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Income Loss from continuing operations available to common shareholders Basic.

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Income Loss from continuing operations available to common shareholders Diluted.

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Income Loss From Continuing Operations Including Portion Attributable To Non controlling Interest Diluted.

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Income Loss from Discontinued operations available to common shareholders Basic.

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Income Loss from Discontinued operations available to common shareholders Diluted

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Income (loss) from discontinued operations.

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Income Loss From Discontinued Operations Net Of Tax Attributable To Non controlling Interest Diluted.

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Noncontrolling Interest in Net Income (Loss) Joint Venture Partners, Redeemable, Diluted

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Noncontrolling Interest In Net Income Loss of Limited Partnerships, Redeemable Diluted

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Preferred stock dividends, Diluted.

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

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The amount of net income (loss) from continuing operations per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) derived from continuing operations during the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount of income (loss) from a disposal group, net of income tax before extraordinary items allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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This element represents the overall income (loss) from a disposal group that is classified as a component of the entity, net of income tax, reported as a separate component of income before extraordinary items, which is apportioned to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This item includes the following (net of tax): income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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Per basic share amount, after tax, of income (loss) from the day-to-day business activities of the discontinued operation and gain (loss) from the disposal of the discontinued operation.

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Per diluted share amount, after tax, of income (loss) from the day-to-day business activities of the discontinued operation and gain (loss) from the disposal of the discontinued operation.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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Net Income or Loss Available to Common Stockholders plus adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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Amount after tax of income (loss) attributable to redeemable noncontrolling shareholder, unit holder, partner, or other equity holder of a joint venture.

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Amount after tax of income (loss) attributable to redeemable noncontrolling partner of a limited partnership.

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The excess of the (1) fair value of consideration transferred to the holders of a security in excess of (2) the carrying amount of the security reported on the registrant's balance sheet, which will be deducted from net earnings to derive net earnings available to common shareholders. This amount is generally an adjustment considered in the computation of earnings per share.

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Amount of undistributed earnings (loss) allocated to participating securities for the basic earnings (loss) per share or per unit calculation under the two-class method.

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Amount of undistributed earnings (loss) allocated to participating securities for the diluted earnings (loss) per share or per unit calculation under the two-class method.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Beneficiaries Equity of The Parent Company (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Numerator
Income (loss) from continuing operations, Basic									$ 6,024	$ 38,982	$ (37,309)
Income (loss) from continuing operations, Diluted									6,024	38,982	(37,309)
Net loss attributable to non-controlling interests									44	0	0
Noncontrolling Interest in Net Income (Loss) Joint Venture Partners, Redeemable, Diluted									44	0	0
Net (income) loss attributable to non-controlling interests — LP units									(1)	(357)	863
Noncontrolling Interest In Net Income Loss of Limited Partnerships, Redeemable Diluted									(1)	(357)	863
Amount allocated to unvested restricted shareholders									(349)	(363)	(376)
Amount allocable to unvested restricted shareholders, Diluted									(349)	(363)	(376)
Preferred share/unit dividends, Basic									(6,900)us-gaap_DividendsPreferredStock	(6,900)us-gaap_DividendsPreferredStock	(10,405)us-gaap_DividendsPreferredStock
Preferred share/unit dividends, Diluted									(6,900)bdn_PreferredStockDividendsDiluted	(6,900)bdn_PreferredStockDividendsDiluted	(10,405)bdn_PreferredStockDividendsDiluted
Preferred share/unit redemption premium, basic									0us-gaap_RedemptionPremium	0us-gaap_RedemptionPremium	(4,052)us-gaap_RedemptionPremium
Preferred share/unit redemption Premium, Diluted									0bdn_RedemptionPremiumDiluted	0bdn_RedemptionPremiumDiluted	(4,052)bdn_RedemptionPremiumDiluted
Income Loss from continuing operations available to common shareholders/unitholders, Basic									(1,182)	31,362	(51,279)
Income Loss from continuing operations available to common shareholders Diluted									(1,182)	31,362	(51,279)
Discontinued operations attributable to common unitholders									918	4,207	43,838
Income (loss) from discontinued operations, Diluted									918	4,207	43,838
Discontinued operations attributable to non-controlling interests - LP units									(10)	(55)	(797)
Discontinued operations attributable to non-controlling interests, diluted									(10)	(55)	(797)
Discontinued operations attributable to common shareholders, Basic									908	4,152	43,041
Discontinued operations attributable to common shareholders, Diluted									908	4,152	43,041
Net income (loss) attributable to Common Shareholders/Unitholders									(274)	35,514	(8,238)
Net income (loss) available to common shareholders/unitholders, Diluted									$ (274)	$ 35,514	$ (8,238)
Denominator
Weighted-average shares/units outstanding, Basic									166,202,649	153,140,458	143,257,097
Contingent securities/Stock based compensation									0	1,273,853	0
Weighted-average shares/units outstanding, Diluted									166,202,649	154,414,311	143,257,097
Earnings per Common Share:
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Basic									$ (0.01)	$ 0.20	$ (0.36)
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Diluted									$ (0.01)	$ 0.20	$ (0.36)
Discontinued operations attributable to common shareholders/unitholders, Basic									$ 0.01	$ 0.03	$ 0.30
Discontinued operations attributable to common shareholders, Diluted									$ 0.01	$ 0.03	$ 0.30
Net income (loss) attributable to common shareholders/unitholders, Basic	$ (0.02)us-gaap_EarningsPerShareBasic	$ 0.04us-gaap_EarningsPerShareBasic	$ 0.00us-gaap_EarningsPerShareBasic	$ (0.03)us-gaap_EarningsPerShareBasic	$ 0.12us-gaap_EarningsPerShareBasic	$ 0.06us-gaap_EarningsPerShareBasic	$ 0.03us-gaap_EarningsPerShareBasic	$ 0.01us-gaap_EarningsPerShareBasic	$ 0.00us-gaap_EarningsPerShareBasic	$ 0.23us-gaap_EarningsPerShareBasic	$ (0.06)us-gaap_EarningsPerShareBasic
Net income (loss) attributable to common shareholders/unitholders, Diluted	$ (0.02)us-gaap_EarningsPerShareDiluted	$ 0.04us-gaap_EarningsPerShareDiluted	$ 0.00us-gaap_EarningsPerShareDiluted	$ (0.03)us-gaap_EarningsPerShareDiluted	$ 0.12us-gaap_EarningsPerShareDiluted	$ 0.06us-gaap_EarningsPerShareDiluted	$ 0.03us-gaap_EarningsPerShareDiluted	$ 0.01us-gaap_EarningsPerShareDiluted	$ 0.00us-gaap_EarningsPerShareDiluted	$ 0.23us-gaap_EarningsPerShareDiluted	$ (0.06)us-gaap_EarningsPerShareDiluted