Aggregate purchase price

No definition available.

Name:	bxp_Aggregatepurchaseprice
Namespace Prefix:	bxp_
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Balance Type:	debit
Period Type:	instant

- Definition

Development and management services revenue.

+ References

No definition available.

+ Details

Name:	bxp_DevelopmentAndManagementServices
Namespace Prefix:	bxp_
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Balance Type:	credit
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- Definition

Difference between net cash proceeds received and noncontrolling interest recognized

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of gain (loss), not previously recognized, resulting from the forgiveness of debt pertaining to a real estate property.

+ References

No definition available.

+ Details

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- Definition

Amount classified as secured debt attributable to disposal group held for sale or disposed of.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Gain on Consolidation of Joint Ventures

+ References

No definition available.

+ Details

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- Definition

Ground lease revenue

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Ground lease term (Years)

+ References

No definition available.

+ Details

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- Definition

Net Contractual Sales Price

+ References

No definition available.

+ Details

Name:	bxp_NetContractualSalesPrice
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Non-refundable option payment

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of apartment units

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of floors real estate

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of Joint Venture Partners

+ References

No definition available.

+ Details

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- Definition

ownership interest sold (percent)

+ References

No definition available.

+ Details

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- Definition

Partners Joint Venture Ownership Percentage

+ References

No definition available.

+ Details

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- Definition

Portion allocation to noncontrolling interest based on 45% of the carrying value of the total equity of the property prior to the sale

+ References

No definition available.

+ Details

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- Definition

Proceeds from sale of an interest in a real estate asset

+ References

No definition available.

+ Details

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- Definition

Proceeds from the sale of a condominium interest in real estate

+ References

No definition available.

+ Details

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- Definition

Purchase option date (lease year)

+ References

No definition available.

+ Details

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- Definition

Purchase Option Price for Real Estate Property

+ References

No definition available.

+ Details

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- Definition

Rental revenue supoprt payments to buyer maximum

+ References

No definition available.

+ Details

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- Definition

Sale Price Of Sold Property

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Square Footage Of Signed Lease.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Area of land held.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=8077374&loc=d3e2420-110228

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- Definition

Amount of difference between the carrying amount and the sales price of real estate properties sold as part of discontinued operations.

+ References

No definition available.

+ Details

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- Definition

This element represents the amount of gain (loss) on sale of properties during the reporting period net of the applicable income taxes realized.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 15

-Paragraph a

-Subparagraph 1(ii)

-Article 3

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 974

-SubTopic 10

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-Paragraph 1

-Subparagraph (SX 210.3-15.(a)(1)(ii))

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- Definition

The aggregate amount of write-downs for impairments recognized during the period for long-lived assets held for abandonment, exchange or sale.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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-SubTopic 10

-Section 45

-Paragraph 15

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- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

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- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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- Definition

Net rentable area for properties owned.

+ References

No definition available.

+ Details

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- Definition

Amount of increase in noncontrolling interest from sale of a portion of the parent's controlling interest.

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

No definition available.

+ Details

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- Definition

The cash outflow from the acquisition of a piece of land and anything permanently fixed to it, including buildings, structures on it and so forth, and payments to develop real estate assets by adding improvements on or to a parcel of land. Such improvements may include drainage, utilities, subdividing, access, buildings, and any combination of these elements. Including real estate intended to generate income for the owner; excluding real estate acquired for use by the owner.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585

+ Details

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- Definition

Cash received from the sale of real estate that is held for investment, that is, it is part of an investing activity during the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

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- Details

Name:	us-gaap_RealEstatePropertiesLineItems
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- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

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Real Estate (Narrative) (Details) (USD $)	3 Months Ended								12 Months Ended			0 Months Ended	9 Months Ended	0 Months Ended	7 Months Ended	0 Months Ended				9 Months Ended	0 Months Ended
Real Estate (Narrative) (Details) (USD $)	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	Apr. 10, 2013 Buildings sqft	Dec. 31, 2013	May 31, 2013 partners sqft	Dec. 31, 2013	Jul. 29, 2014	Aug. 20, 2014	Aug. 22, 2014	Oct. 02, 2014	Oct. 03, 2014	Oct. 24, 2014	Dec. 30, 2014	May 23, 2011 Y sqft	Apr. 10, 2014 floor sqft	Oct. 30, 2014	Nov. 06, 2014	Nov. 12, 2014 sqft	Oct. 22, 2014 sqft	Aug. 31, 2014 sqft	Sep. 17, 2014 sqft	May 20, 2014 sqft	Apr. 01, 2014 sqft	Feb. 10, 2014 sqft apartments	Nov. 01, 2014 sqft	Apr. 03, 2014 sqft	Oct. 09, 2013 sqft	Feb. 07, 2014	Feb. 26, 2013
Real Estate Properties [Line Items]
Gains on consolidation of joint ventures									$ 0bxp_GainonConsolidationofJointVentures	$ 385,991,000bxp_GainonConsolidationofJointVentures	$ 0bxp_GainonConsolidationofJointVentures
Payments to Acquire and Develop Real Estate									405,942,000	396,835,000	356,397,000
Revenues contributed by acquisitions	613,707,000us-gaap_Revenues	618,803,000us-gaap_Revenues	589,794,000us-gaap_Revenues	574,694,000us-gaap_Revenues	576,199,000us-gaap_Revenues	571,481,000us-gaap_Revenues	510,033,000us-gaap_Revenues	477,826,000us-gaap_Revenues	2,396,998,000us-gaap_Revenues	2,135,539,000us-gaap_Revenues	1,847,186,000us-gaap_Revenues
Earnings									801,822,000us-gaap_OperatingIncomeLoss	678,120,000us-gaap_OperatingIncomeLoss	640,321,000us-gaap_OperatingIncomeLoss
Gain on forgiveness of debt from discontinued operations									0	20,182,000	0
Proceeds from sales of real estate									419,864,000	250,078,000	61,963,000
Gains on sales of real estate									168,039,000	0	0
Gains on sales of real estate from discontinued operations									0	112,829,000	36,877,000
Impairment loss from discontinued operations									0	3,241,000	0
Impairment loss									0us-gaap_AssetImpairmentCharges	8,306,000us-gaap_AssetImpairmentCharges	0us-gaap_AssetImpairmentCharges
Development and management services									25,316,000bxp_DevelopmentAndManagementServices	29,695,000bxp_DevelopmentAndManagementServices	34,060,000bxp_DevelopmentAndManagementServices
Mountain View Research And Technology Parks [Member]
Real Estate Properties [Line Items]
Gains on consolidation of joint ventures												26,500,000
Revenues contributed by acquisitions													16,700,000
Earnings													400,000
Number of real estate properties												16
Net Rentable Area												604,000
Aggregate purchase price												233,084,000
767 5th Avenue (The General Motors Building) [Member]
Real Estate Properties [Line Items]
Gains on consolidation of joint ventures														359,500,000
Revenues contributed by acquisitions															168,400,000
Earnings															8,400,000
Net Rentable Area														1,800,000
Number of Joint Venture Partners														2
767 5th Avenue (The General Motors Building) [Member] \| Consolidated Properties [Member]
Real Estate Properties [Line Items]
Partners Joint Venture Ownership Percentage														40.00%
Four Two Five Fourth Street [Member]
Real Estate Properties [Line Items]
Non-refundable option payment																										1,000,000
804 carnegie center [Member]
Real Estate Properties [Line Items]
Aggregate purchase price																											3,700,000
Area of Real Estate Property																											130,000
Mountain View Technology Park and Mountain View Research Building Sixteen [Member]
Real Estate Properties [Line Items]
Proceeds from sales of real estate																90,600,000
Gains on sales of real estate																35,900,000
Sale Price Of Sold Property																92,100,000
Land at One Reston Overlook [Member]
Real Estate Properties [Line Items]
Proceeds from sales of real estate																	2,600,000
Gains on sales of real estate																	1,200,000
Land Parcel Within Broad Run Business Park [Member]
Real Estate Properties [Line Items]
Proceeds from sales of real estate																		9,700,000
Gains on sales of real estate																		4,300,000
Area of Land																		15.5
Sale Price Of Sold Property																		9,800,000
Patriots park [Member]
Real Estate Properties [Line Items]
Earnings										10,800,000	5,300,000									8,200,000
Proceeds from sales of real estate																			319,100,000
Gains on sales of real estate																			84,600,000
Rental revenue supoprt payments to buyer maximum																			12,300,000
Number of real estate properties																			3
Sale Price Of Sold Property																			321,000,000
Area of Real Estate Property																			706,000
415 Main Street (formerly Seven Cambridge Center) [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																												231,000
130 Third Avenue [Member]
Real Estate Properties [Line Items]
Proceeds from sales of real estate																					13,600,000
Gains on sales of real estate																					8,300,000
Sale Price Of Sold Property																					14,300,000
Area of Real Estate Property																					129,000
75 Ames Street [Member]
Real Estate Properties [Line Items]
Ground lease term (Years)																							99
Gains on sales of real estate																						33,800,000
Area of Real Estate Property																							250,000
Proceeds from the sale of a condominium interest in real estate																							56,800,000
Development and management services																							11,400,000
Ground lease revenue																							459,000
Mountain View Research Building Sixteen [Member] \| Mountain View Technology Park and Mountain View Research Building Sixteen [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																63,000
Mountain View Technology [Member] \| Mountain View Technology Park and Mountain View Research Building Sixteen [Member]
Real Estate Properties [Line Items]
Number of real estate properties																7
Area of Real Estate Property																135,000
250 West 55th Street [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																													988,000
Six Eighty Folsom Street [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																														525,000
888 Boylston Street [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																															425,000
10 CityPoint [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																															245,000
99Third Avenue [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																																17,000
The Avant at Reston Town Center Residential [Member]
Real Estate Properties [Line Items]
Number of apartment units																																	359
Area of Real Estate Property																																	355,000
Salesforce Tower [Member] \| Consolidated Properties [Member]
Real Estate Properties [Line Items]
Number of floors in building																								61
Area of Real Estate Property																								1,400,000
Ownership Percentage by Parent																								95.00%
Square Footage Of Signed Lease																								714,000
535 Mission Street [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																																		307,000
415 Main Street (formerly Seven Cambridge Center) [Member]
Real Estate Properties [Line Items]
Purchase option date (lease year)																												11
Purchase Option Price for Real Estate Property																												106,000,000
690 Folsom Street [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																																			25,000
767 5th Avenue (The General Motors Building) [Member]
Real Estate Properties [Line Items]
Number of Joint Venture Partners														2
related to rental support payment [Member] \| Patriots park [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																			17,762
Noncontrolling Interests [Member] \| Consolidated Properties [Member]
Real Estate Properties [Line Items]
Net Rentable Area																																				1,246,000
Number of Joint Venture Partners														2
Noncontrolling Interests [Member] \| Time Square Tower [Member] \| Consolidated Properties [Member]
Real Estate Properties [Line Items]
Portion allocation to noncontrolling interest based on carrying value of the total equity of the property prior to the sale																																				243,500,000
ownership interest sold (percent)																																				45.00%
Net Contractual Sales Price																																				684,000,000
Proceeds from sale of an interest in a real estate asset																																				673,100,000
Difference between net cash proceeds received and noncontrolling interest recognized																																				429,600,000
Noncontrolling Interests [Member] \| 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street [Member] \| Consolidated Properties [Member]
Real Estate Properties [Line Items]
Disposal Group, Including Discontinued Operation, Secured Debt																									712,900,000
Ownership Percentage																									45.00%
Sale Price Of Sold Property																									1,827,000,000
Proceeds from sale of an interest in a real estate asset																									1,497,000,000
Difference between net cash proceeds received and noncontrolling interest recognized																									648,400,000
Noncontrolling Interest, Increase from Sale of Parent Equity Interest																									$ 849,000,000
Noncontrolling Interests [Member] \| Salesforce Tower [Member] \| Consolidated Properties [Member]
Real Estate Properties [Line Items]
Ownership Percentage																																					50.00%	5.00%
Ownership Percentage by Parent																																						95.00%
Noncontrolling Interests [Member] \| 601 Lexington Avenue [Member] \| 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street [Member] \| Consolidated Properties [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																									1,669,000
Noncontrolling Interests [Member] \| Atlantic Wharf Office [Member] \| 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street [Member] \| Consolidated Properties [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																									791,000
Noncontrolling Interests [Member] \| One Hundred Federal Street [Member] \| 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street [Member] \| Consolidated Properties [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property																									1,323,000
Noncontrolling Interests [Member] \| Low Rise [Member] \| 601 Lexington Avenue [Member] \| 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street [Member] \| Consolidated Properties [Member]
Real Estate Properties [Line Items]
Number of floors in building																									6
Noncontrolling Interests [Member] \| Office Tower [Member] \| 601 Lexington Avenue [Member] \| 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street [Member] \| Consolidated Properties [Member]
Real Estate Properties [Line Items]
Number of floors in building																									59