Investments in and Advances to Joint Ventures - Additional Information (Detail)		1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 15, 2020 USD ($) Property	Feb. 29, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 USD ($) Property	Dec. 31, 2019 USD ($) Property Investment	Dec. 31, 2018 USD ($) Property	Nov. 20, 2020 USD ($)
Schedule Of Equity Method Investments [Line Items]
Reserve of preferred equity interests, net				$ 19,393,000	$ 15,544,000	$ 11,422,000
Mortgage indebtedness, net			$ 249,260,000	249,260,000	94,874,000
Number of properties existing for mortgage loans | Property	7
Cash			69,742,000	69,742,000	16,080,000
Proceeds from sale of joint venture interests				140,441,000	0	0
Shopping Centers and Land [Member]
Schedule Of Equity Method Investments [Line Items]
Gain on sale of joint venture assets				1,800,000	$ 4,200,000	$ 13,700,000
DDRTC Joint Venture [Member]
Schedule Of Equity Method Investments [Line Items]
Percentage of joint venture sold		15.00%
Proceeds from sale of joint venture interests		$ 140,400,000
Gain (loss) on sale of joint venture interest		$ 45,600,000
BRE DDR Joint Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Gain (loss) on sale of joint venture interest			(200,000)
Echelon Village Plaza And Larkins Corner [Member]
Schedule Of Equity Method Investments [Line Items]
Number of properties existing for mortgage loans | Property	2
BRE DDR Joint Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Number of unconsolidated investments | Investment					2
Maximum preferred investment fixed distribution deferral					2.00%
Gross fair value of properties received			$ 272,300,000	$ 272,300,000
BRE DDR Joint Ventures [Member] | Preferred Equity Fixed Dividend Rate [Member]
Schedule Of Equity Method Investments [Line Items]
Preferred equity fixed dividend rate per annum					8.50%
BRE DDR IV [Member]
Schedule Of Equity Method Investments [Line Items]
Gross fair value of properties received	$ 192,500,000
BRE DDR IV [Member] | Affiliate of Blackstone [Member]
Schedule Of Equity Method Investments [Line Items]
Ownership interest of joint venture partner					95.00%
Consideration paid for transfer of interest	1.00
Restricted and unrestricted cash	5,400,000
Mortgage indebtedness, net	$ 146,600,000
BRE DDR IV [Member] | Affiliates of SITE Centers [Member]
Schedule Of Equity Method Investments [Line Items]
Ownership interest of joint venture partner					5.00%
BRE DDR III [Member]
Schedule Of Equity Method Investments [Line Items]
Cash							$ 4,900,000
BRE DDR III [Member] | Affiliate of Blackstone [Member]
Schedule Of Equity Method Investments [Line Items]
Ownership interest of joint venture partner			95.00%	95.00%
Gross fair value of properties received							79,800,000
BRE DDR III [Member] | Affiliates of SITE Centers [Member]
Schedule Of Equity Method Investments [Line Items]
Ownership interest of joint venture partner			5.00%	5.00%
White Oak Village and Midtowne Park [Member]
Schedule Of Equity Method Investments [Line Items]
Mortgage indebtedness, net							$ 50,000,000.0
Unconsolidated Joint Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Mortgage indebtedness, net			$ 1,029,579,000	$ 1,029,579,000	$ 1,640,146,000
Number of properties sold | Property				2	6	40
Unconsolidated Joint Ventures [Member] | Shopping Centers and Land [Member]
Schedule Of Equity Method Investments [Line Items]
Number of properties sold | Property						3
Proceeds from sale of joint venture assets				$ 27,700,000	$ 356,300,000	$ 786,500,000
Proceeds from sale of joint venture assets to company						$ 35,100,000