Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

RELATED PARTY TRANSACTIONS - Other (Details) - USD ($)	3 Months Ended						9 Months Ended
RELATED PARTY TRANSACTIONS - Other (Details) - USD ($)	Sep. 30, 2026	Jun. 30, 2026	Mar. 31, 2026	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2026	Sep. 30, 2025
Gould Investors L.P. \| Location, Statement of Income, Balance [Axis]: olp:RealEstateOperatingExpenses
Related Party Transactions
Insurance expense recognized of amounts reimbursed to related party	$ 1,016,000			$ 1,006,000			$ 2,298,000	$ 1,469,000
Chairman \| Location, Statement of Income, Balance [Axis]: us-gaap:GeneralAndAdministrativeExpense
Related Party Transactions
Quarterly fees paid	88,000	$ 88,000	$ 88,000	85,000	$ 85,000	$ 85,000
Vice Chairman \| Location, Statement of Income, Balance [Axis]: us-gaap:GeneralAndAdministrativeExpense
Related Party Transactions
Quarterly fees paid	$ 34,000	$ 34,000	$ 34,000	$ 34,000	$ 34,000	$ 34,000
Affiliated Entity \| Gould Investors L.P.
Related Party Transactions
Amount of insurance reimbursed							$ 3,186,000	$ 3,042,000