XML 53 R6.htm IDEA: XBRL DOCUMENT v2.4.1.9
Consolidated Statements of Equity (USD $)
In Thousands, except Share data, unless otherwise specified
Total
USD ($)
Preferred Shares
USD ($)
Common Shares
USD ($)
Additional Paid-in Capital
USD ($)
Cumulative Distributions in Excess of Net Income
USD ($)
Accumulated Other Comprehensive Income (Loss)
USD ($)
Noncontrolling Interests
USD ($)
Corporate Office Properties, L.P.
USD ($)
Corporate Office Properties, L.P.
Common Shares
USD ($)
Corporate Office Properties, L.P.
Accumulated Other Comprehensive Income (Loss)
USD ($)
Corporate Office Properties, L.P.
Noncontrolling Interests
USD ($)
Corporate Office Properties, L.P.
Limited Partner
Corporate Office Properties, L.P.
Limited Partner
Preferred Shares
USD ($)
Corporate Office Properties, L.P.
General Partner
Corporate Office Properties, L.P.
General Partner
Preferred Shares
USD ($)
Balance (COPT: 87,394,512 shares and 93,255,284 shares as of December 31, 2013 and 2014, respectively) at Dec. 31, 2013 $ 1,497,249us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest $ 249,083us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
$ 874us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
$ 1,814,015us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
$ (641,868)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDistributionsInExcessOfNetIncomeMember
$ 3,480us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
$ 71,665us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
$ 1,497,249us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
$ 1,226,318us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
$ 3,605us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
$ 9,443us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
  $ 8,800us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
  $ 249,083us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
Balance (in units/ shares) at Dec. 31, 2013 87,394,512us-gaap_CommonStockSharesOutstanding               91,372,212us-gaap_CommonStockSharesOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Balance (preferred units) at Dec. 31, 2013                         352,000us-gaap_PreferredUnitsOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
  9,431,667us-gaap_PreferredUnitsOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
Increase (Decrease) in Shareholders' Equity                              
Conversion of common units to common shares (COPT: 48,498 shares and 158,000 shares for the three months ended March 31, 2014 and 2015, respectively) 0us-gaap_StockIssuedDuringPeriodValueConversionOfUnits   0us-gaap_StockIssuedDuringPeriodValueConversionOfUnits
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
651us-gaap_StockIssuedDuringPeriodValueConversionOfUnits
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
    (651)us-gaap_StockIssuedDuringPeriodValueConversionOfUnits
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
               
Exercise of share options (in units/shares) 26,614us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised               26,614us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Exercise of share options (COPT: 26,614 shares and 70,374 shares for the three months ended March 31, 2014 and 2015, respectively) 568us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised     568us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
      568us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
568us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Share-based compensation issuance, net of redemptions (in units/shares) 125,307us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation               125,307us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Share-based compensation issuance, net of redemptions (COPT: 125,307 and 162,370 shares issued, net of redemptions for the three months ended March 31, 2014 and 2015, respectively) 1,856us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue   2us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
1,854us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
      1,856us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
1,856us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Redemption of vested equity awards (in units/shares)                 0us-gaap_StockRepurchasedDuringPeriodShares
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Redemption of vested equity awards (1,092)us-gaap_StockRepurchasedDuringPeriodValue     (1,092)us-gaap_StockRepurchasedDuringPeriodValue
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
      (1,092)us-gaap_StockRepurchasedDuringPeriodValue
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
(1,092)us-gaap_StockRepurchasedDuringPeriodValue
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Adjustments to noncontrolling interests resulting from changes in ownership of COPLP 0us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance     (69)us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
    69us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
               
Comprehensive income 3,741ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments       4,741ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDistributionsInExcessOfNetIncomeMember
(1,408)ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
408ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
3,741ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
279ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
(1,472)ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
279ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
  165ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
  4,490ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
Dividends / Distributions to owners of common and preferred units (28,581)us-gaap_Dividends       (28,581)us-gaap_Dividends
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDistributionsInExcessOfNetIncomeMember
    (29,827)us-gaap_Dividends
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
(25,172)us-gaap_Dividends
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
      (165)us-gaap_Dividends
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
  (4,490)us-gaap_Dividends
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
Distributions to owners of common and preferred units in COPLP (1,246)ofc_MinorityInterestDecreaseFromDistributionsToOperatingPartnershipNoncontrollingInterestHolders           (1,246)ofc_MinorityInterestDecreaseFromDistributionsToOperatingPartnershipNoncontrollingInterestHolders
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
               
Adjustment to arrive at fair value of redeemable noncontrolling interest 540ofc_AdjustmenttoEquitytoArriveatFairValueofRedeemableNoncontrollingInterest     540ofc_AdjustmenttoEquitytoArriveatFairValueofRedeemableNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
      540ofc_AdjustmenttoEquitytoArriveatFairValueofRedeemableNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
540ofc_AdjustmenttoEquitytoArriveatFairValueofRedeemableNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Balance (COPT: 87,594,931 shares and 94,536,269 shares as of March 31, 2014 and 2015, respectively) at Mar. 31, 2014 1,473,035us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest 249,083us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
876us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
1,816,467us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
(665,708)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDistributionsInExcessOfNetIncomeMember
2,072us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
70,245us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
1,473,035us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
1,203,297us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
2,133us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
9,722us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
  8,800us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
  249,083us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
Balance (in units/ shares) at Mar. 31, 2014 87,594,931us-gaap_CommonStockSharesOutstanding               91,524,133us-gaap_CommonStockSharesOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Balance (preferred units) at Mar. 31, 2014                         352,000us-gaap_PreferredUnitsOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
  9,431,667us-gaap_PreferredUnitsOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
Balance (COPT: 87,394,512 shares and 93,255,284 shares as of December 31, 2013 and 2014, respectively) at Dec. 31, 2014 1,520,884us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest 199,083us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
933us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
1,969,968us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
(717,264)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDistributionsInExcessOfNetIncomeMember
(1,297)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
69,461us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
1,520,884us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
1,305,219us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
(1,381)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
9,163us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
  8,800us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
  199,083us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
Balance (in units/ shares) at Dec. 31, 2014 93,255,284us-gaap_CommonStockSharesOutstanding               97,092,835us-gaap_CommonStockSharesOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
    3,837,551us-gaap_CommonStockSharesOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
  93,255,284us-gaap_CommonStockSharesOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
 
Balance (preferred units) at Dec. 31, 2014                       352,000us-gaap_PreferredUnitsOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
352,000us-gaap_PreferredUnitsOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
7,431,667us-gaap_PreferredUnitsOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
7,431,667us-gaap_PreferredUnitsOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
Increase (Decrease) in Shareholders' Equity                              
Conversion of common units to common shares (COPT: 48,498 shares and 158,000 shares for the three months ended March 31, 2014 and 2015, respectively) 0us-gaap_StockIssuedDuringPeriodValueConversionOfUnits   2us-gaap_StockIssuedDuringPeriodValueConversionOfUnits
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
2,120us-gaap_StockIssuedDuringPeriodValueConversionOfUnits
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
    (2,122)us-gaap_StockIssuedDuringPeriodValueConversionOfUnits
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
               
Issuance of common units resulting from common shares issued under at-the-market program (in units)                 890,241ofc_StockIssuedDuringPeriodSharesNewIssuesforOtherProgram
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Issuance of common units resulting from common shares issued under at-the-market program (COPT: 890,241 shares for the three months ended March 31, 2015) 26,535ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram   9ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
26,526ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
      26,535ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
26,535ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Exercise of share options (in units/shares) 70,374us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised               70,374us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Exercise of share options (COPT: 26,614 shares and 70,374 shares for the three months ended March 31, 2014 and 2015, respectively) 1,845us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised     1,845us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
      1,845us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
1,845us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Share-based compensation issuance, net of redemptions (in units/shares) 162,370us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation               162,370us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Share-based compensation issuance, net of redemptions (COPT: 125,307 and 162,370 shares issued, net of redemptions for the three months ended March 31, 2014 and 2015, respectively) 1,829us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue   1us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
1,828us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
      1,829us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
1,829us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Redemption of vested equity awards (in units/shares)                 0us-gaap_StockRepurchasedDuringPeriodShares
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Redemption of vested equity awards (2,031)us-gaap_StockRepurchasedDuringPeriodValue     (2,031)us-gaap_StockRepurchasedDuringPeriodValue
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
      (2,031)us-gaap_StockRepurchasedDuringPeriodValue
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
(2,031)us-gaap_StockRepurchasedDuringPeriodValue
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Adjustments to noncontrolling interests resulting from changes in ownership of COPLP 0us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance     (475)us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
    475us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
               
Comprehensive income 11,472ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments       13,355ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDistributionsInExcessOfNetIncomeMember
(2,650)ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
767ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
11,472ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
10,200ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
(2,756)ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
311ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
  165ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
  3,552ofc_ComprehensiveIncomeLossNetOfTaxAfterRedeemableNoncontrollingInterestAdjustments
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
Dividends / Distributions to owners of common and preferred units (29,550)us-gaap_Dividends       (29,550)us-gaap_Dividends
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDistributionsInExcessOfNetIncomeMember
    (30,727)us-gaap_Dividends
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
(27,010)us-gaap_Dividends
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
      (165)us-gaap_Dividends
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
  (3,552)us-gaap_Dividends
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
Distributions to owners of common and preferred units in COPLP (1,177)ofc_MinorityInterestDecreaseFromDistributionsToOperatingPartnershipNoncontrollingInterestHolders           (1,177)ofc_MinorityInterestDecreaseFromDistributionsToOperatingPartnershipNoncontrollingInterestHolders
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
               
Distributions to noncontrolling interests in subsidiaries (4)ofc_MinorityInterestDecreaseFromDistributionsIncludingJointVentures           (4)ofc_MinorityInterestDecreaseFromDistributionsIncludingJointVentures
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
(4)ofc_MinorityInterestDecreaseFromDistributionsIncludingJointVentures
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
    (4)ofc_MinorityInterestDecreaseFromDistributionsIncludingJointVentures
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
       
Adjustment to arrive at fair value of redeemable noncontrolling interest (73)ofc_AdjustmenttoEquitytoArriveatFairValueofRedeemableNoncontrollingInterest     (73)ofc_AdjustmenttoEquitytoArriveatFairValueofRedeemableNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
      (73)ofc_AdjustmenttoEquitytoArriveatFairValueofRedeemableNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
(73)ofc_AdjustmenttoEquitytoArriveatFairValueofRedeemableNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
           
Balance (COPT: 87,594,931 shares and 94,536,269 shares as of March 31, 2014 and 2015, respectively) at Mar. 31, 2015 $ 1,529,730us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest $ 199,083us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
$ 945us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
$ 1,999,708us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
$ (733,459)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDistributionsInExcessOfNetIncomeMember
$ (3,947)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
$ 67,400us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
$ 1,529,730us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
$ 1,316,514us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
$ (4,137)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
$ 9,470us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
  $ 8,800us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
  $ 199,083us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
Balance (in units/ shares) at Mar. 31, 2015 94,536,269us-gaap_CommonStockSharesOutstanding               98,215,820us-gaap_CommonStockSharesOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
    3,679,551us-gaap_CommonStockSharesOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
  94,536,269us-gaap_CommonStockSharesOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
 
Balance (preferred units) at Mar. 31, 2015                       352,000us-gaap_PreferredUnitsOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
352,000us-gaap_PreferredUnitsOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_LimitedPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
7,431,667us-gaap_PreferredUnitsOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
7,431,667us-gaap_PreferredUnitsOutstanding
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_PartnerTypeOfPartnersCapitalAccountAxis
= us-gaap_GeneralPartnerMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember