
Business Acquisition [Line Items]
Purchase Price		$ 14,009
Fund IV | 230-240 W. Broughton Street | GEORGIA
Business Acquisition [Line Items]
Percent Acquired		100.00%
Purchase Price		$ 13,219
Fund IV | 102 E. Broughton Street | GEORGIA
Business Acquisition [Line Items]
Percent Acquired		100.00%
Purchase Price		$ 790