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Discontinued Operations Discontinued Operations (Details Textuals) (Details) (Discontinued Operations [Member]) | 6 Months Ended
--- | ---
Jun. 30, 2013 Properties | Jun. 30, 2012 Properties
Discontinued Operations [Member] |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |
Number of properties sold | 12 | 26

X
- Definition Number of properties sold. + References No definition available. + Details
Name: | bdn_NumberOfPropertiesSold
Namespace Prefix: | bdn_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration