Summary of Significant Accounting Policies - Non-cash Investing and Financing Activities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Significant Noncash Transactions [Line Items]
Consolidation of the net assets (excluding mortgages as disclosed below) of previously unconsolidated joint ventures	$ 272,600	$ 0	$ 0
Joint venture investments related to consolidation of net assets	86,400	0	0
Mortgages assumed, of previously unconsolidated joint ventures	196,600	0	0
Mortgages assumed, shopping center acquisitions	0	9,100	0
Accounts payable related to construction in progress	6,300	11,000	9,300
Dividends declared, but not paid	14,844	44,036	45,300
Write-off of preferred share original issuance costs	0	7,176	0
Land acquired by minority interest partner	0	0	2,300
Conversion of Operating Partnership Units	0	0	900
Retail Value Inc. [Member]
Other Significant Noncash Transactions [Line Items]
Contribution of net assets to RVI	0	0	663,400
Building [Member]
Other Significant Noncash Transactions [Line Items]
Assumption of buildings due to ground lease terminations	$ 3,000	$ 0	$ 2,200