Distributions (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Distributions [Abstract]
Common Share Distributions Payments of Ordinary Dividends	$ 0.41	$ 0.52	$ 0.39
Common Share Distributions Capital Gain	$ 0.02bdn_CommonShareDistributionsCapitalGain	$ 0.00bdn_CommonShareDistributionsCapitalGain	$ 0.00bdn_CommonShareDistributionsCapitalGain
Common Share Distributions Non-taxable Distributions	$ 0.17	$ 0.08	$ 0.21
Common Stock, Dividends, Per Share, Declared	$ 0.60	$ 0.60	$ 0.60
Percentage Of Distributions classified as ordinary income	69.00%	87.00%	65.00%
Percentage Of Distributions classified as capital gain	3.30%	0.00%	0.00%
Percentage Of Distributions classified as non-taxable distribution	27.70%	13.00%	35.00%
Dividends, Preferred Stock	$ 6,900us-gaap_DividendsPreferredStock	$ 6,900us-gaap_DividendsPreferredStock	$ 10,405us-gaap_DividendsPreferredStock
Percentage Of Preferred Distributions classified as ordinary income	100.00%	100.00%	100.00%

Common Share Distributions Capital Gain

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- Definition

Common Share Distributions Non-taxable Distributions

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- Definition

Common Share Distributions Payments of Ordinary Dividends

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Percentage Of Distributions classified as capital gain

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Percentage Of Distributions classified as non-taxable distribution

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Percentage Of Distributions classified as ordinary income

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Percentage Of Preferred Distributions classified as ordinary income

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- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

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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).

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 405

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817

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