Investments in Unconsolidated Joint Ventures Purchase price allocation table (Details) - Santa Monica Business Park [Member] $ in Thousands	Jul. 19, 2018 USD ($)
Schedule of Asset Acquisition [Line Items]
Land and improvements	$ 100,453
Leasehold interest in land	248,944
Site improvements	13,379
Building and improvements	593,669
Tenant improvements	31,329
In-place lease intangibles	47,955
Above-market lease intangible	4,495
Below-market lease intangible	(17,503)
Capital lease obligation	(396,008)
Net assets acquired	$ 626,713