Quarterly report pursuant to Section 13 or 15(d)

Realty Income Office Assets, Operating Leases - Narrative (Details)

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Realty Income Office Assets, Operating Leases - Narrative (Details) - property
 9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Lessor, Lease, Description [Line Items]    
Number of real estate properties 92  
Realty Income Office Assets    
Lessor, Lease, Description [Line Items]    
Number of real estate properties 40  
Realty Income Office Assets | Revenue Benchmark | Customer Concentration Risk | Significant Customer A    
Lessor, Lease, Description [Line Items]    
Concentration risk, percentage 17.60% 17.10%
Realty Income Office Assets | Revenue Benchmark | Customer Concentration Risk | Significant Customer B    
Lessor, Lease, Description [Line Items]    
Concentration risk, percentage 11.90% 11.40%
Realty Income Office Assets | Property Available For Lease Or Sale Member    
Lessor, Lease, Description [Line Items]    
Number of real estate properties 3