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SUBSEQUENT EVENTS (Details) - Subsequent Event - Schuylkill Yards West ft² in Thousands, $ in Millions | Feb. 02, 2021 USD ($) ft²
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Subsequent Event [Line Items] |
Area of building to be constructed | ft² | 570
Estimated project cost | $ 287
Funding committed by other party | $ 58
Ownership interest held by partner | 45.00%

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- Definition Area Of Building To Be Constructed + References No definition available. + Details
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Namespace Prefix: | bdn_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | instant

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- Definition Estimated Project Cost + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
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Period Type: | instant

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- Definition Joint Venture, Funding Committed By Other Party + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Real Estate Investment, Ownership Interest Held By Partner + References No definition available. + Details
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Namespace Prefix: | bdn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
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Period Type: | duration

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