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Share-Based Compensation and Other Compensation Matters (Details 2) (USD $) | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Stock Options |  |  |  |  |  |  |
Exercised (in shares) | (62,888)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised |  | (39,331)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised |  | (61,624)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised |  |
Aggregate Intrinsic Value |  |  |  |  |  |  |
Increase (decrease) in tax benefit from share-based compensation | $ (3,000)us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation |  | $ (122,000)us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation |  | $ 43,000 us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation |  |
Options |  |  |  |  |  |  |
Stock Options |  |  |  |  |  |  |
Outstanding at the beginning of the period (in shares) | 640,927 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | 798,210 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | 945,422 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  |
Forfeited/Expired (in shares) | (18,303)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | (117,952)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | (85,588)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  |
Exercised (in shares) | (62,888)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | (39,331)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | (61,624)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  |
Outstanding at the end of the period (in shares) | 559,736 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | 640,927 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | 798,210 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | 945,422 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember
Exercisable at the end of the period (in shares) | 559,736 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember | [1] | 640,927 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember | [2] | 798,210 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember | [3] |
Exercise price range, options outstanding, low end of range (in dollars per share) | $ 25.52 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 19.63 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 13.60 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 13.4 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember
Exercise price range, options outstanding, high end of range (in dollars per share) | $ 56.00 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 56 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 57 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 57 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember
Weighted Average Exercise Price per Share |  |  |  |  |  |  |
Outstanding at the beginning of the period (in dollars per share) | $ 38.11 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 37.62 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 36.63 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  |
Forfeited/Expired (in dollars per share) | $ 42.12 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 40.91 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 42.98 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  |
Exercised (in dollars per share) | $ 23.70 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 19.67 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 15.08 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  |
Outstanding at the end of the period (in dollars per share) | $ 39.60 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 38.11 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 37.62 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | $ 36.63 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember
Exercisable at the end of the period (in dollars per share) | $ 39.60 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember | [1] | $ 38.11 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember | [2] | $ 37.62 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember | [3] |
Weighted Average Remaining Contractual Term |  |  |  |  |  |  |
Weighted average remaining contractual term | 2 years |  | 2 years |  | 3 years |  | 4 years
Aggregate Intrinsic Value |  |  |  |  |  |  |
Balance outstanding | 167,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | 68,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | 325,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | 510,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember
Aggregate intrinsic value of options exercised | 225,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | 258,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  | 600,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember |  |
Options | Range of Exercise Price One | Vested |  |  |  |  |  |  |
Stock Options |  |  |  |  |  |  |
Exercisable at the end of the period (in shares) | 105,672 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeOneMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | 171,288 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeOneMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | 9,500 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeOneMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  |
Exercise price range, options outstanding, low end of range (in dollars per share) | $ 25.52 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeOneMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 19.63 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeOneMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 13.60 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeOneMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  |
Exercise price range, options outstanding, high end of range (in dollars per share) | $ 30.04 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeOneMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 30.04 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeOneMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 16.73 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeOneMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  |
Options | Range of Exercise Price Two | Vested |  |  |  |  |  |  |
Stock Options |  |  |  |  |  |  |
Exercisable at the end of the period (in shares) | 142,862 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeTwoMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | 145,187 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeTwoMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | 204,736 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeTwoMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  |
Exercise price range, options outstanding, low end of range (in dollars per share) | $ 30.05 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeTwoMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 30.05 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeTwoMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 16.74 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeTwoMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  |
Exercise price range, options outstanding, high end of range (in dollars per share) | $ 41.28 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeTwoMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 41.28 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeTwoMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 30.04 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeTwoMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  |
Options | Range of Exercise Price Three | Vested |  |  |  |  |  |  |
Stock Options |  |  |  |  |  |  |
Exercisable at the end of the period (in shares) | 158,902 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeThreeMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | 160,402 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeThreeMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | 180,962 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeThreeMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  |
Exercise price range, options outstanding, low end of range (in dollars per share) | $ 41.29 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeThreeMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 41.29 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeThreeMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 30.05 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeThreeMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  |
Exercise price range, options outstanding, high end of range (in dollars per share) | $ 42.74 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeThreeMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 42.74 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeThreeMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 41.28 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeThreeMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  |
Options | Range of Exercise Price Four | Vested |  |  |  |  |  |  |
Stock Options |  |  |  |  |  |  |
Exercisable at the end of the period (in shares) | 152,300 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeFourMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | 164,050 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeFourMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | 403,012 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeFourMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  |
Exercise price range, options outstanding, low end of range (in dollars per share) | $ 42.75 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeFourMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 42.75 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeFourMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 41.29 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeFourMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  |
Exercise price range, options outstanding, high end of range (in dollars per share) | $ 56.00 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeFourMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 56.00 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeFourMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  | $ 57.00 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = ofc_ExercisePriceRangeFourMember / ofc_ShareBasedCompensationSharesVestingStatusAxis = ofc_ShareBasedCompensationSharesVestedMember |  |
Performance share units |  |  |  |  |  |  |
Aggregate Intrinsic Value |  |  |  |  |  |  |
Estimated pre-vesting forfeitures (as a percent) | 0.00%ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEstimatedPercentageOfForfeitures / us-gaap_AwardTypeAxis = ofc_PerformanceShareUnitsMember |  |  |  |  |  |
Unrecognized compensation cost | 1,900,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized / us-gaap_AwardTypeAxis = ofc_PerformanceShareUnitsMember |  |  |  |  |  |
Expected weighted average period during which unrecognized compensation cost will be recognized | 2 years |  |  |  |  |  |
Restricted shares |  |  |  |  |  |  |
Aggregate Intrinsic Value |  |  |  |  |  |  |
Unrecognized compensation cost | $ 6,300,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized / us-gaap_AwardTypeAxis = ofc_RestrictedSharesMember |  |  |  |  |  |
Expected weighted average period during which unrecognized compensation cost will be recognized | 2 years |  |  |  |  |  |
Minimum | Options |  |  |  |  |  |  |
Stock Options |  |  |  |  |  |  |
Exercise price range, options forfeited (in dollars per share) | $ 22.34 ofc_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceOfForfeitedOptions / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  | $ 18.08 ofc_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceOfForfeitedOptions / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  | $ 25.52 ofc_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceOfForfeitedOptions / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |
Exercise price range, options exercised (in dollars per share) | $ 19.63 ofc_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceOfExercisedOptions / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  | $ 13.60 ofc_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceOfExercisedOptions / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  | $ 13.40 ofc_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceOfExercisedOptions / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |
Minimum | Restricted shares |  |  |  |  |  |  |
Aggregate Intrinsic Value |  |  |  |  |  |  |
Estimated pre-vesting forfeitures (as a percent) | 0.00%ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEstimatedPercentageOfForfeitures / us-gaap_AwardTypeAxis = ofc_RestrictedSharesMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |  |  |  |  |
Maximum | Options |  |  |  |  |  |  |
Stock Options |  |  |  |  |  |  |
Exercise price range, options forfeited (in dollars per share) | $ 49.60 ofc_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceOfForfeitedOptions / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  | $ 51.62 ofc_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceOfForfeitedOptions / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  | $ 57.00 ofc_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceOfForfeitedOptions / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |
Exercise price range, options exercised (in dollars per share) | $ 28.15 ofc_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceOfExercisedOptions / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  | $ 26.24 ofc_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceOfExercisedOptions / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  | $ 22.49 ofc_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceOfExercisedOptions / us-gaap_AwardTypeAxis = us-gaap_StockOptionMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |
Maximum | Restricted shares |  |  |  |  |  |  |
Aggregate Intrinsic Value |  |  |  |  |  |  |
Estimated pre-vesting forfeitures (as a percent) | 5.00%ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEstimatedPercentageOfForfeitures / us-gaap_AwardTypeAxis = ofc_RestrictedSharesMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |  |  |  |  |
[1] | 105,672 of these options had an exercise price ranging from $25.52 to $30.04; 142,862 had an exercise price ranging from$30.05 to $41.28; 158,902 had an exercise price ranging from $41.29 to $42.74; and 152,300 had an exercise price ranging from $42.75 to $56.00.
[2] | 171,288 of these options had an exercise price ranging from $19.63 to $30.04; 145,187 had an exercise price ranging from$30.05 to $41.28; 160,402 had an exercise price ranging from $41.29 to $42.74; and 164,050 had an exercise price ranging from $42.75 to $56.00.
[3] | 9,500 of these options had an exercise price ranging from $13.60 to $16.73; 204,736 had an exercise price ranging from $16.74 to $30.04; 180,962 had an exercise price ranging from $30.05 to $41.28; and 403,012 had an exercise price ranging from $41.29 to $57.00.

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- Definition The exercise price for purposes of disclosing shares exercised under stock option awards on all stock option plans. + References No definition available. + Details
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- Definition Amount of increase in additional paid in capital (APIC) resulting from a tax benefit associated with share-based compensation plan other than an employee stock ownership plan (ESOP). Includes, but is not limited to, excess tax benefit. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 740 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6419406&loc=d3e23524-113945 + Details
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- Definition Unrecognized cost of unvested share-based compensation awards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3)-(4) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average price of options that were either forfeited or expired. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3)-(4) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of options outstanding, including both vested and non-vested options. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average price at which option holders acquired shares when converting their stock options into shares. + References No definition available. + Details
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- Definition The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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