XML 103 R81.htm IDEA: XBRL DOCUMENT
v3.20.4

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - MAP Venture (Details) $ in Thousands |  | 12 Months Ended |  |
--- | --- | --- | --- | ---
Aug. 01, 2018 USD ($) | Dec. 31, 2020 USD ($) ft² property | Dec. 31, 2019 USD ($) | Jan. 01, 2019 USD ($)
Schedule of Equity Method Investments [Line Items] |  |  |  |
Real estate ventures aggregate indebtedness to third parties |  | $ 963,018 | $ 596,007 |
MAP Venture |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |
Ground lease annual payments |  | $ 11,900 |  |
Ground lease annual rent expense increase percentage through November 2025 |  | 2.50% |  |
Ground lease annual rent expense increase after November 2025 |  | 2.50% |  |
Real estate ventures aggregate indebtedness to third parties | $ 180,800 | $ 185,000 | 185,000 |
MAP Venture | Variable Interest Entity, Not Primary Beneficiary |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |
Number of office properties owned | property |  | 58 |  |
Rentable square feet | ft² |  | 3,924,783 |  |
MAP Venture | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |
Retained earnings |  |  | $ 4,600 | $ 9,200
Secured Debt | MAP Venture |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |
Debt instrument, face amount | $ 185,000 |  |  |
Variable interest rate | 2.45% |  |  |

X
- Definition Equity method investment summarized financial information debt. + References No definition available. + Details
Name: | bdn_EquityMethodInvestmentSummarizedFinancialInformationDebt
Namespace Prefix: | bdn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Ground lease annual payments. + References No definition available. + Details
Name: | bdn_GroundLeaseAnnualPayments
Namespace Prefix: | bdn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Ground lease annual rent expense increase percentage for first ten years. + References No definition available. + Details
Name: | bdn_GroundLeaseAnnualRentExpenseIncreasePercentageForFirstTenYears
Namespace Prefix: | bdn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ground lease annual rent expense increase percentage, thereafter. + References No definition available. + Details
Name: | bdn_GroundLeaseAnnualRentExpenseIncreasePercentageThereafter
Namespace Prefix: | bdn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of office properties owned. + References No definition available. + Details
Name: | bdn_NumberOfOfficePropertiesOwned
Namespace Prefix: | bdn_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Net rentable area for properties owned. + References No definition available. + Details
Name: | us-gaap_NetRentableArea
Namespace Prefix: | us-gaap_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | instant

X
- Definition The cumulative amount of the reporting entity's undistributed earnings or deficit. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(30)(a)(3)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 65 -Paragraph 15 -Subparagraph (g)(2) -URI http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(23)(a)(4)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 65 -Paragraph 2 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -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=120397183&loc=d3e187085-122770 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 65 -Paragraph 2 -Subparagraph (g)(2)(i) -URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641 + Details
Name: | us-gaap_RetainedEarningsAccumulatedDeficit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=bdn_MAPVentureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CumulativeEffectPeriodOfAdoptionAxis=srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |