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Segment Information (Schedule Of Reconciliation Of Net Operating Income To Net Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company's common shareholders / unitholders	$ 511,034	$ 572,347		$ 451,939
Preferred dividends / distributions	(10,500)	(10,500)		(10,500)
Noncontrolling interest-common units of the Operating Partnership	(59,345)	(66,807)		(52,210)
Noncontrolling interest in property partnerships	(71,120)	(62,909)		(47,832)
Interest expense	(412,717)	(378,168)		(374,481)
Gains (losses) from early extinguishments of debt	29,540	16,490		(496)
Company's share of net operating income from joint ventures	(1,826,123)	(1,649,314)		(1,605,435)
Depreciation and amortization expense	(677,764)	(645,649)		(617,547)
Transaction costs	(1,984)	(1,604)		(668)
General and administrative expense	(140,777)	(121,722)		(113,715)
Gains (losses) from investments in securities	(6,417)	1,865		(3,678)
Interest and other income	(18,939)	(10,823)		(5,783)
Income from unconsolidated joint ventures	(46,592)	(2,222)		(11,232)
Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company's common shareholders / unitholders	511,034	572,347		451,939
Preferred dividends / distributions	10,500	10,500		10,500
Noncontrolling interest-common units of the Operating Partnership	59,345	66,807		52,210
Noncontrolling interest in property partnerships	71,120	62,909		47,832
Interest expense	412,717	378,168		374,481
Gains (losses) from early extinguishments of debt	29,540	16,490		(496)
Impairment losses	24,038	11,812		0
Depreciation and amortization expense	677,764	645,649		617,547
Transaction costs	1,984	1,604		668
Payroll and related costs from management services contracts	10,386	9,590		0
General and administrative expense	140,777	121,722		113,715
Gains (losses) from investments in securities	6,417	(1,865)		3,678
Interest and other income	18,939	10,823		5,783
Gains on sales of real estate	709	182,356		7,663
Income from unconsolidated joint ventures	46,592	2,222		11,232
Other revenue	10,386	9,590		0
Net Operating Income	1,739,850	1,551,842		1,495,198
Boston Properties Limited Partnership
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company's common shareholders / unitholders	580,102	656,903		512,866
Preferred dividends / distributions	(10,500)	(10,500)		(10,500)
Noncontrolling interest in property partnerships	(71,120)	(62,909)		(47,832)
Interest expense	(412,717)	(378,168)		(374,481)
Gains (losses) from early extinguishments of debt	29,540	16,490		(496)
Impairment losses				0
Depreciation and amortization expense	(669,956)	(637,891)
Transaction costs	(1,984)	(1,604)		(668)
General and administrative expense	(140,777)	(121,722)		(113,715)
Gains (losses) from investments in securities	(6,417)	1,865		(3,678)
Interest and other income	(18,939)	(10,823)		(5,783)
Income from unconsolidated joint ventures	(46,592)	(2,222)		(11,232)
Boston Properties Limited Partnership | Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company's common shareholders / unitholders	580,102	656,903		512,866
Preferred dividends / distributions	10,500	10,500		10,500
Noncontrolling interest in property partnerships	71,120	62,909		47,832
Interest expense	412,717	378,168		374,481
Gains (losses) from early extinguishments of debt	29,540	16,490		496
Impairment losses	22,272	10,181		0
Depreciation and amortization expense	669,956	637,891		609,407
Transaction costs	1,984	1,604		668
Payroll and related costs from management services contracts	10,386	9,590		0
General and administrative expense	140,777	121,722		113,715
Gains (losses) from investments in securities	6,417	(1,865)		3,678
Interest and other income	18,939	10,823		5,783
Gains on sales of real estate	858	190,716		8,240
Income from unconsolidated joint ventures	46,592	2,222		11,232
Other revenue	10,386	9,590		0
Net Operating Income	1,739,850	1,551,842		1,495,198
Unconsolidated Joint Ventures [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Interest expense	(84,409)	(71,308)		(46,371)
Company's share of net operating income from joint ventures	(97,716)	(79,893)		(64,008)
Depreciation and amortization expense	(102,296)	(103,079)	[1]	(57,079)
Transaction costs	(1,000)	0		0
Income from unconsolidated joint ventures	(46,592)	(2,222)		(11,232)
Unconsolidated Joint Ventures [Member] | Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	(97,716)	(79,893)		(64,008)
Unconsolidated Joint Ventures [Member] | Boston Properties Limited Partnership | Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	(97,716)	(79,893)		(64,008)
Management Service [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Payroll and related costs from management services contracts	(10,386)	(9,590)		0
Other revenue	(40,039)	(45,158)		(34,605)
Management Service [Member] | Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	40,039	45,158		34,605
Management Service [Member] | Boston Properties Limited Partnership
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Payroll and related costs from management services contracts	(10,386)	(9,590)		0
Other revenue	(40,039)	(45,158)		(34,605)
Management Service [Member] | Boston Properties Limited Partnership | Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	40,039	45,158		34,605
Noncontrolling interest - property partnerships [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	183,989	177,365		174,245
Noncontrolling interest - property partnerships [Member] | Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	183,989	177,365		174,245
Noncontrolling interest - property partnerships [Member] | Boston Properties Limited Partnership | Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	$ 183,989	$ 177,365		$ 174,245
[1] During the year ended December 31, 2018, the joint venture that owns Metropolitan Square in Washington, DC, commenced a renovation project and recorded accelerated depreciation expense of approximately $22.4 million related to the remaining book value of the assets to be replaced. The Company’s share of the accelerated depreciation expense totaled approximately $4.5 million.

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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.

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No definition available.

+ Details

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

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_IntersegmentEliminationMember
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Data Type:	na
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X

- Details

Name:	srt_ConsolidatedEntitiesAxis=srt_SubsidiariesMember
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Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	dei_LegalEntityAxis=bxp_UnconsolidatedJointVenturesMember
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Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_ManagementServiceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementEquityComponentsAxis=bxp_NoncontrollinginterestpropertypartnershipsMember
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Data Type:	na
Balance Type:
Period Type: