Capital Lease - fixed purchase price

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- Definition

Contractual Sales Price

+ References

No definition available.

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- Definition

Future payment by an anchor tenant

+ References

No definition available.

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- Definition

Ground Lease Term (in years)

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No definition available.

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- Definition

Net Contractual Sales Price

+ References

No definition available.

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- Definition

Number of apartment units

+ References

No definition available.

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- Definition

Square Footage Of Signed Lease.

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No definition available.

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- Definition

Area of land held.

+ References

No definition available.

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- 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 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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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=84164817&loc=d3e45280-112737

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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

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- Definition

Describes matters pertaining to loans not reflected elsewhere.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (7)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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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 representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date. Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. Excludes amounts related to receivables held-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(3))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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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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- 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

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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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- Definition

Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 8
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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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=63488584&loc=d3e20235-122688

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Real Estate (Narrative) (Details) $ in Thousands										3 Months Ended								5 Months Ended	9 Months Ended	11 Months Ended	12 Months Ended
Real Estate (Narrative) (Details) $ in Thousands	Dec. 20, 2018 USD ($) a	Dec. 13, 2018 USD ($) ft²	Nov. 30, 2018 USD ($) ft²	Nov. 29, 2018 USD ($) ft² a yr	Sep. 27, 2018 USD ($) ft²	May 24, 2018 USD ($) ft²	Feb. 23, 2018 ft² Buildings	Jan. 09, 2018 USD ($) ft²	Jan. 08, 2018 USD ($)	Dec. 31, 2018 USD ($) ft²	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	May 23, 2018 USD ($)	Sep. 26, 2018 USD ($)	Nov. 30, 2018 USD ($) ft²	Dec. 31, 2018 USD ($) ft²	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 01, 2018 ft²	Nov. 09, 2018 ft²	Sep. 01, 2018 ft² apartments	Aug. 07, 2018 ft²	Jun. 07, 2018 ft² apartments	Jan. 24, 2018 ft²	Dec. 31, 2015 USD ($)
Real Estate Properties [Line Items]
Cash held in escrows										$ 95,832				$ 70,602	$ 70,602						$ 95,832	$ 70,602	$ 63,174							$ 73,790
Revenues										705,157	$ 686,284	$ 664,484	$ 661,151	655,229	657,712	$ 656,907	$ 632,228				2,717,076	2,602,076	2,550,820
Proceeds from sales of real estate																					455,409	29,810	122,750
Impairment losses																					11,812	0	1,783
Gains on sales of real estate																					182,356	7,663	80,606
Note receivable										19,468				0							19,468	0
Present value of expected net minimum lease payments										$ 64,187											$ 64,187
500 E Street
Real Estate Properties [Line Items]
Net Contractual Sales Price								$ 118,600
Net Rentable Area \| ft²								262,000
Operating Income (Loss)									$ 100													6,500	7,600
Proceeds from sales of real estate								$ 116,100
Gains on sales of real estate								96,400
91 Hartwell Avenue [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²						119,000
Operating Income (Loss)																		$ 300				500	400
Contractual Sales Price						$ 22,200
Proceeds from sales of real estate						21,700
Gains on sales of real estate						15,500
Quorum Office Park
Real Estate Properties [Line Items]
Net Rentable Area \| ft²					268,000
Operating Income (Loss)																			$ 700			900	900
Contractual Sales Price					$ 35,300
Proceeds from sales of real estate					34,300
Gains on sales of real estate					7,900
6595 Springfield Center Drive [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²		634,000
Contractual Sales Price		$ 98,100
Proceeds from sales of real estate		97,100
Impairment losses		$ 8,700
1333 New Hampshire Avenue [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²			315,000																	315,000
Operating Income (Loss)																				$ 6,700		7,400	6,100
Contractual Sales Price			$ 142,000																	142,000
Future payment by an anchor tenant			5,500																	$ 5,500
Proceeds from sales of real estate			133,700
Gains on sales of real estate			44,400
Tower Oaks Land [Member]
Real Estate Properties [Line Items]
Loans Receivable with Fixed Rates of Interest	0.0192
Contractual Sales Price	$ 46,000
Proceeds from sales of real estate	25,900
Gains on sales of real estate	15,700
Note receivable	$ 21,000
Area of Land \| a	41
17Fifty Presidents Street
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																													276,000
191 Spring Street
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																									171,000
Salesforce Tower
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																								1,421,000
Ownership Percentage by Parent																								95.00%
Signature at Reston
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																												518,000
Number of apartment units \| apartments																												508
Reston Gateway Master Plan
Real Estate Properties [Line Items]
Net Rentable Area \| ft²							1,100,000.0
Square Footage Of Signed Lease \| ft²							850,000
Number of real estate properties \| Buildings							2
Proto Kendall Square
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																										167,000
Number of apartment units \| apartments																										280
343 Madison Avenue [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																											850,000
Ownership Percentage by Parent																											55.00%
Platform 16
Real Estate Properties [Line Items]
Net Rentable Area \| ft²				1,100,000
Capital Lease - fixed purchase price				$ 134,800
Cash held in escrows				$ 15,000
Ground Lease Term (in years) \| yr				65
Area of Land \| a				5.6
Present value of expected net minimum lease payments				$ 12,397
2600 Tower Oaks Boulevard
Real Estate Properties [Line Items]
Net Rentable Area \| ft²										179,000											179,000
Impairment losses										$ 3,100
Boston Properties Limited Partnership
Real Estate Properties [Line Items]
Cash held in escrows										95,832				70,602							$ 95,832	70,602	63,174							$ 73,790
Revenues										705,157	$ 686,284	$ 664,484	$ 661,151	655,229	$ 657,712	$ 656,907	$ 632,228				2,717,076	2,602,076	2,550,820
Proceeds from sales of real estate																					455,409	29,810	122,750
Impairment losses																					10,181	0	1,783
Gains on sales of real estate																					190,716	8,240	$ 82,775
Note receivable										19,468				$ 0							$ 19,468	$ 0
Boston Properties Limited Partnership \| 500 E Street
Real Estate Properties [Line Items]
Gains on sales of real estate								$ 98,900
Boston Properties Limited Partnership \| 91 Hartwell Avenue [Member]
Real Estate Properties [Line Items]
Gains on sales of real estate						$ 15,900
Boston Properties Limited Partnership \| Quorum Office Park
Real Estate Properties [Line Items]
Gains on sales of real estate					$ 9,200
Boston Properties Limited Partnership \| 1333 New Hampshire Avenue [Member]
Real Estate Properties [Line Items]
Gains on sales of real estate			$ 48,400
Boston Properties Limited Partnership \| 2600 Tower Oaks Boulevard
Real Estate Properties [Line Items]
Impairment losses										$ 1,500