XML 84 R63.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Fair Value of Financial Instruments (Details Textuals) (USD $) In Millions, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2011 Properties | Sep. 30, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Weighted Average Fair Value Interest Rate on Debt |  | 3.222%
Fair Value of Financial Instruments (Textuals) [Abstract] |  |
Gross deferred gain on sale of properties | $ 12.9 |
Number of properties sold (in properties) | 2 |

X
- Details
Name: | bdn_FairValueOfFinancialInstrumentsTextualsAbstract
Namespace Prefix: | bdn_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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
- Definition Weighted Average Fair Value Interest Rate on Debt Unobservable Input Fair Value Intererest Rates + References No definition available. + Details
Name: | bdn_WeightedAverageFairValueInterestRateOnDebt
Namespace Prefix: | bdn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of gain on the sale of property that does not qualify for gain recognition as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 40 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 5.U.Q2) -URI http://asc.fasb.org/extlink&oid=6955272&loc=d3e221323-122791 + Details
Name: | us-gaap_DeferredGainOnSaleOfProperty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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