COPT Defense Properties Quarterly report pursuant to Section 13 or 15(d)

Properties, net (Details 6)

Properties, net (Details 6) - Jun. 30, 2015 ft² in Thousands, $ in Millions	USD ($) ft² Property
Newly constructed properties placed in service
Construction and Redevelopment Activities
Square feet of properties placed in service \| ft²	509
Number of real estate properties placed in service	4
Properties redeveloped \| Greater Philadelphia
Construction and Redevelopment Activities
Square feet of properties placed in service \| ft²	111
Properties under construction or contractually committed for construction
Construction and Redevelopment Activities
Number of real estate properties	6
Square footage of real estate properties (in square feet) \| ft²	1,000
Properties under construction or contractually committed for construction \| Northern Virginia
Construction and Redevelopment Activities
Number of real estate properties	4
Properties under construction or contractually committed for construction \| Baltimore and Washington Corridor
Construction and Redevelopment Activities
Number of real estate properties	2
Properties under or approved for redevelopment
Construction and Redevelopment Activities
Number of real estate properties	6
Square footage of real estate properties (in square feet) \| ft²	309
Properties under or approved for redevelopment \| Baltimore and Washington Corridor
Construction and Redevelopment Activities
Number of real estate properties	4
Properties under or approved for redevelopment \| Greater Philadelphia
Construction and Redevelopment Activities
Number of real estate properties	1
Properties under or approved for redevelopment \| St Marys County
Construction and Redevelopment Activities
Number of real estate properties	1
Non-operating properties
Construction and Redevelopment Activities
Sale price of land \| $	$ 18.1
Gain on sale \| $	$ 4.0
Partially operational properties \| Properties under or approved for redevelopment
Construction and Redevelopment Activities
Number of real estate properties	1