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Real Estate Narrative (Details) $ in Thousands |  |  |  |  |  |  | 1 Months Ended | 2 Months Ended | 3 Months Ended | 5 Months Ended | 6 Months Ended | 9 Months Ended | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 20, 2019 USD ($) ft² a | Jul. 16, 2019 USD ($) ft² | Jun. 28, 2019 USD ($) ft² | Jun. 03, 2019 USD ($) | May 09, 2019 USD ($) ft² | Jan. 24, 2019 USD ($) ft² a | Sep. 30, 2019 USD ($) ft² | Jan. 23, 2019 USD ($) | Jun. 02, 2019 USD ($) | Sep. 30, 2019 USD ($) ft² | Jun. 27, 2019 USD ($) | Sep. 30, 2018 USD ($) | Jun. 02, 2019 USD ($) | Jun. 27, 2019 USD ($) | Sep. 30, 2019 USD ($) ft² | Sep. 30, 2018 USD ($) | Dec. 31, 2018 USD ($) | Aug. 27, 2019 USD ($) ft² Real_Estate_Properties | Jul. 19, 2019 USD ($) | Jun. 01, 2019 ft² | Apr. 18, 2019 USD ($) ft² | Jan. 10, 2019 USD ($) ft²
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  | $ 743,553 |  |  | $ 686,284 |  |  | $ 2,203,061 |  | $ 2,011,919 |  |  |  |  |  |
Payments to Acquire Equity Method Investments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 65,499 |  | 314,075 |  |  |  |  |  |
Accelerated depreciation |  |  |  |  |  |  |  |  |  |  | 165,862 |  |  | 157,996 |  |  | 507,867 |  | 480,210 |  |  |  |  |  |
Right of use assets - finance leases |  |  |  |  |  |  | $ 237,394 |  |  |  | 237,394 |  |  |  |  |  | 237,394 |  |  |  |  |  |  |  |
Lease liabilities - finance leases |  |  |  |  |  |  | 221,029 |  |  |  | 221,029 |  |  |  |  |  | 221,029 |  |  |  |  |  |  |  |
Proceeds from sales of real estate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 83,486 |  | 175,577 |  |  |  |  |  |
Gains (loss) on sales of real estate |  |  |  |  |  |  |  |  |  |  | (15) |  |  | 7,863 |  |  | 766 |  | 122,552 |  |  |  |  |  |
Boston Properties Limited Partnership |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  | 743,553 |  |  | 686,284 |  |  | 2,203,061 |  | 2,011,919 |  |  |  |  |  |
Payments to Acquire Equity Method Investments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 65,499 |  | 314,075 |  |  |  |  |  |
Accelerated depreciation |  |  |  |  |  |  |  |  |  |  | 164,020 |  |  | 156,056 |  |  | 501,901 |  | 474,383 |  |  |  |  |  |
Right of use assets - finance leases |  |  |  |  |  |  | 237,394 |  |  |  | 237,394 |  |  |  |  |  | 237,394 |  |  |  |  |  |  |  |
Lease liabilities - finance leases |  |  |  |  |  |  | $ 221,029 |  |  |  | 221,029 |  |  |  |  |  | 221,029 |  |  |  |  |  |  |  |
Proceeds from sales of real estate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 83,486 |  | 175,577 |  |  |  |  |  |
Gains (loss) on sales of real estate |  |  |  |  |  |  |  |  |  |  | $ (15) |  |  | 9,154 |  |  | $ 915 |  | 126,831 |  |  |  |  |  |
325 Main Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of Lease Signed (in years) |  |  |  |  | 15-year |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  | 115,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accelerated depreciation |  |  |  |  | $ 9,900 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
325 Main Street [Member] | Boston Properties Limited Partnership |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accelerated depreciation |  |  |  |  | $ 9,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
20 CityPoint [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 211,000 |  |
200 West Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  |  |  | 261,000 |  |  |  | 261,000 |  |  |  |  |  | 261,000 |  |  |  |  |  |  |  |
Platform 16 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  |  | 1,100,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finance Lease fixed purchase price |  |  |  |  |  | $ 134,800 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Right of use assets - finance leases |  |  |  |  |  | 122,600 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lease liabilities - finance leases |  |  |  |  |  | $ 122,563 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lessee, Finance Lease, Term of Contract |  |  |  |  |  | 65 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Area of Land | a |  |  |  |  |  | 5.6 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2100 Pennsylvania Avenue [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of Lease Signed (in years) |  | 16-year |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  | 470,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Prepaid Rent |  | $ 15,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Right of use assets - finance leases |  | 185,100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lease liabilities - finance leases |  | 165,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 164,977 |  |  |
Finance lease - right of use asset -prepaid rent |  | 15,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finance lease - right of use asset - initial direct costs |  | $ 5,100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lesse, finance lease, term of amortization |  | 75 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lessee, Finance Lease, Term of Contract |  | 75 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Square Footage Of Signed Lease | ft² |  | 300,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carnegie Center [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,700,000
Aggregate purchase price |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 51,500
Deferred purchase price |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 8,600
880 & 890 Winter Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  | $ 1,300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 392,000 |  |  |  |
Aggregate purchase price |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 106,000 |  |  |  |
Number of real estate properties | Real_Estate_Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |
Net income (loss) |  |  |  |  |  |  | $ (200) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
164 Lexington Road [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  | 64,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gross Sale Price |  |  | $ 4,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sales of real estate |  |  | 3,800 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) |  |  |  |  |  |  |  |  |  |  |  |  | $ (100) | (50) |  | $ (100) |  |  | (200) |  |  |  |  |  |
Gains (loss) on sales of real estate |  |  | 2,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
164 Lexington Road [Member] | Boston Properties Limited Partnership |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gains (loss) on sales of real estate |  |  | $ 2,600 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2600 Tower Oaks Boulevard [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  |  | 179,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gross Sale Price |  |  |  |  |  | $ 22,700 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sales of real estate |  |  |  |  |  | $ 21,400 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) |  |  |  |  |  |  |  |  | $ (200) |  |  |  |  | (200) |  |  |  |  | (500) |  |  |  |  |  |
Gains (loss) on sales of real estate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (600) |  |  |  |  |  |  |  |
Impairment loss |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 3,100 |  |  |  |  |
2600 Tower Oaks Boulevard [Member] | Boston Properties Limited Partnership |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Impairment loss |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,500 |  |  |  |  |
One Tower Center [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 410,000 |
Gross Sale Price |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 38,000 |
Proceeds from sales of real estate |  |  |  | $ 36,600 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) |  |  |  |  |  |  |  |  |  | $ (100) |  |  |  | $ (700) | $ (900) |  |  |  | $ (2,000) |  |  |  |  |  |
Gains (loss) on sales of real estate |  |  |  | $ (800) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Impairment loss |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 24,000 |  |  |  |  |  |  |  |
One Tower Center [Member] | Boston Properties Limited Partnership |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Impairment loss |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 22,300 |  |  |  |  |  |  |  |
Future Office Building [Member] | 325 Main Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  | 420,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Square Footage Of Signed Lease | ft² |  |  |  |  | 379,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Future Retail Building [Member] | 325 Main Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  | 41,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Office Properties Under Construction [Member] | 200 West Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  |  |  | 126,000 |  |  |  | 126,000 |  |  |  |  |  | 126,000 |  |  |  |  |  |  |  |
Platform 16 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² | 1,100,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to Acquire Equity Method Investments | $ 28,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finance Lease fixed purchase price | $ 134,800 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lessee, Finance Lease, Term of Contract | 65 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Area of Land | a | 5.6 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership Percentage | 55.00% |  |  |  |  |  | 55.00% | [1] |  |  | 55.00% | [1] |  |  |  |  | 55.00% | [1] |  |  |  |  |  |  |
Joint Venture Partner [Member] | Platform 16 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to Acquire Equity Method Investments | $ 23,100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership Percentage | 45.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
[1] | This entity is a VIE (See Note 2).

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Namespace Prefix: | bxp_
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Balance Type: | debit
Period Type: | instant

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- Definition Finance Lease fixed purchase price + References No definition available. + Details
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Namespace Prefix: | bxp_
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Namespace Prefix: | bxp_
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Balance Type: | debit
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Namespace Prefix: | bxp_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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- Definition Lesse, finance lease, term of amortization + References No definition available. + Details
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Namespace Prefix: | bxp_
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Namespace Prefix: | bxp_
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Balance Type: | na
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