Earnings Per Share and Earnings Per Unit - Computation of Basic and Diluted Earnings Per Common Share/Unit (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net income attributable to common shareholders/unitholders	$ 37,095	$ 36,457	$ 36,433	$ 140,002	$ 40,742	$ 34,454	$ 109,984	$ 215,198
Net income attributable to unvested restricted shares	(66)			(272)			(65)	(136)
Net income attributable to outstanding common shares	$ 37,029			$ 139,730			$ 109,919	$ 215,062
Denominator:
Denominator for basic earnings per share/unit - weighted average shares/units	47,223,842			46,586,030			46,915,323	46,577,704
Effect of Dilutive Securities:
Stock options and non-vested stock	76,000			71,000			71,000	64,000
Denominator for diluted earnings per share/unit - adjusted weighted average shares/units and assumed conversion	47,299,906			46,657,105			46,985,647	46,641,673
Basic earnings per common share/unit attributable to common shareholders/unitholders	$ 0.78			$ 3.00			$ 2.34	$ 4.62
Diluted earnings per common share/unit attributable to common shareholders/unitholders	$ 0.78			$ 2.99			$ 2.34	$ 4.61
Life Storage LP [Member]
Numerator:
Net income attributable to common shareholders/unitholders	$ 37,095	$ 36,457	$ 36,433	$ 140,002	$ 40,742	$ 34,454	$ 109,984	$ 215,198
Net income attributable to unvested restricted shares	(66)			(272)			(65)	(136)
Net income attributable to outstanding common shares	$ 37,029			$ 139,730			$ 109,919	$ 215,062
Denominator:
Denominator for basic earnings per share/unit - weighted average shares/units	47,223,842			46,586,030			46,915,323	46,577,704
Effect of Dilutive Securities:
Stock options and non-vested stock	76,000			71,000			71,000	64,000
Denominator for diluted earnings per share/unit - adjusted weighted average shares/units and assumed conversion	47,299,906			46,657,105			46,985,647	46,641,673
Basic earnings per common share/unit attributable to common shareholders/unitholders	$ 0.78			$ 3.00			$ 2.34	$ 4.62
Diluted earnings per common share/unit attributable to common shareholders/unitholders	$ 0.78			$ 2.99			$ 2.34	$ 4.61