Debt instrument prepayment penalty.

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- Definition

Gross proceeds from sale of property plant and equipment.

+ References

No definition available.

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- Definition

Net gain (loss) on real estate venture transactions including real estate venture formation.

+ References

No definition available.

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- Definition

Number of office properties owned.

+ References

No definition available.

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- Definition

The number of real estate properties sold during the period.

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- Definition

Expected hold period for assets held for use, used as an input to measure fair value

+ References

No definition available.

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- Definition

Amount of lien or mortgage outstanding on real estate investment properties for entities with a substantial portion of business acquiring and holding investment real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Paragraph Column B
-Subsection 28

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-28(Column B))
-URI http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024

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- Definition

Value of input used to measure debt instrument, including, but not limited to, convertible and non-convertible debt.

+ 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)
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- Definition

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

+ References

No definition available.

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- Definition

This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment.

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- 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).

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
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- Definition

Net rentable area for properties owned.

+ References

No definition available.

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- Definition

The cash inflow associated with the sale of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ References

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- 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.

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No definition available.

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INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Brandywine - AI Venture (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) property	Dec. 31, 2019 USD ($) ft²	Dec. 31, 2018 USD ($) ft² property
Schedule of Equity Method Investments [Line Items]
Impairment of properties held for use	$ 0	$ 0
Outstanding indebtedness	1,830,595,000	2,144,418,000
Net gain on real estate venture transactions	75,000	11,639,000	$ 142,233,000
Proceeds from real estate venture sales	$ 0	9,730,000	60,346,000
Fairview Properties
Schedule of Equity Method Investments [Line Items]
Other-than-temporary impairment			$ 4,100,000
Fairview Properties \| Brandywine - AI Venture LLC
Schedule of Equity Method Investments [Line Items]
Number of office properties owned \| property	1		2
Impairment of properties held for use		$ 5,600,000	$ 20,800,000
Impairment hold period			10 years
Falls Church, Virginia \| Brandywine - AI Venture LLC
Schedule of Equity Method Investments [Line Items]
Rentable square feet \| ft²		180,659
Outstanding indebtedness		$ 26,000,000.0
Net gain on real estate venture transactions		2,200,000
Station Square \| Brandywine - AI Venture LLC
Schedule of Equity Method Investments [Line Items]
Rentable square feet \| ft²			510,202
Net gain on real estate venture transactions			$ 1,500,000
Number of properties sold \| property			3
Gross sales price			$ 107,000,000.0
Encumbrances			66,500,000
Debt prepayment penalty			700,000
Gross proceeds from sale			34,800,000
Proceeds from real estate venture sales			$ 17,400,000
Residual Capitalization Rates \| Fairview Properties \| Brandywine - AI Venture LLC
Schedule of Equity Method Investments [Line Items]
Measurement input			0.080
Minimum \| Discount Rates \| Fairview Properties \| Brandywine - AI Venture LLC
Schedule of Equity Method Investments [Line Items]
Measurement input			0.090
Maximum \| Discount Rates \| Fairview Properties \| Brandywine - AI Venture LLC
Schedule of Equity Method Investments [Line Items]
Measurement input			0.095
Brandywine Realty Trust \| Fairview Properties \| Brandywine - AI Venture LLC
Schedule of Equity Method Investments [Line Items]
Impairment of properties held for use		$ 2,800,000	$ 10,400,000