Area Of Undeveloped Land

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Cash Distribtuions to Preferred Unitholders Per Unit

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- Definition

Common Stock Conversion Rate

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in lieu of a cash redemption OP unit to Common Stock conversion

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- Definition

Number Of Series Of Preferred Units Outstanding.

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- Definition

OP Unit Conversion Rate.

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Preferred Units Liquidation Preference

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Ratio of depository shares to shares of Series B Preferred Stock

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Restriction On Redemption Of OP Units From Date Of Issuance In Years

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Series Four Preferred Units

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Series Four Preferred Units Annual Dividend Payable Rate

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- Definition

Square Feet For Parking

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Vehicles In Structured Parking

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- Definition

Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 272

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

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- Definition

Net rentable area for properties owned.

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- Definition

The number of real estate properties owned as of the balance sheet date.

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The percentage rate used to calculate dividend payments on preferred stock.

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

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-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29

-Article 5

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Organization (Details) (USD $)	3 Months Ended	12 Months Ended
Organization (Details) (USD $)	Mar. 31, 2015 sqft Vehicles acre Y	Dec. 31, 2014	Jul. 03, 2014
Real Estate Properties [Line Items]
General and limited partnership interest in the operating partnership (percent)	89.50%	89.50%
Restriction on redemption of OP units from date of issuance (years)	1
in lieu of a cash redemption OP unit to Common Stock conversion (in shares)	1
One OP unit is equivalent to one share of Common Stock (in shares)	1bxp_CommonStockConversionRate
OP unit conversion rate (in shares)	1bxp_OpUnitConversionRate
Number Of Series Of Preferred Units Outstanding	2
Number of vehicles in structured parking	43,341bxp_VehiclesInStructuredParking
Area of parking (in square feet)	14,700,000bxp_SquareFeetForParking
Area of undeveloped land parcels owned (in acres)	483.1bxp_AreaOfUndevelopedLand
Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	168
Net Rentable Area (in sf)	45,500,000
Total Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	10
Net Rentable Area (in sf)	3,300,000
Total Office Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	160
Class A Office Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	129
Office Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	9
Office Technical Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	31
Hotel Property [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	1
Retail Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	5
Retail Properties Under Construction [Member]
Real Estate Properties [Line Items]
Number of real estate properties	1
Residential Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	2
Series B Cumulative Redeemable Preferred Stock [Member]
Real Estate Properties [Line Items]
Ratio of depository shares to shares of Series B Preferred Stock	0.01
Series B, Shares Outstanding (in shares)	80,000	80,000
Series B, Dividend Rate, Percentage	5.25%
Depository shares of Series B Cumulative Redeemable Preferred [Member]
Real Estate Properties [Line Items]
Series B, Shares Outstanding (in shares)	8,000,000
Series B Preferred Units [Member]
Real Estate Properties [Line Items]
Series B, Shares Outstanding (in shares)	80,000
Noncontrolling Interests [Member]
Real Estate Properties [Line Items]
Series Four Preferred Units (in shares)	12,667
Noncontrolling Interests [Member] \| Series Four Preferred Units [Member]
Real Estate Properties [Line Items]
Series Four Preferred Units (in shares)	12,667		12,667
Preferred Units Liquidation Preference	50.00
Quarterly Distributions to Series Four Preferred Units	0.25
Series Four Preferred Units Annual Dividend Payable Rate	2.00%