Aggregate purchase price

No definition available.

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Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Contractual Sales Price

+ References

No definition available.

+ Details

Name:	bxp_ContractualSalesPrice
Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Deferred purchase price

+ References

No definition available.

+ Details

Name:	bxp_Deferredpurchaseprice
Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Net Contractual Sales Price

+ References

No definition available.

+ Details

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Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of apartment units

+ References

No definition available.

+ Details

Name:	bxp_Numberofapartmentunits
Namespace Prefix:	bxp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Square Footage Of Signed Lease.

+ References

No definition available.

+ Details

Name:	bxp_SquareFootageOfSignedLease
Namespace Prefix:	bxp_
Data Type:	xbrli:positiveIntegerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of operating income (loss) attributable to disposal group, including, but not limited to, discontinued operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 974
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-15.(a)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=6875705&loc=d3e641549-123027

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Net rentable area for properties owned.

+ References

No definition available.

+ Details

Name:	us-gaap_NetRentableArea
Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- 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=98514028&loc=d3e3179-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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- Details

Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=bxp_SeventeenFiftyPresidentsStreetMember
Namespace Prefix:
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- Details

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- Details

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- Details

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- Details

Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=bxp_ThreeFourThreeMadisonAvenueMember
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- Details

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- Details

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Real Estate Narrative (Details) $ in Thousands						3 Months Ended			5 Months Ended	9 Months Ended
Real Estate Narrative (Details) $ in Thousands	Sep. 27, 2018 USD ($) ft²	May 24, 2018 USD ($) ft²	Feb. 23, 2018 ft² Buildings	Jan. 09, 2018 USD ($) ft²	Jan. 08, 2018 USD ($)	Sep. 30, 2018 USD ($) ft²	Sep. 26, 2018 USD ($)	Sep. 30, 2017 USD ($)	May 23, 2018 USD ($)	Sep. 30, 2018 USD ($) ft²	Sep. 26, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 01, 2018 ft² apartments	Aug. 30, 2018 USD ($) ft²	Aug. 07, 2018 ft²	Jun. 07, 2018 ft² apartments	Jan. 24, 2018 ft²
Real Estate [Line Items]
Proceeds from sales of real estate										$ 175,577		$ 29,810
Gains on sales of real estate						$ 7,863		$ 2,891		122,552		6,791
Boston Properties Limited Partnership
Real Estate [Line Items]
Proceeds from sales of real estate										175,577		29,810
Gains on sales of real estate						$ 9,154		2,891		$ 126,831		7,368
17Fifty Presidents Street [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²																	276,000
Signature at Reston [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²																518,000
Number of apartment units \| apartments																508
Reston Gateway [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²			1,100,000.0
Square Footage Of Signed Lease \| ft²			850,000
Number of real estate properties \| Buildings			2
Proto Kendall Square [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²													167,000
Number of apartment units \| apartments													280
343 Madison Avenue [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²															850,000
Ownership Percentage by the Company															55.00%
500 E Street [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²				262,000
Net Contractual Sales Price				$ 118,600
Net income (loss)					$ 100			1,700				4,900
Proceeds from sales of real estate				116,100
Gains on sales of real estate				96,400
500 E Street [Member] \| Boston Properties Limited Partnership
Real Estate [Line Items]
Gains on sales of real estate				$ 98,900
91 Hartwell Avenue [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²		119,000
Gross Sale Price		$ 22,200
Net income (loss)								100	$ 300			400
Proceeds from sales of real estate		21,700
Gains on sales of real estate		15,500
91 Hartwell Avenue [Member] \| Boston Properties Limited Partnership
Real Estate [Line Items]
Gains on sales of real estate		$ 15,900
1333 New Hampshire Avenue [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²														316,000
Gross Sale Price														$ 136,500
Quorum Office Park [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²	268,000
Gross Sale Price	$ 35,300
Net income (loss)							$ 200	$ 300			$ 700	$ 700
Proceeds from sales of real estate	34,300
Gains on sales of real estate	7,900
Quorum Office Park [Member] \| Boston Properties Limited Partnership
Real Estate [Line Items]
Gains on sales of real estate	$ 9,200
Carnegie Center purchase option [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²						1,700,000.0				1,700,000.0
Aggregate purchase price						$ 42,400				$ 42,400
Deferred purchase price						$ 9,200				$ 9,200