Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenues
Rental revenue	$ 386,396		$ 377,611		$ 353,080
Tenant recoveries and other real estate operations revenue	93,329		83,386		81,219
Construction contract and other service revenues	106,748		62,363		73,836
Total revenues	586,473		523,360		508,135
Expenses
Property operating expenses	179,934		167,199		159,206
Depreciation and amortization associated with real estate operations	136,086		113,214		107,998
Construction contract and other service expenses	100,058		58,875		70,576
Impairment losses	1,416		5,857		43,678
General, administrative and leasing expenses	31,794		30,869		31,900
Business development expenses and land carry costs	5,573		5,436		5,711
Total operating expenses	454,861		381,450		419,069
Operating income	131,612		141,910		89,066
Interest expense	(92,393)		(82,010)		(86,401)
Interest and other income	4,923		3,834		7,172
Loss on early extinguishment of debt	(9,552)		(27,030)		(943)
Income from continuing operations before equity in income (loss) of unconsolidated entities and income taxes	34,590		36,704		8,894
Equity in income (loss) of unconsolidated entities	229		2,110		(546)
Income tax expense	(310)		(1,978)		(381)
Income from continuing operations	34,509		36,836		7,967
Discontinued operations	26		55,692		12,353
Income before gain on sales of real estate	34,535		92,528		20,320
Gain on sales of real estate, net of income taxes	10,671		9,016		21
Net income	45,206		101,544		20,341
Net (income) loss attributable to noncontrolling interests:
Common units in COPLP	(1,006)		(3,283)		87
Preferred units in COPLP	(660)		(660)		(660)
Other consolidated entities	(3,285)		(3,894)		1,209
Net income	40,255		93,707		20,977
Preferred share/ unit dividends/ distributions	(15,939)		(19,971)		(20,844)
Issuance costs associated with redeemed preferred shares	(1,769)		(2,904)		(1,827)
Net income (loss) attributable to COPT common shareholders	22,547		70,832		(1,694)
Net income attributable to COPT:
Income from continuing operations	40,225		41,366		9,297
Discontinued operations, net	30		52,341		11,680
Net income	40,255		93,707		20,977
Basic earnings per common share
Income (loss) from continuing operations (in dollars per share/unit)	$ 0.25	[1]	$ 0.21	[1]	$ (0.19)	[1]
Discontinued operations (in dollars per share/unit)	$ 0.00	[1]	$ 0.62	[1]	$ 0.16	[1]
Net income (loss) attributable to COPT common shareholders (in dollars per share/unit)	$ 0.25	[1]	$ 0.83	[1]	$ (0.03)	[1]
Diluted earnings per common share
Income (loss) from continuing operations (in dollars per share/unit)	$ 0.25	[1]	$ 0.21	[1]	$ (0.19)	[1]
Discontinued operations (in dollars per share/unit)	$ 0.00	[1]	$ 0.62	[1]	$ 0.16	[1]
Net income (loss) attributable to COPT common shareholders (in dollars per share/unit)	$ 0.25	[1]	$ 0.83	[1]	$ (0.03)	[1]
Corporate Office Properties, L.P.
Revenues
Rental revenue	386,396		377,611		353,080
Tenant recoveries and other real estate operations revenue	93,329		83,386		81,219
Construction contract and other service revenues	106,748		62,363		73,836
Total revenues	586,473		523,360		508,135
Expenses
Property operating expenses	179,934		167,199		159,206
Depreciation and amortization associated with real estate operations	136,086		113,214		107,998
Construction contract and other service expenses	100,058		58,875		70,576
Impairment losses	1,416		5,857		43,678
General, administrative and leasing expenses	31,794		30,869		31,900
Business development expenses and land carry costs	5,573		5,436		5,711
Total operating expenses	454,861		381,450		419,069
Operating income	131,612		141,910		89,066
Interest expense	(92,393)		(82,010)		(86,401)
Interest and other income	4,923		3,834		7,172
Loss on early extinguishment of debt	(9,552)		(27,030)		(943)
Income from continuing operations before equity in income (loss) of unconsolidated entities and income taxes	34,590		36,704		8,894
Equity in income (loss) of unconsolidated entities	229		2,110		(546)
Income tax expense	(310)		(1,978)		(381)
Income from continuing operations	34,509		36,836		7,967
Discontinued operations	26		55,692		12,353
Income before gain on sales of real estate	34,535		92,528		20,320
Gain on sales of real estate, net of income taxes	10,671		9,016		21
Net income	45,206		101,544		20,341
Net (income) loss attributable to noncontrolling interests in consolidated entities	(3,276)		(3,907)		507
Net (income) loss attributable to noncontrolling interests:
Net income	41,930		97,637		20,848
Preferred share/ unit dividends/ distributions	(16,599)		(20,631)		(21,504)
Issuance costs associated with redeemed preferred shares	(1,769)		(2,904)		(1,827)
Net income (loss) attributable to COPT common shareholders	23,562		74,102		(2,483)
Net income attributable to COPT:
Income from continuing operations	41,899		42,875		9,194
Discontinued operations, net	31		54,762		11,654
Net income	$ 41,930		$ 97,637		$ 20,848
Basic earnings per common share
Income (loss) from continuing operations (in dollars per share/unit)	$ 0.25	[2]	$ 0.21	[2]	$ (0.19)	[2]
Discontinued operations (in dollars per share/unit)	$ 0.00	[2]	$ 0.62	[2]	$ 0.15	[2]
Net income (loss) attributable to COPT common shareholders (in dollars per share/unit)	$ 0.25	[2]	$ 0.83	[2]	$ (0.04)	[2]
Diluted earnings per common share
Income (loss) from continuing operations (in dollars per share/unit)	$ 0.25	[2]	$ 0.21	[2]	$ (0.19)	[2]
Discontinued operations (in dollars per share/unit)	$ 0.00	[2]	$ 0.62	[2]	$ 0.15	[2]
Net income (loss) attributable to COPT common shareholders (in dollars per share/unit)	$ 0.25	[2]	$ 0.83	[2]	$ (0.04)	[2]

[1] Basic and diluted earnings per common share are calculated based on amounts attributable to common shareholders of Corporate Office Properties Trust.

[2] Basic and diluted earnings per common unit are calculated based on amounts attributable to common unitholders of Corporate Office Properties, L.P.