Line of Credit Facility, Accordion Feature, Increase Limit

No definition available.

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Balance Type:	credit
Period Type:	instant

- Definition

Line of Credit Facility, Covenant, Maximum Leverage Ratio

+ References

No definition available.

+ Details

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- Definition

Line of Credit Facility, Covenant, Maximum Percent of Payments of Dividends and Distributions

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Line of Credit Facility, Covenant, Maximum Secured Indebtedness to Total Asset Value Ratio

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of Credit Facility, Covenant, Maximum Unsecured Indebtedness to Unencumbered Asset Value Ratio

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Line of Credit Facility, Covenant, Minimum Fixed Charge Coverage Ratio

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
Balance Type:	na
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- Definition

Line of Credit Facility, Covenant, Minimum Unencumbered Cash Flow to Interest Expense on Unsecured Debt Ratio

+ References

No definition available.

+ Details

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Namespace Prefix:	bdn_
Data Type:	xbrli:pureItemType
Balance Type:	na
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- Definition

Maximum Debt Instrument, Basis Spread on Variable Rate

+ References

No definition available.

+ Details

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Namespace Prefix:	bdn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

When presenting a range of interest rates, the highest effective rate for funds borrowed under the debt agreement as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

When presenting a range of interest rates, the lowest effective rate for funds borrowed under the debt agreement as of the balance sheet date.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

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Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Debt Obligations (Details)		3 Months Ended	6 Months Ended
Debt Obligations (Details)	May. 15, 2015 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)
Secured Debt [Member]
Debt Instrument [Line Items]
Mortgage debt principal payment		$ 3,600,000	$ 7,200,000
New Credit Facility [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt term	4 years
Maximum borrowing capacity	$ 600,000,000
Increase in limit	$ 400,000,000
Effective percentage rate, minimum	0.00%
Effective percentage rate, maximum	0.55%
Commitment fee percentage	0.25%
Minimum fixed charge coverage ratio	1.5
Maximum leverage ratio	0.60
Maximum unsecured indebtedness to unencumbered asset value ratio	0.60
Maximum secured indebtedness to total asset value ratio	0.40
Minimum unencumbered cash flow to interest expense on unsecured debt ratio	1.75
Maximum percent of payments of dividends and distributions	95.00%
New Credit Facility [Member] \| Revolving Credit Facility [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Commitment fee percentage	0.125%
New Credit Facility [Member] \| Revolving Credit Facility [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Commitment fee percentage	0.30%
New Credit Facility [Member] \| Revolving Credit Facility [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Basis spread on variable rate	1.20%
New Credit Facility [Member] \| Revolving Credit Facility [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	0.875%
New Credit Facility [Member] \| Revolving Credit Facility [Member] \| LIBOR [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.55%
New Credit Facility [Member] \| Revolving Credit Facility [Member] \| Federal Funds Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
New Credit Facility [Member] \| Letter of Credit [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 65,000,000
New Credit Facility [Member] \| Swing-Loans [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 60,000,000