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Leases - Additional Information (Detail) $ in Millions | 1 Months Ended | 3 Months Ended |
--- | --- | --- | ---
Dec. 31, 2018 ft² Space | May 31, 2018 ft² | Aug. 31, 2017 ft² yr | Mar. 31, 2019 USD ($) ft² | Jun. 30, 2018 ft²
Lessee Lease Description [Line Items] |  |  |  |  |
Cash paid for amounts included in the measurement of lease liabilities | $ |  |  |  | $ 1.8 |
Operating lease liability, weighted-average remaining lease term |  |  |  | 10 years 9 months 18 days |
Operating lease liability, weighted-average discount rate, percent |  |  |  | 6.50% |
Other Current Assets [Member] |  |  |  |  |
Lessee Lease Description [Line Items] |  |  |  |  |
Additional operating lease incentive | $ |  |  |  | $ 4.1 |
ARE-San Francisco No. 19, LLC [Member] | Mission Bay Lease [Member] |  |  |  |  |
Lessee Lease Description [Line Items] |  |  |  |  |
Extended lease term start year |  |  | 2020 |  |
Lease expiration year |  |  | 2030 |  |
Lease space | ft² |  |  | 137,046 | 2,690 |
Lease commencement date |  |  | Sep. 01, 2017 |  |
Lessee operating lease, lease expiration date |  |  | Jan. 31, 2030 |  |
Lease, option to extend, description |  |  |  | The term of the Mission Bay Lease commenced on September 1, 2017, and will expire January 31, 2030, subject to our right to extend the term of the lease for two consecutive five-year periods, which we have excluded from our determination of the lease term. |
Number of consecutive 5 year terms to extend lease | yr |  |  | 2 |  |
Lease extension term |  |  | 5 years |  |
Additional space required to be leased in the future | ft² |  |  | 15,000 |  |
Recognized a right-of-use asset and lease liability | $ |  |  |  | $ 1.3 |
Kilroy Realty Finance Partnership, L.P [Member] | Third Street Lease [Member] |  |  |  |  |
Lessee Lease Description [Line Items] |  |  |  |  |
Lease space | ft² | 67,105 | 135,936 |  |  | 1,726
Lessee operating lease, lease expiration date |  | Jan. 31, 2030 |  |  |
Lease, option to extend, description |  |  |  | our right to extend the term for a consecutive five-year period |
Lease extension term |  | 5 years |  |  |
Lease term start month and year |  | 2018-06 |  |  |
Number of additional spaces delivered | Space | 2 |  |  |  |
Remaining square feet of space expected delivery year |  | 2019 |  |  |

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