Investments in and Advances to Joint Ventures - Summary of Company's Equity Method Joint Ventures Included in Investments in and Advances (Detail)	12 Months Ended
	Dec. 31, 2020 Property
DDRM Properties [Member]
Schedule Of Equity Method Investments [Line Items]
Partner	Madison International Realty
Effective Ownership Percentage	20.00%
Operating Properties	34
Dividend Trust Portfolio JV LP [Member]
Schedule Of Equity Method Investments [Line Items]
Partner	Chinese Institutional Investors
Effective Ownership Percentage	20.00%
Operating Properties	10
DDR-SAU Retail Fund LLC [Member]
Schedule Of Equity Method Investments [Line Items]
Partner	State of Utah
Effective Ownership Percentage	20.00%
Operating Properties	11
Other Joint Venture Interests [Member]
Schedule Of Equity Method Investments [Line Items]
Partner	Various
Operating Properties	4
Minimum [Member] | Other Joint Venture Interests [Member]
Schedule Of Equity Method Investments [Line Items]
Effective Ownership Percentage	20.00%
Maximum [Member] | Other Joint Venture Interests [Member]
Schedule Of Equity Method Investments [Line Items]
Effective Ownership Percentage	79.45%