Acquisitions - Schedule of Company Acquired Shopping Centers (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Concourse Village [Member] | Jupiter, FL [Member]
Business Acquisition [Line Items]
Date Acquired	2020-10
Purchase Price	$ 0.0
Face Value of Mortgage Debt Assumed	$ 13.0
Millenia Crossing [Member] | Orlando, FL [Member]
Business Acquisition [Line Items]
Date Acquired	2020-10
Purchase Price	$ 0.0
Face Value of Mortgage Debt Assumed	$ 20.7
Echelon Village Plaza [Member] | Voorhees, NJ [Member]
Business Acquisition [Line Items]
Date Acquired	2020-10
Purchase Price	$ 0.0
Face Value of Mortgage Debt Assumed	$ 5.4
The Hub [Member] | Hempstead, NY [Member]
Business Acquisition [Line Items]
Date Acquired	2020-10
Purchase Price	$ 0.0
Face Value of Mortgage Debt Assumed	$ 28.0
Larkins Corner [Member] | Boothwyn, PA [Member]
Business Acquisition [Line Items]
Date Acquired	2020-10
Purchase Price	$ 0.0
Face Value of Mortgage Debt Assumed	$ 16.4
Ashbridge Square [Member] | Downingtown, PA [Member]
Business Acquisition [Line Items]
Date Acquired	2020-10
Purchase Price	$ 0.0
Face Value of Mortgage Debt Assumed	$ 32.4
Southmont Plaza [Member] | Easton, PA [Member]
Business Acquisition [Line Items]
Date Acquired	2020-10
Purchase Price	$ 0.0
Face Value of Mortgage Debt Assumed	$ 30.7
Vintage Plaza [Member] | Austin, TX [Member]
Business Acquisition [Line Items]
Date Acquired		2019-10
Purchase Price		$ 12.6
Face Value of Mortgage Debt Assumed		$ 0.0
Midtowne Park [Member] | Anderson, SC [Member]
Business Acquisition [Line Items]
Date Acquired	2020-11
Purchase Price	$ 0.0
Face Value of Mortgage Debt Assumed	$ 15.7
The Blocks [Member] | Portland, OR [Member]
Business Acquisition [Line Items]
Date Acquired		2019-11
Purchase Price		$ 50.5
Face Value of Mortgage Debt Assumed		$ 0.0
White Oak Village [Member] | Richmond, VA [Member]
Business Acquisition [Line Items]
Date Acquired	2020-11
Purchase Price	$ 0.0
Face Value of Mortgage Debt Assumed	$ 34.3
Southtown Center [Member] | Tampa, FL [Member]
Business Acquisition [Line Items]
Date Acquired		2019-12
Purchase Price		$ 22.0
Face Value of Mortgage Debt Assumed		$ 9.1