Repurchase program number of common unit retired for each common share repurchased.

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK).

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The per share amount of a dividend declared, but not paid, as of the financial reporting date.

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Amount of paid and unpaid preferred stock dividends declared with the form of settlement in cash.

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The excess of (1) fair value of the consideration transferred to the holders of the preferred stock over (2) the carrying amount of the preferred stock in the registrant's balance sheet, during the accounting period.

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The price per share at which the preferred stock of an entity that has priority over common stock in the distribution of dividends and in the event of liquidation of the entity is redeemed or may be called at. The redemption features of this preferred stock are solely within the control of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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The cash inflow from the additional capital contribution to the entity.

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Per share or per unit amount of equity securities issued.

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Number of new stock issued during the period.

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Number of stock bought back by the entity at the exercise price or redemption price.

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Amount of stock repurchase plan authorized.

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Number of shares that have been repurchased and retired during the period.

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Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

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Total cost of shares repurchased divided by the total number of shares repurchased.

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BENEFICIARIES' EQUITY OF THE PARENT COMPANY - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Dec. 11, 2019	Apr. 11, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 03, 2019	Jan. 10, 2017
Class of Stock [Line Items]
Dividends, common stock	$ 33,800
Preferred shares authorized (in shares)			20,000,000
Preferred shares outstanding (in shares)			0
Preferred share redemption charge			$ 0	$ 0	$ 3,181
Repurchased and retired (in shares)			1,337,169	1,729,278	0
Share price (in usd per share)			$ 12.92	$ 12.64
Repurchased and retired, value			$ 17,281	$ 21,858
Common stock, par or stated value per share (usd per share)			$ 0.01	$ 0.01
Common Stock, Shares Authorized (in shares)			400,000,000	400,000,000
Cash proceeds, net of issuance costs			$ 0	$ 416	$ 51,225
Offering Program
Class of Stock [Line Items]
Common Stock, Shares Authorized (in shares)							16,000,000
Common shares issued under offering program (in shares)			0	23,311	2,858,991
Weighted average price per share (usd per share)				$ 18.04	$ 18.19
Cash proceeds, net of issuance costs				$ 400	$ 51,200
Common shares remain available for issuance (in shares)			13,117,698
Maximum
Class of Stock [Line Items]
Authorized amount						$ 150,000
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Class of Stock [Line Items]
Dividends, common stock	$ 33,800
Preferred share redemption charge			$ 0	0	3,181
Repurchase program, number of common units retired for each common share repurchased (in units)			1
Cash proceeds, net of issuance costs			$ 0	$ 416	$ 51,225
BRANDYWINE OPERATING PARTNERSHIP, L.P. \| Series E Preferred Stock
Class of Stock [Line Items]
Redemption outstanding shares (in shares)		4,000,000
Redemption price per share (in usd per share)		$ 25.51
Accrued dividends paid in cash		$ 2,000
Preferred share redemption charge		$ 3,200
Dividend Declared
Class of Stock [Line Items]
Dividends payable, amount per share (in usd per share)	$ 0.19
Dividend Declared \| BRANDYWINE OPERATING PARTNERSHIP, L.P.
Class of Stock [Line Items]
Dividends payable, amount per share (in usd per share)	$ 0.19
Redeemable Common Limited Partnership Units
Class of Stock [Line Items]
Antidilutive securities excluded from computation of earnings per share (in units)			981,634	982,871	1,479,799