Partners' Capital - Reconciliation of Change in Total Partners' Capital (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Partners Capital [Line Items]
Exercise of stock options	$ 469			$ 17	$ 3,045
Earned portion of non-vested stock	955	$ 839	$ 1,396	1,370	1,252	$ 1,495
Stock option expense					3	4
Carrying value less than redemption value on redeemed noncontrolling interest					(28)
Adjustment to redemption value on noncontrolling redeemable Operating Partnership units	1,606	150	294	(114)	3,035	(1,470)	$ 2,050
Net income attributable to common shareholders/unitholders	140,002	40,742	34,454	41,120	39,274	33,889	215,198	$ 114,283
Amortization of terminated hedge included in AOCL	229	229	229	229	229	229
Change in fair value of derivatives, net of reclassifications				(129)	(123)	48
Life Storage LP [Member]
Partners Capital [Line Items]
Beginning balance of total controlling partners’ capital	2,041,920	2,046,891	2,057,737	2,013,440	2,019,337	2,028,323	2,057,737	2,028,323
Exercise of stock options	469			17	3,045
Earned portion of non-vested stock	955	840	1,396	1,370	1,252	1,495
Stock option expense					3	4
Carrying value less than redemption value on redeemed noncontrolling interest					(28)
Adjustment to redemption value on noncontrolling redeemable Operating Partnership units	(1,606)	(150)	(294)	114	(3,035)	1,470
Net income attributable to common shareholders/unitholders	140,002	40,742	34,454	41,120	39,274	33,889	215,198	114,283
Amortization of terminated hedge included in AOCL	229	229	229	229	229	229
Change in fair value of derivatives, net of reclassifications				(130)	(123)	48
Distributions	(46,651)	(46,632)	(46,631)	(46,600)	(46,514)	(46,121)
Ending balance of total controlling partners’ capital	2,135,318	2,041,920	2,046,891	2,009,560	2,013,440	2,019,337	2,135,318	2,009,560
Life Storage LP [Member] | Life Storage Holdings, Inc. General Partner [Member]
Partners Capital [Line Items]
Beginning balance of total controlling partners’ capital	20,661	20,710	20,816	20,343	20,373	20,478	20,816	20,478
Forfeiture Of Non Vested Stock						1
Exercise of stock options	4				30
Earned portion of non-vested stock	10	9	14	13	13	15
Carrying value less than redemption value on redeemed noncontrolling interest	(1)				(2)
Net income attributable to common shareholders/unitholders	1,408	409	347	413	395	340
Amortization of terminated hedge included in AOCL	2	2	2	2	2	2
Change in fair value of derivatives, net of reclassifications					(1)
Distributions	(469)	(469)	(469)	(468)	(467)	(463)
Ending balance of total controlling partners’ capital	21,615	20,661	20,710	20,303	20,343	20,373	21,615	20,303
Life Storage LP [Member] | Life Storage, Inc. Limited Partner [Member]
Partners Capital [Line Items]
Beginning balance of total controlling partners’ capital	2,027,676	2,032,827	2,043,796	2,000,301	2,006,274	2,015,432	2,043,796	2,015,432
Forfeiture Of Non Vested Stock						(1)
Exercise of stock options	465			17	3,015
Earned portion of non-vested stock	945	831	1,382	1,357	1,239	1,480
Stock option expense					3	4
Carrying value less than redemption value on redeemed noncontrolling interest	1				(26)
Adjustment to redemption value on noncontrolling redeemable Operating Partnership units	(1,606)	(150)	(294)	114	(3,035)	1,470
Net income attributable to common shareholders/unitholders	138,594	40,333	34,107	40,707	38,879	33,549
Amortization of terminated hedge included in AOCL	(2)	(2)	(2)	(2)	(2)	(2)
Change in fair value of derivatives, net of reclassifications					1
Distributions	(46,182)	(46,163)	(46,162)	(46,132)	(46,047)	(45,658)
Ending balance of total controlling partners’ capital	2,119,891	2,027,676	2,032,827	1,996,362	2,000,301	2,006,274	2,119,891	1,996,362
Accumulated Other Comprehensive Income (Loss) [Member]
Partners Capital [Line Items]
Amortization of terminated hedge included in AOCL	229	229	229	229	229	229
Change in fair value of derivatives, net of reclassifications				(129)	(123)	48
Accumulated Other Comprehensive Income (Loss) [Member] | Life Storage LP [Member]
Partners Capital [Line Items]
Beginning balance of total controlling partners’ capital	(6,417)	(6,646)	(6,875)	(7,204)	(7,310)	(7,587)	(6,875)	(7,587)
Amortization of terminated hedge included in AOCL	229	229	229	229	229	229
Change in fair value of derivatives, net of reclassifications				(130)	(123)	48
Ending balance of total controlling partners’ capital	$ (6,188)	$ (6,417)	$ (6,646)	$ (7,105)	$ (7,204)	$ (7,310)	$ (6,188)	$ (7,105)