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Subsequent Events (Details) $ in Thousands | Apr. 27, 2018 USD ($) ft² | Apr. 26, 2018 | Apr. 23, 2018 USD ($) ft² a yr Buildings | Apr. 19, 2018 USD ($) ft² yr apartments | Apr. 24, 2018 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
--- | --- | --- | --- | --- | --- | --- | ---
Subsequent Event [Line Items] |  |  |  |  |  |  |
Mortgage notes payable, net |  |  |  |  |  | $ 2,974,930 | $ 2,979,281
Unsecured term loan |  |  |  |  |  | $ 0 | $ 0
Delayed Draw Facility [Member] | Subsequent Event [Member] |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |
Unsecured term loan |  |  |  |  | $ 500,000 |  |
Interest Rate Based on LIBOR or CDOR [Member] | Delayed Draw Facility [Member] |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |
Margin added to Calculated Interest Rate |  |  |  |  |  | 0.90% |
Interest Rate Based on LIBOR or CDOR [Member] | Delayed Draw Facility [Member] | Subsequent Event [Member] |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |
Margin added to Calculated Interest Rate |  |  |  |  | 0.90% |  |
The Hub on Causeway - Residential [Member] | Subsequent Event [Member] |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |
Ownership Percentage |  |  |  | 50.00% |  |  |
Construction Loan Facility Borrowing Capacity |  |  |  | $ 180,000 |  |  |
Debt Instrument, Basis Spread on Variable Rate |  |  |  | 2.00% |  |  |
Number of extensions |  |  |  | 2 |  |  |
Extension Option (in years) | yr |  |  |  | 1 |  |  |
Number of apartment units | apartments |  |  |  | 440 |  |  |
Net Rentable Area (in sf) | ft² |  |  |  | 320,000 |  |  |
540 Madison Avenue [Member] | Subsequent Event [Member] |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |
Ownership Percentage | 60.00% |  |  |  |  |  |
Mortgage notes payable, net | $ 120,000 |  |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate | 1.10% | 1.50% |  |  |  |  |
Net Rentable Area (in sf) | ft² | 284,000 |  |  |  |  |  |
Santa Monica Business Park [Member] | Subsequent Event [Member] |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |
Net purchase price |  |  | $ 616,000 |  |  |  |
Area of Land | a |  |  | 47 |  |  |  |
number of buildings | Buildings |  |  | 21 |  |  |  |
Net Rentable Area (in sf) | ft² |  |  | 1,200,000.0 |  |  |  |
rentable square feet subject to a ground lease (percetnage) |  |  | 70.00% |  |  |  |
Term of Lease Signed (in years) | yr |  |  | 80 |  |  |  |

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