Acquisitions and Developments in Progress - Summary of Acquisitions (Details) $ in Thousands				6 Months Ended
	Feb. 06, 2020 USD ($) ft²	Jun. 10, 2019 USD ($) ft²	Mar. 07, 2019 USD ($) ft²	Jun. 30, 2020 USD ($) ft²	Jun. 30, 2019 USD ($) ft²
Fullerton Metrocenter - Fee Interest
Business Acquisition [Line Items]
Square footage | ft²	154,700
Purchase price of asset acquisition	$ 55,000
2020 acquisitions
Business Acquisition [Line Items]
Square footage | ft²				154,700
Purchase price of asset acquisition				$ 55,000
Capitalized closing costs and adjustments				$ 240
North Benson Center
Business Acquisition [Line Items]
Square footage | ft²			70,500
Purchase price of asset acquisition			$ 25,340
Paradise Valley Marketplace - Parcel
Business Acquisition [Line Items]
Square footage | ft²		0
Purchase price of asset acquisition		$ 1,343
2019 acquisitions
Business Acquisition [Line Items]
Square footage | ft²					70,500
Purchase price of asset acquisition					$ 26,683
Capitalized closing costs and adjustments					$ 291