Accrued interest payable on construction loan.

No definition available.

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Namespace Prefix:	bdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Commercial space square feet.

+ References

No definition available.

+ Details

Name:	bdn_CommercialSpaceSquareFeet
Namespace Prefix:	bdn_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity method investment summarized financial information debt net.

+ References

No definition available.

+ Details

Name:	bdn_EquityMethodInvestmentSummarizedFinancialInformationDebtNet
Namespace Prefix:	bdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of car structured parking facility.

+ References

No definition available.

+ Details

Name:	bdn_NumberOfCarStructuredParkingFacility
Namespace Prefix:	bdn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of contemporary glass tower development square feet.

+ References

No definition available.

+ Details

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Namespace Prefix:	bdn_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of floors of a building

+ References

No definition available.

+ Details

Name:	bdn_NumberOfFloorsOfBuilding
Namespace Prefix:	bdn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of luxury apartments.

+ References

No definition available.

+ Details

Name:	bdn_NumberOfLuxuryApartments
Namespace Prefix:	bdn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Interest rate of mortgage loan within investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Paragraph Column B
-Subsection 29

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29(Column B))
-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

+ Details

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Namespace Prefix:	srt_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the carrying value of a short-term real estate loan to finance building costs. The funds are disbursed as needed or in accordance with a prearranged plan; generally, a portion of the funds is disbursed at inception and the remainder as construction progresses. The money is repaid on completion of the project, usually from the proceeds of a mortgage loan. The rate is normally higher than the prime rate, and there is usually an origination fee. The effective yield on these loans tends to be high, and the lender has a security interest in the real property. Note that there are separate concepts for the current and noncurrent portions of long-term construction loans.

+ 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(19))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_ConstructionLoan
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, before allowance for credit loss, of financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919230-210447

+ Details

Name:	us-gaap_NotesReceivableGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow from repayment of borrowings to finance the cost of construction.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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

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Data Type:	xbrli:stringItemType
Balance Type:	na
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	bdn_JointVentureMembersAxis=bdn_LCORCalSTRSMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - 1919 Ventures (Details) $ in Thousands	Jun. 26, 2018 USD ($)	Oct. 27, 2014 ft² story apartment car	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Outstanding indebtedness			$ 585,068	$ 365,707
1919 Ventures
Schedule of Equity Method Investments [Line Items]
Number of floors of a building \| story		29
Square foot of contemporary glass tower development \| ft²		455,000
Number of luxury apartments \| apartment		321
Square feet of commercial space \| ft²		24,000
Number of car structured parking facility \| car		215
Note receivable	$ 44,400
Loan interest rate	4.00%
Repayment of construction loan	$ 88,800
Construction loan, principal amount	88,600
Accrued interest on construction loan	200
LCOR/CalSTRS \| 1919 Ventures
Schedule of Equity Method Investments [Line Items]
Outstanding indebtedness	44,400
Other Assets \| 1919 Ventures
Schedule of Equity Method Investments [Line Items]
Note receivable	$ 44,400