Life Storage Inc - Registered Shares (LSI) 10-Q 4 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Oct. 30, 2014
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Trading Symbol	'SSS	'
Entity Registrant Name	'SOVRAN SELF STORAGE INC	'
Entity Central Index Key	'0000944314	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	33,757,474

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investment in storage facilities:	'	'
Land	$381,794	$312,053
Building, equipment, and construction in progress	1,731,340	1,552,584
Real estate investment property, at cost, total	2,113,134	1,864,637
Less: accumulated depreciation	-400,306	-366,472
Investment in storage facilities, net	1,712,828	1,498,165
Cash and cash equivalents	7,476	9,524
Accounts receivable	5,663	5,119
Receivable from unconsolidated joint ventures	714	883
Investment in unconsolidated joint ventures	38,911	30,391
Prepaid expenses	7,302	5,978
Fair value of interest rate swap agreements	547	794
Other assets	7,843	11,021
Total Assets	1,781,284	1,561,875
Liabilities	'	'
Line of credit	'	49,000
Term notes	750,000	575,000
Accounts payable and accrued liabilities	43,807	37,741
Deferred revenue	7,269	6,708
Fair value of interest rate swap agreements	10,458	7,523
Mortgages payable	2,160	2,254
Total Liabilities	813,694	678,226
Noncontrolling redeemable Operating Partnership Units at redemption value	14,817	12,940
Shareholders' Equity	'	'
Common stock $.01 par value, 100,000,000 shares authorized, 33,708,457 shares issued and outstanding at September 30, 2014 (32,532,991 at December 31, 2013)	349	337
Additional paid-in capital	1,157,820	1,066,399
Dividends in excess of net income	-168,628	-162,450
Accumulated other comprehensive loss	-9,593	-6,402
Treasury stock at cost, 1,171,886 shares	-27,175	-27,175
Total Shareholders' Equity	952,773	870,709
Total Liabilities and Shareholders' Equity	$1,781,284	$1,561,875

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]	'	'
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	33,708,457	32,532,991
Common stock, shares outstanding	33,708,457	32,532,991
Treasury stock at cost, shares	1,171,886	1,171,886

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues	'	'	'	'
Rental income	$79,092	$65,309	$223,438	$186,997
Other operating income	6,157	5,146	17,712	14,445
Total operating revenues	85,249	70,455	241,150	201,442
Expenses	'	'	'	'
Property operations and maintenance	17,913	15,568	51,431	45,288
Real estate taxes	8,312	6,953	24,433	19,735
General and administrative	10,041	8,965	30,400	26,745
Acquisition costs	1,210	776	5,926	1,263
Operating leases of storage facilities	1,997	'	5,991	'
Depreciation and amortization	13,357	11,293	37,780	33,852
Total operating expenses	52,830	43,555	155,961	126,883
Income from operations	32,419	26,900	85,189	74,559
Other income (expenses)	'	'	'	'
Interest expense	-9,116	-7,923	-25,331	-24,827
Interest income	1	1	31	2
Gain on sale of real estate	1,777	'	1,777	421
Equity in income of joint ventures	662	575	1,553	1,417
Income from continuing operations	25,743	19,553	63,219	51,572
Income from discontinued operations	'	246	'	651
Net income	25,743	19,799	63,219	52,223
Net income attributable to noncontrolling interest	-154	-124	-381	-331
Net income attributable to common shareholders	$25,589	$19,675	$62,838	$51,892
Earnings per common share attributable to common shareholders - basic	'	'	'	'
Continuing operations	$0.77	$0.62	$1.92	$1.65
Discontinued operations	'	$0.01	'	$0.02
Earnings per share-basic	$0.77	$0.63	$1.92	$1.67
Earnings per common share attributable to common shareholders - diluted	'	'	'	'
Continuing operations	$0.77	$0.61	$1.91	$1.64
Discontinued operations	'	$0.01	'	$0.02
Earnings per share-diluted	$0.77	$0.62	$1.91	$1.66
Common shares used in basic earnings per share calculation	33,234,660	31,469,026	32,806,164	31,077,910
Common shares used in diluted earnings per share calculation	33,398,648	31,625,635	32,972,262	31,235,049
Dividends declared per common share	$0.68	$0.53	$2.04	$1.49

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Net income	$25,743	$19,799	$63,219	$52,223
Other comprehensive income:	'	'	'	'
Change in fair value of derivatives net of reclassification to interest expense	2,464	-3,572	-3,191	5,189
Total comprehensive income	28,207	16,227	60,028	57,412
Comprehensive income attributable to noncontrolling interest	-170	-102	-362	-364
Comprehensive income attributable to common shareholders	$28,037	$16,125	$59,666	$57,048

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (Unaudited) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Operating Activities	'	'
Net income	$63,219	$52,223
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	37,780	34,118
Amortization of deferred financing fees	619	640
Gain on sale of real estate	-1,777	-421
Equity in income of joint ventures	-1,553	-1,417
Distributions from unconsolidated joint venture	2,280	1,898
Non-vested stock earned	3,540	2,067
Stock option expense	186	261
Changes in assets and liabilities (excluding the effects of acquisitions):	'	'
Accounts receivable	-514	-122
Prepaid expenses	-1,186	-481
Receipts from joint ventures	252	74
Accounts payable and other liabilities	5,680	-3,531
Deferred revenue	-894	304
Net cash provided by operating activities	107,632	85,613
Investing Activities	'	'
Acquisitions of storage facilities	-229,709	-50,193
Improvements, equipment additions, and construction in progress	-20,257	-18,979
Net proceeds from the sale of real estate	5,063	4,367
Investment in unconsolidated joint ventures	-9,383	-4,111
Property deposit	-776	99
Net cash used in investing activities	-255,062	-68,817
Financing Activities	'	'
Net proceeds from sale of common stock	87,707	91,103
Proceeds from line of credit	125,000	120,000
Repayments of line of credit	-174,000	-176,000
Proceeds from term notes	175,000	325,000
Repayments of term notes	'	-325,000
Financing costs	-711	-1,554
Dividends paid-common stock	-67,113	-46,326
Distributions to noncontrolling interest holders	-406	-297
Redemption of operating partnership units	'	-306
Mortgage principal payments	-95	-1,009
Net cash provided by (used in) financing activities	145,382	-14,389
Net (decrease) increase in cash	-2,048	2,407
Cash at beginning of period	9,524	7,255
Cash at end of period	7,476	9,662
Supplemental cash flow information	'	'
Cash paid for interest, net of interest capitalized	$20,091	$24,876

Basis_of_Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Basis of Presentation	'
	1	BASIS OF PRESENTATION
	The accompanying unaudited financial statements of Sovran Self Storage, Inc. 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, 2014 are not necessarily indicative of the results that may be expected for the year ending December 31, 2014.
	Reclassification: Certain amounts from the 2013 financial statements have been reclassified as discontinued operations as a result of the sale of four storage facilities in 2013 (see Note 5).

Organization

Organization	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Organization	'
	2	ORGANIZATION
	Sovran Self Storage, Inc. (the “Company,” “We,” “Our,” or “Sovran”), a self-administered and self-managed real estate investment trust (a “REIT”), was formed on April 19, 1995 to own and operate self-storage facilities throughout the United States. On June 26, 1995, the Company commenced operations effective with the completion of its initial public offering. At September 30, 2014, we had an ownership interest in, leased, and/or managed 503 self-storage properties in 25 states under the name Uncle Bob’s Self Storage ®. Among our 503 self-storage properties are 28 properties that we manage for an unconsolidated joint venture (Sovran HHF Storage Holdings LLC) of which we are a 20% owner, 30 properties that we manage for an unconsolidated joint venture (Sovran HHF Storage Holdings II LLC) of which we are a 15% owner, 17 properties that we manage and have no ownership interest, and four properties we lease. Approximately 39% of the Company’s revenue is derived from stores in the states of Texas and Florida.
	All of the Company’s assets are owned by, and all its operations are conducted through, Sovran Acquisition Limited Partnership (the “Operating Partnership”). Sovran Holdings, Inc., a wholly-owned subsidiary of the Company (the “Subsidiary”), is the sole general partner of the Operating Partnership; the Company is a limited partner of the Operating Partnership, and through its ownership of the Subsidiary and its limited partnership interest controls the operations of the Operating Partnership, holding a 99.4% ownership interest therein as of September 30, 2014. The remaining ownership interests in the Operating Partnership (the “Units”) are held by certain former owners of assets acquired by the Operating Partnership subsequent to its formation.
	We consolidate all wholly owned subsidiaries. Partially owned subsidiaries and joint ventures are consolidated when we control the entity. Our consolidated financial statements include the accounts of the Company, the Operating Partnership, Uncle Bob’s Management, LLC (the Company’s taxable REIT subsidiary), Locke Sovran I, LLC (a wholly-owned subsidiary), and Locke Sovran II, LLC (a wholly-owned subsidiary). 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.
	On June 30, 2011, the Company entered into a newly formed joint venture agreement with an owner of a self-storage facility in New Jersey (West Deptford JV LLC). As part of the agreement the Company contributed $4.2 million to the joint venture for a $2.8 million mortgage note at 8%, a 20% common interest, and a $1.4 million preferred interest with an 8% preferred return. The Company had concluded that this joint venture is a variable interest entity pursuant to the guidance in FASB ASC Topic 810, “Consolidation” on the basis that the total equity investment in the joint venture is not sufficient to permit the joint venture to finance its activities without additional subordinated financial support from its investors. On February 5, 2013 the Company entered into a Membership Interest Purchase Agreement to sell its common and preferred interests in West Deptford JV LLC to the other joint venture partner for approximately $1.4 million, resulting in a gain of $0.4 million. Simultaneous with this transaction the joint venture partner also repaid the $2.8 million mortgage note held by the Company. As a result of these transactions the Company no longer holds any ownership interest in this joint venture. The results of operations of this joint venture are included in our 2013 consolidated financial statements through the February 5, 2013 date of divesture.
	Included in the consolidated balance sheets are noncontrolling redeemable operating partnership units. 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. At September 30, 2014 and December 31, 2013, there were 198,913 noncontrolling redeemable operating partnership Units outstanding. These unitholders are entitled to receive distributions per unit equivalent to the dividends declared per share on the 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 Company’s common stock, 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 EITF D-98, “Classification and Measurement of Redeemable Securities” which was codified in FASB ASC Topic 480-10-S99. The application of the FASB 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 redeemable Operating Partnership Units is reflected in dividends in excess of net income. Accordingly, in the accompanying consolidated balance sheet, noncontrolling redeemable Operating Partnership Units are reflected at redemption value at September 30, 2014 and December 31, 2013, equal to the number of Units outstanding multiplied by the fair market value of the Company’s common stock at that date. Redemption value exceeded the value determined under the Company’s historical basis of accounting at those dates.
	(dollars in thousands)		Nine Months
			Ended
			Sep. 30, 2014
	Beginning balance noncontrolling redeemable Operating Partnership Units		$	12,940
	Net income attributable to noncontrolling interests – consolidated joint venture			381
	Distributions			(406	)
	Adjustment to redemption value			1,902
	Ending balance noncontrolling redeemable Operating Partnership Units		$	14,817

Stock_Based_Compensation

Stock Based Compensation	9 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based 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”. The Company recognizes compensation cost in its financial statements for all share based payments granted, modified, or settled during the period. 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, 2014 and 2013, the Company recorded compensation expense (included in general and administrative expense) of $37,000 and $43,000, respectively, related to stock options and $1,129,000 and $795,000, respectively, related to amortization of non-vested stock grants. For the nine months ended September 30, 2014 and 2013, the Company recorded compensation expense (included in general and administrative expense) of $186,000 and $261,000, respectively, related to stock options and $3,451,000 and $1,977,000, respectively, related to amortization of non-vested stock grants.
	During the three months ended September 30, 2014 and 2013, employees exercised 3,962 and 23,835 stock options respectively, and 31,078 and 13,334 shares of non-vested stock, respectively, vested. During the nine months ended September 30, 2014 and 2013, employees exercised 12,962 and 121,845 stock options respectively, and 48,678 and 32,796 shares of non-vested stock, respectively, vested.

Investment_in_Storage_Faciliti

Investment in Storage Facilities	9 Months Ended
	Sep. 30, 2014
Real Estate [Abstract]	'
Investment in Storage Facilities	'
	4	INVESTMENT IN STORAGE FACILITIES
	The following summarizes our activity in storage facilities during the nine months ended September 30, 2014.
	(dollars in thousands)
	Cost:
	Beginning balance		$	1,864,637
	Acquisition of storage facilities			232,763
	Improvements and equipment additions			21,232
	Net decrease in construction in progress			(975	)
	Dispositions			(4,523	)
	Ending balance		$	2,113,134
	Accumulated Depreciation:
	Beginning balance		$	366,472
	Depreciation expense during the period			35,057
	Dispositions			(1,223	)
	Ending balance		$	400,306
	The assets and liabilities of the acquired storage facilities, which primarily consist of tangible and intangible assets, are measured at fair value on the date of acquisition in accordance with the principles of FASB ASC Topic 820, “Fair Value Measurements and Disclosures.” During the nine months ended September 30, 2014 the Company acquired 28 self-storage facilities and the purchase price of the facilities has been assigned as follows (as of September 30, 2014 the purchase price assignments relating to the five facilities acquired during the three months ended September 30, 2014 are preliminary):
	(dollars in thousands)										Consideration paid						Acquisition Date Fair Value
	State		Number of			Date of			Purchase		Cash Paid		Loan		Net Other		Land		Building,		In-Place		Acquisition
			Properties			Acquisition			Price				Assumed		Liabilities				Equipment, and		Customers		Costs
															(Assets)				Improvements		Leases		Expensed
															Assumed
	2014
	Florida			2			1/9/14		$	54,000	$	53,599	$	—	$	401	$	23,309	$	29,867	$	824	$	1,672
	Texas			1			1/17/14			9,000		8,962		—		38		3,999		4,856		145		215
	Texas			1			2/10/14			8,900		8,857		—		43		2,235		6,564		101		203
	Maine			2			2/11/14			14,750		14,601		—		149		2,639		11,824		287		406
	Illinois			1			3/31/14			8,700		8,582		—		118		1,837		6,724		139		223
	Illinois			1			5/5/14			5,500		5,487		—		13		598		4,902		—		44
	Texas			1			5/13/14			6,075		6,017		—		58		2,000		3,935		140		180
	Missouri			7			5/22/14			35,050		34,786		—		264		9,420		24,835		795		615
	New Jersey			1			6/5/14			12,600		12,526		—		74		5,161		7,201		238		280
	New York			1			6/11/14			8,000		7,988		—		12		1,741		6,106		153		201
	New Jersey			1			6/12/14			2,500		2,430		—		70		—		2,319		181		63
	Georgia			1			6/12/14			7,700		7,616		—		84		2,263		5,293		144		178
	New Jersey			3			6/18/14			18,325		18,221		—		104		2,543		15,377		405		539
	New Jersey			1			7/10/14			11,590		11,572		—		18		1,512		9,880		198		320
	Florida			1			8/28/14			10,200		10,111		—		89		2,958		7,055		187		183
	Virginia			1			9/5/14			6,400		6,373		—		27		2,349		3,947		104		266
	Texas			1			9/10/14			11,200		11,046		—		154		4,657		6,349		194		195
	Tennessee			1			9/18/14			6,550		6,535		—		15		759		5,749		42		143
	Total 2014			28					$	237,040	$	235,309	$	—	$	1,731	$	69,980	$	162,783	$	4,277	$	5,926
	All of the properties acquired were purchased from unrelated third parties. The operating results of the acquired facilities have been included in the Company’s operations since the respective acquisition dates. Of the $235.3 million paid at closing for the properties acquired during the nine months ended September 30, 2014, $5.6 million represented deposits that were paid in 2013 when certain of these properties originally went under contract.
	The Company measures the fair value of in-place customer lease intangible assets based on the Company’s experience with customer turnover. The Company amortizes in-place customer leases on a straight-line basis over 12 months (the estimated future benefit period). In-place customer leases are included in other assets on the Company’s balance sheet as follows:
	(Dollars in thousands)		Sep. 30,			Dec. 31,
			2014			2013
	In-place customer leases		$	18,920		$	14,643
	Accumulated amortization			(16,274	)		(13,551	)
	Net carrying value at the end of period		$	2,646		$	1,092
	Amortization expense related to in-place customer leases was $1.2 million and $0.8 million for the three months ended September 30, 2014 and 2013, respectively and was $2.7 million and $2.7 million for the nine months ended September 30, 2014 and 2013, respectively. The Company expects to record $4.0 million and $1.4 million of amortization expense for the years ended December 31, 2014 and 2015, respectively.
	As noted above, during the nine months ended September 30, 2014, the Company acquired 28 properties. The following pro forma information is based on the combined historical financial statements of the Company and the 28 properties acquired, and presents the Company’s results as if the acquisitions had occurred as of January 1, 2013:
			Three months ended						Nine months ended
			September 30,						September 30,
	(dollars in thousands)		2014			2013			2014		2013
	Total revenues		$	85,774		$	76,372		$	248,705	$	218,383
	Net income attributable to common shareholders		$	27,795		$	20,018		$	70,712	$	43,984
	Earnings per common share
	Basic		$	0.83		$	0.6		$	2.11	$	1.31
	Diluted		$	0.83		$	0.59		$	2.1	$	1.31
	The following table summarizes the revenues and earnings related to the 28 properties since the acquisition dates that are included in the Company’s consolidated statements of operations for the three and nine months ended September 30, 2014.
			Three months			Nine months
			ended September 30,			ended September 30,
			2014			2014
	Total revenues		$	5,562		$	10,047
Net loss attributable to common shareholders		$	(1,199	)	$	(5,774	)
The above net losses attributable to common shareholders were primarily due to the acquisition costs incurred in connection with the 2014 acquisitions.

Discontinued_Operations

Discontinued Operations	9 Months Ended
	Sep. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Discontinued Operations	'
	5	DISCONTINUED OPERATIONS
	In the 4th quarter of 2013, the Company sold four non-strategic storage facilities in Florida (2), Ohio (1), and Virginia (1) for net proceeds of approximately $11.7 million resulting in a gain of approximately $2.4 million. The operations of these facilities are reported as discontinued operations. Cash flows of discontinued operations have not been segregated from the cash flows of continuing operations on the accompanying consolidated statement of cash flows for the nine months ended September 30, 2013. Through September 30, 2014 the Company has not reported any dispositions of facilities as discontinued operations. The following is a summary of the amounts reported as discontinued operations in 2013:
	(dollars in thousands)		Jul. 1, 2013			Jan. 1, 2013
			to			to
			Sep. 30, 2013			Sep. 30, 2013
	Total revenue		$	528		$	1,490
	Property operations and maintenance expense			(152	)		(450	)
	Real estate taxes			(41	)		(123	)
	Depreciation and amortization expense			(89	)		(266	)
	Net realized gain on sale of property			—			—
	Total income from discontinued operations		$	246		$	651
	Income from continuing operations attributable to common shareholders was $25.6 million and $19.4 million for the three months ended September 30, 2014, and 2013, respectively. Income from continuing operations attributable to common shareholders was $62.8 million and $51.2 million for the nine months ended September 30, 2014, and 2013, respectively. Income from discontinued operations attributable to common shareholders was $0 and $0.2 million for the three months ended September 30, 2014, and 2013, respectively. Income from discontinued operations attributable to common shareholders was $0 and $0.6 million for the nine months ended September 30, 2014, and 2013, respectively.

Unsecured_Line_of_Credit_and_T

Unsecured Line of Credit and Term Notes	9 Months Ended
	Sep. 30, 2014
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)		Sep. 30,		Dec. 31,
			2014		2013
	Revolving line of credit borrowings		$	—	$	49,000
	Term note due April 13, 2016			150,000		150,000
	Term note due June 4, 2020			225,000		225,000
	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		—
	Total term notes payable		$	750,000	$	575,000
	On April 8, 2014, the Company entered into a $175 million term note maturing April 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. The proceeds from this term note were used to repay the $115 million outstanding on the Company’s line of credit at April 8, 2014, with the excess proceeds used for acquisitions.
	On June 4, 2013, the Company entered into an amendment to its unsecured credit arrangements. As part of the amended agreement, the Company entered into a $225 million unsecured term note maturing June 4, 2020 bearing interest at LIBOR plus a margin based on the Company’s credit rating (at September 30, 2014 the margin is 1.65%). The agreement also provides for a $175 million (expandable to $250 million) revolving line of credit bearing interest at a variable rate equal to LIBOR plus a margin based on the Company’s credit rating (at September 30, 2014 the margin is 1.50%), and requires a 0.20% facility fee. The interest rate at September 30, 2014 on the Company’s available line of credit was approximately 1.65% (1.67% at December 31, 2013). At September 30, 2014, there was $174.3 million available on the unsecured line of credit net of outstanding letters of credit of $0.7 million and without considering the additional availability under the expansion feature. The revolving line of credit has a maturity date of June 4, 2018, but can be extended for two one-year periods at the Company’s option with the payment of an extension fee equal to 0.125% of the total line of credit commitment.
	In addition, on June 4, 2013, as part of the amendment to its unsecured credit arrangement, the Company secured an additional $100 million term note with a delayed draw feature that was used to fund the Company’s term notes that matured in September 2013. The delayed draw term note matures June 4, 2020 and bears interest at LIBOR plus a margin based on the Company’s credit rating (at September 30, 2014 the margin is 1.65%).
	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 proceeds from this term note were used to fund acquisitions and investments in unconsolidated joint ventures.
	The Company also maintains a $150 million unsecured term note maturing April 13, 2016 bearing interest at 6.38%. The interest rate on the $150 million unsecured term note increases to 8.13% if the notes are not rated by at least one rating agency, the credit rating on the notes is downgraded or 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, 2014, the Company was in compliance with its debt 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, 2014 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.

Mortgages_Payable_and_Debt_Mat

Mortgages Payable and Debt Maturities	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Mortgages Payable and Debt Maturities	'
	7	MORTGAGES PAYABLE AND DEBT MATURITIES
	Mortgages payable at September 30, 2014 and December 31, 2013 consist of the following:
	(dollars in thousands)		September 30,		December 31,
			2014		2013
	5.99% mortgage notes due May 1, 2026, secured by one self-storage facility with an aggregate net book value of $4.4 million, principal and interest paid monthly (effective interest rate 6.21%)			2,160		2,254
	Total mortgages payable		$	2,160	$	2,254
	The table below summarizes the Company’s debt obligations and interest rate derivatives at September 30, 2014. 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)		2014		2015		2016		2017		2018		Thereafter		Total		Fair
																	Value
	Line of credit - variable rate LIBOR + 1.50% (1.65% at September 30, 2014)			—		—		—		—		—		—		—		—
	Notes Payable:
	Term note - fixed rate 6.38%			—		—	$	150,000		—		—		—	$	150,000	$	163,809
	Term note - variable rate LIBOR+1.65% (1.81% at September 30, 2014)			—		—		—		—		—	$	225,000	$	225,000	$	225,000
	Term note - variable rate LIBOR+1.65% (1.80% at September 30, 2014)			—		—		—		—		—	$	100,000	$	100,000	$	100,000
	Term note - fixed rate 5.54%			—		—		—		—		—	$	100,000	$	100,000	$	109,513
	Term note - fixed rate 4.533%			—		—		—		—		—	$	175,000	$	175,000	$	175,881
	Mortgage notes - fixed rate 5.99%		$	33	$	134	$	142	$	151	$	160	$	1,540	$	2,160	$	2,273
	Interest rate derivatives – asset			—		—		—		—		—		—		—	$	(547	)
	Interest rate derivatives – liability			—		—		—		—		—		—		—	$	10,458

Derivative_Financial_Instrumen

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative Financial Instruments	'
	8	DERIVATIVE FINANCIAL INSTRUMENTS
	Interest rate swaps are used 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. 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.
	The 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, the interest rate swaps are recorded in the consolidated balance sheet at fair value and the related gains or losses are deferred in shareholders’ equity 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 deminimus for the three and nine months ended September 30, 2014, and 2013.
	The Company has interest rate swap agreements in effect at September 30, 2014 as detailed below to effectively convert a total of $325 million of variable-rate debt to fixed-rate debt.
	Notional Amount		Effective			Expiration			Fixed Rate			Floating
			Date			Date			Paid			Rate Received
	$125 Million			9/1/11			8/1/18			2.37	%		1 month LIBOR
	$100 Million			12/30/11			12/29/17			1.6125	%		1 month LIBOR
	$100 Million			9/4/13			9/4/18			1.371	%		1 month LIBOR
	$100 Million			12/29/17			11/29/19			3.968	%		1 month LIBOR
	$125 Million			8/1/18			6/1/20			4.193	%		1 month LIBOR
	The interest rate swap agreements are the only derivative instruments, as defined by FASB ASC Topic 815 “Derivatives and Hedging”, held by the Company. During the three months ended September 30, 2014 and 2013, the net reclassification from AOCL to interest expense was $1.4 million and $1.5 million, respectively, based on payments made under the swap agreements. During the nine months ended September 30, 2014 and 2013, the net reclassification from AOCL to interest expense was $4.1 million and $4.0 million, respectively, based on payments made under the swap agreements. Based on current interest rates, the Company estimates that payments under the interest rate swaps will be approximately $5.5 million for the 12 months ended September 30, 2015. Payments made under the interest rate swap agreements will be reclassified to interest expense as settlements occur. The fair value of the swap agreements, including accrued interest, was an asset of $0.5 million and a liability of $10.5 million at September 30, 2014, and an asset of $0.8 million and a liability of $7.5 million at December 31, 2013.
	The Company’s agreements with its interest rate swap counterparties contain provisions pursuant to which the Company could be declared in default of its derivative obligations if the Company defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender. The interest rate swap agreements also incorporate other loan covenants of the Company. Failure to comply with the loan covenant provisions would result in the Company being in default on the interest rate swap agreements. As of September 30, 2014, the Company had not posted any collateral related to the interest rate swap agreements. If the Company had breached any of these provisions as of September 30, 2014, it could have been required to settle its obligations under the agreements at their net termination value of $9.9 million.
	The changes in AOCL for the three and nine months ended September 30, 2014 and September 30, 2013 are summarized as follows:
	(dollars in thousands)		Jul. 1, 2014			Jul. 1, 2013			Jan. 1, 2014			Jan. 1, 2013
			to			to			to			to
			Sep. 30, 2014			Sep. 30, 2013			Sep. 30, 2014			Sep. 30, 2013
	Accumulated other comprehensive loss beginning of period		$	(12,057	)	$	(6,481	)	$	(6,402	)	$	(15,242	)
	Realized loss reclassified from accumulated other comprehensive loss to interest expense			1,392			1,474			4,134			3,979
	Unrealized (loss) gain from changes in the fair value of the effective portion of the interest rate swaps			1,072			(5,046	)		(7,325	)		1,210
	(Loss) gain included in other comprehensive loss			2,464			(3,572	)		(3,191	)		5,189
	Accumulated other comprehensive loss end of period		$	(9,593	)	$	(10,053	)	$	(9,593	)	$	(10,053	)

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2014
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” in determining the fair value of its financial and nonfinancial assets and liabilities. ASC Topic 820 establishes a valuation hierarchy for disclosure of the inputs to valuation used to measure fair value. This hierarchy prioritizes the inputs into three broad levels as follows. Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration. Level 3 inputs are unobservable inputs based on our own assumptions used to measure assets and liabilities at fair value. A financial asset or liability’s classification within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement.
	Refer to Note 7 for presentation of the fair values of debt obligations which are disclosed at fair value on a recurring basis.
	The following table provides the assets and liabilities carried at fair value measured on a recurring basis as of September 30, 2014 and December 31, 2013 (in thousands):
			Asset (Liability)			Level 1		Level 2			Level 3
	September 30, 2014
	Interest rate swaps			547			—		547			—
	Interest rate swaps			(10,458	)		—		(10,458	)		—
	December 31, 2013
	Interest rate swaps			794			—		794			—
	Interest rate swaps			(7,523	)		—		(7,523	)		—
	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.
	During the nine months ended September 30, 2014, assets and liabilities measured at fair value on a non-recurring basis included the assets acquired and liabilities assumed in connection with the acquisition of 28 storage facilities (see note 4). To determine the fair value of land, the Company used prices per acre derived from observed transactions involving comparable land in similar locations, which is considered a Level 2 input. To determine the fair value of buildings, equipment and improvements, the Company used current replacement cost based on information derived from construction industry data by geographic region which is considered a Level 2 input. This replacement cost is then adjusted for the age, condition, and economic obsolescence associated with these assets, which are considered Level 3 inputs. The fair value of in-place customer leases is based on the rent lost due to the amount of time required to replace existing customers which is based on the Company’s historical experience with turnover in its facilities, which is a Level 3 input. Other assets acquired and liabilities assumed in the acquisitions consist primarily of prepaid or accrued real estate taxes and deferred revenues from advance monthly rentals paid by customers. The fair values of these assets and liabilities are based on their carrying values as they typically turn over within one year from the acquisition date and these are Level 3 inputs.

Investment_in_Joint_Ventures

Investment in Joint Ventures	9 Months Ended
	Sep. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
Investment in Joint Ventures	'
	10	INVESTMENT IN JOINT VENTURES
	The Company has a 20% ownership interest in Sovran HHF Storage Holdings LLC (“Sovran HHF”), a joint venture that was formed in May 2008 to acquire self-storage properties that are managed by the Company. The carrying value of the Company’s investment at September 30, 2014 and December 31, 2013 was $26.2 million and $17.4 million, respectively. Twenty-five properties were acquired by Sovran HHF in 2008 for approximately $171.5 million and three additional properties were acquired by Sovran HHF in June 2014 for $34.4 million. In 2008, the Company contributed $18.6 million in cash to the joint venture as its share of capital required to fund acquisitions. In 2012 the Company contributed an additional $1.2 million in cash to the joint venture. In 2013 the Company received a return of capital distribution of $3.4 million as part of the refinancing of Sovran HHF. In 2014, the Company contributed $9.3 million in cash to the joint venture as its share of capital required to fund acquisitions and deposits on future acquisitions.
	As of September 30, 2014, the carrying value of the Company’s investment in Sovran HHF exceeds its share of the underlying equity in net assets of Sovran HHF by approximately $1.7 million as a result of the capitalization of certain acquisition related costs in 2008. This difference is included in the carrying value of the investment, which is assessed for other-than-temporary impairment on a periodic basis. No other-than-temporary impairments have been recorded on this investment.
	The Company has a 15% ownership interest in Sovran HHF Storage Holdings II LLC (“Sovran HHF II”), a joint venture that was formed in 2011 to acquire self-storage properties that are managed by the Company. The carrying value of the Company’s investment at September 30, 2014 and December 31, 2013 was $12.7 million and $12.8 million, respectively. Twenty properties were acquired by Sovran HHF II during 2011 for approximately $166.1 million. During 2011, the Company contributed $12.8 million to the joint venture as its share of capital required to fund the acquisitions. Ten additional properties were acquired by Sovran HHF II during 2012 for approximately $29 million. During 2012, the Company contributed $2.4 million to the joint venture as its share of capital required to fund the acquisitions. The carrying value of this investment is assessed for other-than-temporary impairment on a periodic basis and no such impairments have been recorded on this investment.
	As manager of Sovran HHF and Sovran HHF II, the Company earns a management and call center fee of 7% of gross revenues which totaled $1.0 million and $0.9 million for the three months ended September 30, 2014 and 2013, respectively. The management and call center fees earned by the Company for the nine months ended September 30, 2014 and 2013 totaled $2.8 million and $2.5 million, respectively.
	The Company’s share of Sovran HHF and Sovran HHF II’s income for the three months ended September 30, 2014 and 2013 was $624,000 and $552,000 respectively. The Company’s share of Sovran HHF and Sovran HHF II’s income for the nine months ended September 30, 2014 and 2013 was $1,417,000 and $1,373,000, respectively.
	The Company also has a 49% ownership interest in Iskalo Office Holdings, LLC, which owns the building that houses the Company’s headquarters and other tenants. The carrying value of the Company’s investment is a liability of $0.4 million at September 30, 2014 and $0.5 million at December 31, 2013, and is included in accounts payable and accrued liabilities in the accompanying consolidated balance sheets. The Company’s share of Iskalo Office Holdings, LLC’s income for the three months ended September 30, 2014 and 2013 was $38,000 and $23,000, respectively. The Company’s share of Iskalo Office Holdings, LLC’s income for the nine months ended September 30, 2014 and 2013 was $102,000 and $44,000, respectively. The Company paid rent to Iskalo Office Holdings, LLC of $261,000 and $231,000 during the three months ended September 30, 2014 and 2013, respectively. The Company paid rent to Iskalo Office Holdings, LLC of $764,000 and $576,000 during the nine months ended September 30, 2014 and 2013, respectively.
	A summary of the unconsolidated joint ventures’ financial statements as of and for the nine months ended September 30, 2014 is as follows:
	(dollars in thousands)		Sovran HHF			Sovran HHF			Iskalo Office
			Storage			Storage			Holdings, LLC
			Holdings LLC			Holdings II LLC
	Balance Sheet Data:
	Investment in storage facilities, net		$	189,678		$	185,656		$	—
	Investment in office building			—			—			4,829
	Other assets			17,478			4,687			920
	Total Assets		$	207,156		$	190,343		$	5,749
	Due to the Company		$	344		$	382		$	—
	Mortgages payable			80,861			103,068			6,487
	Other liabilities			3,447			2,358			551
	Total Liabilities			84,652			105,808			7,038
	Unaffiliated partners’ equity (deficiency)			98,003			71,861			(881	)
	Company equity (deficiency)			24,501			12,674			(408	)
	Total Partners’ Equity (Deficiency)			122,504			84,535			(1,289	)
	Total Liabilities and Partners’ Equity (Deficiency)		$	207,156		$	190,343		$	5,749
	Income Statement Data:
	Total revenues		$	18,218		$	21,310		$	1,081
	Property operating expenses			(5,797	)		(7,448	)		(400	)
	Administrative, management and call center fees			(1,376	)		(1,581	)		—
	Acquisition costs			(926	)		—			—
	Depreciation and amortization of customer list			(3,242	)		(3,117	)		(172	)
	Amortization of financing fees			(137	)		(152	)		(8	)
	Income tax expense			(78	)		(301	)		—
	Interest expense			(3,209	)		(3,866	)		(292	)
	Net income		$	3,453		$	4,845		$	209
	The Company does not guarantee the debt of Sovran HHF, Sovran HHF II, or Iskalo Office Holdings, LLC.
	We do not expect to have material future cash outlays relating to these joint ventures outside our share of capital for future acquisitions of properties.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2014
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.
	For the three months ended September 30, 2014 and 2013, the Company recorded federal and state income tax expense of $0.4 million and $0.3 million, respectively. For the nine months ended September 30, 2014 and 2013, the Company recorded federal and state income tax expense of $1.0 million and $1.0 million, respectively. At September 30, 2014 and 2013, 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, 2014 and 2013, the Company had no interest or penalties related to uncertain tax positions. Net income taxes payable and the deferred tax liability of our taxable REIT subsidiary are classified within accounts payable and accrued liabilities in the consolidated balance sheet. As of September 30, 2014, the Company’s taxable REIT subsidiary has a current tax liability of $0.3 million and a deferred tax liability of $0.8 million. The tax years 2011-2013 remain open to examination by the major taxing jurisdictions to which the Company is subject.

Earnings_Per_Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	12	EARNINGS PER SHARE
	The Company reports earnings per share data in accordance ASC Topic 260, “Earnings Per Share.” Effective January 1, 2009, FASB ASC Topic 260 was updated for the issuance of FASB Staff Position (“FSP”) EITF 03-6-1, “Determining Whether Instruments Granted in Share-Based Payment Transactions Are Participating Securities”, or FSP EITF 03-6-1, with transition guidance included in FASB ASC Topic 260-10-65-2. Under FSP EITF 03-6-1, unvested share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents, whether paid or unpaid, are participating securities and shall be included in the computation of earnings-per-share pursuant to the two-class method. The Company has calculated its basic and diluted earnings per share using the two-class method. The following table sets forth the computation of basic and diluted earnings per common share utilizing the two-class method.
	(in thousands except per share data)		Three Months		Three Months		Nine Months		Nine Months
			Ended		Ended		Ended		Ended
			Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
	Numerator:
	Net income from continuing operations attributable to common shareholders		$	25,589	$	19,431	$	62,838	$	51,245
	Denominator:
	Denominator for basic earnings per share – weighted average shares			33,235		31,469		32,806		31,078
	Effect of Dilutive Securities:
	Stock options and non-vested stock			164		157		166		157
	Denominator for diluted earnings per share – adjusted weighted average shares and assumed conversion			33,399		31,626		32,972		31,235
	Basic earnings per common share from continuing operations attributable to common shareholders		$	0.77	$	0.62	$	1.92	$	1.65
	Basic earnings per common share attributable to common shareholders		$	0.77	$	0.63	$	1.92	$	1.67
	Diluted earnings per common share from continuing operations attributable to common shareholders		$	0.77	$	0.61	$	1.91	$	1.64
	Diluted earnings per common share attributable to common shareholders		$	0.77	$	0.62	$	1.91	$	1.66
	Not included in the effect of dilutive securities above are 6,000 stock options and 125,775 unvested restricted shares for the three months ended September 30, 2014, and 121,916 unvested restricted shares for the three months ended September 30, 2013, because their effect would be antidilutive. Not included in the effect of dilutive securities above are 6,667 stock options and 145,690 unvested restricted shares for the nine months ended September 30, 2014, and 2,667 stock options and 88,901 unvested restricted shares for the nine months ended September 30, 2013, because their effect would be antidilutive.

Shareholders_Equity

Shareholders' Equity	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Shareholders' Equity	'
	13	SHAREHOLDERS’ EQUITY
	The following is a reconciliation of the changes in total shareholders’ equity for the period:
	(dollars in thousands)		Nine Months
			Ended
			September 30, 2014
	Beginning balance of total shareholders’ equity		$	870,709
	Net proceeds from the issuance of common stock			87,179
	Exercise of stock options			527
	Earned portion of non-vested stock			3,451
	Stock option expense			186
	Deferred compensation outside directors			89
	Adjustment to redemption value on noncontrolling redeemable Operating Partnership units			(1,902	)
	Net income attributable to common shareholders			62,838
	Change in fair value of derivatives			(3,191	)
	Dividends			(67,113	)
	Ending balance of total shareholders’ equity		$	952,773
	On May 12, 2014, the Company entered into a continuous equity offering program (“Equity Program”) with Wells Fargo Securities, LLC (“Wells Fargo”), Jefferies LLC (“Jefferies”), SunTrust Robinson Humphrey, Inc. (“SunTrust”), Piper Jaffray & Co. (“Piper”), HSBC Securities (USA) Inc. (“HSBC”), and BB&T Capital Markets, a division of BB&T Securities, LLC (“BB&T”), pursuant to which the Company may sell from time to time up to $225 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 three months ended September 30, 2014, the Company issued 424,403 shares of common stock under the Equity Program at a weighted average issue price of $78.46 per share, generating net proceeds of $32.9 million after deducting $0.4 million of sales commissions paid to HSBC. During the nine months ended September 30, 2014, the Company issued 674,403 shares of common stock under the Equity Program at a weighted average issue price of $77.95 per share, generating net proceeds of $51.9 million after deducting $0.7 million of sales commissions paid to Piper and HSBC. As of September 30, 2014, the Company had $172.4 million available for issuance under the Equity Program.
	During the three months ended March 31, 2014, the Company issued 359,102 shares of common stock under a previous equity program at a weighted average issue price of $74.32 per share, generating net proceeds of $26.4 million after deducting $0.3 million of sales commissions payable to SunTrust.
	In addition to sales commissions, the Company incurred expenses of $0.2 million in connection with these equity programs during 2014. The Company used the proceeds from the equity programs to fund a portion of the acquisition of 28 storage facilities.
	In 2013, the Company implemented a Dividend Reinvestment Plan. The Company issued 129,837 shares under the plan in 2014.

Recent_Accounting_Pronouncemen

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2014
Accounting Changes and Error Corrections [Abstract]	'
Recent Accounting Pronouncements	'
	14	RECENT ACCOUNTING PRONOUNCEMENTS
	In July 2013, the FASB issued ASU 2013-11, “Income Taxes (Topic 740): Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists.” This ASU provides explicit guidance regarding the presentation in the statement of financial position of an unrecognized tax benefit when net operating losses or tax credit carryforwards exist. It is effective for fiscal years, and interim periods within those years, beginning after December 15, 2013, with early adoption permitted, and is applicable to the Company’s fiscal year beginning January 1, 2014. The adoption of this guidance did not have a material impact on the Company’s consolidated financial statements.
	In April 2014, the FASB issued ASU 2014-08, “Presentation of Financial Statements (Topic 205) and Property, Plant and Equipment (Topic 360): Reporting Discontinued Operations and disclosures of Components of an Entity”. Under this ASU, only disposals representing a strategic shift in operations should be presented as discontinued operations. Those strategic shifts should have a major effect on the organization’s operations and financial results. The ASU also requires new disclosures of both discontinued operations and certain other disposals that do not meet the definition of a discontinued operation. It is effective for fiscal years, and interim periods within those years, beginning after December 15, 2014, with early adoption permitted. We have adopted this guidance effective January 1, 2014 and the adoption is expected to significantly reduce the classification of property sales by the Company as discontinued operations.
	The following table summarizes the revenues and expenses up to the date of sale of the one property sold in 2014 that are included in the Company’s consolidated statements of operations for the three and nine months ended September 30, 2014 and 2013.
			Three months ended				Nine months ended
			September 30,				September 30,
	(dollars in thousands)		2014		2013		2014		2013
	Total revenues		$	80	$	180	$	465	$	526
	Property operations and maintenance expense			23		50		111		161
	Real estate tax expense			3		18		51		54
	Depreciation and amortization expense			9		26		60		76
	Gain on sale of real estate			1,777		—		1,777		—
	In May 2014, FASB issued ASU 2014-09, “Revenue from Contracts with Customers,” 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, 2016. The Company has 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 Company is currently evaluating the new standard to determine the impact it may have on the consolidated financial statements.
	In June 2014, the FASB issued ASU 2014-12, “Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period,” which requires a reporting entity to treat a performance target that affects vesting and that could be achieved after the requisite service period as a performance condition. ASU 2014-12 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. Early adoption is permitted. ASU 2014-12 may be adopted either prospectively for share-based payment awards granted or modified on or after the effective date, or retrospectively, using a modified retrospective approach. The modified retrospective approach would apply to share-based payment awards outstanding as of the beginning of the earliest annual period presented in the financial statements on adoption, and to all new or modified awards thereafter. The Company is currently evaluating the new standard to determine the impact it may have on the consolidated financial statements.

Commitment_and_Contingencies

Commitment and Contingencies	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitment and Contingencies	'
	15	COMMITMENT AND CONTINGENCIES
	At September 30, 2014, the Company was under contract to acquire five self-storage facilities for cash consideration of approximately $56.6 million. Three of these facilities were acquired in October 2014 for $41.1 million and were funded with draws on the Company’s line of credit. At September 30, 2014, Sovran HHF, a joint venture in which the Company has a 20% ownership interest, was under contract to acquire 11 self-storage facilities for cash consideration of approximately $153.0 million. The Company’s cash contribution to Sovran HHF for the purchase of the 11 facilities would be approximately $21.0 million. The purchase of these facilities by the Company or Sovran HHF is subject to customary conditions to closing, and there is no assurance that these facilities will be acquired.
	The Company was also under contract as of September 30, 2014 to sell one self storage facility for cash consideration of approximately $6.3 million. The sale of this facility by the Company is subject to customary conditions to closing, and there is no assurance that this facility will be sold.
	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 seeks to obtain declaratory, injunctive and monetary relief for a class of consumers based upon alleged violations by the Company of the New Jersey Truth in Customer Contract, Warranty and Notice Act, the New Jersey Consumer Fraud Act and the New Jersey Insurance Producer Licensing Act. 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 Company intends to vigorously defend the action, and the possibility of any adverse outcome cannot be determined at this time.

Subsequent_Events

Subsequent Events	9 Months Ended
	Sep. 30, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	16	SUBSEQUENT EVENTS
	On October 2, 2014, the Company declared a quarterly dividend of $0.68 per common share. The dividend was paid on October 28, 2014 to shareholders of record on October 14, 2014. The total dividend paid amounted to $22.9 million.

Basis_of_Presentation_Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2014
Accounting Changes and Error Corrections [Abstract]	'
Reclassification	'
	Reclassification: Certain amounts from the 2013 financial statements have been reclassified as discontinued operations as a result of the sale of four storage facilities in 2013 (see Note 5).
Fair Value Measurements and Disclosures	'
	The assets and liabilities of the acquired storage facilities, which primarily consist of tangible and intangible assets, are measured at fair value on the date of acquisition in accordance with the principles of FASB ASC Topic 820, “Fair Value Measurements and Disclosures.”
Income Taxes	'
	In July 2013, the FASB issued ASU 2013-11, “Income Taxes (Topic 740): Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists.” This ASU provides explicit guidance regarding the presentation in the statement of financial position of an unrecognized tax benefit when net operating losses or tax credit carryforwards exist. It is effective for fiscal years, and interim periods within those years, beginning after December 15, 2013, with early adoption permitted, and is applicable to the Company’s fiscal year beginning January 1, 2014. The adoption of this guidance did not have a material impact on the Company’s consolidated financial statements.
Discontinued Operations and Disclosures of Components of Entity	'
	In April 2014, the FASB issued ASU 2014-08, “Presentation of Financial Statements (Topic 205) and Property, Plant and Equipment (Topic 360): Reporting Discontinued Operations and disclosures of Components of an Entity”. Under this ASU, only disposals representing a strategic shift in operations should be presented as discontinued operations. Those strategic shifts should have a major effect on the organization’s operations and financial results. The ASU also requires new disclosures of both discontinued operations and certain other disposals that do not meet the definition of a discontinued operation. It is effective for fiscal years, and interim periods within those years, beginning after December 15, 2014, with early adoption permitted. We have adopted this guidance effective January 1, 2014 and the adoption is expected to significantly reduce the classification of property sales by the Company as discontinued operations.
Revenue from Contracts with Customers	'
	In May 2014, FASB issued ASU 2014-09, “Revenue from Contracts with Customers,” 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, 2016. The Company has 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 Company is currently evaluating the new standard to determine the impact it may have on the consolidated financial statements.
Accounting for Share-Based Payments	'
	In June 2014, the FASB issued ASU 2014-12, “Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period,” which requires a reporting entity to treat a performance target that affects vesting and that could be achieved after the requisite service period as a performance condition. ASU 2014-12 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. Early adoption is permitted. ASU 2014-12 may be adopted either prospectively for share-based payment awards granted or modified on or after the effective date, or retrospectively, using a modified retrospective approach. The modified retrospective approach would apply to share-based payment awards outstanding as of the beginning of the earliest annual period presented in the financial statements on adoption, and to all new or modified awards thereafter. The Company is currently evaluating the new standard to determine the impact it may have on the consolidated financial statements.

Organization_Tables

Organization (Tables)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Redeemable Noncontrolling Interest	'
	Redemption value exceeded the value determined under the Company’s historical basis of accounting at those dates.
	(dollars in thousands)	Nine Months
		Ended
		Sep. 30, 2014
	Beginning balance noncontrolling redeemable Operating Partnership Units	$	12,940
	Net income attributable to noncontrolling interests – consolidated joint venture		381
	Distributions		(406	)
	Adjustment to redemption value		1,902
	Ending balance noncontrolling redeemable Operating Partnership Units	$	14,817

Investment_in_Storage_Faciliti1

Investment in Storage Facilities (Tables)	9 Months Ended
	Sep. 30, 2014
Real Estate [Abstract]	'
Summary of Activity in Storage Facilities	'
	The following summarizes our activity in storage facilities during the nine months ended September 30, 2014.
	(dollars in thousands)
	Cost:
	Beginning balance	$	1,864,637
	Acquisition of storage facilities		232,763
	Improvements and equipment additions		21,232
	Net decrease in construction in progress		(975	)
	Dispositions		(4,523	)
	Ending balance	$	2,113,134
	Accumulated Depreciation:
	Beginning balance	$	366,472
	Depreciation expense during the period		35,057
	Dispositions		(1,223	)
	Ending balance	$	400,306
Schedule of Acquired Facilities and Purchase Price of Facilities	'
	During the nine months ended September 30, 2014 the Company acquired 28 self-storage facilities and the purchase price of the facilities has been assigned as follows (as of September 30, 2014 the purchase price assignments relating to the five facilities acquired during the three months ended September 30, 2014 are preliminary):
	(dollars in thousands)									Consideration paid						Acquisition Date Fair Value
	State	Number of			Date of			Purchase		Cash Paid		Loan		Net Other		Land		Building,		In-Place		Acquisition
		Properties			Acquisition			Price				Assumed		Liabilities				Equipment, and		Customers		Costs
														(Assets)				Improvements		Leases		Expensed
														Assumed
	2014
	Florida		2			1/9/14		$	54,000	$	53,599	$	—	$	401	$	23,309	$	29,867	$	824	$	1,672
	Texas		1			1/17/14			9,000		8,962		—		38		3,999		4,856		145		215
	Texas		1			2/10/14			8,900		8,857		—		43		2,235		6,564		101		203
	Maine		2			2/11/14			14,750		14,601		—		149		2,639		11,824		287		406
	Illinois		1			3/31/14			8,700		8,582		—		118		1,837		6,724		139		223
	Illinois		1			5/5/14			5,500		5,487		—		13		598		4,902		—		44
	Texas		1			5/13/14			6,075		6,017		—		58		2,000		3,935		140		180
	Missouri		7			5/22/14			35,050		34,786		—		264		9,420		24,835		795		615
	New Jersey		1			6/5/14			12,600		12,526		—		74		5,161		7,201		238		280
	New York		1			6/11/14			8,000		7,988		—		12		1,741		6,106		153		201
	New Jersey		1			6/12/14			2,500		2,430		—		70		—		2,319		181		63
	Georgia		1			6/12/14			7,700		7,616		—		84		2,263		5,293		144		178
	New Jersey		3			6/18/14			18,325		18,221		—		104		2,543		15,377		405		539
	New Jersey		1			7/10/14			11,590		11,572		—		18		1,512		9,880		198		320
	Florida		1			8/28/14			10,200		10,111		—		89		2,958		7,055		187		183
	Virginia		1			9/5/14			6,400		6,373		—		27		2,349		3,947		104		266
	Texas		1			9/10/14			11,200		11,046		—		154		4,657		6,349		194		195
	Tennessee		1			9/18/14			6,550		6,535		—		15		759		5,749		42		143
	Total 2014		28					$	237,040	$	235,309	$	—	$	1,731	$	69,980	$	162,783	$	4,277	$	5,926
Schedule of Fair Value of In-Place Customer Lease Intangible Assets	'
	In-place customer leases are included in other assets on the Company’s balance sheet as follows:
	(Dollars in thousands)	Sep. 30,			Dec. 31,
		2014			2013
	In-place customer leases	$	18,920		$	14,643
	Accumulated amortization		(16,274	)		(13,551	)
	Net carrying value at the end of period	$	2,646		$	1,092
Pro Forma Information Based on Combined Historical Financial Statements on Properties Acquired	'
	The following pro forma information is based on the combined historical financial statements of the Company and the 28 properties acquired, and presents the Company’s results as if the acquisitions had occurred as of January 1, 2013:
		Three months ended						Nine months ended
		September 30,						September 30,
	(dollars in thousands)	2014			2013			2014		2013
	Total revenues	$	85,774		$	76,372		$	248,705	$	218,383
	Net income attributable to common shareholders	$	27,795		$	20,018		$	70,712	$	43,984
	Earnings per common share
	Basic	$	0.83		$	0.6		$	2.11	$	1.31
	Diluted	$	0.83		$	0.59		$	2.1	$	1.31
Summary of Revenues and Earnings Related to Properties Included in Company's Consolidated Statements of Operations	'
	The following table summarizes the revenues and earnings related to the 28 properties since the acquisition dates that are included in the Company’s consolidated statements of operations for the three and nine months ended September 30, 2014.
		Three months			Nine months
		ended September 30,			ended September 30,
		2014			2014
	Total revenues	$	5,562		$	10,047
	Net loss attributable to common shareholders	$	(1,199	)	$	(5,774	)

Discontinued_Operations_Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Summary of Amount Reported as Discontinued Operations	'
	The following is a summary of the amounts reported as discontinued operations in 2013:
	(dollars in thousands)	Jul. 1, 2013			Jan. 1, 2013
		to			to
		Sep. 30, 2013			Sep. 30, 2013
	Total revenue	$	528		$	1,490
	Property operations and maintenance expense		(152	)		(450	)
	Real estate taxes		(41	)		(123	)
	Depreciation and amortization expense		(89	)		(266	)
	Net realized gain on sale of property		—			—
	Total income from discontinued operations	$	246		$	651

Unsecured_Line_of_Credit_and_T1

Unsecured Line of Credit and Term Notes (Tables)	9 Months Ended
	Sep. 30, 2014
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)	Sep. 30,		Dec. 31,
		2014		2013
	Revolving line of credit borrowings	$	—	$	49,000
	Term note due April 13, 2016		150,000		150,000
	Term note due June 4, 2020		225,000		225,000
	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		—
	Total term notes payable	$	750,000	$	575,000

Mortgages_Payable_and_Debt_Mat1

Mortgages Payable and Debt Maturities (Tables)	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Summary of Mortgage Payable	'
	Mortgages payable at September 30, 2014 and December 31, 2013 consist of the following:
	(dollars in thousands)	September 30,		December 31,
		2014		2013
	5.99% mortgage notes due May 1, 2026, secured by one self-storage facility with an aggregate net book value of $4.4 million, principal and interest paid monthly (effective interest rate 6.21%)		2,160		2,254
	Total mortgages payable	$	2,160	$	2,254
Summary of Debt Obligation 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)	2014		2015		2016		2017		2018		Thereafter		Total		Fair
																Value
	Line of credit - variable rate LIBOR + 1.50% (1.65% at September 30, 2014)		—		—		—		—		—		—		—		—
	Notes Payable:
	Term note - fixed rate 6.38%		—		—	$	150,000		—		—		—	$	150,000	$	163,809
	Term note - variable rate LIBOR+1.65% (1.81% at September 30, 2014)		—		—		—		—		—	$	225,000	$	225,000	$	225,000
	Term note - variable rate LIBOR+1.65% (1.80% at September 30, 2014)		—		—		—		—		—	$	100,000	$	100,000	$	100,000
	Term note - fixed rate 5.54%		—		—		—		—		—	$	100,000	$	100,000	$	109,513
	Term note - fixed rate 4.533%		—		—		—		—		—	$	175,000	$	175,000	$	175,881
	Mortgage notes - fixed rate 5.99%	$	33	$	134	$	142	$	151	$	160	$	1,540	$	2,160	$	2,273
	Interest rate derivatives – asset		—		—		—		—		—		—		—	$	(547	)
	Interest rate derivatives – liability		—		—		—		—		—		—		—	$	10,458

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Summary of Interest Rate Swap Agreements	'
	The Company has interest rate swap agreements in effect at September 30, 2014 as detailed below to effectively convert a total of $325 million of variable-rate debt to fixed-rate debt.
	Notional Amount	Effective			Expiration			Fixed Rate			Floating
		Date			Date			Paid			Rate Received
	$125 Million		9/1/11			8/1/18			2.37	%		1 month LIBOR
	$100 Million		12/30/11			12/29/17			1.6125	%		1 month LIBOR
	$100 Million		9/4/13			9/4/18			1.371	%		1 month LIBOR
	$100 Million		12/29/17			11/29/19			3.968	%		1 month LIBOR
	$125 Million		8/1/18			6/1/20			4.193	%		1 month LIBOR
Summary of Changes in AOCL	'
	The changes in AOCL for the three and nine months ended September 30, 2014 and September 30, 2013 are summarized as follows:
	(dollars in thousands)	Jul. 1, 2014			Jul. 1, 2013			Jan. 1, 2014			Jan. 1, 2013
		to			to			to			to
		Sep. 30, 2014			Sep. 30, 2013			Sep. 30, 2014			Sep. 30, 2013
	Accumulated other comprehensive loss beginning of period	$	(12,057	)	$	(6,481	)	$	(6,402	)	$	(15,242	)
	Realized loss reclassified from accumulated other comprehensive loss to interest expense		1,392			1,474			4,134			3,979
	Unrealized (loss) gain from changes in the fair value of the effective portion of the interest rate swaps		1,072			(5,046	)		(7,325	)		1,210
	(Loss) gain included in other comprehensive loss		2,464			(3,572	)		(3,191	)		5,189
	Accumulated other comprehensive loss end of period	$	(9,593	)	$	(10,053	)	$	(9,593	)	$	(10,053	)

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Assets and Liabilities Carried at Fair Value Measured on Recurring Basis	'
	The following table provides the assets and liabilities carried at fair value measured on a recurring basis as of September 30, 2014 and December 31, 2013 (in thousands):
		Asset (Liability)			Level 1		Level 2			Level 3
	September 30, 2014
	Interest rate swaps		547			—		547			—
	Interest rate swaps		(10,458	)		—		(10,458	)		—
	December 31, 2013
	Interest rate swaps		794			—		794			—
	Interest rate swaps		(7,523	)		—		(7,523	)		—

Investment_in_Joint_Ventures_T

Investment in Joint Ventures (Tables)	9 Months Ended
	Sep. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
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, 2014 is as follows:
	(dollars in thousands)	Sovran HHF			Sovran HHF			Iskalo Office
		Storage			Storage			Holdings, LLC
		Holdings LLC			Holdings II LLC
	Balance Sheet Data:
	Investment in storage facilities, net	$	189,678		$	185,656		$	—
	Investment in office building		—			—			4,829
	Other assets		17,478			4,687			920
	Total Assets	$	207,156		$	190,343		$	5,749
	Due to the Company	$	344		$	382		$	—
	Mortgages payable		80,861			103,068			6,487
	Other liabilities		3,447			2,358			551
	Total Liabilities		84,652			105,808			7,038
	Unaffiliated partners’ equity (deficiency)		98,003			71,861			(881	)
	Company equity (deficiency)		24,501			12,674			(408	)
	Total Partners’ Equity (Deficiency)		122,504			84,535			(1,289	)
	Total Liabilities and Partners’ Equity (Deficiency)	$	207,156		$	190,343		$	5,749
	Income Statement Data:
	Total revenues	$	18,218		$	21,310		$	1,081
	Property operating expenses		(5,797	)		(7,448	)		(400	)
	Administrative, management and call center fees		(1,376	)		(1,581	)		—
	Acquisition costs		(926	)		—			—
	Depreciation and amortization of customer list		(3,242	)		(3,117	)		(172	)
	Amortization of financing fees		(137	)		(152	)		(8	)
	Income tax expense		(78	)		(301	)		—
	Interest expense		(3,209	)		(3,866	)		(292	)
	Net income	$	3,453		$	4,845		$	209

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Computation of Basic and Diluted Earnings Per Common Share	'
	The following table sets forth the computation of basic and diluted earnings per common share utilizing the two-class method.
	(in thousands except per share data)	Three Months		Three Months		Nine Months		Nine Months
		Ended		Ended		Ended		Ended
		Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
	Numerator:
	Net income from continuing operations attributable to common shareholders	$	25,589	$	19,431	$	62,838	$	51,245
	Denominator:
	Denominator for basic earnings per share – weighted average shares		33,235		31,469		32,806		31,078
	Effect of Dilutive Securities:
	Stock options and non-vested stock		164		157		166		157
	Denominator for diluted earnings per share – adjusted weighted average shares and assumed conversion		33,399		31,626		32,972		31,235
	Basic earnings per common share from continuing operations attributable to common shareholders	$	0.77	$	0.62	$	1.92	$	1.65
	Basic earnings per common share attributable to common shareholders	$	0.77	$	0.63	$	1.92	$	1.67
	Diluted earnings per common share from continuing operations attributable to common shareholders	$	0.77	$	0.61	$	1.91	$	1.64
	Diluted earnings per common share attributable to common shareholders	$	0.77	$	0.62	$	1.91	$	1.66

Shareholders_Equity_Tables

Shareholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Reconciliation of Changes in Total Shareholders' Equity	'
	The following is a reconciliation of the changes in total shareholders’ equity for the period:
	(dollars in thousands)	Nine Months
		Ended
		September 30, 2014
	Beginning balance of total shareholders’ equity	$	870,709
	Net proceeds from the issuance of common stock		87,179
	Exercise of stock options		527
	Earned portion of non-vested stock		3,451
	Stock option expense		186
	Deferred compensation outside directors		89
	Adjustment to redemption value on noncontrolling redeemable Operating Partnership units		(1,902	)
	Net income attributable to common shareholders		62,838
	Change in fair value of derivatives		(3,191	)
	Dividends		(67,113	)
	Ending balance of total shareholders’ equity	$	952,773

Recent_Accounting_Pronouncemen1

Recent Accounting Pronouncements (Tables)	9 Months Ended
	Sep. 30, 2014
Accounting Changes and Error Corrections [Abstract]	'
Summary of Revenues and Expenses of Property Up to the Date of Sale	'
	The following table summarizes the revenues and expenses up to the date of sale of the one property sold in 2014 that are included in the Company’s consolidated statements of operations for the three and nine months ended September 30, 2014 and 2013.
		Three months ended				Nine months ended
		September 30,				September 30,
	(dollars in thousands)	2014		2013		2014		2013
	Total revenues	$	80	$	180	$	465	$	526
	Property operations and maintenance expense		23		50		111		161
	Real estate tax expense		3		18		51		54
	Depreciation and amortization expense		9		26		60		76
	Gain on sale of real estate		1,777		—		1,777		—

Basis_of_Presentation_Addition

Basis of Presentation - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2014
	Facility
Accounting Policies [Abstract]	'
Number of sale of storage facilities reclassified as discontinued operation	4

Organization_Additional_Inform

Organization - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended		12 Months Ended	9 Months Ended	1 Months Ended	6 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014	Feb. 28, 2013	Jun. 30, 2011	Sep. 30, 2014	Sep. 30, 2014
	Property	Property			Texas and Florida [Member]	West Deptford JV LLC [Member]	West Deptford JV LLC [Member]	Sovran HHF Storage Holdings LLC [Member]	Sovran HHF Storage Holdings II LLC [Member]
	States	States			Revenue [Member]			Property	Property
Organization [Line Items]	'	'	'	'	'	'	'	'	'
Number of self-storage properties owned and managed	503	503	'	'	'	'	'	'	'
Number of states in which self-storage properties owned and managed	25	25	'	'	'	'	'	'	'
Number of properties owned and managed under twenty-percent stake joint venture	'	'	'	'	'	'	'	28	'
Percentage ownership in unconsolidated joint venture	'	'	'	'	'	'	'	20.00%	15.00%
Number of properties managed with no ownership	17	17	'	'	'	'	'	'	'
Number of properties owned and managed under fifteen-percent stake joint venture	'	'	'	'	'	'	'	'	30
Concentration risk, percentage	'	'	'	'	39.00%	'	'	'	'
Number of properties leased	4	4	'	'	'	'	'	'	'
Percentage of ownership interest of the subsidiary and its limited partnership which controls the operations of the Operating Partnership	99.40%	99.40%	'	'	'	'	'	'	'
Percentage ownership in consolidated joint venture	'	'	'	'	'	'	20.00%	'	'
Payments to acquire businesses and interest in affiliates	'	'	'	'	'	'	$4,200,000	'	'
Mortgage note acquired	'	'	'	'	'	'	2,800,000	'	'
Interest rate for mortgage notes acquired	'	'	'	'	'	'	8.00%	'	'
Payments to acquire preferred interest in affiliates	'	'	'	'	'	'	1,400,000	'	'
Preferred interest in investment	'	'	'	'	'	'	8.00%	'	'
Membership Interest Purchase Agreement, common and preferred interests	'	'	'	'	'	1,400,000	'	'	'
Joint venture partner repaid	'	'	'	'	'	2,800,000	'	'	'
Gain on sale of real estate	$1,777,000	$1,777,000	$421,000	'	'	$400,000	'	'	'
Units of redeemable noncontrolling interest in operating partnership	'	198,913	'	198,913	'	'	'	'	'
Noncontrolling limited partnership unit redemption value	'	'One common share or cash	'	'	'	'	'	'	'

Organization_Summary_of_Redeem

Organization - Summary of Redeemable Noncontrolling Interest (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Redeemable Noncontrolling Interest, Equity, Fair Value [Abstract]	'	'	'	'
Beginning balance noncontrolling redeemable Operating Partnership Units	'	'	$12,940	'
Net income attributable to noncontrolling interests - consolidated joint venture	154	124	381	331
Distributions	'	'	-406	-297
Adjustment to redemption value	'	'	1,902	'
Ending balance noncontrolling redeemable Operating Partnership Units	$14,817	'	$14,817	'

Stock_Based_Compensation_Addit

Stock Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'	'	'	'
Stock option expense	$37	$43	$186	$261
Amortization of non-vested stock grants	$1,129	$795	$3,451	$1,977
Stock options exercised by employees	3,962	23,835	12,962	121,845
Number of shares of non-vested stock that vested	31,078	13,334	48,678	32,796

Investment_in_Storage_Faciliti2

Investment in Storage Facilities - Summary of Activity in Storage Facilities (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014
Cost:	'
Beginning balance	$1,864,637
Acquisition of storage facilities	232,763
Improvements and equipment additions	21,232
Net decrease in construction in progress	-975
Dispositions	-4,523
Ending balance	2,113,134
Accumulated Depreciation:	'
Beginning balance	366,472
Depreciation expense during the period	35,057
Dispositions	-1,223
Ending balance	$400,306

Investment_in_Storage_Faciliti3

Investment in Storage Facilities - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
	Facility		Facility
Real Estate [Abstract]	'	'	'	'	'
Number of storage facilities acquired	5	'	28	'	'
Cash paid for properties acquired	'	'	$235,309,000	'	'
Deposits paid at the time of contract	'	'	'	'	5,600,000
Amortization period for in-place customer leases on a straight-line basis	'	'	'12 months	'	'
Amortization expense related to in-place customer leases	1,200,000	800,000	2,700,000	2,700,000	'
Amortization expense for the year	4,000,000	'	4,000,000	'	'
Amortization expense for the next fiscal year following the latest fiscal year	$1,400,000	'	$1,400,000	'	'

Investment_in_Storage_Faciliti4

Investment in Storage Facilities - Schedule of Acquired Facilities and Purchase Price of Facilities (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
	Facility		Facility
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	5	'	28	'
Purchase Price	$237,040,000	'	$237,040,000	'
Cash Paid	'	'	235,309,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	1,731,000	'	1,731,000	'
Land	69,980,000	'	69,980,000	'
Acquisition Date Building, Equipment, and Improvements	162,783,000	'	162,783,000	'
Fair Value In-Place Customers Leases	4,277,000	'	4,277,000	'
Acquisition Costs Expensed	1,210,000	776,000	5,926,000	1,263,000
Florida [Member] | Date Of Acquisition, 1/9/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	2	'
Date of Acquisition	'	'	9-Jan-14	'
Purchase Price	54,000,000	'	54,000,000	'
Cash Paid	'	'	53,599,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	401,000	'	401,000	'
Land	23,309,000	'	23,309,000	'
Acquisition Date Building, Equipment, and Improvements	29,867,000	'	29,867,000	'
Fair Value In-Place Customers Leases	824,000	'	824,000	'
Acquisition Costs Expensed	'	'	1,672,000	'
Florida [Member] | Date Of Acquisition, 8/28/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	28-Aug-14	'
Purchase Price	10,200,000	'	10,200,000	'
Cash Paid	'	'	10,111,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	89,000	'	89,000	'
Land	2,958,000	'	2,958,000	'
Acquisition Date Building, Equipment, and Improvements	7,055,000	'	7,055,000	'
Fair Value In-Place Customers Leases	187,000	'	187,000	'
Acquisition Costs Expensed	'	'	183,000	'
Texas [Member] | Date Of Acquisition, 1/17/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	17-Jan-14	'
Purchase Price	9,000,000	'	9,000,000	'
Cash Paid	'	'	8,962,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	38,000	'	38,000	'
Land	3,999,000	'	3,999,000	'
Acquisition Date Building, Equipment, and Improvements	4,856,000	'	4,856,000	'
Fair Value In-Place Customers Leases	145,000	'	145,000	'
Acquisition Costs Expensed	'	'	215,000	'
Texas [Member] | Date Of Acquisition, 2/10/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	10-Feb-14	'
Purchase Price	8,900,000	'	8,900,000	'
Cash Paid	'	'	8,857,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	43,000	'	43,000	'
Land	2,235,000	'	2,235,000	'
Acquisition Date Building, Equipment, and Improvements	6,564,000	'	6,564,000	'
Fair Value In-Place Customers Leases	101,000	'	101,000	'
Acquisition Costs Expensed	'	'	203,000	'
Texas [Member] | Date Of Acquisition, 5/13/2014[Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	13-May-14	'
Purchase Price	6,075,000	'	6,075,000	'
Cash Paid	'	'	6,017,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	58,000	'	58,000	'
Land	2,000,000	'	2,000,000	'
Acquisition Date Building, Equipment, and Improvements	3,935,000	'	3,935,000	'
Fair Value In-Place Customers Leases	140,000	'	140,000	'
Acquisition Costs Expensed	'	'	180,000	'
Texas [Member] | Date Of Acquisition, 9/10/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	10-Sep-14	'
Purchase Price	11,200,000	'	11,200,000	'
Cash Paid	'	'	11,046,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	154,000	'	154,000	'
Land	4,657,000	'	4,657,000	'
Acquisition Date Building, Equipment, and Improvements	6,349,000	'	6,349,000	'
Fair Value In-Place Customers Leases	194,000	'	194,000	'
Acquisition Costs Expensed	'	'	195,000	'
Maine [Member] | Date Of Acquisition, 2/11/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	2	'
Date of Acquisition	'	'	11-Feb-14	'
Purchase Price	14,750,000	'	14,750,000	'
Cash Paid	'	'	14,601,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	149,000	'	149,000	'
Land	2,639,000	'	2,639,000	'
Acquisition Date Building, Equipment, and Improvements	11,824,000	'	11,824,000	'
Fair Value In-Place Customers Leases	287,000	'	287,000	'
Acquisition Costs Expensed	'	'	406,000	'
Illinois [Member] | Date Of Acquisition, 3/31/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	31-Mar-14	'
Purchase Price	8,700,000	'	8,700,000	'
Cash Paid	'	'	8,582,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	118,000	'	118,000	'
Land	1,837,000	'	1,837,000	'
Acquisition Date Building, Equipment, and Improvements	6,724,000	'	6,724,000	'
Fair Value In-Place Customers Leases	139,000	'	139,000	'
Acquisition Costs Expensed	'	'	223,000	'
Illinois [Member] | Date Of Acquisition, 5/5/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	5-May-14	'
Purchase Price	5,500,000	'	5,500,000	'
Cash Paid	'	'	5,487,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	13,000	'	13,000	'
Land	598,000	'	598,000	'
Acquisition Date Building, Equipment, and Improvements	4,902,000	'	4,902,000	'
Acquisition Costs Expensed	'	'	44,000	'
MISSOURI | Date Of Acquisition, 5/22/2014[Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	7	'
Date of Acquisition	'	'	22-May-14	'
Purchase Price	35,050,000	'	35,050,000	'
Cash Paid	'	'	34,786,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	264,000	'	264,000	'
Land	9,420,000	'	9,420,000	'
Acquisition Date Building, Equipment, and Improvements	24,835,000	'	24,835,000	'
Fair Value In-Place Customers Leases	795,000	'	795,000	'
Acquisition Costs Expensed	'	'	615,000	'
New Jersey [Member] | Date Of Acquisition, 6/5/2014[Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	5-Jun-14	'
Purchase Price	12,600,000	'	12,600,000	'
Cash Paid	'	'	12,526,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	74,000	'	74,000	'
Land	5,161,000	'	5,161,000	'
Acquisition Date Building, Equipment, and Improvements	7,201,000	'	7,201,000	'
Fair Value In-Place Customers Leases	238,000	'	238,000	'
Acquisition Costs Expensed	'	'	280,000	'
New Jersey [Member] | Date Of Acquisition, 6/12/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	12-Jun-14	'
Purchase Price	2,500,000	'	2,500,000	'
Cash Paid	'	'	2,430,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	70,000	'	70,000	'
Acquisition Date Building, Equipment, and Improvements	2,319,000	'	2,319,000	'
Fair Value In-Place Customers Leases	181,000	'	181,000	'
Acquisition Costs Expensed	'	'	63,000	'
New Jersey [Member] | Date Of Acquisition, 6/18/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	3	'
Date of Acquisition	'	'	18-Jun-14	'
Purchase Price	18,325,000	'	18,325,000	'
Cash Paid	'	'	18,221,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	104,000	'	104,000	'
Land	2,543,000	'	2,543,000	'
Acquisition Date Building, Equipment, and Improvements	15,377,000	'	15,377,000	'
Fair Value In-Place Customers Leases	405,000	'	405,000	'
Acquisition Costs Expensed	'	'	539,000	'
New Jersey [Member] | Date Of Acquisition, 7/10/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	10-Jul-14	'
Purchase Price	11,590,000	'	11,590,000	'
Cash Paid	'	'	11,572,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	18,000	'	18,000	'
Land	1,512,000	'	1,512,000	'
Acquisition Date Building, Equipment, and Improvements	9,880,000	'	9,880,000	'
Fair Value In-Place Customers Leases	198,000	'	198,000	'
Acquisition Costs Expensed	'	'	320,000	'
NEW YORK | Date Of Acquisition, 6/11/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	11-Jun-14	'
Purchase Price	8,000,000	'	8,000,000	'
Cash Paid	'	'	7,988,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	12,000	'	12,000	'
Land	1,741,000	'	1,741,000	'
Acquisition Date Building, Equipment, and Improvements	6,106,000	'	6,106,000	'
Fair Value In-Place Customers Leases	153,000	'	153,000	'
Acquisition Costs Expensed	'	'	201,000	'
Georgia [Member] | Date Of Acquisition, 6/12/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	12-Jun-14	'
Purchase Price	7,700,000	'	7,700,000	'
Cash Paid	'	'	7,616,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	84,000	'	84,000	'
Land	2,263,000	'	2,263,000	'
Acquisition Date Building, Equipment, and Improvements	5,293,000	'	5,293,000	'
Fair Value In-Place Customers Leases	144,000	'	144,000	'
Acquisition Costs Expensed	'	'	178,000	'
Virginia [Member] | Date Of Acquisition, 9/5/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	5-Sep-14	'
Purchase Price	6,400,000	'	6,400,000	'
Cash Paid	'	'	6,373,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	27,000	'	27,000	'
Land	2,349,000	'	2,349,000	'
Acquisition Date Building, Equipment, and Improvements	3,947,000	'	3,947,000	'
Fair Value In-Place Customers Leases	104,000	'	104,000	'
Acquisition Costs Expensed	'	'	266,000	'
TENNESSEE | Date Of Acquisition, 9/18/2014 [Member]	'	'	'	'
Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Number of Properties	'	'	1	'
Date of Acquisition	'	'	18-Sep-14	'
Purchase Price	6,550,000	'	6,550,000	'
Cash Paid	'	'	6,535,000	'
Loan Assumed	0	'	0	'
Net Other Liabilities (Assets) Assumed	15,000	'	15,000	'
Land	759,000	'	759,000	'
Acquisition Date Building, Equipment, and Improvements	5,749,000	'	5,749,000	'
Fair Value In-Place Customers Leases	42,000	'	42,000	'
Acquisition Costs Expensed	'	'	$143,000	'

Investment_in_Storage_Faciliti5

Investment in Storage Facilities - Schedule of Fair Value of In-Place Customer Lease Intangible Assets (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Real Estate [Abstract]	'	'
In-place customer leases	$18,920	$14,643
Accumulated amortization	-16,274	-13,551
Net carrying value at the end of period	$2,646	$1,092

Investment_in_Storage_Faciliti6

Investment in Storage Facilities - Pro Forma Information Based on Combined Historical Financial Statements on Properties Acquired (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Investments Schedule [Abstract]	'	'	'	'
Total revenues	$85,774	$76,372	$248,705	$218,383
Net income attributable to common shareholders	$27,795	$20,018	$70,712	$43,984
Basic	$0.83	$0.60	$2.11	$1.31
Diluted	$0.83	$0.59	$2.10	$1.31

Investment_in_Storage_Faciliti7

Investment in Storage Facilities - Summary of Revenues and Earnings Related to Properties Included in Company's Consolidated Statements of Operations (Detail) (USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2014
Investments Schedule [Abstract]	'	'
Total revenues	$5,562	$10,047
Net loss attributable to common shareholders	($1,199)	($5,774)

Discontinued_Operations_Additi

Discontinued Operations - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
					Facility
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'
Number of non-strategic storage facilities sold by Company	'	'	'	'	4
Sales of non-strategic storage facilities	'	'	'	'	$11,700,000
Gain on sale of non-strategic storage facilities	'	'	'	'	2,400,000
Income from continuing operations attributable to common shareholders	25,589,000	19,431,000	62,838,000	51,245,000	'
Income from discontinued operations attributable to common shareholders	$0	$200,000	$0	$600,000	'
Florida [Member]	'	'	'	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'
Number of non-strategic storage facilities sold by Company	'	'	'	'	2
Ohio [Member]	'	'	'	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'
Number of non-strategic storage facilities sold by Company	'	'	'	'	1
Virginia [Member]	'	'	'	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'
Number of non-strategic storage facilities sold by Company	'	'	'	'	1

Discontinued_Operations_Summar

Discontinued Operations - Summary of Amount Reported as Discontinued Operations (Detail) (USD $)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2013
Discontinued Operations and Disposal Groups [Abstract]	'	'	'
Total revenue	$528,000	$1,490,000	'
Property operations and maintenance expense	-152,000	-450,000	'
Real estate taxes	-41,000	-123,000	'
Depreciation and amortization expense	-89,000	-266,000	'
Net realized gain on sale of property	'	'	2,400,000
Total income from discontinued operations	$246,000	$651,000	'

Unsecured_Line_of_Credit_and_T2

Unsecured Line of Credit and Term Notes - Borrowings Outstanding on Unsecured Line of Credit and Term Notes (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Unsecured Line Of Credit And Term Notes [Line Items]	'	'
Revolving line of credit borrowings	'	$49,000
Total term notes payable	750,000	575,000
Term Note Due April 13, 2016 [Member]	'	'
Unsecured Line Of Credit And Term Notes [Line Items]	'	'
Total term notes payable	150,000	150,000
Term Note Due June 4, 2020 [Member]	'	'
Unsecured Line Of Credit And Term Notes [Line Items]	'	'
Total term notes payable	225,000	225,000
Term Note Due June 4, 2020 Second [Member]	'	'
Unsecured Line Of Credit And Term Notes [Line Items]	'	'
Total term notes payable	100,000	100,000
Term Note Due August 5, 2021 [Member]	'	'
Unsecured Line Of Credit And Term Notes [Line Items]	'	'
Total term notes payable	100,000	100,000
Term Note Due April 8, 2024 [Member]	'	'
Unsecured Line Of Credit And Term Notes [Line Items]	'	'
Total term notes payable	$175,000	'

Unsecured_Line_of_Credit_and_T3

Unsecured Line of Credit and Term Notes - Additional Information (Detail) (USD $)

9 Months Ended

0 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

9 Months Ended

Sep. 30, 2014

Dec. 31, 2013

Apr. 08, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2011

Sep. 30, 2014

Sep. 30, 2014

Jun. 04, 2013

Sep. 30, 2014

Dec. 31, 2013

Jun. 04, 2013

Maturity in April, 2024 [Member]

Maturity in April, 2024 [Member]

Maturity in August 2021 [Member]

Maturity in August 2021 [Member]

Maturity in April 2016 [Member]

Maturity on June 4, 2020 [Member]

Maturity on June 4, 2020 [Member]

Maturity on June 4, 2018 [Member]

Maturity on June 4, 2018 [Member]

Term Loan Due in June, 4 2020 [Member]

MortgageLoan

Unsecured Line Of Credit And Term Notes [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Additional secured term note

'

'

$175,000,000

'

'

$100,000,000

'

'

'

'

'

'

Term note stated interest rate

'

'

'

4.53%

'

5.54%

6.38%

'

'

'

'

'

Increase in interest rate on term loan

'

'

'

6.28%

'

7.29%

8.13%

'

'

'

'

'

Revolving line of credit facility agreement

'

'

115,000,000

'

'

'

'

'

'

'

'

'

Line of credit facility, expiration date

'

'

'

8-Apr-24

5-Aug-21

'

13-Apr-16

4-Jun-20

'

4-Jun-18

'

'

Additional secured commitments

750,000,000

575,000,000

'

'

'

'

150,000,000

'

225,000,000

'

'

100,000,000

Basis spread over LIBOR

'

'

'

'

'

'

'

1.65%

'

1.50%

'

'

Revolving line of credit facility agreement

175,000,000

'

'

'

'

'

'

'

'

'

'

'

Revolving line of credit facility agreement, maximum capacity

250,000,000

'

'

'

'

'

'

'

'

'

'

'

Facility fee

'

'

'

'

'

'

'

'

'

0.20%

'

'

Interest rate, line of credit facility

'

'

'

'

'

'

'

'

'

1.65%

1.67%

'

Amount available on unsecured line of credit

'

'

'

'

'

'

'

'

'

174,300,000

'

'

Number of one year extensions

'

'

'

'

'

'

'

'

'

2

'

'

Extension facility fee

0.13%

'

'

'

'

'

'

'

'

'

'

'

Letters of credit outstanding amount

'

'

'

'

'

'

'

'

'

$700,000

'

'

Mortgages_Payable_and_Debt_Mat2

Mortgages Payable and Debt Maturities - Summary of Mortgage Payable (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]	'	'
Mortgages payable	$2,160	$2,254
5.99% Mortgage Notes Due May 1, 2026 [Member]	'	'
Debt Instrument [Line Items]	'	'
Mortgages payable	$2,160	$2,254

Mortgages_Payable_and_Debt_Mat3

Mortgages Payable and Debt Maturities - Summary of Mortgage Payable (Parenthetical) (Detail) (5.99% Mortgage Notes Due May 1, 2026 [Member], USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014
	Facility
5.99% Mortgage Notes Due May 1, 2026 [Member]	'
Debt Instrument [Line Items]	'
Term note stated interest rate	5.99%
Mortgage note due date	1-May-26
Self-storage facilities	1
Aggregate net book value of property pledged for mortgage note	$4.40
Effective interest rate	6.21%

Mortgages_Payable_and_Debt_Mat4

Mortgages Payable and Debt Maturities - Summary of Debt Obligation and Interest Rate Derivatives (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Proforma Debt Instrument [Line Items]	'	'
Line of credit	'	$49,000
Term notes	750,000	575,000
Mortgage note, total	2,160	2,254
Interest rate derivatives - asset	-547	-794
Interest rate derivatives - liability	10,458	7,523
Line of credit - variable rate LIBOR + 1.50% (1.65% at September 30, 2014) [Member]	'	'
Proforma Debt Instrument [Line Items]	'	'
Line of credit	'	'
Term Note-Fixed Rate 6.38% [Member]	'	'
Proforma Debt Instrument [Line Items]	'	'
Payables due 2016	150,000	'
Term notes	150,000	'
Term note, fair value	163,809	'
Term note - variable rate LIBOR+1.65% (1.81% at September 30, 2014) [Member]	'	'
Proforma Debt Instrument [Line Items]	'	'
Payables due Thereafter	225,000	'
Term notes	225,000	'
Term note, fair value	225,000	'
Term note - variable rate LIBOR+1.65% (1.80% at September 30, 2014) [Member]	'	'
Proforma Debt Instrument [Line Items]	'	'
Payables due Thereafter	100,000	'
Term notes	100,000	'
Term note, fair value	100,000	'
Term Note-Fixed Rate 5.54% [Member]	'	'
Proforma Debt Instrument [Line Items]	'	'
Payables due Thereafter	100,000	'
Term notes	100,000	'
Term note, fair value	109,513	'
Term note - fixed rate 4.533% [Member]	'	'
Proforma Debt Instrument [Line Items]	'	'
Payables due Thereafter	175,000	'
Term notes	175,000	'
Term note, fair value	175,881	'
Mortgage Note-Fixed Rate 5.99% [Member]	'	'
Proforma Debt Instrument [Line Items]	'	'
Payable due 2014	33	'
Payable due 2015	134	'
Payables due 2016	142	'
Payables due 2017	151	'
Payable due 2018	160	'
Payables due Thereafter	1,540	'
Mortgage note, total	2,160	'
Debt instrument, fair value	$2,273	'

Mortgages_Payable_and_Debt_Mat5

Mortgages Payable and Debt Maturities - Summary of Debt Obligation and Interest Rate Derivatives (Parenthetical) (Detail)	9 Months Ended
	Sep. 30, 2014
Line of credit - variable rate LIBOR + 1.50% (1.65% at September 30, 2014) [Member]	'
Proforma Debt Instrument [Line Items]	'
Interest rate at end of period	1.65%
Basis spread over LIBOR	1.50%
Term Note-Fixed Rate 6.38% [Member]	'
Proforma Debt Instrument [Line Items]	'
Interest rate at end of period	6.38%
Term note - variable rate LIBOR+1.65% (1.81% at September 30, 2014) [Member]	'
Proforma Debt Instrument [Line Items]	'
Interest rate at end of period	1.81%
Basis spread over LIBOR	1.65%
Term note - variable rate LIBOR+1.65% (1.80% at September 30, 2014) [Member]	'
Proforma Debt Instrument [Line Items]	'
Interest rate at end of period	1.80%
Basis spread over LIBOR	1.65%
Term Note-Fixed Rate 5.54% [Member]	'
Proforma Debt Instrument [Line Items]	'
Interest rate at end of period	5.54%
Term note - fixed rate 4.533% [Member]	'
Proforma Debt Instrument [Line Items]	'
Interest rate at end of period	4.53%
Mortgage Note-Fixed Rate 5.99% [Member]	'
Proforma Debt Instrument [Line Items]	'
Interest rate at end of period	5.99%

Derivative_Financial_Instrumen2

Derivative Financial Instruments - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Derivative [Line Items]	'	'	'	'	'
Interest Expense	$9,116,000	$7,923,000	$25,331,000	$24,827,000	'
Estimated payments to be made under interest rate swaps	'	'	5,500,000	'	'
Estimated payments to be made under interest rate swaps, assets	547,000	'	547,000	'	794,000
Fair value of interest rate swap agreements	10,458,000	'	10,458,000	'	7,523,000
Net termination value	9,900,000	'	9,900,000	'	'
Reclassification Out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	'	'	'	'	'
Derivative [Line Items]	'	'	'	'	'
Interest Expense	1,400,000	1,500,000	4,100,000	4,000,000	'
Interest Rate Swap [Member]	'	'	'	'	'
Derivative [Line Items]	'	'	'	'	'
Notional amount of variable rate debt swapped	$325,000,000	'	$325,000,000	'	'

Derivative_Financial_Instrumen3

Derivative Financial Instruments - Summary of Interest Rate Swap Agreements (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014
Interest Rate Swap [Member]	'
Derivative [Line Items]	'
Notional Amount	$125
Effective Date	1-Sep-11
Expiration Date	1-Aug-18
Fixed Rate Paid	2.37%
Interest Rate Swap [Member] | London Interbank Offered Rate (LIBOR) [Member]	'
Derivative [Line Items]	'
Floating Rate Received	'1 month LIBOR
Interest Rate Swap One [Member]	'
Derivative [Line Items]	'
Notional Amount	100
Effective Date	30-Dec-11
Expiration Date	29-Dec-17
Fixed Rate Paid	1.61%
Interest Rate Swap One [Member] | London Interbank Offered Rate (LIBOR) [Member]	'
Derivative [Line Items]	'
Floating Rate Received	'1 month LIBOR
Interest Rate Swap Two [Member]	'
Derivative [Line Items]	'
Notional Amount	100
Effective Date	4-Sep-13
Expiration Date	4-Sep-18
Fixed Rate Paid	1.37%
Interest Rate Swap Two [Member] | London Interbank Offered Rate (LIBOR) [Member]	'
Derivative [Line Items]	'
Floating Rate Received	'1 month LIBOR
Interest Rate Swap Three [Member]	'
Derivative [Line Items]	'
Notional Amount	100
Effective Date	29-Dec-17
Expiration Date	29-Nov-19
Fixed Rate Paid	3.97%
Interest Rate Swap Three [Member] | London Interbank Offered Rate (LIBOR) [Member]	'
Derivative [Line Items]	'
Floating Rate Received	'1 month LIBOR
Interest Rate Swap Four [Member]	'
Derivative [Line Items]	'
Notional Amount	$125
Effective Date	1-Aug-18
Expiration Date	1-Jun-20
Fixed Rate Paid	4.19%
Interest Rate Swap Four [Member] | London Interbank Offered Rate (LIBOR) [Member]	'
Derivative [Line Items]	'
Floating Rate Received	'1 month LIBOR

Derivative_Financial_Instrumen4

Derivative Financial Instruments - Summary of Changes in AOCL (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative [Line Items]	'	'	'	'
Accumulated other comprehensive loss beginning of period	($12,057)	($6,481)	($6,402)	($15,242)
Unrealized (loss) gain from changes in the fair value of the effective portion of the interest rate swaps	1,072	-5,046	-7,325	1,210
(Loss) gain included in other comprehensive loss	2,464	-3,572	-3,191	5,189
Accumulated other comprehensive loss end of period	-9,593	-10,053	-9,593	-10,053
Reclassification Out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Realized loss reclassified from accumulated other comprehensive loss to interest expense	$1,392	$1,474	$4,134	$3,979

Fair_Value_Measurements_Assets

Fair Value Measurements - Assets and Liabilities Carried at Fair Value Measured on Recurring Basis (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Interest rate swaps	$547	$794
Interest rate swaps	-10,458	-7,523
Interest Rate Swap [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Interest rate swaps	547	794
Interest rate swaps	-10,458	-7,523
Interest Rate Swap [Member] | Level 1 [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Interest rate swaps	'	'
Interest rate swaps	'	'
Interest Rate Swap [Member] | Level 2 [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Interest rate swaps	547	794
Interest rate swaps	-10,458	-7,523
Interest Rate Swap [Member] | Level 3 [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Interest rate swaps	'	'
Interest rate swaps	'	'

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail)	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014
	Facility	Facility
Fair Value Disclosures [Abstract]	'	'
Number of storage facilities acquired	5	28

Investment_in_Joint_Ventures_A

Investment in Joint Ventures - Additional Information (Detail) (USD $)

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

12 Months Ended

12 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2008

Jun. 30, 2014

Dec. 31, 2012

Dec. 31, 2011

Sep. 30, 2014

Dec. 31, 2013

Sovran HHF and Sovran HHF II [Member]

Sovran HHF and Sovran HHF II [Member]

Sovran HHF and Sovran HHF II [Member]

Sovran HHF and Sovran HHF II [Member]

Iskalo Office Holdings, LLC [Member]

Iskalo Office Holdings, LLC [Member]

Iskalo Office Holdings, LLC [Member]

Iskalo Office Holdings, LLC [Member]

Iskalo Office Holdings, LLC [Member]

Sovran HHF Storage Holdings LLC [Member]

Sovran HHF Storage Holdings LLC [Member]

Sovran HHF Storage Holdings LLC [Member]

Sovran HHF Storage Holdings LLC [Member]

Sovran HHF Storage Holdings LLC [Member]

Sovran HHF Storage Holdings II LLC [Member]

Sovran HHF Storage Holdings II LLC [Member]

Sovran HHF Storage Holdings II LLC [Member]

Sovran HHF Storage Holdings II LLC [Member]

Property

Property

Property

Property

Schedule of Equity Method Investments [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ownership interest

'

'

'

'

'

'

'

'

49.00%

'

49.00%

'

'

20.00%

'

'

'

'

'

'

15.00%

'

Investment at carrying value

'

'

'

'

'

'

'

'

($400,000)

'

($400,000)

'

($500,000)

$26,200,000

$17,400,000

'

'

'

'

'

$12,700,000

$12,800,000

Payment for property acquisition

237,040,000

'

237,040,000

'

'

'

'

'

'

'

'

'

'

'

'

'

171,500,000

34,400,000

29,000,000

166,100,000

'

'

Number of properties owned and managed under twenty-percent stake joint venture

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

25

3

'

'

'

'

Contribution of company to joint venture as share in capital

'

'

'

'

'

'

'

'

'

'

'

'

'

9,300,000

'

1,200,000

18,600,000

'

2,400,000

12,800,000

'

'

Receipt of return of capital distribution

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,400,000

'

'

'

'

'

'

'

Excess of investment over net asset due to capitalization of acquisition related costs

'

'

'

'

'

'

'

'

'

'

'

'

'

1,700,000

'

'

'

'

'

'

'

'

Number of properties owned and managed under fifteen-percent stake joint venture

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

10

20

'

'

Management and call center fee as a percentage of revenues

'

'

'

'

7.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Management and call center fee earned

'

'

'

'

1,000,000

900,000

2,800,000

2,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Company's share in income (loss) of joint venture

662,000

575,000

1,553,000

1,417,000

624,000

552,000

1,417,000

1,373,000

38,000

23,000

102,000

44,000

'

'

'

'

'

'

'

'

'

'

Rent paid during the period

'

'

'

'

'

'

'

'

$261,000

$231,000

$764,000

$576,000

'

'

'

'

'

'

'

'

'

'

Investment_in_Joint_Ventures_S

Investment in Joint Ventures - Summary of Unconsolidated Joint Ventures' Financial Statements (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Investment in storage facilities, net	$1,712,828	'	$1,712,828	'	$1,498,165
Other assets	7,843	'	7,843	'	11,021
Total Assets	1,781,284	'	1,781,284	'	1,561,875
Mortgages payable	2,160	'	2,160	'	2,254
Total Liabilities	813,694	'	813,694	'	678,226
Acquisition costs	-1,210	-776	-5,926	-1,263	'
Depreciation and amortization of customer list	-13,357	-11,293	-37,780	-33,852	'
Amortization of financing fees	'	'	-619	-640	'
Income tax expense	-400	-300	-1,000	-1,000	'
Interest expense	-9,116	-7,923	-25,331	-24,827	'
Sovran HHF Storage Holdings LLC [Member]	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Investment in storage facilities, net	189,678	'	189,678	'	'
Investment in office building	0	'	0	'	'
Other assets	17,478	'	17,478	'	'
Total Assets	207,156	'	207,156	'	'
Due to the Company	344	'	344	'	'
Mortgages payable	80,861	'	80,861	'	'
Other liabilities	3,447	'	3,447	'	'
Total Liabilities	84,652	'	84,652	'	'
Unaffiliated partners' equity (deficiency)	98,003	'	98,003	'	'
Company equity (deficiency)	24,501	'	24,501	'	'
Total Partners' Equity (Deficiency)	122,504	'	122,504	'	'
Total Liabilities and Partners' Equity (Deficiency)	207,156	'	207,156	'	'
Total revenues	'	'	18,218	'	'
Property operating expenses	'	'	-5,797	'	'
Administrative, management and call center fees	'	'	-1,376	'	'
Acquisition costs	'	'	-926	'	'
Depreciation and amortization of customer list	'	'	-3,242	'	'
Amortization of financing fees	'	'	-137	'	'
Income tax expense	'	'	-78	'	'
Interest expense	'	'	-3,209	'	'
Net income	'	'	3,453	'	'
Sovran HHF Storage Holdings II LLC [Member]	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Investment in storage facilities, net	185,656	'	185,656	'	'
Investment in office building	0	'	0	'	'
Other assets	4,687	'	4,687	'	'
Total Assets	190,343	'	190,343	'	'
Due to the Company	382	'	382	'	'
Mortgages payable	103,068	'	103,068	'	'
Other liabilities	2,358	'	2,358	'	'
Total Liabilities	105,808	'	105,808	'	'
Unaffiliated partners' equity (deficiency)	71,861	'	71,861	'	'
Company equity (deficiency)	12,674	'	12,674	'	'
Total Partners' Equity (Deficiency)	84,535	'	84,535	'	'
Total Liabilities and Partners' Equity (Deficiency)	190,343	'	190,343	'	'
Total revenues	'	'	21,310	'	'
Property operating expenses	'	'	-7,448	'	'
Administrative, management and call center fees	'	'	-1,581	'	'
Acquisition costs	'	'	0	'	'
Depreciation and amortization of customer list	'	'	-3,117	'	'
Amortization of financing fees	'	'	-152	'	'
Income tax expense	'	'	-301	'	'
Interest expense	'	'	-3,866	'	'
Net income	'	'	4,845	'	'
Iskalo Office Holdings, LLC [Member]	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Investment in storage facilities, net	0	'	0	'	'
Investment in office building	4,829	'	4,829	'	'
Other assets	920	'	920	'	'
Total Assets	5,749	'	5,749	'	'
Due to the Company	0	'	0	'	'
Mortgages payable	6,487	'	6,487	'	'
Other liabilities	551	'	551	'	'
Total Liabilities	7,038	'	7,038	'	'
Unaffiliated partners' equity (deficiency)	-881	'	-881	'	'
Company equity (deficiency)	-408	'	-408	'	'
Total Partners' Equity (Deficiency)	-1,289	'	-1,289	'	'
Total Liabilities and Partners' Equity (Deficiency)	5,749	'	5,749	'	'
Total revenues	'	'	1,081	'	'
Property operating expenses	'	'	-400	'	'
Administrative, management and call center fees	'	'	0	'	'
Acquisition costs	'	'	0	'	'
Depreciation and amortization of customer list	'	'	-172	'	'
Amortization of financing fees	'	'	-8	'	'
Income tax expense	'	'	0	'	'
Interest expense	'	'	-292	'	'
Net income	'	'	$209	'	'

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'	'	'	'
Federal and state income tax expense	$400,000	$300,000	$1,000,000	$1,000,000
Unrecognized tax benefits	0	0	0	0
Interest or penalties related to uncertain tax positions	'	'	0	0
Current taxes payable	300,000	'	300,000	'
Deferred tax liability	$800,000	'	$800,000	'
Tax years open to examination	'	'	'2011-2013	'

Earnings_Per_Share_Computation

Earnings Per Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator:	'	'	'	'
Net income from continuing operations attributable to common shareholders	$25,589	$19,431	$62,838	$51,245
Denominator:	'	'	'	'
Denominator for basic earnings per share - weighted average shares	33,234,660	31,469,026	32,806,164	31,077,910
Effect of Dilutive Securities:	'	'	'	'
Stock options and non-vested stock	164,000	157,000	166,000	157,000
Denominator for diluted earnings per share - adjusted weighted average shares and assumed conversion	33,398,648	31,625,635	32,972,262	31,235,049
Basic earnings per common share from continuing operations attributable to common shareholders	$0.77	$0.62	$1.92	$1.65
Basic earnings per common share attributable to common shareholders	$0.77	$0.63	$1.92	$1.67
Diluted earnings per common share from continuing operations attributable to common shareholders	$0.77	$0.61	$1.91	$1.64
Diluted earnings per common share attributable to common shareholders	$0.77	$0.62	$1.91	$1.66

Earnings_Per_Share_Additional_

Earnings Per Share - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stock Options [Member]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Securities not included in the effect of dilutive securities	6,000	'	6,667	2,667
Restricted Stock [Member]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Securities not included in the effect of dilutive securities	125,775	121,916	145,690	88,901

Shareholders_Equity_Reconcilia

Shareholders' Equity - Reconciliation of Changes in Total Shareholders' Equity (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Equity [Abstract]	'	'	'	'
Beginning balance	'	'	$870,709	'
Net proceeds from the issuance of common stock	'	'	87,179	'
Exercise of stock options	'	'	527	'
Earned portion of non-vested stock	1,129	795	3,451	1,977
Stock option expense	37	43	186	261
Deferred compensation outside directors	'	'	89	'
Adjustment to redemption value on noncontrolling redeemable Operating Partnership units	'	'	-1,902	'
Net income attributable to common shareholders	25,589	19,675	62,838	51,892
Change in fair value of derivatives	2,464	-3,572	-3,191	5,189
Dividends	'	'	-67,113	'
Ending balance	$952,773	'	$952,773	'

Shareholders_Equity_Additional

Shareholders' Equity - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2014	12-May-14
	Facility		Facility
Stockholders Equity [Line Items]	'	'	'	'
Common stock value authorized under equity offering program	'	'	'	$225
Common stock shares issued under equity offering program	424,403	359,102	674,403	'
Weighted average issue price of common stock	$78.46	$74.32	$77.95	'
Proceeds from issuance of common stock	32.9	26.4	51.9	'
Expenses related to equity program	'	'	0.2	'
Acquired storage facilities	5	'	28	'
Common stock, value reserved for future issuance	172.4	'	172.4	'
Shares issued under dividend reinvestment plan	'	'	129,837	'
HSBC [Member]	'	'	'	'
Stockholders Equity [Line Items]	'	'	'	'
Offering related costs and commissions	0.4	'	'	'
Piper and HSBC [Member]	'	'	'	'
Stockholders Equity [Line Items]	'	'	'	'
Offering related costs and commissions	'	'	0.7	'
SunTrust [Member]	'	'	'	'
Stockholders Equity [Line Items]	'	'	'	'
Offering related costs and commissions	'	$0.30	'	'

Recent_Accounting_Pronouncemen2

Recent Accounting Pronouncements - Summary of Revenues and Expenses of Property Up to the Date of Sale (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Real Estate Properties [Line Items]	'	'	'	'
Total revenues	$85,249	$70,455	$241,150	$201,442
Property operations and maintenance expense	17,913	15,568	51,431	45,288
Real estate tax expense	8,312	6,953	24,433	19,735
Depreciation and amortization expense	13,357	11,293	37,780	33,852
Gain on sale of real estate	1,777	'	1,777	421
Real Estate Property One [Member]	'	'	'	'
Real Estate Properties [Line Items]	'	'	'	'
Total revenues	80	180	465	526
Property operations and maintenance expense	23	50	111	161
Real estate tax expense	3	18	51	54
Depreciation and amortization expense	9	26	60	76
Gain on sale of real estate	$1,777	'	$1,777	'

Commitment_and_Contingencies_A

Commitment and Contingencies - Additional Information (Detail) (USD $)	Sep. 30, 2014	Oct. 31, 2014	Sep. 30, 2014	Dec. 31, 2012	Dec. 31, 2008
In Millions, unless otherwise specified	Facility	Subsequent Event [Member]	Sovran HHF Storage Holdings LLC [Member]	Sovran HHF Storage Holdings LLC [Member]	Sovran HHF Storage Holdings LLC [Member]
		Facility	Facility
Commitment And Contingencies [Line Items]	'	'	'	'	'
Number of self-storage facilities under contract to be purchased	5	3	11	'	'
Payment for self-storage facilities under contract	$56.60	$41.10	$153	'	'
Percentage ownership interest by parent	'	'	20.00%	'	'
Cash contribution for purchase of facilities	'	'	21	'	'
Cash contribution to subsidiaries	'	'	9.3	1.2	18.6
Contracted sales price for selling self storage facilities under contract	$6.30	'	'	'	'

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (USD $)	9 Months Ended	0 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Oct. 28, 2014	Oct. 02, 2014
		Subsequent Event [Member]	Subsequent Event [Member]
Subsequent Event [Line Items]	'	'	'
Dividend declared, date	2-Oct-14	'	'
Dividend per common share	'	'	$0.68
Dividend paid, date	28-Oct-14	'	'
Dividend record, date	14-Oct-14	'	'
Dividend paid	'	$22.90	'