Life Storage Inc - Registered Shares (LSI) 10-Q 1 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 17, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	LSI
Entity Registrant Name	LIFE STORAGE, INC.
Entity Central Index Key	944,314
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		46,601,427
Life Storage LP [Member]
Document Information [Line Items]
Entity Registrant Name	LIFE STORAGE LP
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Investment in storage facilities:
Land	$ 788,728	$ 786,628
Building, equipment, and construction in progress	3,584,859	3,534,782
Real estate investment property, at cost, total	4,373,587	4,321,410
Less: accumulated depreciation	(697,970)	(624,314)
Investment in storage facilities, net	3,675,617	3,697,096
Cash and cash equivalents	13,282	9,167
Accounts receivable	7,992	7,331
Receivable from unconsolidated joint ventures	742	1,397
Investment in unconsolidated joint ventures	135,328	133,458
Prepaid expenses	10,544	6,757
Fair value of interest rate swap agreements		205
Trade name	16,500	16,500
Other assets	9,329	4,863
Total Assets	3,869,334	3,876,774
Liabilities
Line of credit	128,000	105,000
Term notes, net	1,610,548	1,609,089
Accounts payable and accrued liabilities	79,194	92,941
Deferred revenue	9,128	9,374
Mortgages payable	12,397	12,674
Total Liabilities	1,839,267	1,829,078
Noncontrolling redeemable Operating Partnership Units at redemption value	20,506	19,373
Shareholders' Equity/ Partners' Capital
Common stock $.01 par value, 100,000,000 shares authorized, 46,600,427 shares outstanding at September 30, 2018 (46,552,222 at December 31, 2017)	466	466
Additional paid-in capital	2,370,329	2,363,171
Dividends in excess of net income	(354,130)	(327,727)
Accumulated other comprehensive loss	(7,104)	(7,587)
Total Shareholders’ Equity	2,009,561	2,028,323
Noncontrolling interest in consolidated subsidiary	0	0
Total Equity	2,009,561	2,028,323
Total Liabilities and Shareholders' Equity/ Partners' Capital	3,869,334	3,876,774
Life Storage LP [Member]
Investment in storage facilities:
Land	788,728	786,628
Building, equipment, and construction in progress	3,584,859	3,534,782
Real estate investment property, at cost, total	4,373,587	4,321,410
Less: accumulated depreciation	(697,970)	(624,314)
Investment in storage facilities, net	3,675,617	3,697,096
Cash and cash equivalents	13,282	9,167
Accounts receivable	7,992	7,331
Receivable from unconsolidated joint ventures	742	1,397
Investment in unconsolidated joint ventures	135,328	133,458
Prepaid expenses	10,544	6,757
Fair value of interest rate swap agreements		205
Trade name	16,500	16,500
Other assets	9,329	4,863
Total Assets	3,869,334	3,876,774
Liabilities
Line of credit	128,000	105,000
Term notes, net	1,610,548	1,609,089
Accounts payable and accrued liabilities	79,194	92,941
Deferred revenue	9,128	9,374
Mortgages payable	12,397	12,674
Total Liabilities	1,839,267	1,829,078
Limited partners' redeemable capital interest at redemption value (215,009 and 217,481 units outstanding at September 30, 2018 and December 31, 2017, respectively)	20,506	19,373
Shareholders' Equity/ Partners' Capital
General partner (468,154 and 467,697 units outstanding at September 30, 2018 and December 31, 2017, respectively)	20,303	20,478
Limited partners (46,132,273 and 46,084,525 units outstanding at September 30, 2018 and December 31, 2017, respectively)	1,996,362	2,015,432
Accumulated other comprehensive loss	(7,104)	(7,587)
Total Controlling Partners' Capital	2,009,561	2,028,323
Noncontrolling interest in consolidated subsidiary	0	0
Total Partners' Capital	2,009,561	2,028,323
Total Liabilities and Shareholders' Equity/ Partners' Capital	$ 3,869,334	$ 3,876,774

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares outstanding	46,600,427	46,552,222
Life Storage LP [Member]
General partner, units outstanding	468,154	467,697
Limited partner, units outstanding	46,132,273	46,084,525
Life Storage LP [Member] | Limited Partners Redeemable Capital Interest at Redemption Value [Member]
Limited partner, units outstanding	215,009	217,481

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues
Rental income	$ 128,818	$ 124,044	$ 376,334	$ 363,284
Other operating income	12,665	11,524	36,251	33,389
Total operating revenues	141,483	135,568	412,585	396,673
Expenses
Property operations and maintenance	30,316	32,662	90,551	92,178
Real estate taxes	15,450	14,498	46,512	43,431
General and administrative	11,742	10,914	35,513	38,309
Payments for rent	141	141	424	283
Depreciation and amortization	27,291	26,149	76,839	101,896
Total operating expenses	84,940	84,364	249,839	276,097
Income from operations	56,543	51,204	162,746	120,576
Other income (expenses)
Interest expense	(17,923)	(16,290)	(52,645)	(47,216)
Interest income	2	1	8	4
Gain on sale of storage facilities	925		925
Gain on sale of real estate	718		718
Equity in income of joint ventures	1,046	752	3,066	2,259
Net income	41,311	35,667	114,818	75,623
Net income attributable to noncontrolling interest in the Operating Partnership	(191)	(171)	(535)	(343)
Net loss attributable to noncontrolling interest in consolidated subsidiary	0	0	0	0
Net income attributable to common shareholders/unitholders	$ 41,120	$ 35,496	$ 114,283	$ 75,280
Earnings per common share/unit attributable to common shareholders/unitholders - basic	$ 0.88	$ 0.76	$ 2.46	$ 1.62
Earnings per common share/unit attributable to common shareholders/unitholders - diluted	$ 0.88	$ 0.76	$ 2.45	$ 1.62
Common shares/units used in basic earnings per share/unit calculation	46,526,362	46,415,782	46,486,587	46,361,747
Common shares/units used in diluted earnings per share/unit calculation	46,627,968	46,520,311	46,580,331	46,472,294
Dividends/distributions declared per common share/unit	$ 1	$ 1	$ 3	$ 2.95
Life Storage LP [Member]
Revenues
Rental income	$ 128,818	$ 124,044	$ 376,334	$ 363,284
Other operating income	12,665	11,524	36,251	33,389
Total operating revenues	141,483	135,568	412,585	396,673
Expenses
Property operations and maintenance	30,316	32,662	90,551	92,178
Real estate taxes	15,450	14,498	46,512	43,431
General and administrative	11,742	10,914	35,513	38,309
Payments for rent	141	141	424	283
Depreciation and amortization	27,291	26,149	76,839	101,896
Total operating expenses	84,940	84,364	249,839	276,097
Income from operations	56,543	51,204	162,746	120,576
Other income (expenses)
Interest expense	(17,923)	(16,290)	(52,645)	(47,216)
Interest income	2	1	8	4
Gain on sale of storage facilities	925		925
Gain on sale of real estate	718		718
Equity in income of joint ventures	1,046	752	3,066	2,259
Net income	41,311	35,667	114,818	75,623
Net income attributable to noncontrolling interest in the Operating Partnership	(191)	(171)	(535)	(343)
Net loss attributable to noncontrolling interest in consolidated subsidiary	0	0	0	0
Net income attributable to common shareholders/unitholders	$ 41,120	$ 35,496	$ 114,283	$ 75,280
Earnings per common share/unit attributable to common shareholders/unitholders - basic	$ 0.88	$ 0.76	$ 2.46	$ 1.62
Earnings per common share/unit attributable to common shareholders/unitholders - diluted	$ 0.88	$ 0.76	$ 2.45	$ 1.62
Common shares/units used in basic earnings per share/unit calculation	46,526,362	46,415,782	46,486,587	46,361,747
Common shares/units used in diluted earnings per share/unit calculation	46,627,968	46,520,311	46,580,331	46,472,294
Dividends/distributions declared per common share/unit	$ 1	$ 1	$ 3	$ 2.95
Net income attributable to general partner	$ 413	$ 357	$ 1,148	$ 756
Net income attributable to limited partners	$ 40,707	$ 35,139	$ 113,135	$ 74,524

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net income	$ 41,311	$ 35,667	$ 114,818	$ 75,623
Other comprehensive income:
Effective portion of gain on derivatives net of reclassification to interest expense	100	802	483	2,661
Total comprehensive income	41,411	36,469	115,301	78,284
Comprehensive income attributable to noncontrolling interest in the Operating Partnership	(191)	(175)	(537)	(355)
Comprehensive loss attributable to noncontrolling interest in consolidated subsidiary	0	0	0	0
Comprehensive income attributable to common shareholders/unitholders	41,220	36,294	114,764	77,929
Life Storage LP [Member]
Net income	41,311	35,667	114,818	75,623
Other comprehensive income:
Effective portion of gain on derivatives net of reclassification to interest expense	100	802	483	2,661
Total comprehensive income	41,411	36,469	115,301	78,284
Comprehensive income attributable to noncontrolling interest in the Operating Partnership	(191)	(175)	(537)	(355)
Comprehensive loss attributable to noncontrolling interest in consolidated subsidiary	0	0	0	0
Comprehensive income attributable to common shareholders/unitholders	$ 41,220	$ 36,294	$ 114,764	$ 77,929

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Operating Activities
Net income	$ 41,311,000	$ 35,667,000	$ 114,818,000	$ 75,623,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	27,291,000	26,149,000	76,839,000	101,896,000
Amortization of debt issuance costs and bond discount			2,672,000	2,496,000
Gain on sale of storage facilities	(925,000)		(925,000)
Gain on sale of real estate	(718,000)		(718,000)
Equity in income of joint ventures	(1,046,000)	(752,000)	(3,066,000)	(2,259,000)
Distributions from unconsolidated joint ventures			6,276,000	5,071,000
Non-vested stock earned			4,203,000	4,905,000
Stock option expense	0	4,000	7,000	11,000
Deferred income taxes			1,115,000	(2,382,000)
Changes in assets and liabilities (excluding the effects of acquisitions):
Accounts receivable			(657,000)	(1,636,000)
Prepaid expenses			(3,787,000)	(2,453,000)
Receipts from joint ventures			655,000	354,000
Accounts payable and other liabilities			(13,720,000)	(618,000)
Deferred revenue			(318,000)	(204,000)
Net cash provided by operating activities			183,394,000	180,804,000
Investing Activities
Acquisitions of storage facilities, net of cash acquired			(19,409,000)	(9,576,000)
Improvements, equipment additions, and construction in progress			(45,020,000)	(65,978,000)
Net proceeds from the sale of real estate			10,576,000	1,994,000
Investment in unconsolidated joint ventures			(5,095,000)	(69,786,000)
Property deposit			(541,000)
Net cash used in investing activities			(59,489,000)	(143,346,000)
Financing Activities
Net proceeds from sale of common stock/partnership units			2,977,000	15,633,000
Purchase of outstanding shares/units				(8,234,000)
Proceeds from line of credit			172,000,000	233,000,000
Repayments of line of credit			(149,000,000)	(157,000,000)
Dividends paid - common stock			(139,235,000)	(137,174,000)
Distributions to noncontrolling interest holders			(650,000)	(641,000)
Redemption of operating partnership units			(232,000)
Mortgage principal payments			(277,000)	(263,000)
Net cash used in financing activities			(114,417,000)	(54,679,000)
Net decrease in cash and restricted cash			9,488,000	(17,221,000)
Cash and restricted cash at beginning of period			9,459,000	23,923,000	$ 23,923,000
Cash and restricted cash at end of period	18,947,000	6,702,000	18,947,000	6,702,000	9,459,000
Supplemental cash flow information
Cash paid for interest, net of interest capitalized			53,636,000	52,633,000
Cash paid for income taxes, net of refunds			1,175,000	1,296,000
Life Storage LP [Member]
Operating Activities
Net income	41,311,000	35,667,000	114,818,000	75,623,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	27,291,000	26,149,000	76,839,000	101,896,000
Amortization of debt issuance costs and bond discount			2,672,000	2,496,000
Gain on sale of storage facilities	(925,000)		(925,000)
Gain on sale of real estate	(718,000)		(718,000)
Equity in income of joint ventures	(1,046,000)	(752,000)	(3,066,000)	(2,259,000)
Distributions from unconsolidated joint ventures			6,276,000	5,071,000
Non-vested stock earned			4,203,000	4,905,000
Stock option expense			7,000	11,000
Deferred income taxes			1,115,000	(2,382,000)
Changes in assets and liabilities (excluding the effects of acquisitions):
Accounts receivable			(657,000)	(1,636,000)
Prepaid expenses			(3,787,000)	(2,453,000)
Receipts from joint ventures			655,000	354,000
Accounts payable and other liabilities			(13,720,000)	(618,000)
Deferred revenue			(318,000)	(204,000)
Net cash provided by operating activities			183,394,000	180,804,000
Investing Activities
Acquisitions of storage facilities, net of cash acquired			(19,409,000)	(9,576,000)
Improvements, equipment additions, and construction in progress			(45,020,000)	(65,978,000)
Net proceeds from the sale of real estate			10,576,000	1,994,000
Investment in unconsolidated joint ventures			(5,095,000)	(69,786,000)
Property deposit			(541,000)
Net cash used in investing activities			(59,489,000)	(143,346,000)
Financing Activities
Net proceeds from sale of common stock/partnership units			2,977,000	15,633,000
Purchase of outstanding shares/units				(8,234,000)
Proceeds from line of credit			172,000,000	233,000,000
Repayments of line of credit			(149,000,000)	(157,000,000)
Distributions to unitholders			(139,235,000)	(137,174,000)
Distributions to noncontrolling interest holders			(650,000)	(641,000)
Redemption of operating partnership units			(232,000)
Mortgage principal payments			(277,000)	(263,000)
Net cash used in financing activities			(114,417,000)	(54,679,000)
Net decrease in cash and restricted cash			9,488,000	(17,221,000)
Cash and restricted cash at beginning of period			9,459,000	23,923,000	23,923,000
Cash and restricted cash at end of period	$ 18,947,000	$ 6,702,000	18,947,000	6,702,000	$ 9,459,000
Supplemental cash flow information
Cash paid for interest, net of interest capitalized			53,636,000	52,633,000
Cash paid for income taxes, net of refunds			$ 1,175,000	$ 1,296,000

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	1. BASIS OF PRESENTATION The accompanying unaudited financial statements of Life Storage, Inc. (the “Parent Company”) and Life Storage LP (the “Operating Partnership”) have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the nine month period ended September 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018.

Organization

Organization	9 Months Ended
	Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	2. ORGANIZATION The Parent Company operates as a self-administered and self-managed real estate investment trust (a “REIT”) that owns and operates self-storage facilities throughout the United States. All of the Parent Company’s assets are owned by, and all its operations are conducted through, the Operating Partnership. Life Storage Holdings, Inc., a wholly-owned subsidiary of the Parent Company (“Holdings”), is the sole general partner of the Operating Partnership; the Parent Company is a limited partner of the Operating Partnership, and, through its ownership of Holdings and its limited partnership interest, controls the operations of the Operating Partnership, holding a 99.5% ownership interest therein as of September 30, 2018. The remaining ownership interests in the Operating Partnership (the “Units”) are held by certain former owners of assets acquired by the Operating Partnership. The Parent Company, the Operating Partnership and their consolidated subsidiaries are collectively referred to in this report as the “Company.” In addition, terms such as “we,” “us,” or “our” used in this report may refer to the Company, the Parent Company and/or the Operating Partnership. At September 30, 2018, we had an ownership interest in, and/or managed 725 self-storage properties in 28 states under the name Life Storage ® We consolidate all wholly-owned subsidiaries and joint ventures are consolidated when we control the entity. Our consolidated financial statements include the accounts of the Parent Company, the Operating Partnership, Life Storage Solutions, LLC (the Parent Company’s taxable REIT subsidiary), Warehouse Anywhere LLC (an entity owned 60% by Life Storage Solutions, LLC), and all other wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated. Investments in joint ventures that we do not control but for which we have significant influence over are accounted for using the equity method. Included in the Parent Company’s consolidated balance sheets are noncontrolling redeemable Operating Partnership Units and included in the Operating Partnership’s consolidated balance sheets are limited partners’ redeemable capital interest at redemption value. These interests are presented in the “mezzanine” section of the consolidated balance sheet because they do not meet the functional definition of a liability or equity under current accounting literature. These represent the outside ownership interests of the limited partners in the Operating Partnership. There were 215,009 and 217,481 noncontrolling redeemable Operating Partnership Units outstanding at September 30, 2018 and December 31, 2017, respectively. These unitholders are entitled to receive distributions per unit equivalent to the dividends declared per share on the Parent Company’s common stock. The Operating Partnership is obligated to redeem each of these limited partnership units in the Operating Partnership at the request of the holder thereof for cash equal to the fair market value of a share of the Parent Company’s common stock based on a 10-day average of the daily market price, at the time of such redemption, provided that the Company at its option may elect to acquire any such Unit presented for redemption for one common share or cash. The Company accounts for these noncontrolling redeemable Operating Partnership Units under the provisions of Accounting Standards Codification (ASC) Topic 480-10-S99. The application of the ASC Topic 480-10-S99 accounting model requires the noncontrolling interest to follow normal noncontrolling interest accounting and then be marked to redemption value at the end of each reporting period if higher (but never adjusted below that normal noncontrolling interest accounting amount). The offset to the adjustment to the carrying amount of the noncontrolling interests is reflected in the Company’s dividends in excess of net income and in the Operating Partnership’s general partner and limited partners capital balances. Accordingly, in the accompanying consolidated balance sheets, noncontrolling interests are reflected at redemption value at September 30, 2018 and December 31, 2017, equal to the number of noncontrolling interest units outstanding multiplied by the fair market value of the Parent Company’s common stock at that date. Redemption value exceeded the value determined under the Company’s historical basis of accounting at those dates. The following is a reconciliation of the Parent Company’s noncontrolling redeemable Operating Partnership Units and the Operating Partnership’s limited partners’ redeemable capital interest for the period: (dollars in thousands) Nine Months Ended September 30, 2018 Beginning balance $ 19,373 Redemption of units (203 ) Net income attributable to noncontrolling interest in the Operating Partnership 535 Distributions (650 ) Adjustment to redemption value 1,451 Ending balance $ 20,506 The disaggregated revenues of the Company presented in accordance with ASC Topic 606 “Revenue from Contracts with Customers” (dollars in thousands) Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Rental income $ 128,818 $ 124,044 $ 376,334 $ 363,284 Management and acquisition fee income 2,661 2,478 7,602 7,479 Revenues related to tenant insurance 5,805 5,833 17,290 16,807 Other 4,199 3,213 11,359 9,103 Total operating revenues $ 141,483 $ 135,568 $ 412,585 $ 396,673 Revenues related to tenant insurance and management and acquisition fee income are included in other operating income in the consolidated statements of operations. During 2018, approximately 21% and 13% of the Company’s revenue was derived from self-storage facilities in the states of Texas and Florida, respectively.

Stock Based Compensation

Stock Based Compensation	9 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Based Compensation	3. STOCK BASED COMPENSATION The Company accounts for stock-based compensation under the provisions of ASC Topic 718, “ Compensation - Stock Compensation For awards with graded vesting, compensation cost is recognized on a straight-line basis over the related vesting period. For the three months ended September 30, 2018 and 2017, the Company recorded compensation expense (included in general and administrative expense) of $0 and $4,000, respectively, related to stock options and $1,456,000 and $1,659,000, respectively, related to amortization of non-vested stock grants and performance-based awards. For the nine months ended September 30, 2018 and 2017, the Company recorded compensation expense of $7,000 and $11,000, respectively, related to stock options and $4,203,000 and $4,905,000, respectively, related to amortization of non-vested stock grants and performance-based awards. During the nine months ended September 30, 2018, 71,606 stock options were exercised by employees and directors. No stock options were exercised by employees and directors during the nine months ended September 30, 2017. During the three months ended September 30, 2018 and 2017, 11,114 and 19,537 shares of non-vested stock, respectively, vested. During the nine months ended September 30, 2018 and 2017, 51,067 and 66,565 shares of non-vested stock, respectively, vested. During the nine months ended September 30, 2018, the Company issued 14,865 shares of non-vested stock to certain employees and non-employee directors which vest over periods ranging from one year to eight years. The fair market value on the date of grant of the non-vested stock issued during the nine months ended September 30, 2018 ranged from $81.86 to $94.08, resulting in an aggregate fair value of $1.4 million. During the nine months ended September 30, 2018, the Company granted performance-based awards that entitle the recipient to earn up to 7,732 shares if certain performance criteria are achieved over a three-year period. The Company estimated the aggregate fair value of the awards on the grant date to be $0.3 million. In September 2018, the Company announced that current Chief Executive Officer, David Rogers, would be retiring effective March 1, 2019. In conjunction with this announcement, the vesting periods of certain restricted stock awards and performance-based awards previously granted to Mr. Rogers were accelerated to reflect his March 1, 2019 retirement date. As a result of this change, an additional $0.2 million of compensation expense was recorded during the three and nine months ended September 30, 2018 and additional compensation expense of $0.7 million and $0.4 million is expected to be recorded during three months ended December 31, 2018 and the three months ended March 31, 2019, respectively.

Cash and Restricted Cash

Cash and Restricted Cash	9 Months Ended
	Sep. 30, 2018
Cash And Cash Equivalents [Abstract]
Cash and Restricted Cash	4. CASH AND RESTRICTED CASH Restricted cash is included in other assets in the consolidated balance sheets and represents those amounts required to be placed in escrow by banks with whom the Company has entered into mortgages and cash placed in escrow related to amounts received upon disposal of real estate, restricted for use on future acquisitions of real estate. The following table provides a reconciliation of cash and restricted cash reported within the consolidated statement of cash flows: (Dollars in thousands) September 30, 2018 December 31, 2017 September 30, 2017 Cash $ 13,282 $ 9,167 $ 6,096 Restricted cash 5,665 292 606 Total cash and restricted cash $ 18,947 $ 9,459 $ 6,702

Investment in Storage Facilitie

Investment in Storage Facilities and Intangible Assets	9 Months Ended
	Sep. 30, 2018
Real Estate [Abstract]
Investment in Storage Facilities and Intangible Assets	5. INVESTMENT IN STORAGE FACILITIES AND INTANGIBLE ASSETS The following summarizes our activity in storage facilities during the nine months ended September 30, 2018: (dollars in thousands) Cost: Beginning balance $ 4,321,410 Acquisitions of storage facilities 19,172 Improvements and equipment additions 29,911 Net increase in construction in progress 15,393 Dispositions (12,299 ) Ending balance $ 4,373,587 Accumulated Depreciation: Beginning balance $ 624,314 Additions during the period 76,844 Dispositions (3,188 ) Ending balance $ 697,970 The Company acquired two self-storage facilities during the nine months ended September 30, 2018. The acquisitions of these facilities were accounted for as asset acquisitions. The costs of the facilities, including closing costs, were allocated to land, building, equipment and improvements, and in-place customer leases based upon their relative fair values. The purchase prices of the facilities acquired in 2018 have been assigned as follows: (dollars in thousands) Consideration paid States Number of Properties Date of Acquisition Purchase Price Cash Paid Value of Operating Partnership Units Issued Mortgage Assumed Net Other Liabilities (Assets) Assumed Land Building, Equipment, and Improvements In-Place Customers Leases Closing Costs Expensed NH 1 9/4/2018 $ 5,641 $ 5,609 $ - $ - $ 32 $ 1,256 $ 4,276 $ 109 $ - CA 1 9/18/2018 $ 13,846 $ 13,800 $ - $ - $ 46 $ 2,089 $ 11,551 $ 206 $ - Total acquired in 2018 2 $ 19,487 $ 19,409 $ - $ - $ 78 $ 3,345 $ 15,827 $ 315 $ - All properties were purchased from unrelated third parties. Non-cash investing activities during the nine months ended September 30, 2018 include the assumption of net other liabilities totaling $78,000. The Company measures the fair value of in-place customer lease intangible assets based on the Company’s experience with customer turnover and the cost to replace the in-place leases. The Company amortizes in-place customer leases on a straight-line basis over 12 months (the estimated future benefit period). The Company measures the value of trade names, which have an indefinite life and are not amortized, by calculating discounted cash flows utilizing the relief from royalty method. In-place customer leases are included in other assets on the Company’s consolidated balance sheets as follows: (Dollars in thousands) September 30, 2018 December 31, 2017 In-place customer leases $ 75,226 $ 75,241 Accumulated amortization (74,920 ) (75,241 ) Net carrying value at the end of period $ 306 $ — Amortization expense related to in-place customer leases was $9,000 and $0.1 million for the three months ended September 30, 2018 and 2017, respectively, and was $9,000 and $24.8 million for the nine months ended September 30, 2018 and 2017, respectively. The Company expects to record $0.1 million and $0.2 million of amortization expense for the years ended December 31, 2018 and December 31, 2019, respectively. Property Dispositions During 2018, the Company sold one non-strategic property and received cash of $9.6 million, resulting in a gain on sale of $0.9 million. Change in Useful Life Estimates As part of the Company’s capital improvement efforts during 2017 and 2018, buildings at certain self-storage facilities were identified for replacement. As a result of the decision to replace these buildings, the Company reassessed the estimated useful lives of the then existing buildings. This useful life reassessment resulted in an increase in depreciation expense of approximately $2.4 million and $2.8 million, respectively, during the three and nine months ended September 30, 2018 and $2.0 million and $3.6 million, respectively, during the three and nine months ended September 30, 2017. The Company estimates that the change in estimated useful lives of buildings identified for replacement as of September 30, 2018 will result in additional increases in depreciation expense of approximately $0.5 million during the fourth quarter of 2018. The accelerated depreciation resulting from the events discussed above reduced both basic and diluted earnings per share/unit by approximately $0.04 and $0.05, for the three and nine months ended September 30, 2018, respectively, and by approximately $0.04 and $0.07 for the three and nine months ended September 30, 2017, respectively.

Unsecured Line of Credit and Te

Unsecured Line of Credit and Term Notes	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Unsecured Line of Credit and Term Notes	6. UNSECURED LINE OF CREDIT AND TERM NOTES Borrowings outstanding on our unsecured line of credit and term notes are as follows: (Dollars in thousands) September 30, 2018 December 31, 2017 Revolving line of credit borrowings $ 128,000 $ 105,000 Term note due June 4, 2020 100,000 100,000 Term note due August 5, 2021 100,000 100,000 Term note due April 8, 2024 175,000 175,000 Senior term note due July 1, 2026 600,000 600,000 Senior term note due December 15, 2027 450,000 450,000 Term note due July 21, 2028 200,000 200,000 Total term note principal balance outstanding $ 1,625,000 $ 1,625,000 Less: unamortized debt issuance costs (9,913 ) (10,962 ) Less: unamortized senior term note discount (4,539 ) (4,949 ) Term notes payable $ 1,610,548 $ 1,609,089 As of September 30, 2018, the Company’s unsecured credit agreement included a $500 million revolving credit facility with a maturity date of December 10, 2019 and a term note in the principal amount of $100 million with a maturity date of June 4, 2020. The term note was initially in the amount of $325 million. In 2017, the Company repaid $225 million under this term note. Such credit agreement provided for interest on the revolving credit facility at a variable annual rate equal to LIBOR plus a margin based on the Company’s credit rating (at September 30, 2018 the margin is 1.10%), interest on the term note at a variable annual rate equal to LIBOR plus a margin based on the Company’s credit rating (at September 30, 2018 the margin is 1.15%), and required an annual 0.15% facility fee on the revolving credit facility. The interest rate on the Company’s line of credit at September 30, 2018 was approximately 3.28% (2.63% at December 31, 2017) and the interest rate on the term note at September 30, 2018 was approximately 3.25% (2.53% at December 31, 2017). At September 30, 2018, there was $371.2 million available on the unsecured revolving line of credit. On October 30, 2018, the Company entered into an amended and restated credit facility which replaced the credit facility discussed above. Under the amended credit facility, the Company’s revolving credit facility remains at $500 million and the maturity date of such facility is extended to March 10, 2023. The new revolving credit facility bears interest at a variable annual rate equal to LIBOR plus a margin based on the Company’s credit rating (at October 30, 2018 the margin is 0.95%) and requires an annual facility fee which varies based upon the Company’s credit rating (at October 30, 2018 the facility fee is 0.15%). Also, under the amended credit facility, the $100 million term note previously existing was replaced with a new $100 million term note, with the maturity date remaining June 4, 2020. The new $100 million term note bears interest at a variable annual rate equal to LIBOR plus a margin based on the Company’s credit rating (at October 30, 2018 the margin is 1.00%). The Company has the option under the new credit facility to increase the total aggregate principal amount of the facilities to $900 million. On December 7, 2017, the Operating Partnership issued $450 million in aggregate principal amount of 3.875% unsecured senior notes due December 15, 2027 (the “2027 Senior Notes”). The 2027 Senior Notes were issued at a 0.477% discount to par value. Interest on the 2027 Senior Notes is payable semi-annually on each June 15 and December 15, beginning on June 15, 2018. The 2027 Senior Notes are fully and unconditionally guaranteed by the Parent Company. Proceeds received upon issuance, net of discount to par of $2.1 million and underwriting discount and other offering expenses of $4.0 million, totaled $443.9 million. On June 20, 2016, the Operating Partnership issued $600 million in aggregate principal amount of 3.50% unsecured senior notes due July 1, 2026 (the “2026 Senior Notes”). The 2026 Senior Notes were issued at a 0.553% discount to par value. Interest on the 2026 Senior Notes is payable semi-annually in arrears on each January 1 and July 1. The 2026 Senior Notes are fully and unconditionally guaranteed by the Parent Company. Proceeds received upon issuance, net of discount to par of $3.3 million and underwriting discount and other offering expenses of $5.5 million, totaled $591.2 million. The indenture under which the 2027 Senior Notes and the 2026 Senior Notes were issued restricts the ability of the Company and its subsidiaries to incur debt unless the Company and its consolidated subsidiaries comply with a leverage ratio not to exceed 60% and an interest coverage ratio of more than 1.5:1 on all outstanding debt, after giving effect to the incurrence of the debt. The indenture also restricts the ability of the Company and its subsidiaries to incur secured debt unless the Company and its consolidated subsidiaries comply with a secured debt leverage ratio not to exceed 40% after giving effect to the incurrence of the debt. The indenture also contains other financial and customary covenants, including a covenant not to own unencumbered assets with a value less than 150% of the unsecured indebtedness of the Company and its consolidated subsidiaries. At September 30, 2018, the Company was in compliance with such covenants. On July 21, 2016, the Company entered into a $200 million term note maturing July 21, 2028 bearing interest at a fixed rate of 3.67%. On April 8, 2014, the Company entered into a $175 million term note maturing April 8, 2024 bearing interest at a fixed rate of 4.533%. The interest rate on the term note increases to 6.283% if the Company is not rated by at least one rating agency or if the Company’s credit rating is downgraded. In 2011, the Company entered into a $100 million term note maturing August 5, 2021 bearing interest at a fixed rate of 5.54%. The interest rate on the term note increases to 7.29% if the notes are not rated by at least one rating agency, the credit rating on the notes is downgraded or if the Company’s credit rating is downgraded. The line of credit and term notes require the Company to meet certain financial covenants, measured on a quarterly basis, including prescribed leverage, fixed charge coverage, minimum net worth, limitations on additional indebtedness and limitations on dividend payouts. At September 30, 2018, the Company was in compliance with such covenants. We believe that if operating results remain consistent with historical levels and levels of other debt and liabilities remain consistent with amounts outstanding at September 30, 2018, the entire availability on the line of credit could be drawn without violating our debt covenants. The Company’s fixed rate term notes contain a provision that allows for the noteholders to call the debt upon a change of control of the Company at an amount that includes a make whole premium based on rates in effect on the date of the change of control. Deferred debt issuance costs and the discount on the outstanding term notes are both presented as reductions of term notes in the accompanying consolidated balance sheets at September 30, 2018 and December 31, 2017. Amortization expense related to deferred debt issuance costs was $0.5 million for each of the three months ended September 30, 2018 and 2017, and $1.6 million for each of the nine months ended September 30, 2018 and 2017, and is included in interest expense in the consolidated statements of operations.

Mortgages Payable and Debt Matu

Mortgages Payable and Debt Maturities	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Mortgages Payable and Debt Maturities	7. MORTGAGES PAYABLE AND DEBT MATURITIES Mortgages payable at September 30, 2018 and December 31, 2017 consist of the following: (dollars in thousands) September 30, 2018 December 31, 2017 4.98% mortgage note due January 1, 2021, secured by one self-storage facility with an aggregate net book value of $9.5 million, principal and interest paid monthly (effective interest rate 5.24%) $ 2,877 $ 2,916 4.065% mortgage note due April 1, 2023, secured by one self- storage facility with an aggregate net book value of $7.5 million, principal and interest paid monthly (effective interest rate 4.31%) 4,051 4,119 5.26% mortgage note due November 1, 2023, secured by one self-storage facility with an aggregate net book value of $7.9 million, principal and interest paid monthly (effective interest rate 5.58%) 3,888 3,939 5.99% mortgage note due May 1, 2026, secured by one self- storage facility with an aggregate net book value of $6.5 million, principal and interest paid monthly (effective interest rate 6.30%) 1,581 1,700 Total mortgages payable $ 12,397 $ 12,674 The table below summarizes the Company’s debt obligations at September 30, 2018. The estimated fair value of financial instruments is subjective in nature and is dependent on a number of important assumptions, including discount rates and relevant comparable market information associated with each financial instrument. The fair value of the fixed rate term notes and mortgage notes were estimated by discounting the future cash flows using the current rates at which similar loans would be made to borrowers with similar credit ratings and for the same remaining maturities. These assumptions are considered Level 2 inputs within the fair value hierarchy as described in Note 9. The carrying values of our variable rate debt instruments approximate their fair values as these debt instruments bear interest at current market rates that approximate market participant rates. This is considered a Level 2 input within the fair value hierarchy. The use of different market assumptions and estimation methodologies may have a material effect on the reported estimated fair value amounts. Accordingly, the estimates presented below are not necessarily indicative of the amounts the Company would realize in a current market exchange. Expected Maturity Date Including Discount (dollars in thousands) 2018 2019 2020 2021 2022 Thereafter Total Fair Value Line of credit - variable rate LIBOR + 1.10% (3.28% at September 30, 2018) — $ 128,000 — — — — $ 128,000 $ 128,000 Notes Payable: Term note - variable rate LIBOR + 1.15% (3.25% at September 30, 2018) — — $ 100,000 — — — $ 100,000 $ 100,000 Term note - fixed rate 5.54% — — — $ 100,000 — — $ 100,000 $ 104,084 Term note - fixed rate 4.533% — — — — — $ 175,000 $ 175,000 $ 176,767 Term note - fixed rate 3.50% — — — — — $ 600,000 $ 600,000 $ 563,528 Term note - fixed rate 3.875% — — — — — $ 450,000 $ 450,000 $ 421,815 Term note - fixed rate 3.67% — — — — — $ 200,000 $ 200,000 $ 180,734 Mortgage note - fixed rate 4.98% $ 14 $ 56 $ 59 $ 2,748 — — $ 2,877 $ 2,887 Mortgage note - fixed rate 4.065% $ 23 $ 96 $ 99 $ 104 $ 108 $ 3,621 $ 4,051 $ 3,911 Mortgage note - fixed rate 5.26% $ 17 $ 71 $ 74 $ 78 $ 83 $ 3,565 $ 3,888 $ 3,944 Mortgage note - fixed rate 5.99% $ 41 $ 170 $ 181 $ 192 $ 203 $ 794 $ 1,581 $ 1,638 Total $ 95 $ 128,393 $ 100,413 $ 103,122 $ 394 $ 1,432,980 $ 1,765,397

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	8. DERIVATIVE FINANCIAL INSTRUMENTS Interest rate swaps have been used by the Company to adjust the proportion of total debt that is subject to variable interest rates. The interest rate swaps require the Company to pay an amount equal to a specific fixed rate of interest times a notional principal amount and to receive in return an amount equal to a variable rate of interest times the same notional amount. The notional amounts are not exchanged. Forward starting interest rate swaps have also been used by the Company to hedge the risk of changes in the interest-related cash outflows associated with the potential issuance of long-term debt. No other cash payments are made unless the contract is terminated prior to its maturity, in which case the contract would likely be settled for an amount equal to its fair value. The Company enters into interest rate swaps with a number of major financial institutions to minimize counterparty credit risk. Interest rate swaps qualify and are designated as hedges of the amount of future cash flows related to interest payments on variable rate debt. Therefore, interest rate swaps are recorded in the consolidated balance sheets at fair value and the related gains or losses are deferred in shareholders’ equity or partners’ capital as Accumulated Other Comprehensive Loss (“AOCL”). These deferred gains and losses are recognized in interest expense during the period or periods in which the related interest payments affect earnings. However, to the extent that the interest rate swaps are not perfectly effective in offsetting the change in value of the interest payments being hedged, the ineffective portion of these contracts is recognized in earnings immediately. Ineffectiveness was de minimis for the three and nine months ended September 30, 2018 and 2017. In 2017, the Company terminated hedges and settled interest rate swap agreements on $225 million of the Company’s variable rate debt in connection with repayment of the related variable rate term notes. As a result of the termination, no gains or losses related to the terminated interest rate swaps are included in AOCL at September 30, 2018 or December 31, 2017. In the third quarter of 2018, the Company’s last remaining interest rate swaps on $100 million of the Company’s variable rate debt expired and were settled by the Company. As a result, no gains or losses related to the expired interest rate swaps are included in AOCL at September 30, 2018. In the fourth quarter of 2015, the Company entered into forward starting interest rate swap agreements with a total notional value of $50 million. In the first quarter of 2016, the Company entered into additional forward starting interest rate swap agreements with a total notional value of $100 million. These forward starting interest rate swap agreements were entered into to hedge the risk of changes in the interest-related cash flows associated with the potential issuance of fixed rate long-term debt. In conjunction with the issuance of the $600 million 2026 Senior Notes (see Note 6), the Company terminated these hedges and settled the forward starting swap agreements for approximately $9.2 million. The $9.2 million was deferred in AOCL and is being amortized as additional interest expense over the ten-year term of the $600 million 2026 Senior Notes or until such time as interest payments on the 2026 Senior Notes are no longer probable. There are no derivative instruments, as defined by FASB ASC Topic 815 “ Derivatives and Hedging The changes in AOCL for the three and nine months ended September 30, 2018 and 2017 are summarized as follows: (dollars in thousands) Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Accumulated other comprehensive loss beginning of period $ (7,204 ) $ (19,616 ) $ (7,587 ) $ (21,475 ) Realized loss reclassified from accumulated other comprehensive loss to interest expense 54 758 363 2,835 Unrealized gain (loss) from changes in the fair value of the effective portion of the interest rate swaps 46 44 120 (174 ) Gain included in other comprehensive loss 100 802 483 2,661 Accumulated other comprehensive loss end of period $ (7,104 ) $ (18,814 ) $ (7,104 ) $ (18,814 )

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	9. FAIR VALUE MEASUREMENTS The Company applies the provisions of ASC Topic 820 “ Fair Value Measurements and Disclosures Refer to Note 7 for presentation of the fair values of debt obligations which are disclosed at fair value on a recurring basis. There were no assets or liabilities carried at fair value measured on a recurring basis as of September 30, 2018. The following table provides the assets carried at fair value measured on a recurring basis as of December 31, 2017 (dollars in thousands): Asset (Liability) Level 1 Level 2 Level 3 December 31, 2017 Interest rate swaps $ 205 — $ 205 — Interest rate swaps are over the counter securities with no quoted readily available Level 1 inputs, and therefore are measured at fair value using inputs that are directly observable in active markets and are classified within Level 2 of the valuation hierarchy, using the income approach.

Investment in Joint Ventures

Investment in Joint Ventures	9 Months Ended
	Sep. 30, 2018
Equity Method Investments And Joint Ventures [Abstract]
Investment in Joint Ventures	10. INVESTMENT IN JOINT VENTURES A summary of the Company’s unconsolidated joint ventures is as follows: Venture Number of Properties at September 30, 2018 Company common ownership interest at September 30, 2018 Carrying value of investment at September 30, 2018 Carrying value of investment at December 31, 2017 Sovran HHF Storage Holdings LLC (“Sovran HHF”) 1 57 20% $86.2 million $85.1 million Sovran HHF Storage Holdings II LLC (“Sovran HHF II”) 2 30 15% $13.1 million $13.3 million 191 III Holdings LLC (“191 III”) 3 6 20% $9.2 million $9.4 million Life Storage-SERS Storage LLC (“SERS”) 4 3 20% $3.6 million $3.6 million Iskalo Office Holdings, LLC (“Iskalo”) 5 N/A 49% ($0.4 million) ($0.4 million) Urban Box Coralway Storage, LLC (“Urban Box”) 6 1 85% $4.5 million $4.1 million SNL/Orix 1200 McDonald Ave., LLC (“McDonald”) 7 1 5% $2.8 million $2.7 million SNL Orix Merrick, LLC (“Merrick”) 8 1 5% $2.5 million $2.5 million Review Avenue Partners, LLC (“RAP”) 9 1 40% $11.1 million $11.5 million N 32nd Street Self Storage, LLC (“N32”) 10 1 46% $1.3 million $1.3 million NYX Don Mills Storage LP ("Don Mills") 11 1 17% $1.0 million N/A 1 2 3 4 5 6 7 8 9 10 11 Based on the facts and circumstances of each of the Company’s joint ventures, the Company has determined that none of the joint ventures is a variable interest entity (VIE) in accordance with ASC 810, Consolidation The carrying values of the Company’s investments in joint ventures are assessed for other-than-temporary impairment on a periodic basis and no such impairments have been recorded on any of the Company’s investments in joint ventures. The Company earns management and/or call center fees ranging from 6% to 7% of joint venture gross revenues as property manager of the self-storage facilities owned by HHF, HHF II, 191 III, SERS, Urban Box, McDonald, Merrick, RAP and N32. These fees, which are included in other operating income in the consolidated statements of operations, totaled $2.0 million and $1.9 million for the three months ended September 30, 2018 and 2017, respectively, and $5.8 million and $4.8 million for the nine months ended September 30, 2018 and 2017, respectively. The Company’s share of the unconsolidated joint ventures’ income (loss) is as follows: (dollars in thousands) Venture Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Sovran HHF $ 828 $ 588 $ 2,257 $ 1,750 Sovran HHF II 436 398 1,235 1,100 191 III 7 (14 ) 43 12 SERS 20 (43 ) 107 (43 ) RAP (215 ) (248 ) (648 ) (749 ) Merrick (6 ) — (38 ) — McDonald (10 ) — (10 ) — Urban Box (19 ) — (19 ) — N32 (48 ) — (48 ) — Iskalo 53 71 187 189 $ 1,046 $ 752 $ 3,066 $ 2,259 A summary of the unconsolidated joint ventures’ financial statements as of and for the nine months ended September 30, 2018 is as follows: (dollars in thousands) Balance Sheet Data: Investment in storage facilities, net $ 1,074,916 Investment in office building, net 4,669 Other assets 19,554 Total Assets $ 1,099,139 Due to the Company $ 742 Mortgages payable 458,690 Other liabilities 7,043 Total Liabilities $ 466,475 Unaffiliated partners’ equity 497,724 Company equity 134,940 Total Partners’ Equity 632,664 Total Liabilities and Partners’ Equity $ 1,099,139 Income Statement Data: Total revenues $ 84,591 Property operating expenses (26,249 ) Administrative, management and call center fees (6,640 ) Depreciation and amortization of customer list (19,096 ) Amortization of financing fees (731 ) Income tax expense (232 ) Interest expense (13,284 ) Net income $ 18,359 The Company does not guarantee the debt of any of its equity method investees. We do not expect to have material future cash outlays relating to these joint ventures outside of our share of capital for future acquisitions of properties and our share of the payoff of secured debt held by these joint ventures.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	11. INCOME TAXES The Company qualifies as a REIT under the Internal Revenue Code of 1986, as amended, and will generally not be subject to corporate income taxes to the extent it distributes its taxable income to its shareholders and complies with certain other requirements. The Company has elected to treat one of its subsidiaries as a taxable REIT subsidiary. In general, the Company’s taxable REIT subsidiary may perform additional services for tenants and generally may engage in certain real estate or non-real estate related business. A taxable REIT subsidiary is subject to corporate federal and state income taxes. Deferred tax assets and liabilities are determined based on differences between financial reporting and tax bases of assets and liabilities. The Company recorded federal and state income tax expense of $0.8 million and $0.9 million for the three months ended September 30, 2018 and 2017, respectively. The Company recorded federal and state income tax expense of $1.9 million for the nine months ended September 30, 2018 and federal and state income tax benefit of $1.3 million for the nine months ended September 30, 2017. At September 30, 2018 and 2017, there were no material unrecognized tax benefits. Interest and penalties relating to uncertain tax positions will be recognized in income tax expense when incurred. As of September 30, 2018 and 2017, the Company had no interest or penalties related to uncertain tax positions. Income taxes payable at September 30, 2018 and December 31, 2017 are classified within accounts payable and accrued liabilities in the consolidated balance sheets. Prepaid income taxes at September 30, 2018 and December 31, 2017 are classified within prepaid expenses, while the net deferred tax assets of our taxable REIT subsidiary at September 30, 2018 and December 31, 2017 are classified within other assets in the consolidated balance sheets. As of September 30, 2018, the Company’s taxable REIT subsidiary has prepaid taxes of $0.2 million, deferred tax assets totaling $2.3 million, and a deferred tax liability of $1.5 million. As of December 31, 2017, the Company’s taxable REIT subsidiary has prepaid taxes of $0.1 million, deferred tax assets of $3.6 million and a deferred tax liability of $1.7 million. The tax years 2013-2017 remain open to examination by the major taxing jurisdictions to which the Company is subject. The Tax Cuts and Jobs Act (the “TCJA”) was passed by Congress on December 20, 2017 and signed into law by President Trump on December 22, 2017. The TCJA significantly changed the U.S. federal income tax laws applicable to businesses and their owners, including REITs and their shareholders. Under the TCJA, the corporate income tax rate is reduced from a maximum rate of 35% to a flat 21% rate. The reduced corporate income tax rate, which is effective for taxable years beginning after December 31, 2017, applies to income earned by our taxable REIT subsidiary. As a result, the deferred tax assets and deferred tax liabilities of our taxable REIT subsidiary are measured at September 30, 2018 using the 21% corporate income tax rate.

Earnings Per Share and Earnings

Earnings Per Share and Earnings Per Unit	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share and Earnings Per Unit	12. EARNINGS PER SHARE AND EARNINGS PER UNIT The Company reports earnings per share and earnings per unit data in accordance ASC Topic 260, “ Earnings Per Share The following table sets forth the computation of basic and diluted earnings per common share utilizing the two-class method. Earnings Per Share (in thousands except per share data) Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Numerator: Net income attributable to common shareholders $ 41,120 $ 35,496 $ 114,283 $ 75,280 Denominator: Denominator for basic earnings per share – weighted average shares 46,526 46,416 46,487 46,362 Effect of Dilutive Securities: Stock options and non-vested stock 102 104 93 110 Denominator for diluted earnings per share – adjusted weighted average shares and assumed conversion 46,628 46,520 46,580 46,472 Basic earnings per common share attributable to common shareholders $ 0.88 $ 0.76 $ 2.46 $ 1.62 Diluted earnings per common share attributable to common shareholders $ 0.88 $ 0.76 $ 2.45 $ 1.62 Earnings Per Unit The following table sets forth the computation of basic and diluted earnings per common unit utilizing the two-class method. (in thousands except per unit data) Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Numerator: Net income attributable to common unitholders $ 41,120 $ 35,496 $ 114,283 $ 75,280 Denominator: Denominator for basic earnings per unit – weighted average units 46,526 46,416 46,487 46,362 Effect of Dilutive Securities: Stock options and non-vested stock 102 104 93 110 Denominator for diluted earnings per unit – adjusted weighted average units and assumed conversion 46,628 46,520 46,580 46,472 Basic earnings per common unit attributable to common unitholders $ 0.88 $ 0.76 $ 2.46 $ 1.62 Diluted earnings per common unit attributable to common unitholders $ 0.88 $ 0.76 $ 2.45 $ 1.62 Not included in the effect of dilutive securities above for both earnings per share and earnings per unit are 88,621 unvested restricted shares for the three months ended September 30, 2018, and 17,500 stock options and 133,179 unvested restricted shares for the three months ended September 30, 2017, because their effect would be antidilutive. Not included in the effect of dilutive securities above are 7,333 stock options and 105,935 unvested restricted shares for the nine months ended September 30, 2018, and 14,667 stock options and 139,107 unvested restricted shares for the nine months ended September 30, 2017, because their effect would be antidilutive.

Shareholders' Equity

Shareholders' Equity	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Shareholders' Equity	13. SHAREHOLDERS’ EQUITY The following is a reconciliation of the changes in the Parent Company’s total shareholders’ equity for the period: (dollars in thousands) Nine Months Ended September 30, 2018 Beginning balance of total shareholders’ equity $ 2,028,323 Exercise of stock options 2,977 Earned portion of non-vested stock 4,203 Stock option expense 7 Carrying value less than redemption value on redeemed noncontrolling interest (29 ) Adjustment to redemption value on noncontrolling redeemable Operating Partnership units (1,451 ) Net income attributable to common shareholders 114,283 Amortization of terminated hedge included in AOCL 688 Change in fair value of derivatives (205 ) Dividends (139,235 ) Ending balance of total shareholders’ equity $ 2,009,561 On June 14, 2018, the Company entered into a continuous equity offering program (“Equity Program”) with Wells Fargo Securities, LLC, Jefferies LLC, SunTrust Robinson Humphrey, Inc., HSBC Securities (USA) Inc., BB&T Capital Markets, a division of BB&T Securities, LLC, and BTIG, LLC, pursuant to which the Company may sell up to $300 million in aggregate offering price of shares of the Company’s common stock. Actual sales under the Equity Program will depend on a variety of factors and conditions, including, but not limited to, market conditions, the trading price of the Company’s common stock, and determinations of the appropriate sources of funding for the Company. The Company expects to continue to offer, sell and issue shares of common stock under the Equity Program from time to time based on various factors and conditions, although the Company is under no obligation to sell any shares under the Equity program. During the nine months ended September 30, 2018, the Company did not issue any shares of common stock under the Equity Program and as of September 30, 2018, the entire $300 million authorized under the Equity Program remains available for issuance. On August 2, 2017, the Company’s Board of Directors authorized the repurchase of up to $200 million of the Company’s outstanding common shares (“Buyback Program”). The Buyback Program allows the Company to purchase shares of its common stock in accordance with applicable securities laws on the open market, through privately negotiated transactions, or through other methods of acquiring shares. The Buyback Program may be suspended or discontinued at any time. The Company did not repurchase any outstanding common shares under the Buyback Program during the nine months ended September 30, 2018. In 2013, the Company implemented a Dividend Reinvestment Plan. The Company issued 199,809 shares under the plan during the nine months ended September 30, 2017. On August 2, 2017, the Company’s Board of Directors suspended the Dividend Reinvestment Plan.

Partners' Capital

Partners' Capital	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Partners' Capital	14. PARTNERS’ CAPITAL The following is a reconciliation of the changes in total partners’ capital for the period: (dollars in thousands) Nine Months Ended September 30, 2018 Beginning balance of total controlling partners’ capital $ 2,028,323 Exercise of stock options 2,977 Earned portion of non-vested stock 4,203 Stock option expense 7 Carrying value less than redemption value on redeemed noncontrolling interest (29 ) Adjustment to redemption value on limited partners’ redeemable capital interests (1,451 ) Net income attributable to common unitholders 114,283 Amortization of terminated hedge included in AOCL 688 Change in fair value of derivatives (205 ) Distributions (139,235 ) Ending balance of total controlling partners’ capital $ 2,009,561

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2018
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	15. RECENT ACCOUNTING PRONOUNCEMENTS In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” which supersedes the revenue recognition requirements in “Revenue Recognition (Topic 605),” and requires an entity to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. ASU 2014-09 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017 and is therefore effective for the Company as of January 1, 2018. The Company had the option to apply the provisions of ASU 2014-09 either retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying the new guidance recognized at the date of initial application (the modified retrospective transition method). The Company elected to adopt the standard using the modified retrospective transition method. Leases are specifically excluded from the scope of ASU 2014-09, therefore, upon analysis, the Company concluded that the adoption of the new standard did not have any impact on the timing or amounts of the Company’s rental revenue from customers which represents over of the Company’s total operating revenues. We have evaluated the other revenue streams material to the Company and have concluded that the adoption of the new standard did not have any material impact on the timing or amounts of the Company’s material revenue streams and no cumulative effect adjustment is required as of the date of initial application. Payment from such revenue streams is due and generally collected upon invoice. Also, as part of the Company’s adoption of ASU 2014-09, the Company has elected to apply the guidance only to contracts that are not completed contracts at the date of initial application. Further, related to the Company’s management fee revenue stream which relates to managing self-storage facilities for third-parties and unconsolidated joint ventures, the Company has elected to apply a practical expedient provided in the new standard which allows the Company to recognize revenue in the amount of management fees to which the Company has a right to invoice as that amount corresponds directly with the value to the customer of the entity’s performance completed to date In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842)”. This guidance revises existing practice related to accounting for leases under Accounting Standards Codification Topic 840 Leases In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a Consensus of the Emerging Issues Task Force)” in an effort to reduce existing diversity in practice related to the classification of certain cash receipts and cash payments on the statements of cash flows. The guidance addresses the classification of cash flows related to, among other things, distributions received from equity method investees. The amendments in this update are effective for annual periods beginning after December 15, 2017, and interim periods within those annual periods. The Company has elected to use the nature of the distribution approach to classify distributions received from its equity method investees. This approach requires distributions to be classified in the statement of cash flows on the basis of the nature of the activity or activities of the investee that generated the distribution as either a return on investment (classified as a cash inflow from operating activities) or a return of investment (classified as a cash inflow from investing activities). The adoption of ASU 2016-15 effective January 1, 2018 did not have a material impact on the Company’s consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash (a Consensus of the Emerging Issues Task Force)” which requires restricted cash and restricted cash equivalents to be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The amendments in this update are effective for annual periods beginning after December 15, 2017 and interim periods within those fiscal years. Early adoption of this update is permitted. Other than modifications to the statement of cash flows and the additional disclosures in Note 4, the adoption of ASU 2016-18 on January 1, 2018 did not have an impact on the Company’s consolidated financial statements. The consolidated statement of cash flows for the nine months ended September 30, 2017 has been modified to conform to the presentation requirements of ASU 2016-18 which entail including restricted cash along with cash in the beginning balance, ending balance and net change in cash and restricted cash on the consolidated statement of cash flows. In January 2017, the FASB issued ASU 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business” which is intended to assist entities with evaluating whether a set of transferred assets and activities is a business. The amendments in this update are effective for annual periods beginning after December 15, 2017 and interim periods within those fiscal years. Early adoption of this update is permitted and the Company adopted this update effective January 1, 2017. The adoption of ASU 2017-01 is expected to have potential impact on the accounting treatment of properties acquired subsequent to the adoption date. Property acquisitions treated as business combinations under previous guidance may no longer be treated as business combinations subsequent to the adoption of ASU 2017-01. To the extent that properties that we acquire do not meet the definition of a “business” under ASU 2017-01, future acquisitions of properties may be accounted for as asset acquisitions resulting in the capitalization of acquisition costs incurred in connection with these transactions and the allocation of the purchase price and related acquisition costs to the assets acquired based on their relative fair values. The two properties acquired during the nine months ended September 30, 2018 would likely have been accounted for as business combinations prior to the adoption of ASU 2017-01. In February 2017, the FASB issued ASU 2017-05, “Other Income – Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets” which clarifies the scope and application of ASC 610-20 on the sale or transfer of nonfinancial assets, including real estate, and in substance nonfinancial assets to noncustomers, including partial sales. The amendments in this update are effective for annual periods beginning after December 15, 2017, and interim periods within those annual periods. The implementation of this update as of January 1, 2018 could potentially impact the accounting treatment of future real estate sales of the Company if such sales are to parties who are also customers of the Company, though the implementation did not have an impact on the Company’s consolidated financial statements for the period ending September 30, 2018. In May 2017, the FASB issued ASU 2017-09, “Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting” which provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The amendments in this update are effective for annual periods beginning after December 15, 2017, and interim periods within those annual periods. The implementation of this update as of January 1, 2018 did not have a material impact on the Company’s financial statements, however, all future changes to the terms or conditions of any of the Company’s share-based payment awards are subject to the guidance in ASU 2017-09 and could potentially be accounted for differently than under the previous guidance concerning such changes. In August 2018, the FASB issued ASU 2018-15, “Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract” which provides guidance to help entities evaluate the accounting for implementation, setup, and other upfront costs (collectively referred to as implementation costs) incurred by entities that are a customer in a hosting arrangement that is a service contract. The amendments in this update are effective for annual periods beginning after December 15, 2019, and interim periods within those annual periods. The Company is currently evaluating the impact of adopting ASU 2018-15 on its consolidated financial statements.

Commitment and Contingencies

Commitment and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitment and Contingencies	16. COMMITMENT AND CONTINGENCIES At September 30, 2018, the Company was under contract to acquire three self-storage facilities for an aggregate purchase price of $29.3 million. Two of these three self-storage facilities were acquired by the Company subsequent to September 30, 2018 for an aggregate purchase price of $22.1 million. The purchase of the remaining facility is subject to customary conditions to closing, and there is no assurance that this facility will be acquired. On or about August 25, 2014, a putative class action was filed against the Company in the Superior Court of New Jersey Law Division Burlington County. The action sought to obtain declaratory, injunctive and monetary relief for a class of consumers based upon alleged violations by the Company of various statutory laws. On October 17, 2014, the action was removed from the Superior Court of New Jersey Law Division Burlington County to the United States District Court for the District of New Jersey. The parties subsequently reached a settlement of all claims for an aggregate amount of $8.0 million, and the settlement was approved by the court on June 12, 2018. The Company is in the process of making payments under the settlement to the members of the class and has made most of the required payments as of September 30, 2018. The aggregate remaining settlement amount of $0.2 million has been recorded as a liability in the Company’s consolidated balance sheet.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	17. SUBSEQUENT EVENTS On October 2, 2018, the Company declared a quarterly dividend of $1.00 per common share. The dividend was paid on October 26, 2018 to shareholders of record on October 16, 2018. The total dividend paid amounted to $46.6 million. Subsequent to September 30, 2018, the Company entered into contracts to acquire two self-storage facilities for an aggregate purchase price of $19.2 million. The purchases of these two facilities are subject to customary conditions to closing and there is no assurance that these facilities will be acquired.

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Changes And Error Corrections [Abstract]
Revenue from Contracts with Customers	In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” which supersedes the revenue recognition requirements in “Revenue Recognition (Topic 605),” and requires an entity to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. ASU 2014-09 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017 and is therefore effective for the Company as of January 1, 2018. The Company had the option to apply the provisions of ASU 2014-09 either retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying the new guidance recognized at the date of initial application (the modified retrospective transition method). The Company elected to adopt the standard using the modified retrospective transition method. Leases are specifically excluded from the scope of ASU 2014-09, therefore, upon analysis, the Company concluded that the adoption of the new standard did not have any impact on the timing or amounts of the Company’s rental revenue from customers which represents over of the Company’s total operating revenues. We have evaluated the other revenue streams material to the Company and have concluded that the adoption of the new standard did not have any material impact on the timing or amounts of the Company’s material revenue streams and no cumulative effect adjustment is required as of the date of initial application. Payment from such revenue streams is due and generally collected upon invoice. Also, as part of the Company’s adoption of ASU 2014-09, the Company has elected to apply the guidance only to contracts that are not completed contracts at the date of initial application. Further, related to the Company’s management fee revenue stream which relates to managing self-storage facilities for third-parties and unconsolidated joint ventures, the Company has elected to apply a practical expedient provided in the new standard which allows the Company to recognize revenue in the amount of management fees to which the Company has a right to invoice as that amount corresponds directly with the value to the customer of the entity’s performance completed to date
Leases	In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842)”. This guidance revises existing practice related to accounting for leases under Accounting Standards Codification Topic 840 Leases
Statement of Cash Flows	In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a Consensus of the Emerging Issues Task Force)” in an effort to reduce existing diversity in practice related to the classification of certain cash receipts and cash payments on the statements of cash flows. The guidance addresses the classification of cash flows related to, among other things, distributions received from equity method investees. The amendments in this update are effective for annual periods beginning after December 15, 2017, and interim periods within those annual periods. The Company has elected to use the nature of the distribution approach to classify distributions received from its equity method investees. This approach requires distributions to be classified in the statement of cash flows on the basis of the nature of the activity or activities of the investee that generated the distribution as either a return on investment (classified as a cash inflow from operating activities) or a return of investment (classified as a cash inflow from investing activities). The adoption of ASU 2016-15 effective January 1, 2018 did not have a material impact on the Company’s consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash (a Consensus of the Emerging Issues Task Force)” which requires restricted cash and restricted cash equivalents to be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The amendments in this update are effective for annual periods beginning after December 15, 2017 and interim periods within those fiscal years. Early adoption of this update is permitted. Other than modifications to the statement of cash flows and the additional disclosures in Note 4, the adoption of ASU 2016-18 on January 1, 2018 did not have an impact on the Company’s consolidated financial statements. The consolidated statement of cash flows for the nine months ended September 30, 2017 has been modified to conform to the presentation requirements of ASU 2016-18 which entail including restricted cash along with cash in the beginning balance, ending balance and net change in cash and restricted cash on the consolidated statement of cash flows.
Business Combinations	In January 2017, the FASB issued ASU 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business” which is intended to assist entities with evaluating whether a set of transferred assets and activities is a business. The amendments in this update are effective for annual periods beginning after December 15, 2017 and interim periods within those fiscal years. Early adoption of this update is permitted and the Company adopted this update effective January 1, 2017. The adoption of ASU 2017-01 is expected to have potential impact on the accounting treatment of properties acquired subsequent to the adoption date. Property acquisitions treated as business combinations under previous guidance may no longer be treated as business combinations subsequent to the adoption of ASU 2017-01. To the extent that properties that we acquire do not meet the definition of a “business” under ASU 2017-01, future acquisitions of properties may be accounted for as asset acquisitions resulting in the capitalization of acquisition costs incurred in connection with these transactions and the allocation of the purchase price and related acquisition costs to the assets acquired based on their relative fair values. The two properties acquired during the nine months ended September 30, 2018 would likely have been accounted for as business combinations prior to the adoption of ASU 2017-01.
Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets	In February 2017, the FASB issued ASU 2017-05, “Other Income – Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets” which clarifies the scope and application of ASC 610-20 on the sale or transfer of nonfinancial assets, including real estate, and in substance nonfinancial assets to noncustomers, including partial sales. The amendments in this update are effective for annual periods beginning after December 15, 2017, and interim periods within those annual periods. The implementation of this update as of January 1, 2018 could potentially impact the accounting treatment of future real estate sales of the Company if such sales are to parties who are also customers of the Company, though the implementation did not have an impact on the Company’s consolidated financial statements for the period ending September 30, 2018.
Compensation – Stock Compensation	In May 2017, the FASB issued ASU 2017-09, “Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting” which provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The amendments in this update are effective for annual periods beginning after December 15, 2017, and interim periods within those annual periods. The implementation of this update as of January 1, 2018 did not have a material impact on the Company’s financial statements, however, all future changes to the terms or conditions of any of the Company’s share-based payment awards are subject to the guidance in ASU 2017-09 and could potentially be accounted for differently than under the previous guidance concerning such changes. In August 2018, the FASB issued ASU 2018-15, “Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract” which provides guidance to help entities evaluate the accounting for implementation, setup, and other upfront costs (collectively referred to as implementation costs) incurred by entities that are a customer in a hosting arrangement that is a service contract. The amendments in this update are effective for annual periods beginning after December 15, 2019, and interim periods within those annual periods. The Company is currently evaluating the impact of adopting ASU 2018-15 on its consolidated financial statements.

Organization (Tables)

Organization (Tables)	9 Months Ended
	Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Reconciliation of Noncontrolling Interests	The following is a reconciliation of the Parent Company’s noncontrolling redeemable Operating Partnership Units and the Operating Partnership’s limited partners’ redeemable capital interest for the period: (dollars in thousands) Nine Months Ended September 30, 2018 Beginning balance $ 19,373 Redemption of units (203 ) Net income attributable to noncontrolling interest in the Operating Partnership 535 Distributions (650 ) Adjustment to redemption value 1,451 Ending balance $ 20,506
Summary of Disaggregated Revenues	The disaggregated revenues of the Company presented in accordance with ASC Topic 606 “Revenue from Contracts with Customers” (dollars in thousands) Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Rental income $ 128,818 $ 124,044 $ 376,334 $ 363,284 Management and acquisition fee income 2,661 2,478 7,602 7,479 Revenues related to tenant insurance 5,805 5,833 17,290 16,807 Other 4,199 3,213 11,359 9,103 Total operating revenues $ 141,483 $ 135,568 $ 412,585 $ 396,673

Cash and Restricted Cash (Table

Cash and Restricted Cash (Tables)	9 Months Ended
	Sep. 30, 2018
Cash And Cash Equivalents [Abstract]
Summary of Reconciliation of Cash and Restricted Cash	The following table provides a reconciliation of cash and restricted cash reported within the consolidated statement of cash flows: (Dollars in thousands) September 30, 2018 December 31, 2017 September 30, 2017 Cash $ 13,282 $ 9,167 $ 6,096 Restricted cash 5,665 292 606 Total cash and restricted cash $ 18,947 $ 9,459 $ 6,702

Investment in Storage Facilit_2

Investment in Storage Facilities and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Real Estate [Abstract]
Summary of Activity in Storage Facilities	The following summarizes our activity in storage facilities during the nine months ended September 30, 2018: (dollars in thousands) Cost: Beginning balance $ 4,321,410 Acquisitions of storage facilities 19,172 Improvements and equipment additions 29,911 Net increase in construction in progress 15,393 Dispositions (12,299 ) Ending balance $ 4,373,587 Accumulated Depreciation: Beginning balance $ 624,314 Additions during the period 76,844 Dispositions (3,188 ) Ending balance $ 697,970
Schedule of Acquired Facilities and Purchase Price of Facilities	The purchase prices of the facilities acquired in 2018 have been assigned as follows: (dollars in thousands) Consideration paid States Number of Properties Date of Acquisition Purchase Price Cash Paid Value of Operating Partnership Units Issued Mortgage Assumed Net Other Liabilities (Assets) Assumed Land Building, Equipment, and Improvements In-Place Customers Leases Closing Costs Expensed NH 1 9/4/2018 $ 5,641 $ 5,609 $ - $ - $ 32 $ 1,256 $ 4,276 $ 109 $ - CA 1 9/18/2018 $ 13,846 $ 13,800 $ - $ - $ 46 $ 2,089 $ 11,551 $ 206 $ - Total acquired in 2018 2 $ 19,487 $ 19,409 $ - $ - $ 78 $ 3,345 $ 15,827 $ 315 $ -
Schedule of Fair Value of In-Place Customer Lease Intangible Assets	In-place customer leases are included in other assets on the Company’s consolidated balance sheets as follows: (Dollars in thousands) September 30, 2018 December 31, 2017 In-place customer leases $ 75,226 $ 75,241 Accumulated amortization (74,920 ) (75,241 ) Net carrying value at the end of period $ 306 $ —

Unsecured Line of Credit and _2

Unsecured Line of Credit and Term Notes (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Borrowings Outstanding on Unsecured Line of Credit and Term Notes	Borrowings outstanding on our unsecured line of credit and term notes are as follows: (Dollars in thousands) September 30, 2018 December 31, 2017 Revolving line of credit borrowings $ 128,000 $ 105,000 Term note due June 4, 2020 100,000 100,000 Term note due August 5, 2021 100,000 100,000 Term note due April 8, 2024 175,000 175,000 Senior term note due July 1, 2026 600,000 600,000 Senior term note due December 15, 2027 450,000 450,000 Term note due July 21, 2028 200,000 200,000 Total term note principal balance outstanding $ 1,625,000 $ 1,625,000 Less: unamortized debt issuance costs (9,913 ) (10,962 ) Less: unamortized senior term note discount (4,539 ) (4,949 ) Term notes payable $ 1,610,548 $ 1,609,089

Mortgages Payable and Debt Ma_2

Mortgages Payable and Debt Maturities (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Summary of Mortgage Payable	Mortgages payable at September 30, 2018 and December 31, 2017 consist of the following: (dollars in thousands) September 30, 2018 December 31, 2017 4.98% mortgage note due January 1, 2021, secured by one self-storage facility with an aggregate net book value of $9.5 million, principal and interest paid monthly (effective interest rate 5.24%) $ 2,877 $ 2,916 4.065% mortgage note due April 1, 2023, secured by one self- storage facility with an aggregate net book value of $7.5 million, principal and interest paid monthly (effective interest rate 4.31%) 4,051 4,119 5.26% mortgage note due November 1, 2023, secured by one self-storage facility with an aggregate net book value of $7.9 million, principal and interest paid monthly (effective interest rate 5.58%) 3,888 3,939 5.99% mortgage note due May 1, 2026, secured by one self- storage facility with an aggregate net book value of $6.5 million, principal and interest paid monthly (effective interest rate 6.30%) 1,581 1,700 Total mortgages payable $ 12,397 $ 12,674
Summary of Debt Obligations and Interest Rate Derivatives	Accordingly, the estimates presented below are not necessarily indicative of the amounts the Company would realize in a current market exchange. Expected Maturity Date Including Discount (dollars in thousands) 2018 2019 2020 2021 2022 Thereafter Total Fair Value Line of credit - variable rate LIBOR + 1.10% (3.28% at September 30, 2018) — $ 128,000 — — — — $ 128,000 $ 128,000 Notes Payable: Term note - variable rate LIBOR + 1.15% (3.25% at September 30, 2018) — — $ 100,000 — — — $ 100,000 $ 100,000 Term note - fixed rate 5.54% — — — $ 100,000 — — $ 100,000 $ 104,084 Term note - fixed rate 4.533% — — — — — $ 175,000 $ 175,000 $ 176,767 Term note - fixed rate 3.50% — — — — — $ 600,000 $ 600,000 $ 563,528 Term note - fixed rate 3.875% — — — — — $ 450,000 $ 450,000 $ 421,815 Term note - fixed rate 3.67% — — — — — $ 200,000 $ 200,000 $ 180,734 Mortgage note - fixed rate 4.98% $ 14 $ 56 $ 59 $ 2,748 — — $ 2,877 $ 2,887 Mortgage note - fixed rate 4.065% $ 23 $ 96 $ 99 $ 104 $ 108 $ 3,621 $ 4,051 $ 3,911 Mortgage note - fixed rate 5.26% $ 17 $ 71 $ 74 $ 78 $ 83 $ 3,565 $ 3,888 $ 3,944 Mortgage note - fixed rate 5.99% $ 41 $ 170 $ 181 $ 192 $ 203 $ 794 $ 1,581 $ 1,638 Total $ 95 $ 128,393 $ 100,413 $ 103,122 $ 394 $ 1,432,980 $ 1,765,397

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Summary of Changes in AOCL	The changes in AOCL for the three and nine months ended September 30, 2018 and 2017 are summarized as follows: (dollars in thousands) Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Accumulated other comprehensive loss beginning of period $ (7,204 ) $ (19,616 ) $ (7,587 ) $ (21,475 ) Realized loss reclassified from accumulated other comprehensive loss to interest expense 54 758 363 2,835 Unrealized gain (loss) from changes in the fair value of the effective portion of the interest rate swaps 46 44 120 (174 ) Gain included in other comprehensive loss 100 802 483 2,661 Accumulated other comprehensive loss end of period $ (7,104 ) $ (18,814 ) $ (7,104 ) $ (18,814 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Assets and Liabilities Carried at Fair Value Measured on Recurring Basis	The following table provides the assets carried at fair value measured on a recurring basis as of December 31, 2017 (dollars in thousands): Asset (Liability) Level 1 Level 2 Level 3 December 31, 2017 Interest rate swaps $ 205 — $ 205 —

Investment in Joint Ventures (T

Investment in Joint Ventures (Tables)	9 Months Ended
	Sep. 30, 2018
Equity Method Investments And Joint Ventures [Abstract]
Summary of Company's Unconsolidated Joint Ventures	A summary of the Company’s unconsolidated joint ventures is as follows: Venture Number of Properties at September 30, 2018 Company common ownership interest at September 30, 2018 Carrying value of investment at September 30, 2018 Carrying value of investment at December 31, 2017 Sovran HHF Storage Holdings LLC (“Sovran HHF”) 1 57 20% $86.2 million $85.1 million Sovran HHF Storage Holdings II LLC (“Sovran HHF II”) 2 30 15% $13.1 million $13.3 million 191 III Holdings LLC (“191 III”) 3 6 20% $9.2 million $9.4 million Life Storage-SERS Storage LLC (“SERS”) 4 3 20% $3.6 million $3.6 million Iskalo Office Holdings, LLC (“Iskalo”) 5 N/A 49% ($0.4 million) ($0.4 million) Urban Box Coralway Storage, LLC (“Urban Box”) 6 1 85% $4.5 million $4.1 million SNL/Orix 1200 McDonald Ave., LLC (“McDonald”) 7 1 5% $2.8 million $2.7 million SNL Orix Merrick, LLC (“Merrick”) 8 1 5% $2.5 million $2.5 million Review Avenue Partners, LLC (“RAP”) 9 1 40% $11.1 million $11.5 million N 32nd Street Self Storage, LLC (“N32”) 10 1 46% $1.3 million $1.3 million NYX Don Mills Storage LP ("Don Mills") 11 1 17% $1.0 million N/A 1 2 3 4 5 6 7 8 9 10 11
Company's Share of Unconsolidated Joint Ventures' Income (Loss)	The Company’s share of the unconsolidated joint ventures’ income (loss) is as follows: (dollars in thousands) Venture Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Sovran HHF $ 828 $ 588 $ 2,257 $ 1,750 Sovran HHF II 436 398 1,235 1,100 191 III 7 (14 ) 43 12 SERS 20 (43 ) 107 (43 ) RAP (215 ) (248 ) (648 ) (749 ) Merrick (6 ) — (38 ) — McDonald (10 ) — (10 ) — Urban Box (19 ) — (19 ) — N32 (48 ) — (48 ) — Iskalo 53 71 187 189 $ 1,046 $ 752 $ 3,066 $ 2,259
Summary of Unconsolidated Joint Ventures' Financial Statements	A summary of the unconsolidated joint ventures’ financial statements as of and for the nine months ended September 30, 2018 is as follows: (dollars in thousands) Balance Sheet Data: Investment in storage facilities, net $ 1,074,916 Investment in office building, net 4,669 Other assets 19,554 Total Assets $ 1,099,139 Due to the Company $ 742 Mortgages payable 458,690 Other liabilities 7,043 Total Liabilities $ 466,475 Unaffiliated partners’ equity 497,724 Company equity 134,940 Total Partners’ Equity 632,664 Total Liabilities and Partners’ Equity $ 1,099,139 Income Statement Data: Total revenues $ 84,591 Property operating expenses (26,249 ) Administrative, management and call center fees (6,640 ) Depreciation and amortization of customer list (19,096 ) Amortization of financing fees (731 ) Income tax expense (232 ) Interest expense (13,284 ) Net income $ 18,359

Earnings Per Share and Earnin_2

Earnings Per Share and Earnings Per Unit (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Common Share/Unit	The following table sets forth the computation of basic and diluted earnings per common share utilizing the two-class method. Earnings Per Share (in thousands except per share data) Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Numerator: Net income attributable to common shareholders $ 41,120 $ 35,496 $ 114,283 $ 75,280 Denominator: Denominator for basic earnings per share – weighted average shares 46,526 46,416 46,487 46,362 Effect of Dilutive Securities: Stock options and non-vested stock 102 104 93 110 Denominator for diluted earnings per share – adjusted weighted average shares and assumed conversion 46,628 46,520 46,580 46,472 Basic earnings per common share attributable to common shareholders $ 0.88 $ 0.76 $ 2.46 $ 1.62 Diluted earnings per common share attributable to common shareholders $ 0.88 $ 0.76 $ 2.45 $ 1.62 Earnings Per Unit The following table sets forth the computation of basic and diluted earnings per common unit utilizing the two-class method. (in thousands except per unit data) Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Numerator: Net income attributable to common unitholders $ 41,120 $ 35,496 $ 114,283 $ 75,280 Denominator: Denominator for basic earnings per unit – weighted average units 46,526 46,416 46,487 46,362 Effect of Dilutive Securities: Stock options and non-vested stock 102 104 93 110 Denominator for diluted earnings per unit – adjusted weighted average units and assumed conversion 46,628 46,520 46,580 46,472 Basic earnings per common unit attributable to common unitholders $ 0.88 $ 0.76 $ 2.46 $ 1.62 Diluted earnings per common unit attributable to common unitholders $ 0.88 $ 0.76 $ 2.45 $ 1.62

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Reconciliation of Changes in Parent Company's Total Shareholders' Equity	The following is a reconciliation of the changes in the Parent Company’s total shareholders’ equity for the period: (dollars in thousands) Nine Months Ended September 30, 2018 Beginning balance of total shareholders’ equity $ 2,028,323 Exercise of stock options 2,977 Earned portion of non-vested stock 4,203 Stock option expense 7 Carrying value less than redemption value on redeemed noncontrolling interest (29 ) Adjustment to redemption value on noncontrolling redeemable Operating Partnership units (1,451 ) Net income attributable to common shareholders 114,283 Amortization of terminated hedge included in AOCL 688 Change in fair value of derivatives (205 ) Dividends (139,235 ) Ending balance of total shareholders’ equity $ 2,009,561

Partners' Capital (Tables)

Partners' Capital (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Reconciliation of Changes in Total Partners' Capital	The following is a reconciliation of the changes in total partners’ capital for the period: (dollars in thousands) Nine Months Ended September 30, 2018 Beginning balance of total controlling partners’ capital $ 2,028,323 Exercise of stock options 2,977 Earned portion of non-vested stock 4,203 Stock option expense 7 Carrying value less than redemption value on redeemed noncontrolling interest (29 ) Adjustment to redemption value on limited partners’ redeemable capital interests (1,451 ) Net income attributable to common unitholders 114,283 Amortization of terminated hedge included in AOCL 688 Change in fair value of derivatives (205 ) Distributions (139,235 ) Ending balance of total controlling partners’ capital $ 2,009,561

Organization - Additional Infor

Organization - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2018PropertyStateshares	Dec. 31, 2017shares
Organization [Line Items]
Number of self-storage properties owned and managed	725
Number of states in which self-storage properties owned and managed | State	28
Number of properties managed under joint ventures	101
Number of properties managed with no ownership	57
Noncontrolling limited partnership unit redemption value	one common share or cash
Geographic Concentration Risk [Member] | Texas [Member] | Revenue [Member]
Organization [Line Items]
Concentration risk, percentage	21.00%
Geographic Concentration Risk [Member] | Florida [Member] | Revenue [Member]
Organization [Line Items]
Concentration risk, percentage	13.00%
Life Storage LP [Member]
Organization [Line Items]
Percentage of ownership interest of the subsidiary and its limited partnership which controls the operations of the Operating Partnership	99.50%
Units of redeemable noncontrolling interest in operating partnership | shares	215,009	217,481
Warehouse Anywhere LLC [Member] | Life Storage Solutions, LLC [Member]
Organization [Line Items]
Percentage of ownership interest of the subsidiary and its limited partnership which controls the operations of the Operating Partnership	60.00%

Organization - Summary of Recon

Organization - Summary of Reconciliation of Noncontrolling Interests (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Redeemable Noncontrolling Interest Equity Fair Value [Abstract]
Noncontrolling interest, beginning balance			$ 19,373
Redemption of units			(203)
Net income attributable to noncontrolling interest in the Operating Partnership	$ 191	$ 171	535	$ 343
Distributions			(650)
Adjustment to redemption value			1,451
Noncontrolling interest, ending balance	$ 20,506		$ 20,506

Organization - Summary of Disag

Organization - Summary of Disaggregated Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation Of Revenue [Line Items]
Rental income	$ 128,818	$ 124,044	$ 376,334	$ 363,284
Total operating revenues	141,483	135,568	412,585	396,673
Management and Acquisition Fee Income [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues other than rental income	2,661	2,478	7,602	7,479
Revenues Related to Tenant Insurance [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues other than rental income	5,805	5,833	17,290	16,807
Other Operating Income [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues other than rental income	$ 4,199	$ 3,213	$ 11,359	$ 9,103

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Detail) - USD ($)	3 Months Ended				9 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option expense			$ 0	$ 4,000	$ 7,000	$ 11,000
Amortization of non-vested stock grants and performance-based awards			$ 1,456,000	$ 1,659,000	$ 4,203,000	$ 4,905,000
Stock options exercised by employees and directors					71,606	0
Number of shares of non-vested stock that vested			11,114	19,537	51,067	66,565
Chief Executive Officer, David Rogers [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense			$ 200,000		$ 200,000
Chief Executive Officer, David Rogers [Member] | Scenario, Forecast [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 400,000	$ 700,000
Non-Vested Shares [Member] | Employees and Non-employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of non-vested stock issued					14,865
Aggregate fair value					$ 1,400,000
Non-Vested Shares [Member] | Employees and Non-employee Directors [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option plan, share based compensation, vesting period (in years)					8 years
Fair market value of the non-vested stock on the date of grant					$ 94.08
Non-Vested Shares [Member] | Employees and Non-employee Directors [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option plan, share based compensation, vesting period (in years)					1 year
Fair market value of the non-vested stock on the date of grant					$ 81.86
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option plan, share based compensation, vesting period (in years)					3 years
Aggregate fair value					$ 300,000
Performance Shares [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted under performance plan					7,732

Cash and Restricted Cash - Summ

Cash and Restricted Cash - Summary of Reconciliation of Cash and Restricted Cash (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Cash And Cash Equivalents [Abstract]
Cash and cash equivalents	$ 13,282	$ 9,167	$ 6,096
Restricted cash	5,665	292	606
Total cash and restricted cash	$ 18,947	$ 9,459	$ 6,702	$ 23,923

Investment in Storage Facilit_3

Investment in Storage Facilities and Intangible Assets - Summary of Activity in Storage Facilities (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Cost:
Beginning balance	$ 4,321,410
Acquisitions of storage facilities	19,172
Improvements and equipment additions	29,911
Net increase in construction in progress	15,393
Dispositions	(12,299)
Ending balance	4,373,587
Accumulated Depreciation:
Beginning balance	624,314
Additions during the period	76,844
Dispositions	(3,188)
Ending balance	$ 697,970

Investment in Storage Facilit_4

Investment in Storage Facilities and Intangible Assets - Additional Information (Detail)	3 Months Ended			9 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)$ / shares	Sep. 30, 2017USD ($)$ / shares	Sep. 30, 2018USD ($)Property$ / shares	Sep. 30, 2017USD ($)$ / shares
Investment Holdings [Line Items]
Number of storage facilities acquired | Property				2
Net other liabilities assumed				$ 78,000
Amortization period for in-place customer leases on a straight-line basis				12 months
Amortization expense related to in-place customer leases		$ 9,000	$ 100,000	$ 9,000	$ 24,800,000
Amortization expense expected for 2018		100,000		100,000
Amortization expense expected for 2019		200,000		200,000
Net proceeds from the sale of real estate				10,576,000	1,994,000
Gain on sale of non-strategic property		718,000		718,000
Increase in depreciation expense due to facility replacement		$ 2,400,000	$ 2,000,000	$ 2,800,000	$ 3,600,000
Accelerated depreciation reduced basic and diluted earnings per share | $ / shares		$ 0.04	$ 0.04	$ 0.05	$ 0.07
Scenario, Forecast [Member]
Investment Holdings [Line Items]
Increase in depreciation expense due to facility replacement	$ 500,000
Property Dispositions [Member]
Investment Holdings [Line Items]
Number Of Properties Sold | Property				1
Net proceeds from the sale of real estate				$ 9,600,000
Gain on sale of non-strategic property				$ 900,000

Investment in Storage Facilit_5

Investment in Storage Facilities and Intangible Assets - Schedule of Acquired Facilities and Purchase Price of Facilities (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)Property
Investment Holdings [Line Items]
Number of Properties | Property	2
Purchase Price	$ 19,487
Consideration paid, Cash Paid	19,409
Consideration paid, Net Other Liabilities (Assets) Assumed	78
Land	3,345
Building, Equipment, and Improvements	15,827
In-Place Customer Leases	$ 315
NH [Member] | Date of Acquisition, 9/4/2018 [Member]
Investment Holdings [Line Items]
Number of Properties | Property	1
Date of Acquisition	Sep. 4, 2018
Purchase Price	$ 5,641
Consideration paid, Cash Paid	5,609
Consideration paid, Net Other Liabilities (Assets) Assumed	32
Land	1,256
Building, Equipment, and Improvements	4,276
In-Place Customer Leases	$ 109
CA [Member] | Date of Acquisition, 9/18/2018 [Member]
Investment Holdings [Line Items]
Number of Properties | Property	1
Date of Acquisition	Sep. 18, 2018
Purchase Price	$ 13,846
Consideration paid, Cash Paid	13,800
Consideration paid, Net Other Liabilities (Assets) Assumed	46
Land	2,089
Building, Equipment, and Improvements	11,551
In-Place Customer Leases	$ 206

Investment in Storage Facilit_6

Investment in Storage Facilities and Intangible Assets - Schedule of Fair Value of In-Place Customer Lease Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Real Estate [Abstract]
In-place customer leases	$ 75,226	$ 75,241
Accumulated amortization	(74,920)	$ (75,241)
Net carrying value at the end of period	$ 306

Unsecured Line of Credit and _3

Unsecured Line of Credit and Term Notes - Borrowings Outstanding on Unsecured Line of Credit and Term Notes (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Unsecured Line Of Credit And Term Notes [Line Items]
Revolving line of credit borrowings	$ 128,000	$ 105,000
Total term note principal balance outstanding	1,625,000	1,625,000
Less: unamortized debt issuance costs	(9,913)	(10,962)
Less: unamortized senior term note discount	(4,539)	(4,949)
Term notes payable	1,610,548	1,609,089
Term Note Due June 4, 2020 [Member]
Unsecured Line Of Credit And Term Notes [Line Items]
Total term note principal balance outstanding	100,000	100,000
Term Note Due August 5, 2021 [Member]
Unsecured Line Of Credit And Term Notes [Line Items]
Total term note principal balance outstanding	100,000	100,000
Term Note Due April 8, 2024 [Member]
Unsecured Line Of Credit And Term Notes [Line Items]
Total term note principal balance outstanding	175,000	175,000
Senior Term Note Due July 1, 2026 [Member]
Unsecured Line Of Credit And Term Notes [Line Items]
Total term note principal balance outstanding	600,000	600,000
Senior Term Note Due December 15, 2027 [Member]
Unsecured Line Of Credit And Term Notes [Line Items]
Total term note principal balance outstanding	450,000	450,000
Term Note Due July 21, 2028 [Member]
Unsecured Line Of Credit And Term Notes [Line Items]
Total term note principal balance outstanding	$ 200,000	$ 200,000

Unsecured Line of Credit and _4

Unsecured Line of Credit and Term Notes - Additional Information (Detail) - USD ($)	Oct. 30, 2018	Dec. 07, 2017	Jul. 21, 2016	Jun. 20, 2016	Apr. 08, 2014	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2011
Debt Instrument [Line Items]
Term notes, outstanding amount						$ 1,625,000,000		$ 1,625,000,000		$ 1,625,000,000
Unamortized senior term note discount						4,539,000		4,539,000		$ 4,949,000
Amortization expense related to deferred debt issuance costs								2,672,000	$ 2,496,000
Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio percentage				60.00%
Indenture covenant percentage on unencumbered assets				150.00%
Minimum [Member]
Debt Instrument [Line Items]
Interest coverage ratio on debt				150.00%
Secured Debt [Member] | Maximum [Member]
Debt Instrument [Line Items]
Leverage ratio percentage				40.00%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Revolving credit limit						$ 500,000,000		$ 500,000,000
Basis spread over LIBOR								1.10%
Facility fee								0.15%
Interest rate, line of credit facility						3.28%		3.28%		2.63%
Amount available on unsecured revolving line of credit						$ 371,200,000		$ 371,200,000
Line of credit facility, expiration date								Dec. 10, 2019
Revolving Credit Facility [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Revolving credit limit	$ 500,000,000
Basis spread over LIBOR	0.95%
Facility fee	0.15%
Line of credit facility, expiration date	Mar. 10, 2023
Maturity in April 8, 2024 [Member]
Debt Instrument [Line Items]
Debt instrument,maturity date					Apr. 8, 2024
Debt instrument stated interest rate					4.533%
Additional secured term note					$ 175,000,000
Maturity in April 8, 2024 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument stated interest rate					6.283%
Senior Term Note Due July 1, 2026 [Member] | Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument,maturity date				Jul. 1, 2026
Debt instrument principal amount				$ 600,000,000		600,000,000		$ 600,000,000
Debt instrument stated interest rate				3.50%
Debt instrument percentage discount to par				0.553%
Unamortized senior term note discount				$ 3,300,000
Underwriting discount and other offering expenses				5,500,000
Proceeds from senior notes, net				$ 591,200,000
Term Note Due July 21, 2028 [Member]
Debt Instrument [Line Items]
Debt instrument,maturity date			Jul. 21, 2028
Term notes, outstanding amount						200,000,000		200,000,000		$ 200,000,000
Debt instrument stated interest rate			3.67%
Additional secured term note			$ 200,000,000
Senior Notes and Term Notes [Member]
Debt Instrument [Line Items]
Amortization expense related to deferred debt issuance costs						500,000	$ 500,000	$ 1,600,000	$ 1,600,000
Term Note Due June 4, 2020 [Member]
Debt Instrument [Line Items]
Basis spread over LIBOR								1.15%
Debt instrument,maturity date								Jun. 4, 2020
Debt instrument principal amount						325,000,000		$ 325,000,000
Repayments of unsecured term note										225,000,000
Term notes, outstanding amount						$ 100,000,000		$ 100,000,000		$ 100,000,000
Debt instrument variable interest rate						3.25%		3.25%		2.53%
Term Note Due June 4, 2020 [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Basis spread over LIBOR	1.00%
Debt instrument,maturity date	Jun. 4, 2020
Debt instrument principal amount	$ 100,000,000
Term Note | Revolving Credit Facility [Member] | Maximum [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt instrument principal amount	$ 900,000,000
Senior Term Note Due December 15, 2027 [Member] | Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument,maturity date		Dec. 15, 2027
Debt instrument principal amount		$ 450,000,000
Debt instrument stated interest rate		3.875%
Debt instrument,first required payment		Jun. 15, 2018
Debt instrument percentage discount to par		0.477%
Unamortized senior term note discount		$ 2,100,000
Underwriting discount and other offering expenses		4,000,000
Proceeds from senior notes, net		$ 443,900,000
Term Note Due August 5, 2021 [Member]
Debt Instrument [Line Items]
Debt instrument,maturity date											Aug. 5, 2021
Term notes, outstanding amount						$ 100,000,000		$ 100,000,000		$ 100,000,000
Debt instrument stated interest rate											5.54%
Additional secured term note											$ 100,000,000
Term Note Due August 5, 2021 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument stated interest rate											7.29%

Mortgages Payable and Debt Ma_3

Mortgages Payable and Debt Maturities - Summary of Mortgage Payable (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Mortgages payable	$ 12,397	$ 12,674
4.98% Mortgage Note Due January 1, 2021 [Member]
Debt Instrument [Line Items]
Mortgages payable	2,877	2,916
4.065% Mortgage Note Due April 1, 2023 [Member]
Debt Instrument [Line Items]
Mortgages payable	4,051	4,119
5.26% Mortgage Note Due November 1, 2023 [Member]
Debt Instrument [Line Items]
Mortgages payable	3,888	3,939
5.99% Mortgage Note Due May 1, 2026 [Member]
Debt Instrument [Line Items]
Mortgages payable	$ 1,581	$ 1,700

Mortgages Payable and Debt Ma_4

Mortgages Payable and Debt Maturities - Summary of Mortgage Payable (Parenthetical) (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)Facility
4.98% Mortgage Note Due January 1, 2021 [Member]
Debt Instrument [Line Items]
Interest rate	4.98%
Mortgage note due date	Jan. 1, 2021
Self-storage facilities | Facility	1
Aggregate net book value of property pledged for mortgage note | $	$ 9.5
Effective interest rate	5.24%
4.065% Mortgage Note Due April 1, 2023 [Member]
Debt Instrument [Line Items]
Interest rate	4.065%
Mortgage note due date	Apr. 1, 2023
Self-storage facilities | Facility	1
Aggregate net book value of property pledged for mortgage note | $	$ 7.5
Effective interest rate	4.31%
5.26% Mortgage Note Due November 1, 2023 [Member]
Debt Instrument [Line Items]
Interest rate	5.26%
Mortgage note due date	Nov. 1, 2023
Self-storage facilities | Facility	1
Aggregate net book value of property pledged for mortgage note | $	$ 7.9
Effective interest rate	5.58%
5.99% Mortgage Note Due May 1, 2026 [Member]
Debt Instrument [Line Items]
Interest rate	5.99%
Mortgage note due date	May 1, 2026
Self-storage facilities | Facility	1
Aggregate net book value of property pledged for mortgage note | $	$ 6.5
Effective interest rate	6.30%

Mortgages Payable and Debt Ma_5

Mortgages Payable and Debt Maturities - Summary of Debt Obligation and Interest Rate Derivatives (Detail) $ in Thousands	Sep. 30, 2018USD ($)
Debt Instrument [Line Items]
Payables due 2018	$ 95
Payables due 2019	128,393
Payables due 2020	100,413
Payables due 2021	103,122
Payables due 2022	394
Payables due Thereafter	1,432,980
Debt obligations	1,765,397
Line of credit - variable rate LIBOR + 1.10% (3.28% at September 30, 2018) [Member]
Debt Instrument [Line Items]
Payables due 2019	128,000
Debt obligations	128,000
Debt instrument, fair value	128,000
Term note - variable rate LIBOR+1.15% (3.25% at September 30, 2018) [Member]
Debt Instrument [Line Items]
Payables due 2020	100,000
Debt obligations	100,000
Term note, fair value	100,000
Term Note - Fixed Rate 5.54% [Member]
Debt Instrument [Line Items]
Payables due 2021	100,000
Debt obligations	100,000
Term note, fair value	104,084
Term Note - Fixed Rate 4.533% [Member]
Debt Instrument [Line Items]
Payables due Thereafter	175,000
Debt obligations	175,000
Term note, fair value	176,767
Term Note - Fixed Rate 3.50% [Member]
Debt Instrument [Line Items]
Payables due Thereafter	600,000
Debt obligations	600,000
Term note, fair value	563,528
Term Note - Fixed Rate 3.875% [Member]
Debt Instrument [Line Items]
Payables due Thereafter	450,000
Debt obligations	450,000
Term note, fair value	421,815
Term Note - Fixed Rate 3.67% [Member]
Debt Instrument [Line Items]
Payables due Thereafter	200,000
Debt obligations	200,000
Term note, fair value	180,734
Mortgage Note - Fixed Rate 4.98% [Member]
Debt Instrument [Line Items]
Payables due 2018	14
Payables due 2019	56
Payables due 2020	59
Payables due 2021	2,748
Debt obligations	2,877
Debt instrument, fair value	2,887
Mortgage Note - Fixed Rate 4.065% [Member]
Debt Instrument [Line Items]
Payables due 2018	23
Payables due 2019	96
Payables due 2020	99
Payables due 2021	104
Payables due 2022	108
Payables due Thereafter	3,621
Debt obligations	4,051
Debt instrument, fair value	3,911
Mortgage Note - Fixed Rate 5.26% [Member]
Debt Instrument [Line Items]
Payables due 2018	17
Payables due 2019	71
Payables due 2020	74
Payables due 2021	78
Payables due 2022	83
Payables due Thereafter	3,565
Debt obligations	3,888
Debt instrument, fair value	3,944
Mortgage Note - Fixed Rate 5.99% [Member]
Debt Instrument [Line Items]
Payables due 2018	41
Payables due 2019	170
Payables due 2020	181
Payables due 2021	192
Payables due 2022	203
Payables due Thereafter	794
Debt obligations	1,581
Debt instrument, fair value	$ 1,638

Mortgages Payable and Debt Ma_6

Mortgages Payable and Debt Maturities - Summary of Debt Obligation and Interest Rate Derivatives (Parenthetical) (Detail)	9 Months Ended
	Sep. 30, 2018
Line of credit - variable rate LIBOR + 1.10% (3.28% at September 30, 2018) [Member]
Debt Instrument [Line Items]
Interest rate at end of period	3.28%
Basis spread over LIBOR	1.10%
Term note - variable rate LIBOR+1.15% (3.25% at September 30, 2018) [Member]
Debt Instrument [Line Items]
Interest rate at end of period	3.25%
Basis spread over LIBOR	1.15%
Term Note - Fixed Rate 5.54% [Member]
Debt Instrument [Line Items]
Interest rate	5.54%
Term Note - Fixed Rate 4.533% [Member]
Debt Instrument [Line Items]
Interest rate	4.533%
Term Note - Fixed Rate 3.50% [Member]
Debt Instrument [Line Items]
Interest rate	3.50%
Term Note - Fixed Rate 3.875% [Member]
Debt Instrument [Line Items]
Interest rate	3.875%
Term Note - Fixed Rate 3.67% [Member]
Debt Instrument [Line Items]
Interest rate	3.67%
Mortgage Note - Fixed Rate 4.98% [Member]
Debt Instrument [Line Items]
Interest rate	4.98%
Mortgage Note - Fixed Rate 4.065% [Member]
Debt Instrument [Line Items]
Interest rate	4.065%
Mortgage Note - Fixed Rate 5.26% [Member]
Debt Instrument [Line Items]
Interest rate	5.26%
Mortgage Note - Fixed Rate 5.99% [Member]
Debt Instrument [Line Items]
Interest rate	5.99%

Derivative Financial Instrume_3

Derivative Financial Instruments - Additional Information (Detail) - USD ($)	Jun. 20, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Mar. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Cash flow hedge ineffectiveness		Ineffectiveness was de minimis for the three and nine months ended September 30, 2018 and 2017.		Ineffectiveness was de minimis for the three and nine months ended September 30, 2018 and 2017.
Repayments of variable rate term notes						$ 225,000,000
Effective portion of gain (loss) on derivatives net of reclassification to interest expense		$ 100,000	$ 802,000	$ 483,000	$ 2,661,000
Derivative notional amount							$ 100,000,000	$ 50,000,000
Realized (gain) loss on derivatives net of accumulated other comprehensive loss to interest expense		54,000	758,000	363,000	2,835,000
Fair value of interest rate swap agreements, asset						205,000
Interest Rate Swaps Settled in 2018 [Member]
Derivative [Line Items]
Effective portion of gain (loss) on derivatives net of reclassification to interest expense				0		$ 0
Derivative notional amount		100,000,000		100,000,000
Realized (gain) loss on derivatives net of accumulated other comprehensive loss to interest expense				$ 0
Senior Term Note Due July 1, 2026 [Member]
Derivative [Line Items]
Settlement of forward starting swap agreements	$ 9,200,000
Amortized period on interest expense				10 years
Interest Expense [Member]
Derivative [Line Items]
Realized (gain) loss on derivatives net of accumulated other comprehensive loss to interest expense		(200,000)	$ 500,000	$ (300,000)	$ 2,100,000
Unsecured Senior Notes [Member] | Senior Term Note Due July 1, 2026 [Member]
Derivative [Line Items]
Debt instrument principal amount	$ 600,000,000	$ 600,000,000		$ 600,000,000

Derivative Financial Instrume_4

Derivative Financial Instruments - Summary of Changes in AOCL (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss beginning of period			$ 2,028,323
Realized loss reclassified from accumulated other comprehensive loss to interest expense	$ 54	$ 758	363	$ 2,835
Unrealized gain (loss) from changes in the fair value of the effective portion of the interest rate swaps	46	44	120	(174)
Gain included in other comprehensive loss	100	802	483	2,661
Accumulated other comprehensive loss end of period	2,009,561		2,009,561		$ 2,028,323
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss beginning of period	(7,204)	(19,616)	(7,587)	(21,475)	(21,475)
Accumulated other comprehensive loss end of period	$ (7,104)	$ (18,814)	$ (7,104)	$ (18,814)	$ (7,587)

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - Fair Value, Measurements, Recurring [Member]	Sep. 30, 2018USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 0
Liabilities measured at fair value	$ 0

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Carried at Fair Value Measured on Recurring Basis (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of interest rate swap agreements, asset	$ 205
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of interest rate swap agreements, asset	205
Interest Rate Swap [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of interest rate swap agreements, asset	$ 205

Investment in Joint Ventures -

Investment in Joint Ventures - Summary of Company's Unconsolidated Joint Ventures (Detail) $ in Millions	Sep. 30, 2018USD ($)Property	Dec. 31, 2017USD ($)
Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of Properties | Property	57
Company common ownership interest	20.00%
Carrying value of investment	$ 86.2	$ 85.1
Sovran HHF Storage Holdings II LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of Properties | Property	30
Company common ownership interest	15.00%
Carrying value of investment	$ 13.1	13.3
191 III Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of Properties | Property	6
Company common ownership interest	20.00%
Carrying value of investment	$ 9.2	9.4
Life Storage-SERS Storage LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of Properties | Property	3
Company common ownership interest	20.00%
Carrying value of investment	$ 3.6	3.6
Iskalo Office Holdings, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Company common ownership interest	49.00%
Carrying value of investment	$ (0.4)	(0.4)
Urban Box Coralway Storage, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of Properties | Property	1
Company common ownership interest	85.00%
Carrying value of investment	$ 4.5	4.1
SNL/Orix 1200 McDonald Ave., LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of Properties | Property	1
Company common ownership interest	5.00%
Carrying value of investment	$ 2.8	2.7
SNL Orix Merrick, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of Properties | Property	1
Company common ownership interest	5.00%
Carrying value of investment	$ 2.5	2.5
Review Avenue Partners LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of Properties | Property	1
Company common ownership interest	40.00%
Carrying value of investment	$ 11.1	11.5
N 32nd Street Self Storage, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of Properties | Property	1
Company common ownership interest	46.00%
Carrying value of investment	$ 1.3	$ 1.3
NYX Don Mills Storage LP [Member]
Schedule of Equity Method Investments [Line Items]
Number of Properties | Property	1
Company common ownership interest	17.00%
Carrying value of investment	$ 1

Investment in Joint Ventures _2

Investment in Joint Ventures - Summary of Company's Unconsolidated Joint Ventures (Parenthetical) (Detail) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2018USD ($)Property	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)Property
Schedule of Equity Method Investments [Line Items]
Number of storage facilities acquired | Property	2
Payment for property acquisition	$ 19,409	$ 9,576
Mortgages payable	12,397		$ 12,674
Distributions from unconsolidated joint ventures	6,276	5,071
Payment for property acquisition	19,487
Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Contribution of company to joint venture as share in capital	2,900
Distributions from unconsolidated joint ventures	4,200
Excess of investment over net asset due to capitalization of acquisition related costs	1,700
Sovran HHF Storage Holdings II LLC [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from unconsolidated joint ventures	1,500
191 III Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Contribution of company to joint venture as share in capital	100
Distributions from unconsolidated joint ventures	300
Life Storage-SERS Storage LLC [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from unconsolidated joint ventures	100
Iskalo Office Holdings, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from unconsolidated joint ventures	200
Rent paid during the period	900	$ 900
Urban Box Coralway Storage, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Contribution of company to joint venture as share in capital	500
SNL/Orix 1200 McDonald Ave., LLC [Member]
Schedule of Equity Method Investments [Line Items]
Contribution of company to joint venture as share in capital	100
Non-recourse mortgage loan principal outstanding	11,100
SNL Orix Merrick, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Contribution of company to joint venture as share in capital	100
Non-recourse mortgage loan principal outstanding	12,100
Review Avenue Partners LLC [Member] | Common Stock Shares [Member]
Schedule of Equity Method Investments [Line Items]
Contribution of company to joint venture as share in capital	300
NYX Don Mills Storage LP [Member] | Common Stock Shares [Member]
Schedule of Equity Method Investments [Line Items]
Contribution of company to joint venture as share in capital	$ 1,000
Arizona [Member] | Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	11
Arizona [Member] | N 32nd Street Self Storage, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	1
Colorado [Member] | Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	4
Florida [Member] | Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	3
Florida [Member] | Urban Box Coralway Storage, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	1
Georgia [Member] | Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	1
Georgia [Member] | Life Storage-SERS Storage LLC [Member] | Additional Storage Facilities [Member]
Schedule of Equity Method Investments [Line Items]
Number of storage facilities acquired | Property	3		3
Mortgages payable			$ 22,000
Payment for property acquisition			$ 39,100
Kentucky [Member] | Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	2
Nevada [Member] | Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	5
New Jersey [Member] | Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	2
New Jersey [Member] | Sovran HHF Storage Holdings II LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	17
Ohio [Member] | Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	6
Pennsylvania [Member] | Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	1
Pennsylvania [Member] | Sovran HHF Storage Holdings II LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	3
Tennessee [Member] | Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	2
Texas [Member] | Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	20
Texas [Member] | Sovran HHF Storage Holdings II LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	10
Arizona, Nevada and Tennessee [Member] | Sovran HHF Storage Holdings LLC [Member] | Storage Facilities [Member]
Schedule of Equity Method Investments [Line Items]
Number of storage facilities acquired | Property			18
Payment for property acquisition			$ 330,000
Mortgages payable			$ 135,000
Number of properties collateral for debt | Property			16
California [Member] | 191 III Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	6
California [Member] | 191 III Holdings LLC [Member] | Six Storage Facilities [Member]
Schedule of Equity Method Investments [Line Items]
Number of storage facilities acquired | Property			6
Mortgages payable			$ 57,200
Payment for property acquisition			$ 104,100
New York [Member] | SNL/Orix 1200 McDonald Ave., LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	1
New York [Member] | SNL Orix Merrick, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	1
New York [Member] | Review Avenue Partners LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of self-storage facilities | Property	1

Investment in Joint Ventures _3

Investment in Joint Ventures - Additional Information (Detail) - Sovran HHF, Sovran HHF II, 191 III, SERS, Urban Box, McDonald, Merrick, RAP and N32 [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Schedule of Equity Method Investments [Line Items]
Management and call center fee earned	$ 2	$ 1.9	$ 5.8	$ 4.8
Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Management and call center fee as a percentage of revenues			6.00%
Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Management and call center fee as a percentage of revenues			7.00%

Investment in Joint Ventures _4

Investment in Joint Ventures - Company's Share of Unconsolidated Joint Ventures' Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	$ 1,046	$ 752	$ 3,066	$ 2,259
Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	828	588	2,257	1,750
Sovran HHF Storage Holdings II LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	436	398	1,235	1,100
191 III Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	7	(14)	43	12
Life Storage-SERS Storage LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	20	(43)	107	(43)
Review Avenue Partners LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	(215)	(248)	(648)	(749)
SNL Orix Merrick, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	(6)		(38)
SNL/Orix 1200 McDonald Ave., LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	(10)		(10)
Urban Box Coralway Storage, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	(19)		(19)
N 32nd Street Self Storage, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	(48)		(48)
Iskalo Office Holdings, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	$ 53	$ 71	$ 187	$ 189

Investment in Joint Ventures _5

Investment in Joint Ventures - Summary of Unconsolidated Joint Ventures' Financial Statements (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Investment in storage facilities, net	$ 3,675,617		$ 3,675,617		$ 3,697,096
Other assets	9,329		9,329		4,863
Total Assets	3,869,334		3,869,334		3,876,774
Mortgages payable	12,397		12,397		12,674
Total Liabilities	1,839,267		1,839,267		1,829,078
Unaffiliated partners’ equity	0		0		0
Company equity	2,009,561		2,009,561		2,028,323
Total Equity	2,009,561		2,009,561		$ 2,028,323
Depreciation and amortization of customer list	(27,291)	$ (26,149)	(76,839)	$ (101,896)
Amortization of financing fees			(2,672)	(2,496)
Income tax expense	(800)	(900)	(1,900)	1,300
Interest expense	(17,923)	$ (16,290)	(52,645)	$ (47,216)
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Investment in storage facilities, net	1,074,916		1,074,916
Investment in office building, net	4,669		4,669
Other assets	19,554		19,554
Total Assets	1,099,139		1,099,139
Due to the Company	742		742
Mortgages payable	458,690		458,690
Other liabilities	7,043		7,043
Total Liabilities	466,475		466,475
Unaffiliated partners’ equity	497,724		497,724
Company equity	134,940		134,940
Total Equity	632,664		632,664
Total Liabilities and Partners’ Equity	$ 1,099,139		1,099,139
Total revenues			84,591
Property operating expenses			(26,249)
Administrative, management and call center fees			(6,640)
Depreciation and amortization of customer list			(19,096)
Amortization of financing fees			(731)
Income tax expense			(232)
Interest expense			(13,284)
Net income			$ 18,359

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal and state income tax expense (benefit)	$ 800,000	$ 900,000	$ 1,900,000	$ (1,300,000)
Interest or penalties related to uncertain tax positions			0	$ 0
Prepaid taxes	200,000		200,000		$ 100,000
Deferred tax assets	2,300,000		2,300,000		3,600,000
Deferred tax liability	$ 1,500,000		$ 1,500,000		$ 1,700,000
Tax years open to examination			2013 2017
Corporate income tax rate			21.00%		35.00%

Earnings Per Share and Earnin_3

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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net income attributable to common shareholders/unitholders	$ 41,120	$ 35,496	$ 114,283	$ 75,280
Denominator:
Denominator for basic earnings per share/unit – weighted average shares/units	46,526,362	46,415,782	46,486,587	46,361,747
Effect of Dilutive Securities:
Stock options and non-vested stock	102,000	104,000	93,000	110,000
Denominator for diluted earnings per share/unit - adjusted weighted average shares/units and assumed conversion	46,627,968	46,520,311	46,580,331	46,472,294
Basic earnings per common share/unit attributable to common shareholders/unitholders	$ 0.88	$ 0.76	$ 2.46	$ 1.62
Diluted earnings per common share/unit attributable to common shareholders/unitholders	$ 0.88	$ 0.76	$ 2.45	$ 1.62
Life Storage LP [Member]
Numerator:
Net income attributable to common shareholders/unitholders	$ 41,120	$ 35,496	$ 114,283	$ 75,280
Denominator:
Denominator for basic earnings per share/unit – weighted average shares/units	46,526,362	46,415,782	46,486,587	46,361,747
Effect of Dilutive Securities:
Stock options and non-vested stock	102,000	104,000	93,000	110,000
Denominator for diluted earnings per share/unit - adjusted weighted average shares/units and assumed conversion	46,627,968	46,520,311	46,580,331	46,472,294
Basic earnings per common share/unit attributable to common shareholders/unitholders	$ 0.88	$ 0.76	$ 2.46	$ 1.62
Diluted earnings per common share/unit attributable to common shareholders/unitholders	$ 0.88	$ 0.76	$ 2.45	$ 1.62

Earnings Per Share and Earnin_4

Earnings Per Share and Earnings Per Unit - Additional Information (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities not included in the effect of dilutive securities	88,621	133,179	105,935	139,107
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities not included in the effect of dilutive securities		17,500	7,333	14,667

Shareholders' Equity - Reconcil

Shareholders' Equity - Reconciliation of Changes in Parent Company's Total Shareholders' Equity (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Beginning balance			$ 2,028,323
Exercise of stock options			2,977
Earned portion of non-vested stock			4,203
Stock option expense			7
Carrying value less than redemption value on redeemed noncontrolling interest			(29)
Adjustment to redemption value on noncontrolling redeemable Operating Partnership units			(1,451)
Net income attributable to common shareholders	$ 41,120	$ 35,496	114,283	$ 75,280
Amortization of terminated hedge included in AOCL			688
Change in fair value of derivatives			(205)
Dividends			(139,235)
Ending balance	$ 2,009,561		$ 2,009,561

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 14, 2018	Aug. 02, 2017
Stockholders Equity [Line Items]
Common stock value authorized under equity offering program			$ 300,000,000
Buyback Program, authorized repurchase amount				$ 200,000,000
Stock repurchased during period, shares	0
Shares issued under dividend reinvestment plan		199,809
Equity Program [Member]
Stockholders Equity [Line Items]
Common stock remains available for issuance	$ 300,000,000

Partners' Capital - Reconciliat

Partners' Capital - Reconciliation of Change in Total Partners' Capital (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Partners Capital [Line Items]
Exercise of stock options			$ 2,977
Earned portion of non-vested stock			4,203
Stock option expense			7
Carrying value less than redemption value on redeemed noncontrolling interest			(29)
Adjustment to redemption value on limited partners’ redeemable capital interests			(1,451)
Net income attributable to common unitholders	$ 41,120	$ 35,496	114,283	$ 75,280
Amortization of terminated hedge included in AOCL			688
Change in fair value of derivatives			(205)
Life Storage LP [Member]
Partners Capital [Line Items]
Beginning balance of total controlling partners’ capital			2,028,323
Exercise of stock options			2,977
Earned portion of non-vested stock			4,203
Stock option expense			7
Carrying value less than redemption value on redeemed noncontrolling interest			(29)
Adjustment to redemption value on limited partners’ redeemable capital interests			(1,451)
Net income attributable to common unitholders	41,120	$ 35,496	114,283	$ 75,280
Amortization of terminated hedge included in AOCL			688
Change in fair value of derivatives			(205)
Distributions			(139,235)
Ending balance of total controlling partners’ capital	$ 2,009,561		$ 2,009,561

Recent Accounting Pronounceme_3

Recent Accounting Pronouncements - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)Property
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of properties acquired | Property	2
Land and Building [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated operating leases, aggregate annual minimum payments | $	$ 3
Revenue [Member] | Product Concentration [Member] | Revenue From Rental Products [Member] | Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk, percentage	90.00%

Commitment and Contingencies -

Commitment and Contingencies - Additional Information (Detail) $ in Thousands	Nov. 01, 2018USD ($)Property	Sep. 30, 2018USD ($)Property
Commitment And Contingencies [Line Items]
Number of storage facilities to be acquired | Property		3
Aggregate purchase price of business to be acquired		$ 29,300
Number of storage facilities acquired | Property		2
Aggregate purchase price		$ 19,409
New Jersey [Member] | Class Action [Member]
Commitment And Contingencies [Line Items]
Settlement agreement, amount		8,000
Remaining settlement, amount		$ 200
Subsequent Event [Member]
Commitment And Contingencies [Line Items]
Number of storage facilities to be acquired | Property	2
Aggregate purchase price of business to be acquired	$ 19,200
Subsequent Event [Member] | Date of Acquisition, Subsequent to 9/30/2018 [Member]
Commitment And Contingencies [Line Items]
Number of storage facilities acquired | Property	2
Aggregate purchase price	$ 22,100

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) $ / shares in Units, $ in Millions	Nov. 01, 2018USD ($)Property	Oct. 26, 2018USD ($)	Oct. 02, 2018$ / shares	Sep. 30, 2018USD ($)Property
Subsequent Event [Line Items]
Number of storage facilities to be acquired | Property				3
Aggregate purchase price of business to be acquired				$ 29.3
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividend declared, date			Oct. 2, 2018
Dividend per common share | $ / shares			$ 1
Dividend paid, date			Oct. 26, 2018
Dividend record, date			Oct. 16, 2018
Dividend paid		$ 46.6
Number of storage facilities to be acquired | Property	2
Aggregate purchase price of business to be acquired	$ 19.2