Acquisitions and Developments in Progress - Summary of Acquisitions (Details) $ in Thousands					9 Months Ended
	Feb. 06, 2020 USD ($) ft²	Aug. 13, 2019 USD ($) ft²	Jun. 10, 2019 USD ($) ft²	Mar. 07, 2019 USD ($) ft²	Sep. 30, 2020 USD ($) ft²	Sep. 30, 2019 USD ($) 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
Southlake Town Square - Parcel
Business Acquisition [Line Items]
Square footage | ft²		3,100
Purchase price of asset acquisition		$ 3,293
2019 acquisitions
Business Acquisition [Line Items]
Square footage | ft²						73,600
Purchase price of asset acquisition						$ 29,976
Capitalized closing costs and adjustments						$ 316