Investments in and Advances to Unconsolidated Affiliates - Schedule of Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Due from (to) Related Parties	$ 290	$ 363
Other	2,615	1,881
Investments in and advances to unconsolidated affiliates	256,332	249,807
Distributions in excess of income from, and investments in, unconsolidated affiliates	$ 15,272	15,616
KLA/ABS
Schedule of Equity Method Investments [Line Items]
Cost method investment, ownership percentage	36.70%
Cost Method Investment	$ 78,526	72,391
Self Storage Management
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	95.00%
Equity method investments	$ 207	207
Fund IV Other Portfolio
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	98.57%
Equity method investments	$ 12,394	11,719
650 Bald Hill Road
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	90.00%
Equity method investments	$ 12,532	12,550
Fund IV
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 24,926	24,269
Fund V Family Center at Riverdale
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	89.42%
Equity method investments	$ 12,679	11,824
Tri City Plaza
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	90.00%
Equity method investments	$ 7,309	7,024
Frederick County Acquisitions
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	90.00%
Equity method investments	$ 10,647	10,837
Fund V
Schedule of Equity Method Investments [Line Items]
Equity method investments	30,635	29,685
Core Portfolio
Schedule of Equity Method Investments [Line Items]
Equity method investments	119,133	121,011
Other	$ 2,500
Core Portfolio \| 840 N. Michigan
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	88.43%
Equity method investments	$ 54,924	55,863
Core Portfolio \| Renaissance Portfolio
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	20.00%
Equity method investments	$ 28,742	29,270
Core Portfolio \| Gotham Plaza
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	49.00%
Equity method investments	$ 28,589	28,683
Core Portfolio \| Georgetown Portfolio
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	50.00%
Equity method investments	$ 3,870	4,624
Core Portfolio \| 1238 Wisconsin Avenue
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	80.00%
Equity method investments	$ 3,008	2,571
Core Portfolio \| Crossroads
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	49.00%
Distributions in excess of income from, and investments in, unconsolidated affiliates	$ 15,272	$ 15,616

Cost method investment, ownership percentage.

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Receivables to be collected from (obligations owed to) related parties, net as of the balance sheet date where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth.

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