Fair Value of Financial Instruments (Details Textuals)	Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Weighted Average Fair Value Interest Rate on Debt	4.534%

Weighted Average Fair Value Interest Rate on Debt Unobservable Input Fair Value Intererest Rates

No definition available.

Name:	bdn_WeightedAverageFairValueInterestRateOnDebt
Namespace Prefix:	bdn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant