XML 102 R80.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Real Estate Investments - Summary of Office Properties Sold (Parenthetical) (Details) |  |  | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Mar. 31, 2017 USD ($) property | Mar. 15, 2017 USD ($) ft² | Dec. 31, 2017 USD ($) ft² | Mar. 31, 2017 USD ($) property | Dec. 31, 2016 USD ($) | Jun. 30, 2016 USD ($) | Mar. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2018 USD ($) ft² property | Dec. 31, 2017 USD ($) ft² | Dec. 31, 2016 USD ($) | Dec. 31, 2016 | Dec. 31, 2016 property | Dec. 31, 2016 ft² | Dec. 31, 2016 Office
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Properties | property |  |  |  |  |  |  |  |  |  | 97 |  |  |  |  |  |
Aggregate carrying values of properties |  |  |  | $ 3,832,348,000 |  |  |  |  |  | $ 3,953,319,000 | $ 3,832,348,000 |  |  |  |  |
Provision for impairment |  |  |  |  |  |  | $ 1,800,000 |  |  | $ 71,707,000 | 3,057,000 | $ 40,517,000 |  |  |  |
Rentable Square Feet | ft² |  |  |  |  |  |  |  |  |  | 1,414,457 |  |  |  |  |  |
Sales Price |  |  |  |  |  |  |  |  |  | $ 359,300,000 |  |  |  |  |  |
Proceeds from the sale of properties |  |  |  |  |  |  |  |  |  | 324,090,000 | 171,860,000 | 784,331,000 |  |  |  |
Assets held for sale, net |  |  |  | $ 392,000 |  |  |  |  |  | 11,599,000 | 392,000 |  |  |  |  |
Gain/(Loss) on Sale |  |  |  |  |  |  |  |  |  | $ 2,932,000 | $ 31,657,000 | 116,983,000 |  |  |  |
Office Properties [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Properties | property |  |  |  |  |  |  |  |  |  | 88 |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,239,632 |
Sales Price |  |  |  |  |  | $ 820,000,000 |  |  |  |  |  | 820,000,000 |  |  |  |
Proceeds from the sale of properties |  |  |  |  |  |  |  |  |  |  |  | 769,799,000 |  |  |  |
Gain/(Loss) on Sale | [1] |  |  |  |  |  |  |  |  |  |  | 116,983,000 |  |  |  |
200, 210 & 220 Lake Drive East (Woodland Falls) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value of real estate prior to impairment |  |  |  |  |  | $ 25,800,000 |  |  |  |  |  | 25,800,000 |  |  |  |
Impairment Hold Period |  |  |  |  |  | 10 years |  |  |  |  |  |  |  |  |  |
Provision for impairment |  |  |  |  |  | $ 7,300,000 |  |  |  |  |  |  |  |  |  |
Aggregate carrying value |  |  |  |  |  | 18,500,000 |  |  |  |  |  | 18,500,000 |  |  |  |
200, 210 & 220 Lake Drive East (Woodland Falls) [Member] | Office Properties [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  | 215,465 |  |  |  |  |  |  | 215,465 |  |  |  |  |
Sales Price |  |  |  | $ 19,000,000 |  |  |  |  |  |  | $ 19,000,000 |  |  |  |  |
Proceeds from the sale of properties |  |  |  |  |  |  |  |  |  |  | 17,771,000 |  |  |  |  |
Gain/(Loss) on Sale | [1],[2] |  |  |  |  |  |  |  |  |  | $ (249,000) |  |  |  |  |
Philadelphia Marine Center (Marine Piers) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  | 181,900 | 181,900 |  |  |  |  |  |  | 181,900 |  |  |  |  |
Sales Price |  |  | $ 21,400,000 | $ 21,400,000 |  |  |  |  |  |  | $ 21,400,000 |  |  |  |  |
Payment by cash on purchases |  |  | 12,000,000.0 |  |  |  |  |  |  |  | 12,000,000.0 |  |  |  |  |
Balance payment on purchases |  |  | $ 9,400,000 | 9,400,000 |  |  |  |  |  |  | $ 9,400,000 |  |  |  |  |
Date of second installment payment |  |  | Jan. 31, 2020 |  |  |  |  |  |  |  | Jan. 31, 2020 |  |  |  |  |
Proceeds from the sale of properties |  |  | $ 11,200,000 |  |  |  |  |  |  |  | $ 11,200,000 |  |  |  |  |
Assets held for sale, net |  |  | 4,700,000 | 4,700,000 |  |  |  |  |  |  | 4,700,000 |  |  |  |  |
Gain/(Loss) on Sale |  |  | 6,500,000 |  |  |  |  |  |  |  | 6,500,000 |  |  |  |  |
Deferred gain on sale |  |  | $ 9,400,000 | $ 9,400,000 |  |  |  |  |  |  | $ 9,400,000 |  |  |  |  |
11700, 11710, 11720 & 11740 Beltsville Drive (Calverton) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Provision for impairment on assets held for sale |  |  |  |  | $ 1,700,000 | 3,000,000.0 |  |  |  |  |  |  |  |  |  |
Purchase price reduction |  |  |  |  | $ 1,700,000 |  |  |  |  |  |  |  |  |  |  |
11700, 11710, 11720 & 11740 Beltsville Drive (Calverton) [Member] | Office Properties [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  | 313,810 |  |  |  |  |  |  | 313,810 |  |  |  |  |
Sales Price |  |  |  | $ 9,000,000 |  |  |  |  |  |  | $ 9,000,000 |  |  |  |  |
Proceeds from the sale of properties |  |  |  |  |  |  |  |  |  |  | 8,354,000 |  |  |  |  |
Gain/(Loss) on Sale | [1],[3] |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |
1200 & 1220 Concord Avenue (Concord Airport Plaza) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Provision for impairment on assets held for sale |  |  |  |  |  |  |  |  |  |  | $ 32,000.0 |  |  |  |  |
Proceeds after closing costs and prorations |  |  |  |  |  | 11,500 |  |  |  |  |  |  |  |  |  |
1200 & 1220 Concord Avenue (Concord Airport Plaza) [Member] | Office Properties [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  | 350,256 |  |  |  |  |  |  | 350,256 |  |  |  |  |
Sales Price |  |  |  | $ 33,100,000 |  |  |  |  |  |  | $ 33,100,000 |  |  |  |  |
Proceeds from the sale of properties |  |  |  |  |  |  |  |  |  |  | 32,010,000 |  |  |  |  |
Gain/(Loss) on Sale | [1] |  |  |  |  |  |  |  |  |  | 551,000 |  |  |  |  |
196/198 Van Buren Street (Herndon Metro Plaza I&II) [Member] | Office Properties [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Impairment of properties held for use |  |  |  |  |  |  |  | $ 7,400,000 |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 197,225 |
Sales Price |  |  |  |  |  | 44,500,000 |  |  |  |  |  | 44,500,000 |  |  |  |
Proceeds from the sale of properties |  |  |  |  |  |  |  |  |  |  |  | 43,412,000 |  |  |  |
Gain/(Loss) on Sale | [1],[4] |  |  |  |  |  |  |  |  |  |  | (752,000) |  |  |  |
Och Ziff Portfolio [Member] | Office Properties [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,924,783 |
Sales Price |  |  |  |  |  | 398,100,000 |  |  |  |  |  | 398,100,000 |  |  |  |
Proceeds from the sale of properties |  |  |  |  |  |  |  |  |  |  |  | 353,971,000 |  |  |  |
Gain/(Loss) on Sale | [1],[5] |  |  |  |  |  |  |  |  |  |  | (372,000) |  |  |  |
Provision for impairment on assets held for sale |  |  |  |  |  |  |  |  | $ 45,400,000 |  |  |  |  |  |  |
Residual Capitalization Rates [Member] | 200, 210 & 220 Lake Drive East (Woodland Falls) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Measurement input for impairment on assets held for sale |  |  |  |  |  |  |  |  |  |  |  |  | 0.0875 |  |  |
Discount Rates [Member] | 200, 210 & 220 Lake Drive East (Woodland Falls) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Measurement input for impairment on assets held for sale |  |  |  |  |  |  |  |  |  |  |  |  | 0.0900 |  |  |
Other [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Properties |  | 4 |  |  | 4 |  |  |  |  | 1 |  |  |  | 3 |  | 2
Impairment of properties held for use |  | $ 1,000,000.0 |  |  |  |  |  |  |  | $ 14,800,000 |  | 7,300,000 |  |  |  |
Carrying value of real estate prior to impairment |  |  |  | 10,200,000 |  | 25,800,000 |  |  |  | $ 52,800,000 | 10,200,000 | $ 25,800,000 |  |  |  |
Impairment Hold Period |  | 10 years |  |  |  |  |  |  |  | 10 years |  | 10 years |  |  |  |
Provision for impairment |  |  |  | 0 |  |  |  |  |  |  |  |  |  |  |  |
Aggregate carrying value |  |  |  |  |  | $ 18,500,000 |  |  |  |  |  | $ 18,500,000 |  |  |  |
Other [Member] | 200, 210 & 220 Lake Drive East (Woodland Falls) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Properties | property |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 |  |
Other [Member] | Impairment on Held for Use Properties [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate carrying values of properties |  |  |  | $ 9,200,000 |  |  |  |  |  | $ 38,000,000 | $ 9,200,000 |  |  |  |  |
Other [Member] | Residual Capitalization Rates [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Measurement input for impairment on assets held for sale |  | 0.0900 |  |  | 0.0900 |  |  |  |  | 0.075 |  |  | 0.0875 |  |  |
Other [Member] | Discount Rates [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Measurement input for impairment on assets held for sale |  | 0.0925 |  |  | 0.0925 |  |  |  |  | 0.095 |  |  | 0.0900 |  |  |
[1] | Gain/(Loss) on Sale is net of closing and other transaction related costs.
[2] | As of December 31, 2016, the Company evaluated the recoverability of the carrying value of its properties that triggered assessment under the undiscounted cash flow model. Based on the Company’s evaluation, it was determined that due to the reduction in the Company’s intended hold period of three properties located in the Other segment, the Company would not recover the carrying values of these properties. Accordingly, the Company recorded impairment charges on these properties of $7.3 million at December 31, 2016, reducing the aggregate carrying values of the properties from $25.8 million to their estimated fair value of $18.5 million. The Company measured these impairments based on a discounted cash flow analysis, using a hold period of 10 years and residual capitalization rates and discount rates of 8.75% and 9.00%, respectively. The results were comparable to indicative pricing in the market. The assumptions used to determine fair value under the income approach are Level 3 inputs in accordance with the fair value hierarchy established by Accounting Standards Codification (ASC) Topic 820, “Fair Value Measurements and Disclosures.” The loss on sale in the table above represents additional closing costs.
[3] | During the fourth quarter of 2016, the Company recognized a $3.0 million impairment related to these properties. During the first quarter of 2017, there was a price reduction of $1.7 million under the agreement of sale and an additional impairment of $1.7 million was recognized.
[4] | During the three-month period ended March 31, 2016, the Company recognized a provision for impairment totaling approximately $7.4 million on the properties. See “Held for Use Impairment” section below. The loss on sale primarily relates to additional closing costs recognized at closing.
[5] | During the three-month period ended December 31, 2015, the Company recognized a provision for impairment totaling approximately $45.4 million. The loss on sale represents additional closing costs recognized at closing.

X
- Definition Carrying value of real estate prior to impairment. + References No definition available. + Details
Name: | bdn_CarryingValueOfRealEstatePriorToImpairment
Namespace Prefix: | bdn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Date of second installment payment. + References No definition available. + Details
Name: | bdn_DateOfSecondInstallmentPayment
Namespace Prefix: | bdn_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Purchase price reduction. + References No definition available. + Details
Name: | bdn_PurchasePriceReduction
Namespace Prefix: | bdn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Expected hold period for assets held for use, used as an input to measure fair value + References No definition available. + Details
Name: | bdn_RealEstatePropertiesImpairmentHoldPeriod
Namespace Prefix: | bdn_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Value of input used to measure alternative investment. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
Name: | us-gaap_AlternativeInvestmentMeasurementInput
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228 + Details
Name: | us-gaap_AssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount classified as assets attributable to disposal group held for sale or disposed of. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 45 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=109222160&loc=d3e1107-107759 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 5B -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721673-107760 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=109222160&loc=SL51721533-107759 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 5C -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721675-107760 + Details
Name: | us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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 No definition available. + Details
Name: | us-gaap_DeferredGainOnSaleOfProperty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation. + References No definition available. + Details
Name: | us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before tax of gain (loss) recognized on the sale or disposal of a disposal group. Excludes discontinued operations. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2443-110228 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230 + Details
Name: | us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount or range of possible amounts of gain that could be realized upon the resolution of a contingency. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 30 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6397426&loc=d3e17499-108355 + Details
Name: | us-gaap_GainContingencyUnrecordedAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2921-110230 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 958 -SubTopic 220 -Section 45 -Paragraph 11 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=114873921&loc=SL114875236-224282 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228 + Details
Name: | us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The aggregate amount of write-downs for impairments recognized during the period for long-lived assets held for abandonment, exchange or sale. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2611-110228 + Details
Name: | us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

X
- Definition Aggregate of the carrying amounts as of the balance sheet date of investments in building and building improvements. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(d)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_InvestmentBuildingAndBuildingImprovements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Net rentable area for properties owned. + References No definition available. + Details
Name: | us-gaap_NetRentableArea
Namespace Prefix: | us-gaap_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of real estate properties owned as of the balance sheet date. + References No definition available. + Details
Name: | us-gaap_NumberOfRealEstateProperties
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Cash inflow related to a property which is traded for the promise to provide a replacement like-kind property in the near future also known as a tax deferred exempt exchange. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromDelayedTaxExemptExchange
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This element represents the carrying value, net of accumulated deprecation, as of the date of the statement of financial position of a property sold during the reporting period, but which sale is accounted for under the deposit method and, therefore, which property continues to be included in the statement of financial position. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=99394158&loc=d3e6831-110236 + Details
Name: | us-gaap_RetailLandSalesDepositMethodPropertyCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=srt_OfficeBuildingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=bdn_A200210220LakeDriveEastWoodlandFallsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=bdn_PhiladelphiaMarineCenterMarinePiersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=bdn_A11700117101172011740BeltsvilleDriveCalvertonMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=bdn_A1200And1220ConcordAvenueInConcordMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=bdn_A196198VanBurenStreetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=bdn_OchZiffPortfolioMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputCapRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=us-gaap_AllOtherSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis=bdn_ImpairmentOnPropertiesHeldForUseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |