Investment in Unconsolidated Ventures - Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
ASSETS
Real estate properties, net of accumulated depreciation of $67,399 and $66,945	$ 639,989			$ 651,603
Cash and cash equivalents	28,117			20,281	$ 21,865
Other assets	17,766			16,786
Total Assets	721,142			732,118
Liabilities:
Mortgages payable, net of deferred costs of $1,185 and $1,421	422,935			403,792
Accounts payable and accrued liabilities	24,272			22,631
Total Liabilities	484,345			482,048
Commitments and contingencies
Equity:
Total unconsolidated joint venture equity	236,797	$ 245,746	$ 243,334	250,070	$ 257,115	$ 249,150	$ 214,202	$ 202,951
Total Liabilities and Equity	721,142			732,118
Deferred costs	4,486			4,941
Unconsolidated Joint Ventures
ASSETS
Real estate properties, net of accumulated depreciation of $67,399 and $66,945	278,096			318,304
Cash and cash equivalents	8,504			6,591
Other assets	50,789			35,372
Total Assets	337,389			360,267
Liabilities:
Mortgages payable, net of deferred costs of $1,185 and $1,421	242,763			255,261
Accounts payable and accrued liabilities	11,547			8,222
Total Liabilities	254,310			263,483
Commitments and contingencies
Equity:
Total unconsolidated joint venture equity	83,079			96,784
Total Liabilities and Equity	337,389			360,267
BRT's interest in joint venture equity	34,501			42,576
Unconsolidated Joint Ventures
Equity:
Real estate properties, net of accumulated depreciation	67,399			66,945
Unconsolidated Joint Ventures | Mortgages payable
Equity:
Deferred costs	$ 1,185			$ 1,421