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Risk Management and Use of Financial Instruments (Fair Values of Derivative Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified | 0 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 16, 2014 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Derivatives, Fair Value [Line Items] |  |  |  |
Concentration Risk, Percentage |  | 10.00%us-gaap_ConcentrationRiskPercentage1 | 10.00%us-gaap_ConcentrationRiskPercentage1 | 10.00%us-gaap_ConcentrationRiskPercentage1
Long Term Debt Maturities Repayments Of Principal |  | $ 2,459,463 bdn_LongTermDebtMaturitiesRepaymentsOfPrincipal |  |
Derivative, Gain (Loss) on Derivative, Net | (800)us-gaap_DerivativeGainLossOnDerivativeNet | (828)us-gaap_DerivativeGainLossOnDerivativeNet | 0 us-gaap_DerivativeGainLossOnDerivativeNet | (2,985)us-gaap_DerivativeGainLossOnDerivativeNet
Note Five [Member] | Unsecured Debt [Member] |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |
Debt Instrument, Repurchased Face Amount | 114,900 us-gaap_DebtInstrumentRepurchasedFaceAmount / us-gaap_DebtInstrumentAxis = bdn_NoteFiveMember / us-gaap_LongtermDebtTypeAxis = us-gaap_UnsecuredDebtMember |  |  |
Three Year Term Loan [Member] | Unsecured Debt [Member] |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |
Debt Instrument, Repurchased Face Amount | 150,000 us-gaap_DebtInstrumentRepurchasedFaceAmount / us-gaap_DebtInstrumentAxis = bdn_ThreeYearTermLoanMember / us-gaap_LongtermDebtTypeAxis = us-gaap_UnsecuredDebtMember |  |  |
Other Assets [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | 3.300% Interest Rate Swap Maturing January 30, 2021 [Member] |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement |  |  | 549 us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherAssetsMember / us-gaap_DerivativeByNatureAxis = bdn_A3300InterestRateSwapMaturingJanuary302021Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Other Assets [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | 3.090% Interest Rate Swap Maturing October 30, 2019 [Member] |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement |  |  | 218 us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherAssetsMember / us-gaap_DerivativeByNatureAxis = bdn_A3090InterestRateSwapMaturingOctober302019Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Other Liabilities [Member] |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |
Notional Amount |  | 278,610 invest_DerivativeNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember | 428,610 invest_DerivativeNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember |
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement |  | (3,490)us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember | (1,421)us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember |
Other Liabilities [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | 3.623% Interest Rate Swap Maturing February 1, 2019 [Member] |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |
Derivative, Fixed Interest Rate |  | 3.623%us-gaap_DerivativeFixedInterestRate / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3623InterestRateSwapMaturingFebruary12019Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |  |
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement |  | (2,649)us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3623InterestRateSwapMaturingFebruary12019Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember | (545)us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3623InterestRateSwapMaturingFebruary12019Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Derivative Liability, Notional Amount |  | 200,000 us-gaap_DerivativeLiabilityNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3623InterestRateSwapMaturingFebruary12019Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember | 200,000 us-gaap_DerivativeLiabilityNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3623InterestRateSwapMaturingFebruary12019Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Other Liabilities [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | 2.703% Interest Rate Swap Maturing February 1, 2016 [Member] |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |
Derivative, Fixed Interest Rate |  | 2.703%us-gaap_DerivativeFixedInterestRate / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2703InterestRateSwapMaturingFebruary12016Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |  |
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement |  | 0 us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2703InterestRateSwapMaturingFebruary12016Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember | (887)us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2703InterestRateSwapMaturingFebruary12016Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Derivative Liability, Notional Amount |  | 0 us-gaap_DerivativeLiabilityNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2703InterestRateSwapMaturingFebruary12016Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember | 77,000 us-gaap_DerivativeLiabilityNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2703InterestRateSwapMaturingFebruary12016Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Other Liabilities [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | 2.470% Interest Rate Swap Maturing February 1, 2015 [Member] |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |
Derivative, Fixed Interest Rate |  | 2.47%us-gaap_DerivativeFixedInterestRate / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2470InterestRateSwapMaturingFebruary12015Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |  |
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement |  | 0 us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2470InterestRateSwapMaturingFebruary12015Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember | (283)us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2470InterestRateSwapMaturingFebruary12015Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Derivative Liability, Notional Amount |  | 0 us-gaap_DerivativeLiabilityNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2470InterestRateSwapMaturingFebruary12015Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember | 50,000 us-gaap_DerivativeLiabilityNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2470InterestRateSwapMaturingFebruary12015Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Other Liabilities [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | 2.513% Interest Rate Swap Maturing May 1, 2015 [Member] |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |
Derivative, Fixed Interest Rate |  | 2.513%us-gaap_DerivativeFixedInterestRate / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2513InterestRateSwapMaturingMay12015Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |  |
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement |  | 0 us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2513InterestRateSwapMaturingMay12015Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember | (162)us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2513InterestRateSwapMaturingMay12015Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Derivative Liability, Notional Amount |  | 0 us-gaap_DerivativeLiabilityNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2513InterestRateSwapMaturingMay12015Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember | 23,000 us-gaap_DerivativeLiabilityNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2513InterestRateSwapMaturingMay12015Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Other Liabilities [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | 2.750% Interest Rate Swap Maturing September 30, 2017 [Member] |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |
Derivative, Fixed Interest Rate |  | 2.75%us-gaap_DerivativeFixedInterestRate / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2750InterestRateSwapMaturingSeptember302017Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |  |
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement |  | (253)us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2750InterestRateSwapMaturingSeptember302017Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember | (311)us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2750InterestRateSwapMaturingSeptember302017Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Derivative Liability, Notional Amount |  | 27,062 us-gaap_DerivativeLiabilityNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2750InterestRateSwapMaturingSeptember302017Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember | 27,062 us-gaap_DerivativeLiabilityNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A2750InterestRateSwapMaturingSeptember302017Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Other Liabilities [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | 3.300% Interest Rate Swap Maturing January 30, 2021 [Member] |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |
Derivative, Fixed Interest Rate |  | 3.30%us-gaap_DerivativeFixedInterestRate / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3300InterestRateSwapMaturingJanuary302021Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |  |
Derivative Asset, Notional Amount |  | 25,774 us-gaap_DerivativeAssetNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3300InterestRateSwapMaturingJanuary302021Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember | 25,774 us-gaap_DerivativeAssetNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3300InterestRateSwapMaturingJanuary302021Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement |  | (334)us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3300InterestRateSwapMaturingJanuary302021Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |  |
Other Liabilities [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | 3.090% Interest Rate Swap Maturing October 30, 2019 [Member] |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |
Derivative, Fixed Interest Rate |  | 3.09%us-gaap_DerivativeFixedInterestRate / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3090InterestRateSwapMaturingOctober302019Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |  |
Derivative Asset, Notional Amount |  | 25,774 us-gaap_DerivativeAssetNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3090InterestRateSwapMaturingOctober302019Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember | 25,774 us-gaap_DerivativeAssetNotionalAmount / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3090InterestRateSwapMaturingOctober302019Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement |  | $ (254)us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLiabilitiesMember / us-gaap_DerivativeByNatureAxis = bdn_A3090InterestRateSwapMaturingOctober302019Member / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis = us-gaap_CashFlowHedgingMember |  |

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- Definition Long term-debt maturities repayments of principal + References No definition available. + Details
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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13537-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13531-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592 + Details
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- Definition Face (par) amount of the original debt instrument that was repurchased. + References No definition available. + Details
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- Definition Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312 + Details
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- Definition Nominal or face amount used to calculate payments on the derivative asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5579245-113959 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Notional Amount -URI http://asc.fasb.org/extlink&oid=6519104 + Details
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- Definition Fixed interest rate related to the interest rate derivative. + References No definition available. + Details
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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5618551-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (a),(c),(d),(e) -URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624171-113959 + Details
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