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Unsecured Senior Notes Unsecured Senior Notes (Narrative) (Details) - USD ($) $ in Thousands |  | 6 Months Ended
--- | --- | ---
Jan. 20, 2016 | Jun. 30, 2016 | Jun. 30, 2015
Debt Instrument [Line Items] |  |  |  |
Proceeds from Issuance of Unsecured Debt |  | $ 997,080 |  | $ 0
Boston Properties Limited Partnership |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Proceeds from Issuance of Unsecured Debt |  | $ 997,080 |  | $ 0
Boston Properties Limited Partnership | Senior Notes [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Maximum Leverage Ratio |  | 60.00% |  |
Maximum Secured Debt Leverage Ratio |  | 50.00% |  |
Minimum Interest Coverage Ratio |  | 1.50 |  |
Minimum Unencumbered Asset Value Percentage Of Unsecured Debt |  | 150.00% |  |
Principal Amount |  | $ 6,300,000 |  |
Unsecured Senior Notes 3.766% | Boston Properties Limited Partnership | Senior Notes [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Principal Amount | $ 1,000,000 | $ 1,000,000 |  |
Coupon/Stated Rate | 3.65% | 3.65% |  |
Senior Notes Pricing | 99.708% |  |  |
Effective Rate | 3.766% | 3.766% | [1] |
Proceeds from Issuance of Unsecured Debt | $ 988,900 |  |  |
[1] | Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs.

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- Definition Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 + Details
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- Definition Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399 + Details
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- Definition The cash inflow from the issuance of long-term debt that is not secured by collateral. Excludes proceeds from tax exempt unsecured debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3255-108585 + Details
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