Real Estate - Schedule of Property Dispositions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposition of properties	$ 57,161	$ 10,521	$ 683
Disposed of by sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale price	222,153	66,325
Gain on disposition of properties	$ 57,161	$ 9,787
Core Portfolio | Disposed of by sale | Henderson Avenue (Parcel) - Dallas, TX
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date sold	Oct. 07, 2022
Sale price	$ 3,050
Gain on disposition of properties	$ (194)
Core Portfolio | Disposed of by sale | 330-340 River St Cambridge, MA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date sold	Dec. 13, 2022
Sale price	$ 26,400
Gain on disposition of properties	$ 7,439
Core Portfolio | Disposed of by sale | 60 Orange St - Bloomfield, NJ.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date sold		Jan. 29, 2021
Sale price		$ 16,400
Gain on disposition of properties		$ 4,612
Fund III | Disposed of by sale | 654 Broadway - New York, NY
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date sold		May 19, 2021
Sale price		$ 10,000
Gain on disposition of properties		$ 111
Fund III | Disposed of by sale | Cortlandt Crossing (Sewer Project and Retention Pond) - Cortlandt, NY
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date sold	Feb. 09, 2022
Sale price	$ 65,533
Gain on disposition of properties	$ 13,255
Fund IV | Disposed of by sale | Ne Grocer Portfolio Selected Assets Pennsylvania
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date sold	Jan. 26, 2022
Sale price	$ 45,350
Gain on disposition of properties	$ 13,784
Fund IV | Disposed of by sale | Lincoln Place Fairview Heights, IL
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date sold	May 25, 2022
Sale price	$ 40,670
Gain on disposition of properties	$ 12,216
Fund IV | Disposed of by sale | Wake Forest Crossing - Wake Forest, NC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date sold	Aug. 24, 2022
Sale price	$ 38,919
Gain on disposition of properties	$ 8,885
Fund IV | Disposed of by sale | NE Grocer Portfolio (Selected Assets) - Maine
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date sold		Jun. 18, 2021
Sale price		$ 39,925
Gain on disposition of properties		$ 5,064
Fund V | Disposed of by sale | New Towne (Parcel) - Canton, MI
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date sold	Feb. 01, 2022
Sale price	$ 2,231
Gain on disposition of properties	$ 1,776