Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

v2.4.0.8
Document and Entity Information (USD $)
In Millions, except Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Feb. 19, 2014
Jun. 28, 2013
Entity Information [Line Items]      
Entity Registrant Name CORPORATE OFFICE PROPERTIES TRUST    
Entity Central Index Key 0000860546    
Document Type 10-K    
Document Period End Date Dec. 31, 2013    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Public Float     $ 1,700.0
Entity Common Stock, Shares Outstanding   87,429,122  
Document Fiscal Year Focus 2013    
Document Fiscal Period Focus FY    
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-K    
Document Period End Date Dec. 31, 2013    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Non-accelerated Filer    
Entity Public Float     $ 16.3
Document Fiscal Year Focus 2013    
Document Fiscal Period Focus FY