Life Storage Inc - Registered Shares (LSI) 10-Q 5 Aug 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014	Jul. 30, 2014
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
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	'	33,280,092

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investment in storage facilities:	'	'
Land	$370,243	$312,053
Building, equipment, and construction in progress	1,693,331	1,552,584
Real estate investment property, at cost, total	2,063,574	1,864,637
Less: accumulated depreciation	-389,310	-366,472
Investment in storage facilities, net	1,674,264	1,498,165
Cash and cash equivalents	6,959	9,524
Accounts receivable	5,332	5,119
Receivable from unconsolidated joint ventures	543	883
Investment in unconsolidated joint ventures	36,750	30,391
Prepaid expenses	8,264	5,978
Fair value of interest rate swap agreements	'	794
Other assets	8,179	11,021
Total Assets	1,740,291	1,561,875
Liabilities	'	'
Line of credit	8,000	49,000
Term notes	750,000	575,000
Accounts payable and accrued liabilities	35,040	37,741
Deferred revenue	7,736	6,708
Fair value of interest rate swap agreements	12,376	7,523
Mortgages payable	2,191	2,254
Total Liabilities	815,343	678,226
Noncontrolling redeemable Operating Partnership Units at redemption value	15,348	12,940
Shareholders' Equity	'	'
Common stock $.01 par value, 100,000,000 shares authorized, 33,240,930 shares issued and outstanding at June 30, 2014 (32,532,991 at December 31, 2013)	344	337
Additional paid-in capital	1,120,650	1,066,399
Dividends in excess of net income	-172,162	-162,450
Accumulated other comprehensive loss	-12,057	-6,402
Treasury stock at cost, 1,171,886 shares	-27,175	-27,175
Total Shareholders' Equity	909,600	870,709
Total Liabilities and Shareholders' Equity	$1,740,291	$1,561,875

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 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	33,240,930	32,532,991
Common stock, shares outstanding	33,240,930	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		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenues	'	'	'	'
Rental income	$74,394	$62,127	$144,347	$121,688
Other operating income	6,050	4,982	11,555	9,299
Total operating revenues	80,444	67,109	155,902	130,987
Expenses	'	'	'	'
Property operations and maintenance	16,453	14,594	33,518	29,719
Real estate taxes	8,055	6,363	16,121	12,782
General and administrative	10,404	8,988	20,360	17,781
Acquisition costs	1,938	'	4,716	486
Operating leases of storage facilities	1,997	'	3,994	'
Depreciation and amortization	12,481	11,358	24,423	22,559
Total operating expenses	51,328	41,303	103,132	83,327
Income from operations	29,116	25,806	52,770	47,660
Other income (expenses)	'	'	'	'
Interest expense	-8,872	-8,446	-16,216	-16,904
Interest income	24	1	31	1
Gain on sale of real estate	'	'	'	421
Equity in income of joint ventures	433	455	892	842
Income from continuing operations	20,701	17,816	37,477	32,020
Income from discontinued operations	'	236	'	404
Net income	20,701	18,052	37,477	32,424
Net income attributable to noncontrolling interest	-125	-115	-228	-207
Net income attributable to common shareholders	$20,576	$17,937	$37,249	$32,217
Earnings per common share attributable to common shareholders - basic	'	'	'	'
Continuing operations	$0.63	$0.56	$1.14	$1.03
Discontinued operations	'	$0.01	'	$0.01
Earnings per share-basic	$0.63	$0.57	$1.14	$1.04
Earnings per common share attributable to common shareholders - diluted	'	'	'	'
Continuing operations	$0.62	$0.56	$1.14	$1.03
Discontinued operations	'	$0.01	'	$0.01
Earnings per share-diluted	$0.62	$0.57	$1.14	$1.04
Common shares used in basic earnings per share calculation	32,799,837	31,275,850	32,591,917	30,882,352
Common shares used in diluted earnings per share calculation	32,979,708	31,425,016	32,759,069	31,039,756
Dividends declared per common share	$0.68	$0.48	$1.36	$0.96

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement Of Income And Comprehensive Income [Abstract]	'	'	'	'
Net income	$20,701	$18,052	$37,477	$32,424
Other comprehensive income:	'	'	'	'
Change in fair value of derivatives net of reclassification to interest expense	-3,726	7,222	-5,655	8,761
Total comprehensive income	16,975	25,274	31,822	41,185
Comprehensive income attributable to noncontrolling interest	-103	-161	-194	-262
Comprehensive income attributable to common shareholders	$16,872	$25,113	$31,628	$40,923

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (Unaudited) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Operating Activities	'	'
Net income	$37,477	$32,424
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	24,413	22,737
Amortization of deferred financing fees	407	422
Gain on sale of real estate	'	-421
Equity in income of joint ventures	-892	-842
Distributions from unconsolidated joint venture	1,487	1,160
Non-vested stock earned	2,381	1,242
Stock option expense	149	219
Changes in assets and liabilities (excluding the effects of acquisitions):	'	'
Accounts receivable	-189	'
Prepaid expenses	-2,205	-648
Receipts from joint ventures	423	201
Accounts payable and other liabilities	-2,978	-7,934
Deferred revenue	-211	589
Net cash provided by operating activities	60,262	49,149
Investing Activities	'	'
Acquisitions of storage facilities	-183,835	-22,349
Improvements, equipment additions, and construction in progress	-11,717	-10,005
Net proceeds from the sale of real estate	'	4,367
Investment in unconsolidated joint ventures	-7,053	-2,655
Property deposits	-395	-75
Net cash used in investing activities	-203,000	-30,717
Financing Activities	'	'
Net proceeds from sale of common stock	51,728	56,770
Proceeds from line of credit	104,000	98,000
Repayments of line of credit	-145,000	-139,000
Proceeds from term notes	175,000	225,000
Repayments of term notes	'	-225,000
Financing costs	-711	-1,554
Dividends paid-common stock	-44,510	-29,675
Distributions to noncontrolling interest holders	-271	-191
Redemption of operating partnership units	'	-306
Mortgage principal payments	-63	-90
Net cash provided by (used in) financing activities	140,173	-16,046
Net (decrease) increase in cash	-2,565	2,386
Cash at beginning of period	9,524	7,255
Cash at end of period	6,959	9,641
Supplemental cash flow information	'	'
Cash paid for interest, net of interest capitalized	$14,075	$16,650

Basis_of_Presentation

Basis of Presentation	6 Months Ended
	Jun. 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 six month period ended June 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 a result of the sale of 4 storage facilities in 2013 (see Note 5).

Organization

Organization	6 Months Ended
	Jun. 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 June 30, 2014, we had an ownership interest in, leased, and/or managed 501 self-storage properties in 25 states under the name Uncle Bob’s Self Storage ®. Among our 501 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, 19 properties that we manage and have no ownership interest, and four properties we lease. Approximately 40% 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 June 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 June 30, 2014, there were 198,913 noncontrolling redeemable operating partnership Units outstanding (198,913 at December 31, 2013). 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 June 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)		Six Months
			Ended
			Jun. 30, 2014
	Beginning balance noncontrolling redeemable Operating Partnership Units		$	12,940
	Net income attributable to noncontrolling interests – consolidated joint venture			228
	Distributions			(271	)
	Adjustment to redemption value			2,451
	Ending balance noncontrolling redeemable Operating Partnership Units		$	15,348

Stock_Based_Compensation

Stock Based Compensation	6 Months Ended
	Jun. 30, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock Based Compensation	'
	3	STOCK BASED COMPENSATION
	The Company accounts for stock-based compensation under the provisions of ASC Topic 718, “Compensation—Stock Compensation”. 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 June 30, 2014 and 2013, the Company recorded compensation expense (included in general and administrative expense) of $113,000 and $162,000, respectively, related to stock options and $1,129,000 and $586,000, respectively, related to amortization of non-vested stock grants. For the six months ended June 30, 2014 and 2013, the Company recorded compensation expense (included in general and administrative expense) of $149,000 and $219,000, respectively, related to stock options and $2,322,000 and $1,182,000, respectively, related to amortization of non-vested stock grants.
	During the three months ended June 30, 2014 and 2013, employees exercised 7,500 and 14,200 stock options respectively, and 7,720 and 8,480 shares of non-vested stock, respectively, vested. During the six months ended June 30, 2014 and 2013, employees exercised 9,000 and 121,845 stock options respectively, and 17,600 and 19,462 shares of non-vested stock, respectively, vested.

Investment_in_Storage_Faciliti

Investment in Storage Facilities	6 Months Ended
	Jun. 30, 2014
Real Estate [Abstract]	'
Investment in Storage Facilities	'
	4	INVESTMENT IN STORAGE FACILITIES
	The following summarizes our activity in storage facilities during the six months ended June 30, 2014.
	(dollars in thousands)
	Cost:
	Beginning balance		$	1,864,637
	Acquisition of storage facilities			187,325
	Improvements and equipment additions			14,204
	Net decrease in construction in progress			(2,368	)
	Dispositions			(224	)
	Ending balance		$	2,063,574
	Accumulated Depreciation:
	Beginning balance		$	366,472
	Depreciation expense during the period			22,944
	Dispositions			(106	)
	Ending balance		$	389,310
	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 six months ended June 30, 2014 the Company acquired 23 self-storage facilities and the preliminary purchase price of the facilities has been assigned as follows (as of June 30, 2014 the purchase price assignments relating to the 16 facilities acquired during the three months ended June 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		Closing
			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	$	1,663
	Texas			1			1/17/14			9,000		8,962		—		38		3,999		4,856		145		211
	Texas			1			2/10/14			8,900		8,857		—		43		2,235		6,564		101		198
	Maine			2			2/11/14			14,750		14,601		—		149		2,639		11,824		287		397
	Illinois			1			3/31/14			8,700		8,582		—		118		1,837		6,724		139		219
	Illinois			1			5/5/14			5,500		5,487		—		13		598		4,902		—		40
	Texas			1			5/13/14			6,075		6,017		—		58		2,000		3,935		140		175
	Missouri			7			5/22/14			35,050		34,786		—		264		9,550		24,709		791		583
	New Jersey			1			6/5/14			12,600		12,526		—		74		5,161		7,201		238		276
	New York			1			6/11/14			8,000		7,988		—		12		1,741		6,106		153		196
	New Jersey			1			6/12/14			2,500		2,430		—		70		—		2,319		181		59
	Georgia			1			6/12/14			7,700		7,616		—		84		2,263		5,293		144		174
	New Jersey			3			6/18/14			18,088		17,984		—		104		2,544		15,150		394		525
	Total 2014			23					$	190,863	$	189,435	$	—	$	1,428	$	57,876	$	129,450	$	3,537	$	4,716
	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 $189.4 million paid at closing for the properties acquired during the six months ended June 30, 2014, $5.6 million represented deposits that were paid in 2013 when 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)		Jun. 30,			Dec. 31,
			2014			2013
	In-place customer leases		$	18,179		$	14,643
	Accumulated amortization			(15,030	)		(13,551	)
	Net carrying value at the end of period		$	3,149		$	1,092
	Amortization expense related to in-place customer leases was $0.8 million and $1.0 million for the three months ended June 30, 2014 and 2013, respectively and was $1.5 million and $1.9 million for the six months ended June 30, 2014 and 2013, respectively. The Company expects to record $3.7 million and $1.0 million of amortization expense for the years ended December 31, 2014 and 2015, respectively.
	As noted above, during the six months ended June 30, 2014, the Company acquired 23 properties. The following pro forma information is based on the combined historical financial statements of the Company and the 23 properties acquired, and presents the Company’s results as if the acquisitions had occurred as of January 1, 2013:
			Three months ended						Six months ended
			June 30,						June 30,
	(dollars in thousands)		2014			2013			2014		2013
	Total revenues		$	82,310		$	71,923		$	161,122	$	140,339
	Net income attributable to common shareholders		$	22,765		$	17,151		$	42,572	$	25,748
	Earnings per common share
	Basic		$	0.69		$	0.52		$	1.29	$	0.78
	Diluted		$	0.69		$	0.52		$	1.28	$	0.78
	The following table summarizes the revenues and earnings related to the 23 properties since the acquisition dates that are included in the Company’s consolidated statements of operations for the three and six months ended June 30, 2014.
			Three months			Six months
			ended June 30,			ended June 30,
			2014			2014
	Total revenues		$	3,023		$	4,484
	Net loss attributable to common shareholders		$	(2,112	)	$	(4,877	)
	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	6 Months Ended
	Jun. 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 six months ended June 30, 2013. Through June 30, 2014 the Company has not disposed of any facilities. The following is a summary of the amounts reported as discontinued operations in 2013:
	(dollars in thousands)		Apr. 1, 2013			Jan. 1, 2013
			to			to
			Jun. 30, 2013			Jun. 30, 2013
	Total revenue		$	506		$	962
	Property operations and maintenance expense			(140	)		(298	)
	Real estate tax expense			(41	)		(82	)
	Depreciation and amortization expense			(89	)		(178	)
	Net realized gain on sale of property			—			—
	Total income from discontinued operations		$	236		$	404
	Income from continuing operations attributable to common shareholders was $20.6 million and $17.7 million for the three months ended June 30, 2014, and 2013, respectively. Income from continuing operations attributable to common shareholders was $37.2 million and $31.8 million for the six months ended June 30, 2014, and 2013, respectively. Income from discontinued operations attributable to common shareholders was $0 and $0.2 million for the three months ended June 30, 2014, and 2013, respectively. Income from discontinued operations attributable to common shareholders was $0 and $0.4 million for the six months ended June 30, 2014, and 2013, respectively.

Unsecured_Line_of_Credit_and_T

Unsecured Line of Credit and Term Notes	6 Months Ended
	Jun. 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)		Jun. 30,		Dec. 31,
			2014		2013
	Revolving line of credit borrowings		$	8,000	$	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 June 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 June 30, 2014 the margin is 1.50%), and requires a 0.20% facility fee. The interest rate at June 30, 2014 on the Company’s available line of credit was approximately 1.65% (1.67% at December 31, 2013). At June 30, 2014, there was $166.3 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 June 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 June 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 June 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	6 Months Ended
	Jun. 30, 2014
Debt Disclosure [Abstract]	'
Mortgages Payable and Debt Maturities	'
	7	MORTGAGES PAYABLE AND DEBT MATURITIES
	Mortgages payable at June 30, 2014 and December 31, 2013 consist of the following:
	(dollars in thousands)		June 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%)			2,191		2,254
	Total mortgages payable		$	2,191	$	2,254
	The table below summarizes the Company’s debt obligations and interest rate derivatives at June 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 June 30, 2014)			—		—		—		—	$	8,000		—	$	8,000	$	8,000
	Notes Payable:
	Term note - fixed rate 6.38%			—		—	$	150,000		—		—		—	$	150,000	$	164,776
	Term note - variable rate LIBOR+1.65% (1.80% at June 30, 2014)			—		—		—		—		—	$	225,000	$	225,000	$	225,000
	Term note - variable rate LIBOR+1.65% (1.80% at June 30, 2014)			—		—		—		—		—	$	100,000	$	100,000	$	100,000
	Term note - fixed rate 5.54%			—		—		—		—		—	$	100,000	$	100,000	$	112,443
	Term note - fixed rate 4.533%			—		—		—		—		—	$	175,000	$	175,000	$	179,287
	Mortgage notes - fixed rate 5.99%		$	64	$	134	$	142	$	151	$	160	$	1,540	$	2,191	$	2,306
	Interest rate derivatives – liability			—		—		—		—		—		—		—	$	12,376

Derivative_Financial_Instrumen

Derivative Financial Instruments	6 Months Ended
	Jun. 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 six months ended June 30, 2014, and 2013.
	The Company has interest rate swap agreements in effect at June 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 June 30, 2014 and 2013, the net reclassification from AOCL to interest expense was $1.4 million and $1.1 million, respectively, based on payments made under the swap agreements. During the six months ended June 30, 2014 and 2013, the net reclassification from AOCL to interest expense was $2.7 million and $2.5 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 June 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 a liability of $12.4 million at June 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 June 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 June 30, 2014, it could have been required to settle its obligations under the agreements at their net termination value of $12.4 million.
	The changes in AOCL for the three and six months ended June 30, 2014 and June 30, 2013 are summarized as follows:
	(dollars in thousands)		Apr. 1, 2014			Apr. 1, 2013			Jan. 1, 2014			Jan. 1, 2013
			to			to			to			to
			Jun. 30, 2014			Jun. 30, 2013			Jun. 30, 2014			Jun. 30, 2013
	Accumulated other comprehensive loss beginning of period		$	(8,331	)	$	(13,703	)	$	(6,402	)	$	(15,242	)
	Realized loss reclassified from accumulated other comprehensive loss to interest expense			1,381			1,129			2,742			2,504
	Unrealized (loss) gain from changes in the fair value of the effective portion of the interest rate swaps			(5,107	)		6,093			(8,397	)		6,257
	(Loss) gain included in other comprehensive loss			(3,726	)		7,222			(5,655	)		8,761
	Accumulated other comprehensive loss end of period		$	(12,057	)	$	(6,481	)	$	(12,057	)	$	(6,481	)

Fair_Value_Measurements

Fair Value Measurements	6 Months Ended
	Jun. 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 June 30, 2014 and December 31, 2013 (in thousands):
			Asset (Liability)			Level 1		Level 2			Level 3
	June 30, 2014
	Interest rate swaps			(12,376	)		—		(12,376	)		—
	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 six months ended June 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 23 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	6 Months Ended
	Jun. 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 June 30, 2014 and December 31, 2013 was $24.0 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 $7.0 million in cash to the joint venture as its share of capital required to fund acquisitions.
	As of June 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 June 30, 2014 and December 31, 2013 was $12.8 million. 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 $0.9 million and $0.8 million for the three months ended June 30, 2014 and 2013, respectively. The management and call center fees earned by the Company for the six months ended June 30, 2014 and 2013 totaled $1.8 million and $1.6 million, respectively.
	The Company’s share of Sovran HHF and Sovran HHF II’s income for the three months ended June 30, 2014 and 2013 was $367,000 and $456,000 respectively. The Company’s share of Sovran HHF and Sovran HHF II’s income for the six months ended June 30, 2014 and 2013 was $793,000 and $821,000, 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 June 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 (loss) for the three months ended June 30, 2014 and 2013 was $32,000 and ($1,000), respectively. The Company’s share of Iskalo Office Holdings, LLC’s income for the six months ended June 30, 2014 and 2013 was $64,000 and $21,000, respectively. The Company paid rent to Iskalo Office Holdings, LLC of $252,000 and $165,000 during the three months ended June 30, 2014 and 2013, respectively. The Company paid rent to Iskalo Office Holdings, LLC of $503,000 and $345,000 during the six months ended June 30, 2014 and 2013, respectively.
	A summary of the unconsolidated joint ventures’ financial statements as of and for the six months ended June 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		$	190,594		$	186,243		$	—
	Investment in office building			—			—			4,878
	Other assets			4,951			4,762			687
	Total Assets		$	195,545		$	191,005		$	5,565
	Due to the Company		$	239		$	311		$	—
	Mortgages payable			81,273			103,247			6,514
	Other liabilities			2,859			2,215			417
	Total Liabilities			84,371			105,773			6,931
	Unaffiliated partners’ equity (deficiency)			88,939			72,453			(920	)
	Company equity (deficiency)			22,235			12,779			(446	)
	Total Partners’ Equity (Deficiency)			111,174			85,232			(1,366	)
	Total Liabilities and Partners’ Equity (Deficiency)		$	195,545		$	191,005		$	5,565
	Income Statement Data:
	Total revenues		$	11,401		$	14,008		$	719
	Property operating expenses			(3,638	)		(4,970	)		(274	)
	Administrative, management and call center fees			(865	)		(1,039	)		—
	Acquisition costs			(926	)		—			—
	Depreciation and amortization of customer list			(2,013	)		(2,075	)		(115	)
	Amortization of financing fees			(92	)		(102	)		(5	)
	Income tax expense			(44	)		(201	)		—
	Interest expense			(2,144	)		(2,571	)		(194	)
	Net income		$	1,679		$	3,050		$	131
	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	6 Months Ended
	Jun. 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 June 30, 2014 and 2013, the Company recorded federal and state income tax expense of $0.3 million and $0.3 million, respectively. For the six months ended June 30, 2014 and 2013, the Company recorded federal and state income tax expense of $0.6 million and $0.7 million, respectively. At June 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 June 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 June 30, 2014, the Company’s taxable REIT subsidiary has a current tax liability of $0.1 million and a deferred tax liability of $0.9 million. The tax years 2010-2013 remain open to examination by the major taxing jurisdictions to which the Company is subject.

Earnings_Per_Share

Earnings Per Share	6 Months Ended
	Jun. 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		Six Months		Six Months
			Ended		Ended		Ended		Ended
			Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
	Numerator:
	Net income from continuing operations attributable to common shareholders		$	20,576	$	17,703	$	37,249	$	31,816
	Denominator:
	Denominator for basic earnings per share – weighted average shares			32,800		31,276		32,592		30,882
	Effect of Dilutive Securities:
	Stock options and non-vested stock			180		149		167		158
	Denominator for diluted earnings per share – adjusted weighted average shares and assumed conversion			32,980		31,425		32,759		31,040
	Basic earnings per common share from continuing operations attributable to common shareholders		$	0.63	$	0.56	$	1.14	$	1.03
	Basic earnings per common share attributable to common shareholders		$	0.63	$	0.57	$	1.14	$	1.04
	Diluted earnings per common share from continuing operations attributable to common shareholders		$	0.62	$	0.56	$	1.14	$	1.03
	Diluted earnings per common share attributable to common shareholders		$	0.62	$	0.57	$	1.14	$	1.04
	Not included in the effect of dilutive securities above are 8,000 stock options and 142,417 unvested restricted shares for the three months ended June 30, 2014, and 8,000 stock option and 67,447 unvested restricted shares for the three months ended June 30, 2013, because their effect would be antidilutive. Not included in the effect of dilutive securities above are 4,000 stock options and 155,648 unvested restricted shares for the six months ended June 30, 2014, and 4,000 stock options and 72,394 unvested restricted shares for the six months ended June 30, 2013, because their effect would be antidilutive.

Shareholders_Equity

Shareholders' Equity	6 Months Ended
	Jun. 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)		Six Months
			Ended
			June 30, 2014
	Beginning balance of total shareholders’ equity		$	870,709
	Net proceeds from the issuance of common stock			51,372
	Exercise of stock options			356
	Earned portion of non-vested stock			2,322
	Stock option expense			149
	Deferred compensation outside directors			59
	Adjustment to redemption value on noncontrolling redeemable Operating Partnership units			(2,451	)
	Net income attributable to common shareholders			37,249
	Change in fair value of derivatives			(5,655	)
	Dividends			(44,510	)
	Ending balance of total shareholders’ equity		$	909,600
	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 June 30, 2014, the Company issued 250,000 shares of common stock under the Equity Program at a weighted average issue price of $77.08 per share, generating net proceeds of $19.0 million after deducting $0.2 million of sales commissions paid to Piper. 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 $0.1 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 23 storage facilities. As of June 30, 2014, the Company had $205.7 million available for issuance under the Equity Program.
	In 2013, the Company implemented a Dividend Reinvestment. The Company issued 90,675 shares under the plan in 2014.

Recent_Accounting_Pronouncemen

Recent Accounting Pronouncements	6 Months Ended
	Jun. 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.
	In May 2014, FASB issued ASU No. 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, and is to be applied retrospectively, with early application not permitted. The Company is currently evaluating the new standard.
	In June 2014, the FASB issued ASU No. 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.

Commitment_and_Contingencies

Commitment and Contingencies	6 Months Ended
	Jun. 30, 2014
Commitments And Contingencies Disclosure [Abstract]	'
Commitment and Contingencies	'
	15	COMMITMENT AND CONTINGENCIES
	At June 30, 2014, the Company was under contract to acquire one self-storage facility for cash consideration of approximately $11.8 million. The facility was acquired in July 2014 and was funded through operating cash flow.
	The Company was also under contract as of June 30, 2014 to sell one self storage facility for cash consideration of approximately $5.2 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.

Subsequent_Events

Subsequent Events	6 Months Ended
	Jun. 30, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	16	SUBSEQUENT EVENTS
	On July 2, 2014, the Company declared a quarterly dividend of $0.68 per common share. The dividend was paid on July 28, 2014 to shareholders of record on July 14, 2014. The total dividend paid amounted to $22.6 million.
	In July 2014, the Company acquired one self-storage facility for $11.8 million.

Basis_of_Presentation_Policies

Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2014
Real Estate [Abstract]	'
Reclassification	'
	Reclassification: Certain amounts from the 2013 financial statements have been reclassified as discontinued operations a result of the sale of 4 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 No. 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, and is to be applied retrospectively, with early application not permitted. The Company is currently evaluating the new standard.
Accounting for Share-Based Payments	'
	In June 2014, the FASB issued ASU No. 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.

Organization_Tables

Organization (Tables)	6 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Redeemable Noncontrolling Interest	'
	stock at that date. Redemption value exceeded the value determined under the Company’s historical basis of accounting at those dates.
	(dollars in thousands)	Six Months
		Ended
		Jun. 30, 2014
	Beginning balance noncontrolling redeemable Operating Partnership Units	$	12,940
	Net income attributable to noncontrolling interests – consolidated joint venture		228
	Distributions		(271	)
	Adjustment to redemption value		2,451
	Ending balance noncontrolling redeemable Operating Partnership Units	$	15,348

Investment_in_Storage_Faciliti1

Investment in Storage Facilities (Tables)	6 Months Ended
	Jun. 30, 2014
Real Estate [Abstract]	'
Summary of Activity in Storage Facilities	'
	The following summarizes our activity in storage facilities during the six months ended June 30, 2014.
	(dollars in thousands)
	Cost:
	Beginning balance	$	1,864,637
	Acquisition of storage facilities		187,325
	Improvements and equipment additions		14,204
	Net decrease in construction in progress		(2,368	)
	Dispositions		(224	)
	Ending balance	$	2,063,574
	Accumulated Depreciation:
	Beginning balance	$	366,472
	Depreciation expense during the period		22,944
	Dispositions		(106	)
	Ending balance	$	389,310
Schedule of Acquired Facilities and Purchase Price of Facilities	'
	During the six months ended June 30, 2014 the Company acquired 23 self-storage facilities and the preliminary purchase price of the facilities has been assigned as follows:
	(dollars in thousands)									Consideration paid						Acquisition Date Fair Value
	State	Number of			Date of			Purchase		Cash Paid		Loan		Net Other		Land		Building,		In-Place		Closing
		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	$	1,663
	Texas		1			1/17/14			9,000		8,962		—		38		3,999		4,856		145		211
	Texas		1			2/10/14			8,900		8,857		—		43		2,235		6,564		101		198
	Maine		2			2/11/14			14,750		14,601		—		149		2,639		11,824		287		397
	Illinois		1			3/31/14			8,700		8,582		—		118		1,837		6,724		139		219
	Illinois		1			5/5/14			5,500		5,487		—		13		598		4,902		—		40
	Texas		1			5/13/14			6,075		6,017		—		58		2,000		3,935		140		175
	Missouri		7			5/22/14			35,050		34,786		—		264		9,550		24,709		791		583
	New Jersey		1			6/5/14			12,600		12,526		—		74		5,161		7,201		238		276
	New York		1			6/11/14			8,000		7,988		—		12		1,741		6,106		153		196
	New Jersey		1			6/12/14			2,500		2,430		—		70		—		2,319		181		59
	Georgia		1			6/12/14			7,700		7,616		—		84		2,263		5,293		144		174
	New Jersey		3			6/18/14			18,088		17,984		—		104		2,544		15,150		394		525
	Total 2014		23					$	190,863	$	189,435	$	—	$	1,428	$	57,876	$	129,450	$	3,537	$	4,716
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)	Jun. 30,			Dec. 31,
		2014			2013
	In-place customer leases	$	18,179		$	14,643
	Accumulated amortization		(15,030	)		(13,551	)
	Net carrying value at the end of period	$	3,149		$	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 23 properties acquired, and presents the Company’s results as if the acquisitions had occurred as of January 1, 2013:
		Three months ended						Six months ended
		June 30,						June 30,
	(dollars in thousands)	2014			2013			2014		2013
	Total revenues	$	82,310		$	71,923		$	161,122	$	140,339
	Net income attributable to common shareholders	$	22,765		$	17,151		$	42,572	$	25,748
	Earnings per common share
	Basic	$	0.69		$	0.52		$	1.29	$	0.78
	Diluted	$	0.69		$	0.52		$	1.28	$	0.78
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 23 properties since the acquisition dates that are included in the Company’s consolidated statements of operations for the three and six months ended June 30, 2014.
		Three months			Six months
		ended June 30,			ended June 30,
		2014			2014
	Total revenues	$	3,023		$	4,484
	Net loss attributable to common shareholders	$	(2,112	)	$	(4,877	)

Discontinued_Operations_Tables

Discontinued Operations (Tables)	6 Months Ended
	Jun. 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)	Apr. 1, 2013			Jan. 1, 2013
		to			to
		Jun. 30, 2013			Jun. 30, 2013
	Total revenue	$	506		$	962
	Property operations and maintenance expense		(140	)		(298	)
	Real estate tax expense		(41	)		(82	)
	Depreciation and amortization expense		(89	)		(178	)
	Net realized gain on sale of property		—			—
	Total income from discontinued operations	$	236		$	404

Unsecured_Line_of_Credit_and_T1

Unsecured Line of Credit and Term Notes (Tables)	6 Months Ended
	Jun. 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)	Jun. 30,		Dec. 31,
		2014		2013
	Revolving line of credit borrowings	$	8,000	$	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)	6 Months Ended
	Jun. 30, 2014
Debt Disclosure [Abstract]	'
Summary of Mortgage Payable	'
	Mortgages payable at June 30, 2014 and December 31, 2013 consist of the following:
	(dollars in thousands)	June 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%)		2,191		2,254
	Total mortgages payable	$	2,191	$	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 June 30, 2014)		—		—		—		—	$	8,000		—	$	8,000	$	8,000
	Notes Payable:
	Term note - fixed rate 6.38%		—		—	$	150,000		—		—		—	$	150,000	$	164,776
	Term note - variable rate LIBOR+1.65% (1.80% at June 30, 2014)		—		—		—		—		—	$	225,000	$	225,000	$	225,000
	Term note - variable rate LIBOR+1.65% (1.80% at June 30, 2014)		—		—		—		—		—	$	100,000	$	100,000	$	100,000
	Term note - fixed rate 5.54%		—		—		—		—		—	$	100,000	$	100,000	$	112,443
	Term note - fixed rate 4.533%		—		—		—		—		—	$	175,000	$	175,000	$	179,287
	Mortgage notes - fixed rate 5.99%	$	64	$	134	$	142	$	151	$	160	$	1,540	$	2,191	$	2,306
	Interest rate derivatives – liability		—		—		—		—		—		—		—	$	12,376

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	6 Months Ended
	Jun. 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 June 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 six months ended June 30, 2014 and June 30, 2013 are summarized as follows:
	(dollars in thousands)	Apr. 1, 2014			Apr. 1, 2013			Jan. 1, 2014			Jan. 1, 2013
		to			to			to			to
		Jun. 30, 2014			Jun. 30, 2013			Jun. 30, 2014			Jun. 30, 2013
	Accumulated other comprehensive loss beginning of period	$	(8,331	)	$	(13,703	)	$	(6,402	)	$	(15,242	)
	Realized loss reclassified from accumulated other comprehensive loss to interest expense		1,381			1,129			2,742			2,504
	Unrealized (loss) gain from changes in the fair value of the effective portion of the interest rate swaps		(5,107	)		6,093			(8,397	)		6,257
	(Loss) gain included in other comprehensive loss		(3,726	)		7,222			(5,655	)		8,761
	Accumulated other comprehensive loss end of period	$	(12,057	)	$	(6,481	)	$	(12,057	)	$	(6,481	)

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 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 June 30, 2014 and December 31, 2013 (in thousands):
		Asset (Liability)			Level 1		Level 2			Level 3
	June 30, 2014
	Interest rate swaps		(12,376	)		—		(12,376	)		—
	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)	6 Months Ended
	Jun. 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 six months ended June 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	$	190,594		$	186,243		$	—
	Investment in office building		—			—			4,878
	Other assets		4,951			4,762			687
	Total Assets	$	195,545		$	191,005		$	5,565
	Due to the Company	$	239		$	311		$	—
	Mortgages payable		81,273			103,247			6,514
	Other liabilities		2,859			2,215			417
	Total Liabilities		84,371			105,773			6,931
	Unaffiliated partners’ equity (deficiency)		88,939			72,453			(920	)
	Company equity (deficiency)		22,235			12,779			(446	)
	Total Partners’ Equity (Deficiency)		111,174			85,232			(1,366	)
	Total Liabilities and Partners’ Equity (Deficiency)	$	195,545		$	191,005		$	5,565
	Income Statement Data:
	Total revenues	$	11,401		$	14,008		$	719
	Property operating expenses		(3,638	)		(4,970	)		(274	)
	Administrative, management and call center fees		(865	)		(1,039	)		—
	Acquisition costs		(926	)		—			—
	Depreciation and amortization of customer list		(2,013	)		(2,075	)		(115	)
	Amortization of financing fees		(92	)		(102	)		(5	)
	Income tax expense		(44	)		(201	)		—
	Interest expense		(2,144	)		(2,571	)		(194	)
	Net income	$	1,679		$	3,050		$	131

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	6 Months Ended
	Jun. 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		Six Months		Six Months
		Ended		Ended		Ended		Ended
		Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
	Numerator:
	Net income from continuing operations attributable to common shareholders	$	20,576	$	17,703	$	37,249	$	31,816
	Denominator:
	Denominator for basic earnings per share – weighted average shares		32,800		31,276		32,592		30,882
	Effect of Dilutive Securities:
	Stock options and non-vested stock		180		149		167		158
	Denominator for diluted earnings per share – adjusted weighted average shares and assumed conversion		32,980		31,425		32,759		31,040
	Basic earnings per common share from continuing operations attributable to common shareholders	$	0.63	$	0.56	$	1.14	$	1.03
	Basic earnings per common share attributable to common shareholders	$	0.63	$	0.57	$	1.14	$	1.04
	Diluted earnings per common share from continuing operations attributable to common shareholders	$	0.62	$	0.56	$	1.14	$	1.03
	Diluted earnings per common share attributable to common shareholders	$	0.62	$	0.57	$	1.14	$	1.04

Shareholders_Equity_Tables

Shareholders' Equity (Tables)	6 Months Ended
	Jun. 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)	Six Months
		Ended
		June 30, 2014
	Beginning balance of total shareholders’ equity	$	870,709
	Net proceeds from the issuance of common stock		51,372
	Exercise of stock options		356
	Earned portion of non-vested stock		2,322
	Stock option expense		149
	Deferred compensation outside directors		59
	Adjustment to redemption value on noncontrolling redeemable Operating Partnership units		(2,451	)
	Net income attributable to common shareholders		37,249
	Change in fair value of derivatives		(5,655	)
	Dividends		(44,510	)
	Ending balance of total shareholders’ equity	$	909,600

Basis_of_Presentation_Addition

Basis of Presentation - Additional Information (Detail)	6 Months Ended
	Jun. 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 $)	6 Months Ended		12 Months Ended	1 Months Ended	6 Months Ended			6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Feb. 28, 2013	Jun. 30, 2011	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014
	Property			West Deptford JV LLC [Member]	West Deptford JV LLC [Member]	Sovran HHF Storage Holdings LLC [Member]	Sovran HHF Storage Holdings II LLC [Member]	Texas and Florida [Member]
	States					Property	Property	Revenue [Member]
Organization [Line Items]	'	'	'	'	'	'	'	'
Number of self-storage properties owned and managed	501	'	'	'	'	'	'	'
Number of states in which self-storage properties owned and managed	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	19	'	'	'	'	'	'	'
Number of properties owned and managed under fifteen-percent stake joint venture	'	'	'	'	'	'	30	'
Concentration risk, percentage	'	'	'	'	'	'	'	40.00%
Number of properties leased	4	'	'	'	'	'	'	'
Percentage of ownership interest of the subsidiary and its limited partnership which controls the operations of the Operating Partnership	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	'	$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		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 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	125	115	228	207
Distributions	'	'	-271	'
Adjustment to redemption value	'	'	2,451	'
Ending balance noncontrolling redeemable Operating Partnership Units	$15,348	'	$15,348	'

Stock_Based_Compensation_Addit

Stock Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'	'
Stock option expense	$113	$162	$149	$219
Amortization of non-vested stock grants	$1,129	$586	$2,322	$1,182
Stock options exercised by employees	7,500	14,200	9,000	121,845
Number of shares of non-vested stock that vested	7,720	8,480	17,600	19,462

Investment_in_Storage_Faciliti2

Investment in Storage Facilities - Summary of Activity in Storage Facilities (Detail) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014
Cost:	'
Beginning balance	$1,864,637
Acquisition of storage facilities	187,325
Improvements and equipment additions	14,204
Net decrease in construction in progress	-2,368
Dispositions	-224
Ending balance	2,063,574
Accumulated Depreciation:	'
Beginning balance	366,472
Depreciation expense during the period	22,944
Dispositions	-106
Ending balance	$389,310

Investment_in_Storage_Faciliti3

Investment in Storage Facilities - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
	Facility		Facility
Real Estate [Abstract]	'	'	'	'	'
Number of storage facilities acquired	16	'	23	'	'
Cash paid for properties acquired	'	'	$189,435,000	'	'
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	800,000	1,000,000	1,500,000	1,900,000	'
Amortization expense for the year	3,700,000	'	3,700,000	'	'
Amortization expense for the next fiscal year following the latest fiscal year	$1,000,000	'	$1,000,000	'	'

Investment_in_Storage_Faciliti4

Investment in Storage Facilities - Schedule of Acquired Facilities and Purchase Price of Facilities (Detail) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2013
	Facility	Facility
Finite-Lived Intangible Assets [Line Items]	'	'	'
Number of Properties	16	23	'
Purchase Price	$190,863,000	$190,863,000	'
Cash Paid	'	189,435,000	'
Loan Assumed	0	0	'
Net Other Liabilities (Assets) Assumed	1,428,000	1,428,000	'
Land	57,876,000	57,876,000	'
Acquisition Date Building, Equipment, and Improvements	129,450,000	129,450,000	'
Fair Value In-Place Customers Leases	3,537,000	3,537,000	'
Closing Costs Expensed	1,938,000	4,716,000	486,000
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	'
Closing Costs Expensed	'	1,663,000	'
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	'
Closing Costs Expensed	'	211,000	'
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	'
Closing Costs Expensed	'	198,000	'
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	'
Closing Costs Expensed	'	175,000	'
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	'
Closing Costs Expensed	'	397,000	'
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	'
Closing Costs Expensed	'	219,000	'
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	'
Closing Costs Expensed	'	40,000	'
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	9,550,000	9,550,000	'
Acquisition Date Building, Equipment, and Improvements	24,709,000	24,709,000	'
Fair Value In-Place Customers Leases	791,000	791,000	'
Closing Costs Expensed	'	583,000	'
NEW JERSEY | 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	'
Closing Costs Expensed	'	276,000	'
NEW JERSEY | 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	'
Closing Costs Expensed	'	59,000	'
NEW JERSEY | 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	18,088,000	18,088,000	'
Cash Paid	'	17,984,000	'
Loan Assumed	0	0	'
Net Other Liabilities (Assets) Assumed	104,000	104,000	'
Land	2,544,000	2,544,000	'
Acquisition Date Building, Equipment, and Improvements	15,150,000	15,150,000	'
Fair Value In-Place Customers Leases	394,000	394,000	'
Closing Costs Expensed	'	525,000	'
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	'
Closing Costs Expensed	'	196,000	'
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	'
Closing Costs Expensed	'	$174,000	'

Investment_in_Storage_Faciliti5

Investment in Storage Facilities - Schedule of Fair Value of In-Place Customer Lease Intangible Assets (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Real Estate [Abstract]	'	'
In-place customer leases	$18,179	$14,643
Accumulated amortization	-15,030	-13,551
Net carrying value at the end of period	$3,149	$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		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Investments Schedule [Abstract]	'	'	'	'
Total revenues	$82,310	$71,923	$161,122	$140,339
Net income attributable to common shareholders	$22,765	$17,151	$42,572	$25,748
Basic	$0.69	$0.52	$1.29	$0.78
Diluted	$0.69	$0.52	$1.28	$0.78

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	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2014
Investments Schedule [Abstract]	'	'
Total revenues	$3,023	$4,484
Net loss attributable to common shareholders	($2,112)	($4,877)

Discontinued_Operations_Additi

Discontinued Operations - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 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	'	0	'	'	2,400,000
Income from continuing operations attributable to common shareholders	20,576,000	17,703,000	37,249,000	31,816,000	'
Income from discontinued operations attributable to common shareholders	$0	$200,000	$0	$400,000	'
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	6 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2013	Dec. 31, 2013
Discontinued Operations And Disposal Groups [Abstract]	'	'	'
Total revenue	$506	$962	'
Property operations and maintenance expense	-140	-298	'
Real estate tax expense	-41	-82	'
Depreciation and amortization expense	-89	-178	'
Net realized gain on sale of property	0	'	2,400
Total income from discontinued operations	$236	$404	'

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 $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Unsecured Line Of Credit And Term Notes [Line Items]	'	'
Revolving line of credit borrowings	$8,000	$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 $)

6 Months Ended

0 Months Ended

6 Months Ended

6 Months Ended

6 Months Ended

12 Months Ended

6 Months Ended

Jun. 30, 2014

Dec. 31, 2013

Apr. 08, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 04, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2011

Jun. 30, 2014

Jun. 04, 2013

Maturity in April, 2024 [Member]

Maturity in April, 2024 [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]

Maturity in August 2021 [Member]

Maturity in August 2021 [Member]

Maturity in April 2016 [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

4-Jun-20

'

4-Jun-18

'

5-Aug-21

'

13-Apr-16

'

Additional secured commitments

750,000,000

575,000,000

'

'

'

225,000,000

'

'

'

'

150,000,000

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

'

'

'

'

'

'

166,300,000

'

'

'

'

'

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 $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]	'	'
Mortgages payable	$2,191	$2,254
5.99% Mortgage Notes Due May 1, 2026 [Member]	'	'
Debt Instrument [Line Items]	'	'
Mortgages payable	$2,191	$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 $)	6 Months Ended
In Millions, unless otherwise specified	Jun. 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 $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Proforma Debt Instrument [Line Items]	'	'
Line of credit	$8,000	$49,000
Term notes	750,000	575,000
Mortgage note, total	2,191	2,254
Interest rate derivatives - liability	12,376	7,523
Line of credit - variable rate LIBOR + 1.50% (1.65% at June 30, 2014) [Member]	'	'
Proforma Debt Instrument [Line Items]	'	'
Payable due 2018	8,000	'
Line of credit	8,000	'
Debt instrument, fair value	8,000	'
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	164,776	'
Term note - variable rate LIBOR+1.65% (1.80% at June 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 June 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	112,443	'
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	179,287	'
Mortgage Note-Fixed Rate 5.99% [Member]	'	'
Proforma Debt Instrument [Line Items]	'	'
Payable due 2014	64	'
Payable due 2015	134	'
Payables due 2016	142	'
Payables due 2017	151	'
Payable due 2018	160	'
Payables due Thereafter	1,540	'
Mortgage note, total	2,191	'
Debt instrument, fair value	$2,306	'

Mortgages_Payable_and_Debt_Mat5

Mortgages Payable and Debt Maturities - Summary of Debt Obligation and Interest Rate Derivatives (Parenthetical) (Detail)	6 Months Ended
	Jun. 30, 2014
Line of credit - variable rate LIBOR + 1.50% (1.65% at June 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% (1.80% at June 30, 2014) [Member]	'
Proforma Debt Instrument [Line Items]	'
Interest rate at end of period	1.80%
Basis spread over LIBOR	1.65%
Term note - variable rate LIBOR+1.65% (1.80% at June 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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Derivative [Line Items]	'	'	'	'	'
Interest Expense	$8,872,000	$8,446,000	$16,216,000	$16,904,000	'
Estimated payments to be made under interest rate swaps	'	'	5,500,000	'	'
Estimated payments to be made under interest rate swaps, assets	'	'	'	'	794,000
Fair value of interest rate swap agreements	12,376,000	'	12,376,000	'	7,523,000
Net termination value	12,400,000	'	12,400,000	'	'
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	1,100,000	2,700,000	2,500,000	'
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 $)	6 Months Ended
In Millions, unless otherwise specified	Jun. 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		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative [Line Items]	'	'	'	'
Accumulated other comprehensive loss beginning of period	($8,331)	($13,703)	($6,402)	($15,242)
Unrealized (loss) gain from changes in the fair value of the effective portion of the interest rate swaps	-5,107	6,093	-8,397	6,257
(Loss) gain included in other comprehensive loss	-3,726	7,222	-5,655	8,761
Accumulated other comprehensive loss end of period	-12,057	-6,481	-12,057	-6,481
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	$1,381	$1,129	$2,742	$2,504

Fair_Value_Measurements_Assets

Fair Value Measurements - Assets and Liabilities Carried at Fair Value Measured on Recurring Basis (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Interest rate swaps	'	$794
Interest rate swaps	-12,376	-7,523
Interest Rate Swap [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Interest rate swaps	'	794
Interest rate swaps	-12,376	-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	'	794
Interest rate swaps	-12,376	-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	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014
	Facility	Facility
Fair Value Disclosures [Abstract]	'	'
Number of storage facilities acquired	16	23

Investment_in_Joint_Ventures_A

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

3 Months Ended

6 Months Ended

12 Months Ended

3 Months Ended

6 Months Ended

12 Months Ended

3 Months Ended

6 Months Ended

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2012

Dec. 31, 2011

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2008

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2013

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]

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]

Sovran HHF Storage Holdings LLC [Member]

Sovran HHF Storage Holdings LLC [Member]

Sovran HHF Storage Holdings LLC [Member]

Sovran HHF Storage Holdings LLC [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]

Property

Property

Property

Property

Schedule of Equity Method Investments [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ownership interest

'

'

'

'

'

'

15.00%

'

'

'

'

'

20.00%

'

'

'

49.00%

'

49.00%

'

'

Investment at carrying value

'

'

'

'

'

'

$12,800,000

$12,800,000

'

'

'

'

$24,000,000

$17,400,000

'

'

($400,000)

'

($400,000)

'

($500,000)

Payment for property acquisition

190,863,000

'

190,863,000

'

29,000,000

166,100,000

'

'

'

'

'

'

34,400,000

'

'

171,500,000

'

'

'

'

'

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

'

'

'

'

'

'

'

'

'

'

'

'

3

'

'

25

'

'

'

'

'

Contribution of company to joint venture as share in capital

'

'

'

'

2,400,000

12,800,000

'

'

'

'

'

'

7,000,000

'

1,200,000

18,600,000

'

'

'

'

'

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

'

'

'

'

'

'

'

'

900,000

800,000

1,800,000

1,600,000

'

'

'

'

'

'

'

'

'

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

433,000

455,000

892,000

842,000

'

'

'

'

367,000

456,000

793,000

821,000

'

'

'

'

32,000

-1,000

64,000

21,000

'

Rent paid during the period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$252,000

$165,000

$503,000

$345,000

'

Investment_in_Joint_Ventures_S

Investment in Joint Ventures - Summary of Unconsolidated Joint Ventures' Financial Statements (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Investment in storage facilities, net	$1,674,264	'	$1,674,264	'	$1,498,165
Other assets	8,179	'	8,179	'	11,021
Total Assets	1,740,291	'	1,740,291	'	1,561,875
Mortgages payable	2,191	'	2,191	'	2,254
Total Liabilities	815,343	'	815,343	'	678,226
Acquisition costs	-1,938	'	-4,716	-486	'
Depreciation and amortization of customer list	-12,481	-11,358	-24,423	-22,559	'
Amortization of financing fees	'	'	-407	-422	'
Income tax expense	-300	-300	-600	-700	'
Interest expense	-8,872	-8,446	-16,216	-16,904	'
Sovran HHF Storage Holdings LLC [Member]	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Investment in storage facilities, net	190,594	'	190,594	'	'
Investment in office building	0	'	0	'	'
Other assets	4,951	'	4,951	'	'
Total Assets	195,545	'	195,545	'	'
Due to the Company	239	'	239	'	'
Mortgages payable	81,273	'	81,273	'	'
Other liabilities	2,859	'	2,859	'	'
Total Liabilities	84,371	'	84,371	'	'
Unaffiliated partners' equity (deficiency)	88,939	'	88,939	'	'
Company equity (deficiency)	22,235	'	22,235	'	'
Total Partners' Equity (Deficiency)	111,174	'	111,174	'	'
Total Liabilities and Partners' Equity (Deficiency)	195,545	'	195,545	'	'
Total revenues	'	'	11,401	'	'
Property operating expenses	'	'	-3,638	'	'
Administrative, management and call center fees	'	'	-865	'	'
Acquisition costs	'	'	-926	'	'
Depreciation and amortization of customer list	'	'	-2,013	'	'
Amortization of financing fees	'	'	-92	'	'
Income tax expense	'	'	-44	'	'
Interest expense	'	'	-2,144	'	'
Net income	'	'	1,679	'	'
Sovran HHF Storage Holdings II LLC [Member]	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Investment in storage facilities, net	186,243	'	186,243	'	'
Investment in office building	0	'	0	'	'
Other assets	4,762	'	4,762	'	'
Total Assets	191,005	'	191,005	'	'
Due to the Company	311	'	311	'	'
Mortgages payable	103,247	'	103,247	'	'
Other liabilities	2,215	'	2,215	'	'
Total Liabilities	105,773	'	105,773	'	'
Unaffiliated partners' equity (deficiency)	72,453	'	72,453	'	'
Company equity (deficiency)	12,779	'	12,779	'	'
Total Partners' Equity (Deficiency)	85,232	'	85,232	'	'
Total Liabilities and Partners' Equity (Deficiency)	191,005	'	191,005	'	'
Total revenues	'	'	14,008	'	'
Property operating expenses	'	'	-4,970	'	'
Administrative, management and call center fees	'	'	-1,039	'	'
Acquisition costs	'	'	0	'	'
Depreciation and amortization of customer list	'	'	-2,075	'	'
Amortization of financing fees	'	'	-102	'	'
Income tax expense	'	'	-201	'	'
Interest expense	'	'	-2,571	'	'
Net income	'	'	3,050	'	'
Iskalo Office Holdings, LLC [Member]	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Investment in storage facilities, net	0	'	0	'	'
Investment in office building	4,878	'	4,878	'	'
Other assets	687	'	687	'	'
Total Assets	5,565	'	5,565	'	'
Due to the Company	0	'	0	'	'
Mortgages payable	6,514	'	6,514	'	'
Other liabilities	417	'	417	'	'
Total Liabilities	6,931	'	6,931	'	'
Unaffiliated partners' equity (deficiency)	-920	'	-920	'	'
Company equity (deficiency)	-446	'	-446	'	'
Total Partners' Equity (Deficiency)	-1,366	'	-1,366	'	'
Total Liabilities and Partners' Equity (Deficiency)	5,565	'	5,565	'	'
Total revenues	'	'	719	'	'
Property operating expenses	'	'	-274	'	'
Administrative, management and call center fees	'	'	0	'	'
Acquisition costs	'	'	0	'	'
Depreciation and amortization of customer list	'	'	-115	'	'
Amortization of financing fees	'	'	-5	'	'
Income tax expense	'	'	0	'	'
Interest expense	'	'	-194	'	'
Net income	'	'	$131	'	'

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Tax Disclosure [Abstract]	'	'	'	'
Federal and state income tax expense	$0.30	$0.30	$0.60	$0.70
Unrecognized tax benefits	0	0	0	0
Interest or penalties related to uncertain tax positions	'	'	0	0
Current taxes payable	0.1	'	0.1	'
Deferred tax liability	$0.90	'	$0.90	'
Tax years open to examination	'	'	'2010-2013	'

Earnings_Per_Share_Computation

Earnings Per Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator:	'	'	'	'
Net income from continuing operations attributable to common shareholders	$20,576	$17,703	$37,249	$31,816
Denominator:	'	'	'	'
Denominator for basic earnings per share - weighted average shares	32,799,837	31,275,850	32,591,917	30,882,352
Effect of Dilutive Securities:	'	'	'	'
Stock options and non-vested stock	180,000	149,000	167,000	158,000
Denominator for diluted earnings per share - adjusted weighted average shares and assumed conversion	32,979,708	31,425,016	32,759,069	31,039,756
Basic earnings per common share from continuing operations attributable to common shareholders	$0.63	$0.56	$1.14	$1.03
Basic earnings per common share attributable to common shareholders	$0.63	$0.57	$1.14	$1.04
Diluted earnings per common share from continuing operations attributable to common shareholders	$0.62	$0.56	$1.14	$1.03
Diluted earnings per common share attributable to common shareholders	$0.62	$0.57	$1.14	$1.04

Earnings_Per_Share_Additional_

Earnings Per Share - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 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	8,000	8,000	4,000	4,000
Restricted Stock [Member]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Securities not included in the effect of dilutive securities	142,417	67,447	155,648	72,394

Shareholders_Equity_Reconcilia

Shareholders' Equity - Reconciliation of Changes in Total Shareholders' Equity (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Equity [Abstract]	'	'	'	'
Beginning balance	'	'	$870,709	'
Net proceeds from the issuance of common stock	'	'	51,372	'
Exercise of stock options	'	'	356	'
Earned portion of non-vested stock	1,129	586	2,322	1,182
Stock option expense	113	162	149	219
Deferred compensation outside directors	'	'	59	'
Adjustment to redemption value on noncontrolling redeemable Operating Partnership units	'	'	-2,451	'
Net income attributable to common shareholders	20,576	17,937	37,249	32,217
Change in fair value of derivatives	-3,726	7,222	-5,655	8,761
Dividends	'	'	-44,510	'
Ending balance	$909,600	'	$909,600	'

Shareholders_Equity_Additional

Shareholders' Equity - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
In Millions, except Share data, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014	Jun. 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	250,000	359,102	'	'
Weighted average issue price of common stock	$77.08	$74.32	'	'
Proceeds from issuance of common stock	19	26.4	'	'
Expenses related to equity program	'	'	0.1	'
Acquired storage facilities	16	'	23	'
Common stock, value reserved for future issuance	205.7	'	205.7	'
Shares issued under dividend reinvestment plan	'	'	90,675	'
Piper [Member]	'	'	'	'
Stockholders Equity [Line Items]	'	'	'	'
Offering related costs and commissions	0.2	'	'	'
SunTrust [Member]	'	'	'	'
Stockholders Equity [Line Items]	'	'	'	'
Offering related costs and commissions	'	$0.30	'	'

Commitment_and_Contingencies_A

Commitment and Contingencies - Additional Information (Detail) (USD $)	Jun. 30, 2014
In Millions, unless otherwise specified	Facility
Commitments And Contingencies Disclosure [Abstract]	'
Payment for self-storage facilities under contract	$11.80
Number of self-storage facilities under contract to be purchased	1
Contracted sales price for selling self storage facilities under contract	$5.20

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (USD $)	6 Months Ended	1 Months Ended
In Millions, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jul. 31, 2014	Jul. 02, 2014
	Facility	Subsequent Event [Member]	Subsequent Event [Member]
		Facility
Subsequent Event [Line Items]	'	'	'
Dividend declared, date	2-Jul-14	'	'
Dividend per common share	'	'	$0.68
Dividend paid, date	28-Jul-14	'	'
Dividend record, date	14-Jul-14	'	'
Dividend paid	'	$22.60	'
Payment for self-storage facilities under contract	$11.80	$11.80	'
Number of self-storage facilities under contract to be purchased	1	1	'