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Commitments And Contingencies (Details) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2021 USD ($) ft² | Dec. 31, 2020 USD ($)
Commitments And Contingencies [Line Items] |  |
Letter of credit and performance obligations | $ 20,200,000 |
Notes Receivable, Related Parties | 77,640,000 | $ 77,552,000
Property insurance program per occurrence limits | 1,000,000,000.0 |
Per occurrence limit for NBCR Coverage | 1,000,000,000.0 |
Value of program trigger | $ 200,000,000 |
Coinsurance of program trigger | 20.00% |
Program trigger deductible | 20.00% |
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 | $ 240,000,000 |
Annual aggregate limit of the earthquake insurance which covers San Francisco and Los Angeles regions | 240,000,000 |
Amount of earthquake insurance provided by IXP, LLC as direct insurer San Francisco and Los Angeles | 20,000,000 |
Notes receivable, net | 18,891,000 | 18,729,000
Affiliate of Bernstein Companies [Member] |  |
Commitments And Contingencies [Line Items] |  |
Notes receivable, net | $ 10,000,000.0 |
Note receivable fixed interest rate | 8.00% |
Boston Properties Limited Partnership |  |
Commitments And Contingencies [Line Items] |  |
Notes Receivable, Related Parties | $ 77,640,000 | 77,552,000
Operating partnership guarantee to cover liabilities of IXP | 20,000,000.0 |
Notes receivable, net | 18,891,000 | $ 18,729,000
767 Venture, LLC [Member] |  |
Commitments And Contingencies [Line Items] |  |
Maximum funding obligation | 23,100,000 |
Property insurance program per occurrence limits | 1,625,000,000 |
7750 Wisconsin Avenue [Member] |  |
Commitments And Contingencies [Line Items] |  |
Liabilities for Contingent Guarantees | 0 |
6595 Springfield Center Drive [Member] |  |
Commitments And Contingencies [Line Items] |  |
Liabilities for Contingent Guarantees | $ 0 |
325 Main Street |  |
Commitments And Contingencies [Line Items] |  |
Net Rentable Area (in sf) | ft² | 115,000 |
601 Lexington Avenue |  |
Commitments And Contingencies [Line Items] |  |
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP | $ 250,000,000 |
Future Residential Building [Member] | 325 Main Street |  |
Commitments And Contingencies [Line Items] |  |
Net Rentable Area (in sf) | ft² | 200,000 |
Affordable Housing requirement | 25.00% |
Future Office Building [Member] | 325 Main Street |  |
Commitments And Contingencies [Line Items] |  |
Net Rentable Area (in sf) | ft² | 420,000 |
Future Retail Building [Member] | 325 Main Street |  |
Commitments And Contingencies [Line Items] |  |
Net Rentable Area (in sf) | ft² | 41,000 |
Home Ownership Units [Member] | Future Residential Building [Member] | 325 Main Street |  |
Commitments And Contingencies [Line Items] |  |
Affordable Housing requirement | 20.00% |

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