| Cover | Feb. 21, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K/A |
| Amendment Flag | true |
| Amendment Description | On February 21, 2022, we filed a Current Report on Form 8-K (the “Report”) reporting that we and the defendant entered into a settlement agreement with respect to the lawsuit captioned OLP Wyoming Springs, LLC, Plaintiff, v. Harden Healthcare, LLC, Defendant, v Benjamin Hanson, Intervenor (the “Lawsuit”). We are filing this amendment to the Report to disclose that on April 15, 2022, we received approximately $5.4 million representing the amount we were to receive pursuant to the settlement agreement. Such sum will be recognized as other income during the quarter ending June 30, 2022. As a result of the receipt of this payment, the parties to the Lawsuit are, among other things, to seek dismissal of the Lawsuit with prejudice and release each other and certain other persons from claims and liabilities with respect to matters pertaining to the Lawsuit. |
| Document Period End Date | Feb. 21, 2022 |
| Entity File Number | 001-09279 |
| Entity Registrant Name | ONE LIBERTY PROPERTIES, INC. |
| Entity Central Index Key | 0000712770 |
| Entity Tax Identification Number | 13-3147497 |
| Entity Incorporation, State or Country Code | MD |
| Entity Address, Address Line One | 60 Cutter Mill Road |
| Entity Address, Address Line Two | Suite 303 |
| Entity Address, City or Town | Great Neck |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 11021 |
| City Area Code | 516 |
| Local Phone Number | 466-3100 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | OLP |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
