Subsequent Events - Additional Information (Details)						1 Months Ended	12 Months Ended
	Sep. 01, 2021 USD ($)	Feb. 16, 2021 USD ($)	Feb. 12, 2021 USD ($)	Jan. 29, 2021 USD ($)	Jan. 04, 2021 USD ($) Outparcel	Jan. 31, 2021 USD ($) Agreement Store	Dec. 31, 2020 USD ($) Agreement	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Oct. 08, 2019 USD ($)
Subsequent Event [Line Items]
Percentage of annual base rent							0.90%
Proceeds from the disposition of properties, net							$ 20,930,000	$ 88,738,000	$ 63,866,000
Principal payments on mortgages payable							55,449,000	$ 168,211,000	$ 81,726,000
Maximum borrowing capacity										$ 750,000,000.0
Fund IV | Bridge facility
Subsequent Event [Line Items]
Maximum borrowing capacity							$ 79,200,000
Maturity date							Jun. 30, 2021
Fund IV | Bridge facility | Scenario Forecast
Subsequent Event [Line Items]
Repayments of debt	$ 5,000,000.0
Core Portfolio
Subsequent Event [Line Items]
Repayments of debt							$ 26,300,000
COVID-19
Subsequent Event [Line Items]
Number of rent concession agreements | Agreement							288
Number of rent concession agreements for rent deferral | Agreement							226
Subsequent Event | Fund V | Disposed of by sale
Subsequent Event [Line Items]
Number of outparcels sold at unconsolidated property | Outparcel					2
Proceeds from the disposition of properties, net					$ 10,500,000
Repayments of mortgage on property					$ 7,900,000
Subsequent Event | Fund IV | Mortgages
Subsequent Event [Line Items]
Debt instrument, maturity date			Feb. 28, 2022
Principal payments on mortgages payable			$ 1,700,000
Subsequent Event | Fund IV | Bridge facility
Subsequent Event [Line Items]
Repayments of debt		$ 10,000,000.0
Maturity date		Dec. 31, 2021
Line of credit facility option to extend maturity date		Jun. 30, 2022
Additional repayments of lines of credit		$ 5,000,000.0
Subsequent Event | Core Portfolio | Disposed of by sale | 60 Orange Street
Subsequent Event [Line Items]
Proceeds from the disposition of properties, net				$ 16,400,000
Repayments of mortgage on property				$ 6,700,000
Subsequent Event | COVID-19
Subsequent Event [Line Items]
Number of rent concession agreements | Agreement						13
Number of rent concession agreements for rent deferral | Agreement						5
Number of rent concession agreements for rent forgiveness | Agreement						8
Subsequent Event | COVID-19 | Core Portfolio
Subsequent Event [Line Items]
Number of stores | Store						4
Annual base rent amount						$ 1,200,000
Percentage of annual base rent						0.90%
Subsequent Event | COVID-19 | Fund Portfolio
Subsequent Event [Line Items]
Number of stores | Store						7
Annual base rent amount						$ 200,000
Percentage of annual base rent						0.80%