v2.4.0.6

Segment Information (Schedule Of Segment Reporting By Geographic Area And Property Type) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 450,562	$ 413,718
Rental Revenue: Office/Technical	9,847	10,533
Rental Revenue: Residential	5,578	4,481
Rental Revenue: Hotel	8,291	6,816
Rental Revenue: Total	474,278	435,548
Rental Revenue: % of Grand Totals	100.00%	100.00%
Rental Expenses: Class A Office	167,061	150,351
Rental Expenses: Office/Technical	2,826	2,776
Rental Expenses: Residential	2,733	2,715
Rental Expenses: Hotel	7,044	6,099
Rental Expenses: Total	179,664	161,941
Rental Expenses: % Of Grand Totals	100.00%	100.00%
Net operating Income	294,614	273,607
Net operating Income: % of Grand Totals	100.00%	100.00%
Boston [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	161,503	140,217
Rental Revenue: Office/Technical	5,653	6,389
Rental Revenue: Residential	1,067	883
Rental Revenue: Hotel	8,291	6,816
Rental Revenue: Total	176,514	154,305
Rental Revenue: % of Grand Totals	37.22%	35.43%
Rental Expenses: Class A Office	65,732	57,636
Rental Expenses: Office/Technical	1,787	1,705
Rental Expenses: Residential	443	390
Rental Expenses: Hotel	7,044	6,099
Rental Expenses: Total	75,006	65,830
Rental Expenses: % Of Grand Totals	41.75%	40.65%
Net operating Income	101,508	88,475
Net operating Income: % of Grand Totals	34.45%	32.34%
New York [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	122,096	117,589
Rental Revenue: Office/Technical	0	0
Rental Revenue: Residential	0	0
Rental Revenue: Hotel	0	0
Rental Revenue: Total	122,096	117,589
Rental Revenue: % of Grand Totals	25.74%	27.00%
Rental Expenses: Class A Office	41,887	38,429
Rental Expenses: Office/Technical	0	0
Rental Expenses: Residential	0	0
Rental Expenses: Hotel	0	0
Rental Expenses: Total	41,887	38,429
Rental Expenses: % Of Grand Totals	23.31%	23.73%
Net operating Income	80,209	79,160
Net operating Income: % of Grand Totals	27.23%	28.93%
Princeton [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	16,427	14,850
Rental Revenue: Office/Technical	0	0
Rental Revenue: Residential	0	0
Rental Revenue: Hotel	0	0
Rental Revenue: Total	16,427	14,850
Rental Revenue: % of Grand Totals	3.46%	3.41%
Rental Expenses: Class A Office	7,647	7,358
Rental Expenses: Office/Technical	0	0
Rental Expenses: Residential	0	0
Rental Expenses: Hotel	0	0
Rental Expenses: Total	7,647	7,358
Rental Expenses: % Of Grand Totals	4.26%	4.54%
Net operating Income	8,780	7,492
Net operating Income: % of Grand Totals	2.98%	2.74%
San Francisco [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	52,671	50,664
Rental Revenue: Office/Technical	151	52
Rental Revenue: Residential	0	0
Rental Revenue: Hotel	0	0
Rental Revenue: Total	52,822	50,716
Rental Revenue: % of Grand Totals	11.14%	11.64%
Rental Expenses: Class A Office	19,872	19,486
Rental Expenses: Office/Technical	35	24
Rental Expenses: Residential	0	0
Rental Expenses: Hotel	0	0
Rental Expenses: Total	19,907	19,510
Rental Expenses: % Of Grand Totals	11.08%	12.05%
Net operating Income	32,915	31,206
Net operating Income: % of Grand Totals	11.17%	11.40%
Washington, DC [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	97,865	90,398
Rental Revenue: Office/Technical	4,043	4,092
Rental Revenue: Residential	4,511	3,598
Rental Revenue: Hotel	0	0
Rental Revenue: Total	106,419	98,088
Rental Revenue: % of Grand Totals	22.44%	22.52%
Rental Expenses: Class A Office	31,923	27,442
Rental Expenses: Office/Technical	1,004	1,047
Rental Expenses: Residential	2,290	2,325
Rental Expenses: Hotel	0	0
Rental Expenses: Total	35,217	30,814
Rental Expenses: % Of Grand Totals	19.60%	19.03%
Net operating Income	$ 71,202	$ 67,274
Net operating Income: % of Grand Totals	24.17%	24.59%

X

- Definition

Operating Income Loss From Reportable Segments

+ References

No definition available.

+ Details

Name:	bxp_OperatingIncomeLossFromReportableSegments
Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Percentage Of Total Net Operating Income

+ References

No definition available.

+ Details

Name:	bxp_PercentageOfTotalNetOperatingIncome
Namespace Prefix:	bxp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Percentage Of Total Rental Expenses.

+ References

No definition available.

+ Details

Name:	bxp_PercentageOfTotalRentalExpenses
Namespace Prefix:	bxp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

These are percentages not monetary value

+ References

No definition available.

+ Details

Name:	bxp_PercentageOfTotalRevenue
Namespace Prefix:	bxp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Rental Expenses Class Office

+ References

No definition available.

+ Details

Name:	bxp_RentalExpensesClassOffice
Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Rental Expenses Office Technical

+ References

No definition available.

+ Details

Name:	bxp_RentalExpensesOfficeTechnical
Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Rental Expenses Operating Expenses Total.

+ References

No definition available.

+ Details

Name:	bxp_RentalExpensesOperatingExpensesTotal
Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Rental Expenses Residential.

+ References

No definition available.

+ Details

Name:	bxp_RentalExpensesResidential
Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Rental Revenue Class A Office

+ References

No definition available.

+ Details

Name:	bxp_RentalRevenueClassOffice
Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Rental Revenue Office Technical

+ References

No definition available.

+ Details

Name:	bxp_RentalRevenueOfficeTechnical
Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Rental Revenue Residential.

+ References

No definition available.

+ Details

Name:	bxp_RentalRevenueResidential
Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

The aggregate direct costs incurred in operating leased, owned and other hotels.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 2

-Article 5



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.2(d))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

+ Details

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

X

- Definition

Amount, net of promotional allowances, of revenue from managing and operating hotels, including, but not limited to, revenue from occupancy, casino, food and beverage, and retail. Excludes operating lease income.

+ 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(d))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688



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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

+ Details

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

X

- Details

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

X

- Definition

Amount of total revenue for the reportable segments, including revenue from external customers, transactions with other operating segments of the same entity, and (gross) interest revenue. All considered to be "operating revenue" for purposes of the taxonomy.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 22

-Subparagraph (a),(b),(c)

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8736-108599



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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 27

-Subparagraph a, b, c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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