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Derivative and Hedging Instruments Derivative Instrument and Hedging Activities Notional Table (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Fair Value | $ (6,133) | $ (47,144) | $ (10,302)
Boston Properties Limited Partnership | Interest Rate Swap [Member] |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative, Notional Amount |  | 550,000 |
767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative Liability, Notional Amount |  | 350,000 |
Derivative Asset, Notional Amount |  | 100,000 |
Derivative, Notional Amount |  | 450,000 |
Fair Value |  | (8,264) |
Other Liabilities [Member] | 767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Fair Value |  | $ (8,773) |
Other Liabilities [Member] | Minimum [Member] | 767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative, Fixed Interest Rate |  | 2.418% |
Other Liabilities [Member] | Maximum [Member] | 767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative, Fixed Interest Rate |  | 2.95% |
Prepaid Expenses and Other Assets [Member] | 767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Fair Value |  | $ 509 |
Prepaid Expenses and Other Assets [Member] | Minimum [Member] | 767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative, Fixed Interest Rate |  | 2.336% |
Prepaid Expenses and Other Assets [Member] | Maximum [Member] | 767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative, Fixed Interest Rate |  | 2.388% |

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Nominal or face amount used to calculate payments on the derivative asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5579245-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Notional Amount -URI http://asc.fasb.org/extlink&oid=6519104 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5580258-113959 + Details
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- Definition Fixed interest rate related to the interest rate derivative. + References No definition available. + Details
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- Definition Nominal or face amount used to calculate payments on the derivative liability. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Notional Amount -URI http://asc.fasb.org/extlink&oid=6519104 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5579245-113959 + Details
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- Definition Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669646-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e637-108580 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6441202&loc=d3e80720-113993 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959 + Details
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