Investments in Unconsolidated Joint Ventures - Summary of Company's Investments in Unconsolidated Joint Ventures (Detail)	3 Months Ended
	Mar. 31, 2020 ft² Property
Income Statement Equity Method Investments [Line Items]
Number of properties	28
Total GLA | ft²	4,526,500
Brookfield Properties Retail I [Member]
Income Statement Equity Method Investments [Line Items]
Seritage % Ownership	50.00%
Number of properties	4
Total GLA | ft²	520,500
Brookfield Properties Retail II [Member]
Income Statement Equity Method Investments [Line Items]
Seritage % Ownership	50.00%
Number of properties	5
Total GLA | ft²	910,400
The Macerich Company [Member]
Income Statement Equity Method Investments [Line Items]
Seritage % Ownership	50.00%
Number of properties	9
Total GLA | ft²	1,570,200
Simon Property Group Inc [Member]
Income Statement Equity Method Investments [Line Items]
Seritage % Ownership	50.00%
Number of properties	5
Total GLA | ft²	872,200
Invesco Real Estate [Member]
Income Statement Equity Method Investments [Line Items]
Seritage % Ownership	50.00%
Number of properties	1
Total GLA | ft²	103,000
Invesco Real Estate II [Member]
Income Statement Equity Method Investments [Line Items]
Seritage % Ownership	50.00%
Number of properties	1
Total GLA | ft²	226,300
First Washington Realty [Member]
Income Statement Equity Method Investments [Line Items]
Seritage % Ownership	50.00%
Number of properties	1
Total GLA | ft²	163,700
Greenberg Gibbons [Member]
Income Statement Equity Method Investments [Line Items]
Seritage % Ownership	50.00%
Number of properties	1
Total GLA | ft²	160,200
RD Management [Member]
Income Statement Equity Method Investments [Line Items]
Seritage % Ownership	50.00%
Number of properties	1