Quarterly report pursuant to Section 13 or 15(d)

Cover Page

v3.21.2
Cover Page - shares
 9 Months Ended
Sep. 30, 2021
Nov. 30, 2021
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Sep. 30, 2021  
Document Transition Report false  
Entity File Number 001-40873  
Entity Registrant Name Orion Office REIT Inc.  
Entity Incorporation, State or Country Code MD  
Entity Tax Identification Number 87-1656425  
Entity Address, Address Line One 2325 E. Camelback Road, Suite 850  
Entity Address, City or Town Phoenix  
Entity Address, State or Province AZ  
Entity Address, Postal Zip Code 85016  
City Area Code (602)  
Local Phone Number 698-1002  
Title of 12(b) Security Common Stock  
Trading Symbol ONL  
Security Exchange Name NYSE  
Entity Current Reporting Status No  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   56,625,650
Entity Central Index Key 0001873923  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2021  
Document Fiscal Period Focus Q3  
Amendment Flag false