COPT Defense Properties Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Properties, net (Details 5)

Properties, net (Details 5) $ in Thousands			12 Months Ended
Properties, net (Details 5) $ in Thousands	Aug. 28, 2015 USD ($)	Dec. 23, 2013 USD ($)	Dec. 31, 2015 USD ($) ft² Property buillding	Dec. 31, 2014 USD ($) ft² Property buillding	Dec. 31, 2013 USD ($) ft² Property buillding
Dispositions
Gain (loss) on early extinguishment of debt			$ 85,275	$ (9,552)	$ (27,030)
Non-operating Properties [Member]
Dispositions
Gain on Disposition			4,000	5,600
Sale price of non-operating properties			$ 18,100	$ 28,300	$ 3,500
Operating properties, net [Member]
Dispositions
Number of Buildings Disposed \| buillding			9	8	31
Total Rentable Square Feet \| ft²			1,597,000	302,958	2,345,000
Transaction value of operating property dispositions			$ 347,785	$ 28,835	$ 293,301
Gain on Disposition			$ 64,033	$ 5,093	$ 2,671
Operating properties, net [Member] \| 1550 Westbranch Drive [Member]
Dispositions
Number of Buildings Disposed \| buillding			1
Total Rentable Square Feet \| ft²			160,000
Transaction value of operating property dispositions			$ 27,800
Gain on Disposition			$ 0
Operating properties, net [Member] \| 15000 and 15010 Conference Center Drive [Member]
Dispositions
Number of Buildings Disposed \| buillding			2
Total Rentable Square Feet \| ft²			665,000
Transaction value of operating property dispositions			$ 167,335
Gain on Disposition			$ 0
Operating properties, net [Member] \| 13200 Woodland Park Road [Member]
Dispositions
Number of Buildings Disposed \| buillding			1
Total Rentable Square Feet \| ft²			397,000
Transaction value of operating property dispositions			$ 84,000
Gain on Disposition			$ 42,515
Operating properties, net [Member] \| 9900, 9910, 9920 Franklin Square Drive [Member]
Dispositions
Number of Buildings Disposed \| buillding			3
Total Rentable Square Feet \| ft²			135,000
Transaction value of operating property dispositions			$ 24,150
Gain on Disposition			$ 6,468
Operating properties, net [Member] \| 9690 Deereco Road and 375 W Padonia Road [Member]
Dispositions
Number of Buildings Disposed \| buillding			2
Total Rentable Square Feet \| ft²			240,000
Transaction value of operating property dispositions			$ 44,500
Gain on Disposition			$ 15,050
Operating properties, net [Member] \| 4969 and 4979 Mercantile Rd [Member]
Dispositions
Number of Buildings Disposed \| buillding				2
Total Rentable Square Feet \| ft²				96,721
Transaction value of operating property dispositions				$ 5,960
Gain on Disposition				$ 2,124
Operating properties, net [Member] \| 9930 and 9940 Franklin Square [Member]
Dispositions
Number of Buildings Disposed \| buillding				2
Total Rentable Square Feet \| ft²				71,992
Transaction value of operating property dispositions				$ 10,475
Gain on Disposition				$ 2,303
Operating properties, net [Member] \| 5020, 5022, 5024 and 5026 Campbell Boulevard [Member]
Dispositions
Number of Buildings Disposed \| buillding				4
Total Rentable Square Feet \| ft²				134,245
Transaction value of operating property dispositions				$ 12,400
Gain on Disposition				666
Operating properties, net [Member] \| 920 Elkridge Landing Road [Member]
Dispositions
Number of Buildings Disposed \| buillding					1
Total Rentable Square Feet \| ft²					103,000
Transaction value of operating property dispositions					$ 6,900
Gain on Disposition					$ 0
Operating properties, net [Member] \| 4230 Forbes Boulevard [Member]
Dispositions
Number of Buildings Disposed \| buillding					1
Total Rentable Square Feet \| ft²					56,000
Transaction value of operating property dispositions					$ 5,600
Gain on Disposition					$ 1,507
Operating properties, net [Member] \| December 2013 Colorado Springs Portfolio Disposition [Member]
Dispositions
Number of Buildings Disposed \| buillding					15
Total Rentable Square Feet \| ft²					1,165,000
Transaction value of operating property dispositions					$ 133,925
Gain on Disposition					$ 1,164
Operating properties, net [Member] \| December 2013 Portfolio Conveyance [Member]
Dispositions
Number of Buildings Disposed \| buillding					14
Total Rentable Square Feet \| ft²					1,021,000
Transaction value of operating property dispositions					$ 146,876
Gain on Disposition					$ 0
Greater Philadelphia [Member]
Dispositions
Depreciation Expense Resulting From Useful Life Change				$ 12,900
15000 and 15010 Conference Center Drive [Member] \| Northern Virginia [Member] \| Operating properties, net [Member]
Dispositions
Debt settled through the surrender of real estate assets	$ 150,000
Gain (loss) on early extinguishment of debt	$ 84,800
December 2013 Portfolio Conveyance [Member] \| Operating properties, net [Member]
Dispositions
Debt settled through the surrender of real estate assets		$ 146,500
Gain (loss) on early extinguishment of debt		$ 67,800
Newly-constructed properties placed in service [Member]
Dispositions
Square Feet of Properties Placed in Service \| ft²			897,000	692,000	812,000
Number of real estate properties \| Property			7	5	8
Newly Redeveloped Properties Placed In Service [Member] \| Greater Philadelphia and St. Mary's County, Maryland [Member]
Dispositions
Square Feet of Properties Placed in Service \| ft²			170,000
Number of real estate properties \| Property			2
Properties under Construction or Contractually Commited for Construction [Member]
Dispositions
Total Rentable Square Feet \| ft²			1,300,000
Number of real estate properties \| Property			9
Properties under redevelopment [Member]
Dispositions
Total Rentable Square Feet \| ft²			156,000
Number of real estate properties \| Property			4