Acquisitions - Operating Property Acquisitions (Details) $ in Millions		12 Months Ended
	Oct. 15, 2019 USD ($) ft² property	Dec. 31, 2020 ft² property	Dec. 31, 2019 USD ($) property
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Number of buildings acquired | property		0
Rentable Square Feet (unaudited) | ft²		14,620,166
Purchase price			$ 173.0
3101-3243 La Cienega Boulevard, Culver City, CA [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Number of buildings acquired | property	19		19
Rentable Square Feet (unaudited) | ft²	151,908
Purchase price	$ 186.0
Revenue contributed from acquired properties			$ 3.7
Net income (loss) contributed from acquired properties			$ (0.1)