Aggregate purchase price

No definition available.

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- Definition

Contractual Sales Price

+ References

No definition available.

+ Details

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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

Term of Lease Signed (in years)

+ References

No definition available.

+ Details

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- Definition

Area of land held.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Present value of minimum lease payments for capital leases net of executory costs, including amounts paid by the lessee to the lessor for insurance, maintenance and taxes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6455398&loc=d3e45280-112737

+ Details

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- 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

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- 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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Period Type:	duration

- Definition

Net rentable area for properties owned.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- 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=66902209&loc=d3e3179-108585

+ Details

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Data Type:	xbrli:monetaryItemType
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- 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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Data Type:	xbrli:stringItemType
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Period Type:	duration

- 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=63488584&loc=d3e20235-122688

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Period Type:	duration

- Details

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Real Estate Narrative (Details)				3 Months Ended		5 Months Ended		9 Months Ended
Real Estate Narrative (Details)	Aug. 30, 2017 USD ($) a	Jun. 13, 2017 USD ($) ft²	Apr. 19, 2017 USD ($) a	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Jun. 13, 2017 USD ($) ft²	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 16, 2017 ft²	Aug. 24, 2017 ft² yr	Jun. 29, 2017 USD ($) yr apartments	May 27, 2017 ft²	May 15, 2017 USD ($) ft²	Apr. 06, 2017 ft²
Real Estate [Line Items]
Revenues				$ 657,712,000	$ 625,228,000			$ 1,946,847,000	$ 1,914,759,000
Earnings				233,729,000	157,605,000			678,644,000	626,082,000
Proceeds from sales of real estate								29,810,000	122,750,000
Gains on sales of real estate				2,891,000	12,983,000			6,791,000	80,606,000
145 Broadway [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²															485,000
Reservoir Place North [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²													73,000
6595 Springfield Center Drive [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²											623,000
Term of Lease Signed (in years) \| yr											15
888 Boylston Street [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²										417,000
MacArthur Transit Center [Member]
Real Estate [Line Items]
Term of Lease Signed (in years) \| yr												99
Number of apartment units \| apartments												402
Capital Lease Obligations												$ 28,962,000
103 Carnegie Center [Member] \| 103 Carnegie Center [Member]
Real Estate [Line Items]
Revenues						$ 1,100,000
Earnings						$ (100,000)
Net Rentable Area (in sf) \| ft²														96,000
Aggregate purchase price														$ 15,800,000
Boston Properties Limited Partnership
Real Estate [Line Items]
Revenues				657,712,000	625,228,000			1,946,847,000	1,914,759,000
Earnings				235,683,000	162,771,000			684,830,000	635,219,000
Proceeds from sales of real estate								29,810,000	122,750,000
Gains on sales of real estate				$ 2,891,000	12,983,000			$ 7,368,000	82,775,000
30 Shattuck Road [Member]
Real Estate [Line Items]
Area of Land \| a			9.5
Contractual Sales Price			$ 5,000,000
Proceeds from sales of real estate			5,000,000
Gains on sales of real estate			$ 3,700,000
40 Shattuck Road [Member]
Real Estate [Line Items]
Net Rentable Area (in sf) \| ft²		122,000					122,000
Contractual Sales Price		$ 12,000,000					$ 12,000,000
Net income (loss)					$ (33,000)		$ (28,000)		$ (18,000)
Proceeds from sales of real estate		11,900,000
Gains on sales of real estate		28,000
40 Shattuck Road [Member] \| Boston Properties Limited Partnership
Real Estate [Line Items]
Gains on sales of real estate		$ 600,000
Reston Eastgate [Member]
Real Estate [Line Items]
Area of Land \| a	21.7
Contractual Sales Price	$ 14,000,000
Proceeds from sales of real estate	13,200,000
Gains on sales of real estate	$ 2,800,000