Annual report pursuant to Section 13 and 15(d)

Quarterly Data (Unaudited) (Details)

v2.4.1.9
Quarterly Data (Unaudited) (Details) (USD $)
In Thousands, except Per Share data, unless otherwise specified
 3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Revenues $ 146,971us-gaap_Revenues $ 153,015us-gaap_Revenues $ 139,820us-gaap_Revenues $ 146,667us-gaap_Revenues $ 128,802us-gaap_Revenues $ 131,812us-gaap_Revenues $ 136,527us-gaap_Revenues $ 126,219us-gaap_Revenues $ 586,473us-gaap_Revenues $ 523,360us-gaap_Revenues $ 508,135us-gaap_Revenues
Operating income (loss) 37,148us-gaap_OperatingIncomeLoss 37,422us-gaap_OperatingIncomeLoss 31,836us-gaap_OperatingIncomeLoss 25,206us-gaap_OperatingIncomeLoss 34,843us-gaap_OperatingIncomeLoss 30,673us-gaap_OperatingIncomeLoss 40,229us-gaap_OperatingIncomeLoss 36,165us-gaap_OperatingIncomeLoss 131,612us-gaap_OperatingIncomeLoss 141,910us-gaap_OperatingIncomeLoss 89,066us-gaap_OperatingIncomeLoss
Income (loss) from continuing operations 5,874us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest 13,727us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest 9,248us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest 5,660us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest 14,432us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest 10,974us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (232)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest 11,662us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest 34,509us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest 36,836us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest 7,967us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
Discontinued operations 22us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax 191us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax (198)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax 11us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax 71,907us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax (12,974)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax (4,502)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax 1,261us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax 26us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax 55,692us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax 12,353us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
Net income 5,937us-gaap_ProfitLoss 24,548us-gaap_ProfitLoss 9,050us-gaap_ProfitLoss 5,671us-gaap_ProfitLoss 92,672us-gaap_ProfitLoss (2,000)us-gaap_ProfitLoss (4,405)us-gaap_ProfitLoss 15,277us-gaap_ProfitLoss 45,206us-gaap_ProfitLoss 101,544us-gaap_ProfitLoss 20,341us-gaap_ProfitLoss
Net (income) loss attributable to noncontrolling interests in consolidated entities (1,033)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest (1,828)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest (1,160)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest (930)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest (5,656)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest (964)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest (960)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest (257)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest      
Net income 4,904us-gaap_NetIncomeLoss 22,720us-gaap_NetIncomeLoss 7,890us-gaap_NetIncomeLoss 4,741us-gaap_NetIncomeLoss 87,016us-gaap_NetIncomeLoss (2,964)us-gaap_NetIncomeLoss (5,365)us-gaap_NetIncomeLoss 15,020us-gaap_NetIncomeLoss 40,255us-gaap_NetIncomeLoss 93,707us-gaap_NetIncomeLoss 20,977us-gaap_NetIncomeLoss
Preferred share/ unit dividends/ distributions (3,552)us-gaap_PreferredStockDividendsIncomeStatementImpact (3,553)us-gaap_PreferredStockDividendsIncomeStatementImpact (4,344)us-gaap_PreferredStockDividendsIncomeStatementImpact (4,490)us-gaap_PreferredStockDividendsIncomeStatementImpact (4,490)us-gaap_PreferredStockDividendsIncomeStatementImpact (4,490)us-gaap_PreferredStockDividendsIncomeStatementImpact (4,885)us-gaap_PreferredStockDividendsIncomeStatementImpact (6,106)us-gaap_PreferredStockDividendsIncomeStatementImpact (15,939)us-gaap_PreferredStockDividendsIncomeStatementImpact (19,971)us-gaap_PreferredStockDividendsIncomeStatementImpact (20,844)us-gaap_PreferredStockDividendsIncomeStatementImpact
Issuance costs associated with redeemed preferred shares 0us-gaap_OtherPreferredStockDividendsAndAdjustments 0us-gaap_OtherPreferredStockDividendsAndAdjustments (1,769)us-gaap_OtherPreferredStockDividendsAndAdjustments 0us-gaap_OtherPreferredStockDividendsAndAdjustments 0us-gaap_OtherPreferredStockDividendsAndAdjustments 0us-gaap_OtherPreferredStockDividendsAndAdjustments (2,904)us-gaap_OtherPreferredStockDividendsAndAdjustments 0us-gaap_OtherPreferredStockDividendsAndAdjustments (1,769)us-gaap_OtherPreferredStockDividendsAndAdjustments (2,904)us-gaap_OtherPreferredStockDividendsAndAdjustments (1,827)us-gaap_OtherPreferredStockDividendsAndAdjustments
Net income (loss) attributable to COPT common shareholders 1,352us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 19,167us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 1,777us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 251us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 82,526us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic (7,454)us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic (13,154)us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 8,914us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 22,547us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic 70,832us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic (1,694)us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
Basic earnings per common share/unit (in dollars per share/unit) $ 0.01us-gaap_EarningsPerShareBasic $ 0.22us-gaap_EarningsPerShareBasic $ 0.02us-gaap_EarningsPerShareBasic $ 0.00us-gaap_EarningsPerShareBasic $ 0.94us-gaap_EarningsPerShareBasic $ (0.09)us-gaap_EarningsPerShareBasic $ (0.16)us-gaap_EarningsPerShareBasic $ 0.11us-gaap_EarningsPerShareBasic $ 0.25us-gaap_EarningsPerShareBasic [1] $ 0.83us-gaap_EarningsPerShareBasic [1] $ (0.03)us-gaap_EarningsPerShareBasic [1]
Diluted earnings per common share/unit (in dollars per share/unit) $ 0.01us-gaap_EarningsPerShareDiluted $ 0.22us-gaap_EarningsPerShareDiluted $ 0.02us-gaap_EarningsPerShareDiluted $ 0.00us-gaap_EarningsPerShareDiluted $ 0.94us-gaap_EarningsPerShareDiluted $ (0.09)us-gaap_EarningsPerShareDiluted $ (0.16)us-gaap_EarningsPerShareDiluted $ 0.11us-gaap_EarningsPerShareDiluted $ 0.25us-gaap_EarningsPerShareDiluted [1] $ 0.83us-gaap_EarningsPerShareDiluted [1] $ (0.03)us-gaap_EarningsPerShareDiluted [1]
Corporate Office Properties, L.P.                      
Revenues 146,971us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		153,015us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		139,820us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		146,667us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		128,802us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		131,812us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		136,527us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		126,219us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		586,473us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		523,360us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		508,135us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
Operating income (loss) 37,148us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		37,422us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		31,836us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		25,206us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		34,843us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		30,673us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		40,229us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		36,165us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		131,612us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		141,910us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		89,066us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
Income (loss) from continuing operations 5,874us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		13,727us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		9,248us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		5,660us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		14,432us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		10,974us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(232)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		11,662us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		34,509us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		36,836us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		7,967us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
Discontinued operations 22us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		191us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(198)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		11us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		71,907us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(12,974)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(4,502)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		1,261us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		26us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		55,692us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		12,353us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
Net income 5,937us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		24,548us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		9,050us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		5,671us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		92,672us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(2,000)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(4,405)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		15,277us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		45,206us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		101,544us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		20,341us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
Net (income) loss attributable to noncontrolling interests in consolidated entities (805)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(897)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(837)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(737)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(1,735)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(1,035)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(1,473)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		336us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(3,276)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(3,907)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		507us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
Net income 5,132us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		23,651us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		8,213us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		4,934us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		90,937us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(3,035)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(5,878)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		15,613us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		41,930us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		97,637us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		20,848us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
Preferred share/ unit dividends/ distributions (3,717)us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(3,718)us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(4,509)us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(4,655)us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(4,655)us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(4,655)us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(5,050)us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(6,271)us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(16,599)us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(20,631)us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(21,504)us-gaap_PreferredStockDividendsIncomeStatementImpact
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
Issuance costs associated with redeemed preferred shares 0us-gaap_OtherPreferredStockDividendsAndAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		0us-gaap_OtherPreferredStockDividendsAndAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(1,769)us-gaap_OtherPreferredStockDividendsAndAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		0us-gaap_OtherPreferredStockDividendsAndAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		0us-gaap_OtherPreferredStockDividendsAndAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		0us-gaap_OtherPreferredStockDividendsAndAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(2,904)us-gaap_OtherPreferredStockDividendsAndAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		0us-gaap_OtherPreferredStockDividendsAndAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(1,769)us-gaap_OtherPreferredStockDividendsAndAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(2,904)us-gaap_OtherPreferredStockDividendsAndAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		(1,827)us-gaap_OtherPreferredStockDividendsAndAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
Net income (loss) attributable to COPT common shareholders $ 1,415us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 19,933us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 1,935us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 279us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 86,282us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ (7,690)us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ (13,832)us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 9,342us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 23,562us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 74,102us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ (2,483)us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
Basic earnings per common share/unit (in dollars per share/unit) $ 0.01us-gaap_EarningsPerShareBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 0.22us-gaap_EarningsPerShareBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 0.02us-gaap_EarningsPerShareBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 0.00us-gaap_EarningsPerShareBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 0.94us-gaap_EarningsPerShareBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ (0.09)us-gaap_EarningsPerShareBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ (0.16)us-gaap_EarningsPerShareBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 0.11us-gaap_EarningsPerShareBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 0.25us-gaap_EarningsPerShareBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		[2] $ 0.83us-gaap_EarningsPerShareBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		[2] $ (0.04)us-gaap_EarningsPerShareBasic
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		[2]
Diluted earnings per common share/unit (in dollars per share/unit) $ 0.01us-gaap_EarningsPerShareDiluted
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 0.22us-gaap_EarningsPerShareDiluted
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 0.02us-gaap_EarningsPerShareDiluted
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 0.00us-gaap_EarningsPerShareDiluted
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 0.94us-gaap_EarningsPerShareDiluted
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ (0.09)us-gaap_EarningsPerShareDiluted
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ (0.16)us-gaap_EarningsPerShareDiluted
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 0.11us-gaap_EarningsPerShareDiluted
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		$ 0.25us-gaap_EarningsPerShareDiluted
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		[2] $ 0.83us-gaap_EarningsPerShareDiluted
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		[2] $ (0.04)us-gaap_EarningsPerShareDiluted
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember 		[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.