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Amount of cash outflow to acquire in a sale-leaseback recognized in investing activities.

No definition available.

Name:	olp_PurchasePriceToAcquireSaleLeasebackTransactionInvestingActivities
Namespace Prefix:	olp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Represents the real estate acquisition cost capitalized.

No definition available.

Name:	olp_RealEstateAcquisitionCostCapitalized
Namespace Prefix:	olp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The number of tenants affiliated with seller, in sale-leaseback transaction.

No definition available.

Name:	olp_SaleLeaseBackTransactionNumberOfTenantsAffiliatedWithSeller
Namespace Prefix:	olp_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.

Name:	us-gaap_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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Amount of facility held for productive use including, but not limited to, office, production, storage and distribution facilities, acquired at the acquisition date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=73530397&loc=d3e4845-128472

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Amount of real estate acquired, at the acquisition date.

Name:	us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLand
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 55
-Paragraph 37
-URI http://asc.fasb.org/extlink&oid=73531372&loc=d3e2207-128464

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=73530397&loc=d3e4845-128472

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- References

No definition available.