Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Details)

v2.4.0.8
Fair Value Measurements (Details) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2014
Dec. 31, 2013
Sep. 30, 2013
Dec. 31, 2012
Liabilities:        
Interest rate derivatives $ 2,236 $ 3,309    
Redeemable noncontrolling interest 18,436 17,758 16,789 10,298
Corporate Office Properties, L.P.
        
Liabilities:        
Interest rate derivatives 2,236 3,309    
Fair value measurement on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
        
Assets:        
Assets 7,500      
Fair value measurement on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds
        
Assets:        
Marketable securities in deferred compensation plan 7,187 [1]      
Fair value measurement on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Common Shares
        
Assets:        
Marketable securities in deferred compensation plan 110 [1]      
Fair value measurement on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other
        
Assets:        
Marketable securities in deferred compensation plan 203 [1]      
Fair value measurement on a recurring basis | Significant Other Observable Inputs (Level 2)
        
Assets:        
Interest rate derivatives 2,907 [2]      
Warrants to purchase common stock 192 [2]      
Assets 3,099      
Liabilities:        
Deferred compensation plan liability 7,500 [3]      
Interest rate derivatives 2,236      
Liabilities 9,736      
Fair value measurement on a recurring basis | Total Estimated Fair Value
        
Assets:        
Interest rate derivatives 2,907 [2]      
Warrants to purchase common stock 192 [2]      
Assets 10,599      
Liabilities:        
Deferred compensation plan liability 7,500 [3]      
Interest rate derivatives 2,236      
Liabilities 9,736      
Redeemable noncontrolling interest 18,436      
Fair value measurement on a recurring basis | Total Estimated Fair Value | Mutual funds
        
Assets:        
Marketable securities in deferred compensation plan 7,187 [1]      
Fair value measurement on a recurring basis | Total Estimated Fair Value | Common Shares
        
Assets:        
Marketable securities in deferred compensation plan 110 [1]      
Fair value measurement on a recurring basis | Total Estimated Fair Value | Other
        
Assets:        
Marketable securities in deferred compensation plan 203 [1]      
Fair value measurement on a recurring basis | Corporate Office Properties, L.P. | Significant Other Observable Inputs (Level 2)
        
Assets:        
Interest rate derivatives 2,907 [4]      
Warrants to purchase common stock 192 [4]      
Assets 3,099      
Liabilities:        
Interest rate derivatives 2,236      
Fair value measurement on a recurring basis | Corporate Office Properties, L.P. | Significant Unobservable Inputs (Level 3)
        
Liabilities:        
Redeemable noncontrolling interest 18,436      
Fair value measurement on a recurring basis | Corporate Office Properties, L.P. | Total Estimated Fair Value
        
Assets:        
Interest rate derivatives 2,907 [4]      
Warrants to purchase common stock 192 [4]      
Assets 3,099      
Liabilities:        
Interest rate derivatives 2,236      
Redeemable noncontrolling interest $ 18,436      
[1] Included in the line entitled “restricted cash and marketable securities” on COPT’s consolidated balance sheet.
[2] Included in the line entitled “prepaid expenses and other assets” on COPT’s consolidated balance sheet.
[3] Included in the line entitled “other liabilities” on COPT’s consolidated balance sheet.
[4] Included in the line entitled “prepaid expenses and other assets” on COPLP’s consolidated balance sheet.