Earnings per Share - Reconciliation of Net Income (Loss) and Number of Common Shares Used in Computations of Basic Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Numerator - Basic and Diluted
Net loss	$ (95,707)	$ (142,083)	$ (157,693)	$ (209,070)
Net loss attributable to non-controlling interests		31,328		46,110
Preferred dividends	(1,225)	(1,225)	(2,450)	(2,450)
Net loss attributable to Seritage common shareholders	$ (96,932)	$ (111,980)	$ (160,143)	$ (165,410)
Denominator - Basic and Diluted
Weighted average Class A common shares outstanding	56,173	43,677	56,116	43,656
Weighted average Class A common shares outstanding - Diluted	56,173	43,677	56,116	43,656
Loss per share attributable to Class A common shareholders - Basic	$ (1.73)	$ (2.56)	$ (2.85)	$ (3.79)
Loss per share attributable to Class A common shareholders - Diluted	$ (1.73)	$ (2.56)	$ (2.85)	$ (3.79)
Class A Common Shares [Member]
Denominator - Basic and Diluted
Weighted average Class A common shares outstanding	56,173	43,677	56,116	43,656