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Commitments And Contingencies (Details) - USD ($) $ in Millions | 2 Months Ended | 10 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Feb. 28, 2017 | Dec. 31, 2017 | Dec. 31, 2017 | Dec. 31, 2009 | Dec. 31, 2016 | Dec. 31, 2015 | Sep. 18, 2014 | Jan. 10, 2014
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |
Letter of credit and performance obligations |  | $ 9.1 | $ 9.1 |  |  |  |  |
Property insurance program per occurrence limits |  | 1,000.0 | 1,000.0 |  |  |  |  |
Per occurrence limit for NBCR Coverage |  |  | 1,000.0 |  |  |  |  |
Value of program trigger |  | 140.0 | $ 140.0 |  |  |  |  |
Coinsurance of program trigger |  |  | 17.00% |  |  |  |  |
Deductible in insurance as a percentage of the value of the affected property, San Francisco and Los Angeles |  |  | 3.00% |  |  |  |  |
Per occurrence limit of the earthquake insurance which covers San Francisco and Los Angeles regions | $ 170.0 | 240.0 |  |  |  |  |  |
Annual aggregate limit of the earthquake insurance which covers San Francisco and Los Angeles regions | 170.0 | 240.0 |  |  |  |  |  |
Amount of earthquake insurance provided by IXP, LLC as direct insurer San Francisco and Los Angeles |  |  | $ 20.0 |  |  |  |  |
Earthquake Coverage Included In Builders Risk Policy For Below Grade improvements for Salesforce Tower | $ 60.0 |  |  |  |  |  |  |
767 Venture, LLC [Member] |  |  |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |
Maximum funding obligation |  | 193.4 | 193.4 |  |  |  |  |
Property insurance program per occurrence limits |  | 1,625.0 | 1,625.0 |  |  |  |  |
Lehman [Member] |  |  |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |
Bankruptcy claim, amount filed by general creditor |  |  |  | $ 45.3 |  |  |  |
Bankruptcy claim amount allowed by court to creditor |  |  |  |  |  |  |  | $ 45.2
Bankruptcy Claims, Amount of Claims Settled |  | 0.4 | 0.4 |  | $ 1.4 | $ 8.1 | $ 7.7 |
Bankruptcy remaining claim amount allowed by court to creditor |  | $ 27.6 | 27.6 |  |  |  |  |
601 Lexington Avenue |  |  |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP |  |  | $ 250.0 |  |  |  |  |
767 Fifth Partners LLC [Member] |  |  |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |
Ownership Percentage by Parent |  | 60.00% | 60.00% |  |  |  |  |
Boston Properties Limited Partnership |  |  |  |  |  |  |  |
Commitments And Contingencies [Line Items] |  |  |  |  |  |  |  |
Operating partnership guarantee to cover liabilities of IXP |  | $ 20.0 | $ 20.0 |  |  |  |  |

X
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