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

Annual report pursuant to Section 13 and 15(d)

Interest Rate Derivatives (Details)

Interest Rate Derivatives (Details) (USD $)	12 Months Ended
Interest Rate Derivatives (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair value of interest rate derivatives and balance sheet classification
Interest rate derivatives	$ 274,000	$ 6,594,000
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income
Unrealized (losses) gains on interest rate derivatives	(7,799,000)	6,791,000	(7,676,000)
Interest expense
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income
Losses on interest rate derivatives	2,990,000	2,740,000	3,697,000
Loss on early extinguishment of debt
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income
Losses on interest rate derivatives	38,000	0	0
Corporate Office Properties, L.P.
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income
Unrealized (losses) gains on interest rate derivatives	(7,799,000)	6,791,000	(7,676,000)
Corporate Office Properties, L.P. \| Interest expense
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income
Losses on interest rate derivatives	2,990,000	2,740,000	3,697,000
Corporate Office Properties, L.P. \| Loss on early extinguishment of debt
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income
Losses on interest rate derivatives	38,000	0	0
Interest rate swaps
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income
Unrealized (losses) gains on interest rate derivatives	(7,799,000)	6,791,000	(7,676,000)
Approximate amount of losses to be reclassified from AOCL to interest expense over the next 12 months	2,900,000
Interest rate derivatives in liability position, fair value	1,900,000
Termination value to settle obligations under interest rate derivative agreements	2,100,000
Interest rate swaps \| Interest expense
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income
Losses on interest rate derivatives	2,990,000	2,740,000	3,697,000
Interest rate swaps \| Loss on early extinguishment of debt
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income
Losses on interest rate derivatives	38,000	0	0
Interest rate swaps \| Prepaid expenses and other assets
Fair value of interest rate derivatives and balance sheet classification
Interest rate derivatives	274,000	6,594,000
Interest rate swaps \| Interest rate derivative [Member]
Fair value of interest rate derivatives and balance sheet classification
Fair value of Interest rate swaps classified as interest rate derivatives	(1,855,000)	(3,309,000)
Designated
Fair values of interest rate swap derivatives
Fair value of interest rate swaps	(1,581,000)	3,285,000
Designated \| Interest rate swap, effective date January 3, 2012, swap three
Fair values of interest rate swap derivatives
Notional Amount	100,000,000
Fixed Rate (as a percent)	0.832%
Fair value of interest rate swaps	(407,000)	(861,000)
Designated \| Interest rate swap, effective date January 3, 2012, swap four
Fair values of interest rate swap derivatives
Notional Amount	100,000,000
Fixed Rate (as a percent)	0.832%
Fair value of interest rate swaps	(407,000)	(861,000)
Designated \| Interest rate swap, effective date November 2, 2010
Fair values of interest rate swap derivatives
Notional Amount	36,877,000
Fixed Rate (as a percent)	3.83%
Fair value of interest rate swaps	(400,000)	(832,000)
Notional amount of interest rate derivatives after scheduled amortization	36,200,000
Designated \| Interest rate swap, effective date November 2, 2010 \| London Interbank Offered Rate (LIBOR)
Fair values of interest rate swap derivatives
Derivative, Basis Spread on Variable Rate	2.25%
Designated \| Interest rate swap, effective date September 2, 2014, swap one
Fair values of interest rate swap derivatives
Notional Amount	100,000,000
Fixed Rate (as a percent)	0.8055%
Fair value of interest rate swaps	(317,000)	(94,000)
Designated \| Interest rate swap, effective date September 2, 2014, swap two
Fair values of interest rate swap derivatives
Notional Amount	100,000,000
Fixed Rate (as a percent)	0.81%
Fair value of interest rate swaps	(324,000)	(105,000)
Designated \| Interest rate swap, effective date September 1, 2015, swap one
Fair values of interest rate swap derivatives
Notional Amount	100,000,000
Fixed Rate (as a percent)	1.673%
Fair value of interest rate swaps	239,000	3,377,000
Designated \| Interest rate swap, effective date September 1, 2015, swap two
Fair values of interest rate swap derivatives
Notional Amount	100,000,000
Fixed Rate (as a percent)	1.73%
Fair value of interest rate swaps	35,000	3,217,000
Designated \| Interest rate swap, effective date January 3, 2012, swap one
Fair values of interest rate swap derivatives
Notional Amount	100,000,000
Fixed Rate (as a percent)	0.6123%
Fair value of interest rate swaps	0	(279,000)
Designated \| Interest rate swap, effective date January 3, 2012, swap two
Fair values of interest rate swap derivatives
Notional Amount	100,000,000
Fixed Rate (as a percent)	0.61%
Fair value of interest rate swaps	$ 0	$ (277,000)