Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

v3.8.0.1
Document and Entity Information - shares
9 Months Ended
Sep. 30, 2017
Oct. 20, 2017
Entity Information [Line Items]    
Entity Registrant Name CORPORATE OFFICE PROPERTIES TRUST  
Entity Central Index Key 0000860546  
Document Type 10-Q  
Document Period End Date Sep. 30, 2017  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Entity Common Stock, Shares Outstanding   99,609,634
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus Q3  
Corporate Office Properties, L.P.    
Entity Information [Line Items]    
Entity Registrant Name CORPORATE OFFICE PROPERTIES, L.P.  
Entity Central Index Key 0001577966  
Document Type 10-Q  
Document Period End Date Sep. 30, 2017  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus Q3