Commitment and Contingencies (Details) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2026 USD ($) investment	Dec. 31, 2025 investment
Gain Contingencies [Line Items]
Number of investments in loans receivable related to build to suit arrangements \| investment	7	13
Estimated contractual obligation to joint ventures	$ 1,731,652
Weighted average capitalization rate	8.78%
Weighted average remaining lease term	21 years
Tenant Improvements
Gain Contingencies [Line Items]
Other commitment	$ 24,226
Commercial Real Estate Loans
Gain Contingencies [Line Items]
Contractual obligation	363,511
Asset under Construction
Gain Contingencies [Line Items]
Contractual obligation	47,018
Estimated contractual obligation	18,174
Asset under Construction \| Minimum
Gain Contingencies [Line Items]
Contractual obligation	$ 80,646

Estimated Contractual Obligation

No definition available.

Name:	osnl_EstimatedContractualObligation
Namespace Prefix:	osnl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Estimated Contractual Obligation To Joint Ventures

+ References

No definition available.

+ Details

Name:	osnl_EstimatedContractualObligationToJointVentures
Namespace Prefix:	osnl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number Of Investments Related To Build To Suit Assets, Under Construction

+ References

No definition available.

+ Details

Name:	osnl_NumberOfInvestmentsRelatedToBuildToSuitAssetsUnderConstruction
Namespace Prefix:	osnl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Real Estate Investments, Joint Ventures, Subject To Funding, Weighted Average Capitalization Rate

+ References

No definition available.

+ Details

Name:	osnl_RealEstateInvestmentsJointVenturesSubjectToFundingWeightedAverageCapitalizationRate
Namespace Prefix:	osnl_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Real Estate Investments, Joint Ventures, Subject To Funding, Weighted Average Remaining Lease Term

+ References

No definition available.

+ Details

Name:	osnl_RealEstateInvestmentsJointVenturesSubjectToFundingWeightedAverageRemainingLeaseTerm
Namespace Prefix:	osnl_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of contractual obligation, including, but not limited to, long-term debt, lease obligation, purchase obligation, and other commitments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477314/942-235-S99-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-4

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-3

+ Details

Name:	us-gaap_ContractualObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483049/450-30-50-1

+ Details

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

- Definition

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

+ Details

Name:	us-gaap_OtherCommitment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_OtherCommitmentsAxis=osnl_TenantImprovementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=osnl_CommercialRealEstateLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_AssetUnderConstructionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: