XML 122 R60.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Deferred Costs (Details) | 12 Months Ended
--- | ---
Dec. 31, 2019
Accounting Policies [Abstract] |
Remaining lease period - minimum | 1 year
Remaining lease period - maximum | 16 years

X
- Definition Remaining Lease Period - Maximum + References No definition available. + Details
Name: | bdn_RemainingLeasePeriodMaximum
Namespace Prefix: | bdn_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Remaining Lease Period - Minimum + References No definition available. + Details
Name: | bdn_RemainingLeasePeriodMinimum
Namespace Prefix: | bdn_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_AccountingPoliciesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration