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Share Based Compensation - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Jul. 07, 2015
Time Based Restricted Shares and Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
Restricted Share [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs	$ 6.3	$ 3.8	$ 6.3	$ 3.8
Unrecognized compensation costs, weighted average expected recognition period			2 years 3 months 18 days	2 years 3 months 18 days
Restricted Share [Member] \| General and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized	$ 0.5	$ 0.1	$ 0.9	$ 1.0
Seritage Growth Properties 2015 Share Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved for issuance					3,250,000