Partners' Capital - Reconciliation of Change in Total Partners' Capital (Detail) - USD ($) $ 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
Partners Capital [Line Items]
Exercise of stock options				$ 469
Earned portion of non-vested stock	$ 1,107	$ 1,071	$ 1,124	955	$ 839	$ 1,396
Adjustment to redemption value on noncontrolling redeemable Operating Partnership Units	2,948	2,609	(5,542)	1,606	150	294	$ 15
Purchases of equity in consolidated subsidiary from noncontrolling interests							(265)
Net income attributable to common shareholders/unitholders	37,095	36,457	36,433	140,002	40,742	34,454	109,984	$ 215,198
Amortization of terminated hedge included in AOCL	230	229	229	229	229	229
Life Storage LP [Member]
Partners Capital [Line Items]
Beginning balance of total controlling partners’ capital	2,132,681	2,147,719	2,132,894	2,041,920	2,046,891	2,057,737	2,132,894	2,057,737
Exercise of stock options				469
Net proceeds from issuance of Operating Partnership Units	134,226		21,466
Earned portion of non-vested stock	1,107	1,071	1,124	955	840	1,396
Adjustment to redemption value on noncontrolling redeemable Operating Partnership Units	(2,948)	(2,609)	5,542	(1,606)	(150)	(294)
Purchases of equity in consolidated subsidiary from noncontrolling interests	(2,300)
Net income attributable to common shareholders/unitholders	37,095	36,457	36,433	140,002	40,742	34,454	109,984	215,198
Amortization of terminated hedge included in AOCL	230	229	229	229	229	229
Distributions	(50,203)	(50,186)	(49,969)	(46,651)	(46,632)	(46,631)
Ending balance of total controlling partners’ capital	2,249,888	2,132,681	2,147,719	2,135,318	2,041,920	2,046,891	2,249,888	2,135,318
Life Storage LP [Member] | Life Storage Holdings, Inc. General Partner [Member]
Partners Capital [Line Items]
Beginning balance of total controlling partners’ capital	21,558	21,683	21,594	20,661	20,710	20,816	21,594	20,816
Exercise of stock options				4
Net proceeds from issuance of Operating Partnership Units	1,342		212
Earned portion of non-vested stock	12	11	11	10	9	14
Carrying value less than redemption value on redeemed noncontrolling interest				(1)
Purchases of equity in consolidated subsidiary from noncontrolling interests	(23)
Net income attributable to common shareholders/unitholders	373	366	366	1,408	409	347
Amortization of terminated hedge included in AOCL	2	2	2	2	2	2
Distributions	(505)	(504)	(502)	(469)	(469)	(469)
Ending balance of total controlling partners’ capital	22,759	21,558	21,683	21,615	20,661	20,710	22,759	21,615
Life Storage LP [Member] | Life Storage, Inc. Limited Partner [Member]
Partners Capital [Line Items]
Beginning balance of total controlling partners’ capital	2,116,623	2,131,765	2,117,258	2,027,676	2,032,827	2,043,796	2,117,258	2,043,796
Exercise of stock options				465
Net proceeds from issuance of Operating Partnership Units	132,884		21,254
Earned portion of non-vested stock	1,095	1,060	1,113	945	831	1,382
Carrying value less than redemption value on redeemed noncontrolling interest				1
Adjustment to redemption value on noncontrolling redeemable Operating Partnership Units	(2,948)	(2,609)	5,542	(1,606)	(150)	(294)
Purchases of equity in consolidated subsidiary from noncontrolling interests	(2,277)
Net income attributable to common shareholders/unitholders	36,722	36,091	36,067	138,594	40,333	34,107
Amortization of terminated hedge included in AOCL	(2)	(2)	(2)	(2)	(2)	(2)
Distributions	(49,698)	(49,682)	(49,467)	(46,182)	(46,163)	(46,162)
Ending balance of total controlling partners’ capital	2,232,399	2,116,623	2,131,765	2,119,891	2,027,676	2,032,827	2,232,399	2,119,891
Accumulated Other Comprehensive Income (Loss) [Member]
Partners Capital [Line Items]
Amortization of terminated hedge included in AOCL	230	229	229	229	229	229
Accumulated Other Comprehensive Income (Loss) [Member] | Life Storage LP [Member]
Partners Capital [Line Items]
Beginning balance of total controlling partners’ capital	(5,500)	(5,729)	(5,958)	(6,417)	(6,646)	(6,875)	(5,958)	(6,875)
Amortization of terminated hedge included in AOCL	230	229	229	229	229	229
Ending balance of total controlling partners’ capital	$ (5,270)	$ (5,500)	$ (5,729)	$ (6,188)	$ (6,417)	$ (6,646)	$ (5,270)	$ (6,188)