Extra Space Storage (EXR) 10-Q 5 May 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	May 01, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Trading Symbol	EXR
Entity Registrant Name	Extra Space Storage Inc.
Entity Central Index Key	1,289,490
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		125,964,453

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets:
Real estate assets, net	$ 6,770,593	$ 6,770,447
Investments in unconsolidated real estate ventures	79,385	79,570
Cash and cash equivalents	29,311	43,858
Restricted cash	12,231	13,884
Receivables from related parties and affiliated real estate joint ventures	6,251	16,611
Other assets, net	136,586	167,076
Total assets	7,034,357	7,091,446
Liabilities, Noncontrolling Interests and Equity:
Notes payable, net	3,198,870	3,213,588
Exchangeable senior notes, net	612,233	610,314
Notes payable to trusts, net	117,352	117,321
Revolving lines of credit	363,000	365,000
Accounts payable and accrued expenses	77,106	101,388
Other liabilities	79,981	87,669
Total liabilities	4,448,542	4,495,280
Commitments and contingencies
Extra Space Storage Inc. stockholders' equity:
Preferred stock, $0.01 par value, 50,000,000 shares authorized, no shares issued or outstanding	0	0
Common stock, $0.01 par value, 500,000,000 shares authorized, 125,912,164 and 125,881,460 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	1,259	1,259
Additional paid-in capital	2,567,228	2,566,120
Accumulated other comprehensive income	22,816	16,770
Accumulated deficit	(355,187)	(339,257)
Total Extra Space Storage Inc. stockholders' equity	2,236,116	2,244,892
Noncontrolling interest represented by Preferred Operating Partnership units, net of $120,230 notes receivable	147,823	147,920
Noncontrolling interests in Operating Partnership	201,876	203,354
Total noncontrolling interests and equity	2,585,815	2,596,166
Total liabilities, noncontrolling interests and equity	$ 7,034,357	$ 7,091,446

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	125,912,164	125,881,460
Common stock, shares outstanding	125,912,164	125,881,460
Note receivable from noncontrolling interest represented by Preferred Operating Partnership units	$ 120,230	$ 120,230

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues:
Property rental	$ 231,493	$ 199,488
Tenant reinsurance	22,855	20,555
Management fees and other income	8,660	9,360
Total revenues	263,008	229,403
Expenses:
Property operations	66,645	61,112
Tenant reinsurance	3,920	4,311
Acquisition related costs and other	0	4,053
General and administrative	18,808	23,402
Depreciation and amortization	49,432	42,897
Total expenses	138,805	135,775
Income from operations	124,203	93,628
Loss on earnout from prior acquisition	0	(1,544)
Interest expense	(35,970)	(31,359)
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	(1,269)	(1,233)
Interest income	1,102	1,714
Interest income on note receivable from Preferred Operating Partnership unit holder	1,213	1,213
Income before equity in earnings of unconsolidated real estate ventures and income tax expense	89,279	62,419
Equity in earnings of unconsolidated real estate ventures	3,579	2,830
Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of joint venture partner's interest	0	26,923
Income tax expense	(3,124)	(2,765)
Net income	89,734	89,407
Net income allocated to Preferred Operating Partnership noncontrolling interests	(3,951)	(3,180)
Net income allocated to Operating Partnership and other noncontrolling interests	(3,501)	(3,635)
Net income attributable to common stockholders	$ 82,282	$ 82,592
Earnings per common share
Basic (in dollars per share)	$ 0.65	$ 0.66
Diluted (in dollars per share)	$ 0.64	$ 0.66
Weighted average number of shares
Basic (in shares)	125,605,403	124,754,174
Diluted (in shares)	132,618,644	131,956,094
Cash dividends paid per common share (in dollars per share)	$ 0.78	$ 0.59

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 89,734	$ 89,407
Other comprehensive income (loss):
Change in fair value of interest rate swaps	6,334	(31,148)
Total comprehensive income	96,068	58,259
Less: comprehensive income attributable to noncontrolling interests	7,740	5,254
Comprehensive income attributable to common stockholders	$ 88,328	$ 53,005

Condensed Consolidated Stateme6

Condensed Consolidated Statement of Noncontrolling Interests and Equity - 3 months ended Mar. 31, 2017 - USD ($) $ in Thousands	Total	Series A Preferred Operating Partnership [Member]	Series B Preferred Operating Partnership [Member]	Series C Preferred Operating Partnership [Member]	Series D Preferred Operating Partnership [Member]	Common Operating Partnership [Member]	Par Value [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Balance, beginning of period at Dec. 31, 2016	$ 2,596,166	$ 14,385	$ 41,902	$ 10,730	$ 80,903	$ 203,354	$ 1,259	$ 2,566,120	$ 16,770	$ (339,257)
Balance, beginning of period (in shares) at Dec. 31, 2016	125,881,460						125,881,460
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock grants issued	$ 0						$ 0
Restricted stock grants issued (in shares)							31,179
Restricted stock grants canceled (in shares)							(475)
Compensation expense related to stock-based awards	1,990		0	0	0	0		1,990	0	0
Redemption of Operating Partnership units for cash	(1,754)					(872)		(882)
Redemption of Operating Partnership units for cash (in shares)							0
Net income	89,734	1,818	629	676	828	3,501				82,282
Other comprehensive income	6,334	39				249			6,046
Distributions to Operating Partnership units held by noncontrolling interests	(8,443)	(1,954)	(629)	(676)	(828)	(4,356)
Dividends paid on common stock at $0.78 per share	(98,212)									(98,212)
Balance, end of period at Mar. 31, 2017	$ 2,585,815	$ 14,288	$ 41,902	$ 10,730	$ 80,903	$ 201,876	$ 1,259	$ 2,567,228	$ 22,816	$ (355,187)
Balance, end of period (in shares) at Mar. 31, 2017	125,912,164						125,912,164

Condensed Consolidated Stateme7

Condensed Consolidated Statement of Noncontrolling Interests and Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Stockholders' Equity [Abstract]
Dividends paid on common stock, per share (in dollars per share)	$ 0.78	$ 0.59

Condensed Consolidated Stateme8

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income	$ 89,734	$ 89,407
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	49,432	42,897
Amortization of deferred financing costs	3,103	2,823
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	1,269	1,233
Non-cash interest expense related to amortization of premium on notes payable	0	(354)
Compensation expense related to stock-based awards	1,990	1,710
Gain on sale of real estate assets and purchase of joint venture partner's interest	0	(26,923)
Loss on earnout from prior acquisition	0	(1,544)
Distributions from unconsolidated real estate ventures in excess of earnings	1,123	998
Changes in operating assets and liabilities:
Receivables from related parties and affiliated real estate joint ventures	(1,438)	(2,878)
Other assets	4,336	(5,276)
Accounts payable and accrued expenses	(30,069)	(5,642)
Other liabilities	(6,359)	(985)
Net Cash Provided by (Used in) Operating Activities	113,121	95,466
Cash flows from investing activities:
Acquisition of real estate assets	(39,136)	(234,820)
Development and redevelopment of real estate assets	(5,246)	(6,543)
Change in restricted cash	1,653	(1,265)
Investment in unconsolidated real estate ventures	(1,519)	(4,794)
Return of investment in unconsolidated real estate ventures	581	318
Purchase/issuance of notes receivable	0	(10,656)
Principal payments received from notes receivable	44,869	0
Purchase of equipment and fixtures	(1,292)	(908)
Net Cash Provided by (Used in) Investing Activities	(90)	(258,668)
Cash flows from financing activities:
Proceeds from the sale of common stock, net of offering costs	0	73,574
Repurchase of exchangeable senior notes	0	(19,639)
Proceeds from notes payable and revolving lines of credit	169,000	195,976
Principal payments on notes payable and revolving lines of credit	(187,916)	(32,859)
Deferred financing costs	(253)	(1,286)
Net proceeds from exercise of stock options	0	13
Proceeds from termination of interest rate cap	0	1,650
Redemption of Operating Partnership units held by noncontrolling interests	(1,754)	0
Dividends paid on common stock	(98,212)	(73,827)
Distributions to noncontrolling interests	(8,443)	(6,446)
Net cash provided by (used in) financing activities	(127,578)	137,156
Net decrease in cash and cash equivalents	(14,547)	(26,046)
Cash and cash equivalents, beginning of the period	43,858	75,799
Cash and cash equivalents, end of the period	29,311	49,753
Supplemental schedule of cash flow information
Interest paid	37,570	24,873
Income taxes paid	5,059	4,835
Redemption of Operating Partnership units held by noncontrolling interests for common stock
Noncontrolling interests in Operating Partnership	0	(12)
Common stock and paid-in capital	0	12
Tax effect from vesting of restricted stock grants and option exercises
Other assets	0	272
Additional paid-in capital	0	(272)
Accrued construction costs and capital expenditures
Acquisition of real estate assets	4,797	0
Development and redevelopment of real estate assets	990	0
Other liabilities	(5,787)	0
Distribution of real estate from investments in unconsolidated real estate ventures
Real estate assets, net	0	17,261
Investments in unconsolidated real estate ventures	$ 0	$ (17,261)

Organization

Organization	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	ORGANIZATION Extra Space Storage Inc. (the “Company”) is a fully-integrated, self-administered and self-managed real estate investment trust (“REIT”), formed as a Maryland corporation on April 30, 2004, to own, operate, manage, acquire, develop and redevelop professionally managed self-storage properties (“stores”) located throughout the United States. The Company continues the business of Extra Space Storage LLC and its subsidiaries, which had engaged in the self-storage business since 1977. The Company’s interests in its stores is held through its operating partnership, Extra Space Storage LP (the “Operating Partnership”), which was formed on May 5, 2004. The Company’s primary assets are general partner and limited partner interests in the Operating Partnership. This structure is commonly referred to as an umbrella partnership REIT, or UPREIT. The Company has elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended. To the extent the Company continues to qualify as a REIT, it will not be subject to tax, with certain limited exceptions, on the taxable income that is distributed to its stockholders. The Company invests in stores by acquiring wholly-owned stores or by acquiring an equity interest in real estate entities. At March 31, 2017 , the Company had direct and indirect equity interests in 1,020 stores. In addition, the Company managed 421 stores for third parties, bringing the total number of stores which it owns and/or manages to 1,441 . These stores are located in 38 states, Washington, D.C. and Puerto Rico. The Company operates in three distinct segments: (1) rental operations; (2) tenant reinsurance; and (3) property management, acquisition and development. The rental operations activities include rental operations of stores in which we have an ownership interest. No single tenant accounts for more than 5.0% of rental income. Tenant reinsurance activities include the reinsurance of risks relating to the loss of goods stored by tenants in the Company’s stores. The Company’s property management, acquisition and development activities include managing, acquiring and developing stores.

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	BASIS OF PRESENTATION The accompanying unaudited condensed consolidated financial statements of the Company are presented on the accrual basis of accounting in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information, and in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they may not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (including normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2017 , are not necessarily indicative of results that may be expected for the year ending December 31, 2017 . The condensed consolidated balance sheet as of December 31, 2016 has been derived from the Company’s audited financial statements as of that date, but does not include all of the information and footnotes required by GAAP for complete financial statements. For further information refer to the consolidated financial statements and footnotes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 , as filed with the Securities and Exchange Commission. Recently Issued Accounting Standards In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, “ Revenue from Contracts with Customers, ” which amends the guidance for revenue recognition to replace numerous, industry-specific requirements and converges areas under this topic with those of the International Financial Reporting Standards. ASU 2014-09 outlines a five-step process for customer contract revenue recognition that focuses on transfer of control, as opposed to transfer of risk and rewards. The amendment also requires enhanced disclosures regarding the nature, amount, timing and uncertainty of revenues and cash flows from contracts with customers. The new standard will become effective for annual and interim periods beginning after December 15, 2017 with early adoption permitted. The Company has determined that its property rental revenue and tenant reinsurance revenue will not be subject to the guidance in ASU 2014-09, as they qualify as lease contracts and insurance contracts, which are excluded from its scope. The Company's management fee revenue will be included in the scope of the standard. However, based on the Company's initial assessment, it appears that revenue recognized under the standard will not differ materially from revenue recognized under existing guidance. The Company continues to assess the potential impacts of ASU 2014-09. The Company anticipates adopting the standard using the modified retrospective transition method as of January 1, 2018. In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842),” which modifies the accounting for leases, intending to increase transparency and comparability of organizations by requiring balance sheet presentation of leased assets and increased financial statement disclosure of leasing arrangements. ASU 2016-02 will require entities to recognize a liability for their lease obligations and a corresponding asset representing the right to use the underlying asset over the lease term. Lease obligations are to be measured at their present value and accounted for using the effective interest method. The accounting for the leased asset will differ slightly depending on whether the agreement is deemed to be a financing or operating lease. For financing leases, the leased asset is depreciated on a straight-line basis and depreciation expense is recorded separately from the interest expense in the statements of operations, resulting in higher expense in the earlier part of the lease term. For operating leases, the depreciation and interest expense components are combined, recognized evenly over the term of the lease, and presented as a reduction to operating income. ASU 2016-02 requires that assets and liabilities be presented or disclosed separately, and requires additional disclosure of certain qualitative and quantitative information related to these lease agreements. ASU 2016-02 is effective for annual and interim periods beginning after December 15, 2018. The Company is currently assessing the impact of the adoption of ASU 2016-02 on the Company’s consolidated financial statements. In March 2016, the FASB issued ASU 2016-05, "Derivatives and Hedging (Topic 815): Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships." ASU 2016-05 clarifies that a change in the counterparty to a derivative instrument that has been designated as a hedging instrument does not, in and of itself, require re-designation of that hedging relationship provided that all other hedge accounting criteria continue to be met. The Company adopted this guidance on January 1, 2017. The adoption of ASU 2016-05 did not have a material impact on the Company's consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, “ Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting .” ASU 2016-09 simplifies several aspects of the accounting for employee share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. This ASU is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. The Company adopted this guidance prospectively on January 1, 2017, and prior periods have not been adjusted. As a result of the adoption of this guidance, the Company no longer presents the tax effects from vesting of restricted stock grants and stock option exercises on its condensed consolidated statement of noncontrolling interests and equity. In August 2016, the FASB issued ASU 2016-15, "Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments." ASU 2016-15 provides guidance on several specific cash flow issues, including the classification of debt prepayment or debt extinguishment costs, contingent consideration payments, and distributions received from equity method investees. This guidance is effective for fiscal years beginning after December 15, 2017. The Company is currently evaluating the new guidance to determine the impact it may have on its consolidated financial statements. In October 2016, the FASB issued ASU 2016-18, " Statement of Cash Flows (Topic 230)," which requires that a statement of cash flows explains the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. This guidance is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the new guidance to determine the impact it may have on its consolidated financial statements. In January 2017, the FASB issued ASU 2017-01, "Business Combinations (Topic 805): Clarifying the Definition of a Business," which provides guidance on whether transactions should be accounted for as acquisitions or disposals of assets or businesses. Specifically, when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or group of similar identifiable assets, the set of assets is not a business. Additionally, ASU 2017-01 also provides other guidance providing a more robust framework to use in determining whether a set of assets and activities is a business. This guidance is effective for annual periods beginning after December 15, 2017. Early adoption is permitted for transactions for which the acquisition or disposition date occurs before the issuance date or effective date of the amendments, only when the transaction has not been reported in financial statements that have been issued. The Company adopted ASU 2017-01 for new acquisitions beginning on January 1, 2017. The costs related to the acquisitions of stores that qualify as asset acquisitions will be capitalized as part of the purchase.

Fair Value Disclosures

Fair Value Disclosures	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Disclosures	FAIR VALUE DISCLOSURES Derivative Financial Instruments Currently, the Company uses interest rate swaps to manage its interest rate risk. The valuation of these instruments is determined using widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves. The fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash payments and the discounted expected variable cash receipts. The variable cash receipts are based on an expectation of future interest rates (forward curves) derived from observable market interest rate forward curves. The Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts and guarantees. In conjunction with the FASB’s fair value measurement guidance, the Company made an accounting policy election to measure the credit risk of its derivative financial instruments that are subject to master netting agreements on a net basis by counterparty portfolio. Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by the Company and its counterparties. However, as of March 31, 2017 , the Company had assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and determined that the credit valuation adjustments were not significant to the overall valuation of its derivatives. As a result, the Company determined that its derivative valuations in their entirety were classified in Level 2 of the fair value hierarchy. The table below presents the Company’s assets and liabilities measured at fair value on a recurring basis as of March 31, 2017 , aggregated by the level in the fair value hierarchy within which those measurements fall. Fair Value Measurements at Reporting Date Using Description March 31, 2017 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Other assets - Cash Flow Hedge Swap Agreements $ 28,744 $ — $ 28,744 $ — Other liabilities - Cash Flow Hedge Swap Agreements $ (1,073 ) $ — $ (1,073 ) $ — The Company did not have any significant assets or liabilities that are re-measured on a recurring basis using significant unobservable inputs as of March 31, 2017 or December 31, 2016 . Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Long-lived assets held for use are evaluated for impairment when events or circumstances indicate there may be impairment. The Company reviews each store at least annually to determine if any such events or circumstances have occurred or exist. The Company focuses on stores where occupancy and/or rental income have decreased by a significant amount. For these stores, the Company determines whether the decrease is temporary or permanent, and whether the store will likely recover the lost occupancy and/or revenue in the short term. In addition, the Company carefully reviews stores in the lease-up stage and compares actual operating results to original projections. When the Company determines that an event that may indicate impairment has occurred, the Company compares the carrying value of the related long-lived assets to the undiscounted future net operating cash flows attributable to the assets. An impairment loss is recorded if the net carrying value of the assets exceeds the undiscounted future net operating cash flows attributable to the assets. The impairment loss recognized equals the excess of net carrying value over the related fair value of the assets. When real estate assets are identified by management as held for sale, the Company discontinues depreciating the assets and estimates the fair value of the assets, net of selling costs. If the estimated fair value, net of selling costs, of the assets that have been identified as held for sale is less than the net carrying value of the assets, the Company would recognize a loss on the assets held for sale. The operations of assets held for sale or sold during the period are presented as part of normal operations for all periods presented. As of March 31, 2017 , the Company had one parcel of undeveloped land and 36 operating stores classified as held for sale. The estimated fair value less selling costs of each of these assets is greater than the carrying value of the assets, and therefore no loss has been recorded. The Company assesses whether there are any indicators that the value of the Company’s investments in unconsolidated real estate ventures may be impaired annually and when events or circumstances indicate that there may be impairment. An investment is impaired if management’s estimate of the fair value of the investment is less than its carrying value. To the extent impairment has occurred, and is considered to be other than temporary, the loss is measured as the excess of the carrying amount of the investment over the fair value of the investment. In connection with the Company’s acquisition of stores, the purchase price is allocated to the tangible and intangible assets and liabilities acquired based on their relative fair values, which are estimated using significant unobservable inputs. The value of the tangible assets, consisting of land and buildings, is determined as if vacant. Intangible assets, which represent the value of existing tenant relationships, are recorded at their fair values based on the avoided cost to replace the current leases. The Company measures the value of tenant relationships 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 stores. Debt assumed as part of an acquisition is recorded at fair value based on current interest rates compared to contractual rates. Acquisition-related transaction costs, for those qualifying as asset acquisitions, are capitalized as a component of the cost of the assets acquired. Fair Value of Financial Instruments The carrying values of cash and cash equivalents, restricted cash, receivables, other financial instruments included in other assets, accounts payable and accrued expenses, variable-rate notes payable, lines of credit and other liabilities reflected in the condensed consolidated balance sheets at March 31, 2017 and December 31, 2016 approximate fair value. The fair values of the Company’s notes receivable from Preferred Operating Partnership unit holders and other fixed rate notes receivable were based on the discounted estimated future cash flows of the notes (categorized within Level 3 of the fair value hierarchy); the discount rate used approximated the current market rate for loans with similar maturities and credit quality. The fair values of the Company’s fixed-rate notes payable and notes payable to trusts were estimated using the discounted estimated future cash payments to be made on such debt (categorized within Level 3 of the fair value hierarchy); the discount rates used approximated current market rates for loans, or groups of loans, with similar maturities and credit quality. The fair value of the Company’s exchangeable senior notes was estimated using an average market price for similar securities obtained from a third party. The fair values of the Company’s fixed-rate assets and liabilities were as follows for the periods indicated: March 31, 2017 December 31, 2016 Fair Carrying Fair Carrying Notes receivable from Preferred Operating Partnership unit holders $ 124,837 $ 120,230 $ 125,642 $ 120,230 Fixed rate notes receivable $ 21,649 $ 20,608 $ 53,450 $ 52,201 Fixed rate notes payable and notes payable to trusts $ 2,329,582 $ 2,360,128 $ 2,404,996 $ 2,417,558 Exchangeable senior notes $ 691,554 $ 638,170 $ 706,827 $ 638,170

Earnings Per Common Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Common Share	EARNINGS PER COMMON SHARE Basic earnings per common share is computed using the two-class method by dividing net income attributable to common stockholders by the weighted average number of common shares outstanding during the period. All outstanding unvested restricted stock awards contain rights to non-forfeitable dividends and participate in undistributed earnings with common stockholders; accordingly, they are considered participating securities that are included in the two-class method. Diluted earnings per common share measures the performance of the Company over the reporting period while giving effect to all potential common shares that were dilutive and outstanding during the period. The denominator includes the weighted average number of basic shares and the number of additional common shares that would have been outstanding if the potential common shares that were dilutive had been issued, and is calculated using either the two-class, treasury stock or as if-converted method, whichever is most dilutive. Potential common shares are securities (such as options, convertible debt, Series A Participating Redeemable Preferred Units (“Series A Units”), Series B Redeemable Preferred Units (“Series B Units”), Series C Convertible Redeemable Preferred Units (“Series C Units”), Series D Redeemable Preferred Units (“Series D Units”) and common Operating Partnership units (“OP Units”)) that do not have a current right to participate in earnings of the Company but could do so in the future by virtue of their option, redemption or conversion right. In computing the dilutive effect of convertible securities, net income is adjusted to add back any changes in earnings in the period associated with the convertible security. The numerator also is adjusted for the effects of any other non-discretionary changes in income or loss that would result from the assumed conversion of those potential common shares. In computing diluted earnings per common share, only potential common shares that are dilutive (those that reduce earnings per common share) are included. For the three months ended March 31, 2017 and 2016 , options to purchase approximately 103,854 and 67,812 shares of common stock, respectively, were excluded from the computation of earnings per share as their effect would have been anti-dilutive. For the purposes of computing the diluted impact of the potential exchange of the Preferred Operating Partnership units for common shares upon redemption, where the Company has the option to redeem in cash or shares and where the Company has stated the intent and ability to settle the redemption in shares, the Company divided the total value of the Preferred Operating Partnership units by the average share price for the period presented. The average share price for the three months ended March 31, 2017 and 2016 was $75.47 and $86.91 , respectively. The following table presents the number of Preferred Operating Partnership units, and the potential common shares, that were excluded from the computation of earnings per share as their effect would have been anti-dilutive. For the Three Months Ended March 31, 2017 2016 Equivalent Shares (if converted) Equivalent Shares (if converted) Series B Units 555,216 482,133 Series C Units 392,727 341,032 Series D Units 1,071,983 157,747 2,019,926 980,912 The Operating Partnership had $63,170 of its 2.375% Exchangeable Senior Notes due 2033 (the “2013 Notes”) issued and outstanding as of March 31, 2017 . The 2013 Notes could potentially have a dilutive impact on the Company’s earnings per share calculations. The 2013 Notes are exchangeable by holders into shares of the Company’s common stock under certain circumstances per the terms of the indenture governing the 2013 Notes. The exchange price of the 2013 Notes was $53.81 per share as of March 31, 2017 , and could change over time as described in the indenture. The Company has irrevocably agreed to pay only cash for the accreted principal amount of the 2013 Notes relative to its exchange obligations, but retained the right to satisfy the exchange obligation in excess of the accreted principal amount in cash and/or common stock. The Operating Partnership had $575,000 of its 3.125% Exchangeable Senior Notes due 2035 (the “2015 Notes”) issued and outstanding as of March 31, 2017 . The 2015 Notes could potentially have a dilutive impact on the Company’s earnings per share calculations. The 2015 Notes are exchangeable by holders into shares of the Company’s common stock under certain circumstances per the terms of the indenture governing the 2015 Notes. The exchange price of the 2015 Notes was $94.47 per share as of March 31, 2017 , and could change over time as described in the indenture. The Company has irrevocably agreed to pay only cash for the accreted principal amount of the 2015 Notes relative to its exchange obligations, but retained the right to satisfy the exchange obligation in excess of the accreted principal amount in cash and/or common stock. Although the Company has retained the right to satisfy the exchange obligation in excess of the accreted principal amount of the 2013 Notes and 2015 Notes in cash and/or common stock, Accounting Standards Codification (“ASC”) 260, “Earnings per Share,” requires an assumption that shares would be used to pay such exchange obligation, and requires that those shares be included in the Company’s calculation of weighted average common shares outstanding for the diluted earnings per share computation. For the three months ended March 31, 2017 and 2016 , 336,848 and 441,598 shares, respectively, related to the 2013 Notes were included in the computation for diluted earnings per share. For the three months ended March 31, 2017 and 2016 , no shares related to the 2015 Notes were included in the computation for diluted earnings per share as the exchange price exceeded the per share price of the Company’s common stock during these periods. For the purposes of computing the diluted impact on earnings per share of the potential exchange of Series A Units for common shares upon redemption, where the Company has the option to redeem in cash or shares and where the Company has stated the positive intent and ability to settle at least $115,000 of the instrument in cash (or net settle a portion of the Series A Units against the related outstanding note receivable), only the amount of the instrument in excess of $115,000 is considered in the calculation of shares contingently issuable for the purposes of computing diluted earnings per share as allowed by ASC 260-10-45-46. Accordingly, the number of shares included in the computation for diluted earnings per share related to the Series A Units is equal to the number of Series A Units outstanding, with no additional shares included related to the fixed $115,000 amount. The computation of earnings per common share was as follows for the periods presented: For the Three Months Ended March 31, 2017 2016 Net income attributable to common stockholders $ 82,282 $ 82,592 Earnings and dividends allocated to participating securities (197 ) (165 ) Earnings for basic computations 82,085 82,427 Income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units) and Operating Partnership 4,049 5,474 Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units) (1,271 ) (1,271 ) Net income for diluted computations $ 84,863 $ 86,630 Weighted average common shares outstanding: Average number of common shares outstanding - basic 125,605,403 124,754,174 OP Units 5,596,191 5,621,470 Series A Units 875,480 875,480 Shares related to exchangeable senior notes and dilutive stock options 541,570 704,970 Average number of common shares outstanding - diluted 132,618,644 131,956,094 Earnings per common share Basic $ 0.65 $ 0.66 Diluted $ 0.64 $ 0.66

Store Acquisitions

Store Acquisitions	3 Months Ended
	Mar. 31, 2017
Business Combinations [Abstract]
Store Acquisitions	STORE ACQUISITIONS The following table shows the Company’s acquisitions of operating stores for the three months ended March 31, 2017 . The table excludes purchases of raw land or improvements made to existing assets. Consideration Paid Total Property Location Number of Stores Date of Acquisition Cash Paid Net Liabilities/(Assets) Assumed Real estate assets Illinois 1 2/1/2017 $ 9,020 $ 8 $ 9,028 Georgia 1 1/6/2017 16,521 7 16,528 2017 Totals 2 $ 25,541 $ 15 $ 25,556

Variable Interests

Variable Interests	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interests	VARIABLE INTERESTS The Operating Partnership has three wholly-owned unconsolidated subsidiaries (“Trust,” “Trust II” and “Trust III,” together, the “Trusts”) that have issued trust preferred securities to third parties and common securities to the Operating Partnership. The proceeds from the sale of the preferred and common securities were loaned in the form of notes to the Operating Partnership. The Trusts are VIEs because the holders of the equity investment at risk (the trust preferred securities) do not have the power to direct the activities of the entities that most significantly affect the entities’ economic performance because of their lack of voting or similar rights. Because the Operating Partnership’s investment in the Trusts’ common securities was financed directly by the Trusts as a result of its loan of the proceeds to the Operating Partnership, that investment is not considered an equity investment at risk. The Operating Partnership’s investment in the Trusts is not a variable interest because equity interests are variable interests only to the extent that the investment is considered to be at risk, and therefore the Operating Partnership cannot be the primary beneficiary of the Trusts. Since the Company is not the primary beneficiary of the Trusts, they have not been consolidated. A debt obligation has been recorded in the form of notes for the proceeds as discussed above, which are owed to the Trusts. The Company has also included its investment in the Trusts’ common securities in other assets on the condensed consolidated balance sheets. The Company has not provided financing or other support during the periods presented to the Trusts that it was not previously contractually obligated to provide. The Company’s maximum exposure to loss as a result of its involvement with the Trusts is equal to the total amount of the notes discussed above less the amounts of the Company’s investments in the Trusts’ common securities. The net amount is equal to the notes payable that the Trusts owe to third parties for their investments in the Trusts’ preferred securities. Following is a tabular comparison of the assets and liabilities the Company has recorded as a result of its involvement with the Trusts to the maximum exposure to loss the Company is subject to as a result of such involvement as of March 31, 2017 : Notes payable Investment Maximum Difference Trust $ 36,083 $ 1,083 $ 35,000 $ — Trust II 42,269 1,269 41,000 — Trust III 41,238 1,238 40,000 — 119,590 $ 3,590 $ 116,000 — Unamortized debt issuance costs (2,238 ) $ 117,352 The Company had no consolidated VIEs during the three months ended March 31, 2017 .

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	DERIVATIVES The Company is exposed to certain risks arising from both its business operations and economic conditions. The Company principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company manages economic risks, including interest rate, liquidity and credit risk, primarily by managing the amount, sources and duration of its debt funding and by using derivative financial instruments. Specifically, the Company enters into derivative financial instruments to manage exposure that arises from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. The Company’s derivative financial instruments are used to manage differences in the amount, timing and duration of the Company’s known or expected cash receipts and its known or expected cash payments principally related to the Company’s investments and borrowings. Cash Flow Hedges of Interest Rate Risk The Company’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish these objectives, the Company primarily uses interest rate swaps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in accumulated other comprehensive income (“OCI”) and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. A portion of these changes is excluded from accumulated other comprehensive income as it is allocated to noncontrolling interests. During the three months ended March 31, 2017 and 2016 , such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt. In the coming 12 months, the Company estimates that an additional $4,209 will be reclassified as an increase to interest expense. The Company held 28 derivative financial instruments which had a total combined notional amount of $2,052,010 as of March 31, 2017 . Fair Values of Derivative Instruments The table below presents the fair value of the Company’s derivative financial instruments as well as their classification on the condensed consolidated balance sheets: Asset (Liability) Derivatives March 31, 2017 December 31, 2016 Derivatives designated as hedging instruments: Fair Value Other assets $ 28,744 $ 23,844 Other liabilities $ (1,073 ) $ (2,447 ) Effect of Derivative Instruments The tables below present the effect of the Company’s derivative financial instruments on the condensed consolidated statements of operations for the periods presented. No tax effect has been presented as the derivative instruments are held by the Company: Gain (loss) recognized in OCI Location of amounts reclassified from OCI into income Gain (loss) reclassified from OCI Type 2017 2016 2017 2016 Swap Agreements $ 3,006 $ (34,960 ) Interest expense $ (3,330 ) $ (4,454 ) Credit-risk-related Contingent Features The Company has agreements with some of its derivative counterparties that 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 Company also has an agreement with some of its derivative counterparties that incorporates the loan covenant provisions of the Company’s indebtedness with a lender affiliate of the derivative counterparty. Failure to comply with the loan covenant provisions would result in the Company being in default on any derivative instrument obligations covered by the agreement. As of March 31, 2017 , the fair value of derivatives in a net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, related to these agreements was $1,361 . As of March 31, 2017 , the Company had not posted any collateral related to these agreements. If the Company had breached any of these provisions as of March 31, 2017 , it could have been required to settle its obligations under the agreements at their termination value of $1,361 , including accrued interest.

Exchangeable Senior Notes

Exchangeable Senior Notes	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Exchangeable Senior Notes	EXCHANGEABLE SENIOR NOTES In September 2015, the Operating Partnership issued $575,000 of its 3.125% Exchangeable Senior Notes due 2035. Costs incurred to issue the 2015 Notes were approximately $11,992 , consisting primarily of a 2.0% underwriting fee. These costs are being amortized as an adjustment to interest expense over five years , which represents the estimated term based on the first available redemption date, and are included in exchangeable senior notes, net, in the condensed consolidated balance sheets. The 2015 Notes are general unsecured senior obligations of the Operating Partnership and are fully guaranteed by the Company. Interest is payable on April 1 and October 1 of each year beginning April 1, 2016, until the maturity date of October 1, 2035. The 2015 Notes bear interest at 3.125% per annum and contain an exchange settlement feature, which provides that the 2015 Notes may, under certain circumstances, be exchangeable for cash (for the principal amount of the 2015 Notes) and, with respect to any excess exchange value, for cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock, at the Company’s option. The exchange rate of the 2015 Notes as of March 31, 2017 was approximately 10.58 shares of the Company’s common stock per $1,000 principal amount of the 2015 Notes. The Operating Partnership may redeem the 2015 Notes at any time to preserve the Company’s status as a REIT. In addition, on or after October 5, 2020, the Operating Partnership may redeem the 2015 Notes for cash, in whole or in part, at 100% of the principal amount plus accrued and unpaid interest, upon at least 30 days but not more than 60 days prior written notice to the holders of the 2015 Notes. The holders of the 2015 Notes have the right to require the Operating Partnership to repurchase the 2015 Notes for cash, in whole or in part, on October 1 of the years 2020, 2025 and 2030 (unless the Operating Partnership has called the 2015 Notes for redemption), and upon the occurrence of certain designated events, in each case for a repurchase price equal to 100% of the principal amount of the 2015 Notes plus accrued and unpaid interest. Certain events are considered “Events of Default,” as defined in the indenture governing the 2015 Notes, which may result in the accelerated maturity of the 2015 Notes. On June 21, 2013, the Operating Partnership issued $250,000 of its 2.375% Exchangeable Senior Notes due 2033 at a 1.5% discount, or $3,750 . Costs incurred to issue the 2013 Notes were approximately $1,672 . These costs are being amortized as an adjustment to interest expense over five years , which represents the estimated term based on the first available redemption date, and are included in exchangeable senior notes, net, in the condensed consolidated balance sheets. The 2013 Notes are general unsecured senior obligations of the Operating Partnership and are fully guaranteed by the Company. Interest is payable on January 1 and July 1 of each year beginning January 1, 2014, until the maturity date of July 1, 2033. The 2013 Notes bear interest at 2.375% per annum and contain an exchange settlement feature, which provides that the 2013 Notes may, under certain circumstances, be exchangeable for cash (for the principal amount of the 2013 Notes) and, with respect to any excess exchange value, for cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock, at the Company’s option. The exchange rate of the 2013 Notes as of March 31, 2017 was approximately 18.58 shares of the Company’s common stock per $1,000 principal amount of the 2013 Notes. The Operating Partnership may redeem the 2013 Notes at any time to preserve the Company’s status as a REIT. In addition, on or after July 5, 2018, the Operating Partnership may redeem the 2013 Notes for cash, in whole or in part, at 100% of the principal amount plus accrued and unpaid interest, upon at least 30 days but not more than 60 days prior written notice to the holders of the 2013 Notes. The holders of the 2013 Notes have the right to require the Operating Partnership to repurchase the 2013 Notes for cash, in whole or in part, on July 1 of the years 2018, 2023 and 2028, and upon the occurrence of certain designated events, in each case for a repurchase price equal to 100% of the principal amount of the 2013 Notes plus accrued and unpaid interest. Certain events are considered “Events of Default,” as defined in the indenture governing the 2013 Notes, which may result in the accelerated maturity of the 2013 Notes. Additionally, the 2013 Notes and the 2015 Notes can be exchanged during any calendar quarter, if the last reported sale price of the common stock of the Company is greater than or equal to 130% of the exchange price for at least 20 trading days during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter. The price of the Company’s common stock exceeded 130% of the exchange price for the required time period for the 2013 Notes during the quarter ended March 31, 2017 . Therefore, holders of the 2013 Notes may elect to exchange such notes during the quarter ending June 30, 2017. The price of the Company’s common stock did not exceed 130% of the exchange price for the required time period for the 2015 Notes during the quarter ended March 31, 2017 . GAAP requires entities with convertible debt instruments that may be settled entirely or partially in cash upon conversion to separately account for the liability and equity components of the instrument in a manner that reflects the issuer’s economic interest cost. The Company therefore accounts for the liability and equity components of the 2013 Notes and 2015 Notes separately. The equity components are included in paid-in capital in stockholders’ equity in the condensed consolidated balance sheets, and the value of the equity components are treated as original issue discount for purposes of accounting for the debt components. The discounts are being amortized as interest expense over the remaining period of the debt through its first redemption date: July 1, 2018 for the 2013 Notes, and October 1, 2020 for the 2015 Notes. The effective interest rate on the liability components of both the 2013 Notes and the 2015 Notes is 4.0% , which approximated the market rate of interest of similar debt without exchange features (i.e. nonconvertible debt) at the time of issuance. Information about the Company’s 2013 Notes and 2015 Notes, including the total carrying amounts of the equity components, the principal amounts of the liability components, the unamortized discounts and the net carrying amounts was as follows for the periods indicated: March 31, 2017 December 31, 2016 Carrying amount of equity component - 2013 Notes $ — $ — Carrying amount of equity component - 2015 Notes 22,597 22,597 Carrying amount of equity components $ 22,597 $ 22,597 Principal amount of liability component - 2013 Notes $ 63,170 $ 63,170 Principal amount of liability component - 2015 Notes 575,000 575,000 Unamortized discount - equity component - 2013 Notes (992 ) (1,187 ) Unamortized discount - equity component - 2015 Notes (16,281 ) (17,355 ) Unamortized cash discount - 2013 Notes (234 ) (281 ) Unamortized debt issuance costs (8,430 ) (9,033 ) Net carrying amount of liability components $ 612,233 $ 610,314 The amount of interest cost recognized relating to the contractual interest rates and the amortization of the discounts on the liability components of the Notes were as follows for the periods indicated: For the Three Months Ended March 31, 2017 2016 Contractual interest $ 4,867 $ 4,882 Amortization of discount 1,269 1,233 Total interest expense recognized $ 6,136 $ 6,115 Repurchases of 2013 Notes During February 2016, the Company repurchased a total principal amount of $19,639 of the 2013 Notes. The Company paid cash for the principal amount, and issued a total of 130,909 shares of common stock valued at $11,380 for the exchange value in excess of the principal amount. The Company allocated the value of the consideration paid to repurchase the 2013 Notes (1) to the extinguishment of the liability component and (2) to the reacquisition of the equity component. The amount allocated to the extinguishment of the liability component is equal to the fair value of that component immediately prior to extinguishment. The difference between the consideration attributed to the extinguishment of the liability component and the sum of (a) the net carrying amount of the repurchased liability component, and (b) the related unamortized debt issuance costs, is recognized as a gain on debt extinguishment. The remaining settlement consideration is allocated to the reacquisition of the equity component of the repurchased 2013 Notes and recognized as a reduction of stockholders’ equity. Information about the repurchases is as follows: February 2016 Principal amount repurchased $ 19,639 Amount allocated to: Extinguishment of liability component $ 18,887 Reacquisition of equity component 12,132 Total consideration paid for repurchase $ 31,019 Exchangeable senior notes repurchased $ 19,639 Extinguishment of liability component (18,887 ) Discount on exchangeable senior notes (716 ) Related debt issuance costs (36 ) Gain/(loss) on repurchase $ —

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2017
Stockholders' Equity Note [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY On May 6, 2016, the Company filed its current $400,000 "at the market" equity program with the Securities and Exchange Commission using a new shelf registration statement on Form S-3, and entered into separate equity distribution agreements with five sales agents. Under the terms of the current equity distribution agreements, the Company may from time to time offer and sell shares of common stock, up to the aggregate offering price of $400,000 , through its sales agents. During the quarter ended March 31, 2017 , the Company did not issue any shares and had $349,375 available for issuance under the existing equity distribution agreements.

Noncontrolling Interest Represe

Noncontrolling Interest Represented by Preferred Operating Partnership Units	3 Months Ended
	Mar. 31, 2017
Preferred Operating Partnership Units [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest Represented by Preferred Operating Partnership Units	NONCONTROLLING INTEREST REPRESENTED BY PREFERRED OPERATING PARTNERSHIP UNITS Classification of Noncontrolling Interests GAAP requires a company to present ownership interests in subsidiaries held by parties other than the company in the consolidated financial statements within the equity section, but separate from the company’s equity. It also requires the amount of consolidated net income attributable to the parent and to the noncontrolling interest to be clearly identified and presented on the face of the consolidated statement of operations and requires changes in ownership interest to be accounted for similarly as equity transactions. If noncontrolling interests are determined to be redeemable, they are to be carried at their redemption value as of the balance sheet date and reported as temporary equity. The Company has evaluated the terms of the Operating Partnership’s preferred units and classifies the noncontrolling interest represented by such preferred units as stockholders’ equity in the accompanying condensed consolidated balance sheets. The Company will periodically evaluate individual noncontrolling interests for the ability to continue to recognize the noncontrolling interest as permanent equity in the condensed consolidated balance sheets. Any noncontrolling interests that fail to qualify as permanent equity will be reclassified as temporary equity and adjusted to the greater of (1) the carrying amount and (2) the redemption value as of the end of the period in which the determination is made. Series A Participating Redeemable Preferred Units On June 15, 2007, the Operating Partnership entered into a Contribution Agreement with various limited partnerships affiliated with AAAAA Rent-A-Space to acquire ten stores in exchange for 989,980 Series A Units of the Operating Partnership. The stores are located in California and Hawaii. The partnership agreement of the Operating Partnership (as amended, the “Partnership Agreement”) provides for the designation and issuance of the Series A Units. The Series A Units will have priority over all other partnership interests of the Operating Partnership with respect to distributions and liquidation. Under the Partnership Agreement, Series A Units in the amount of $115,000 bear a fixed priority return of 5.0% and have a fixed liquidation value of $115,000 . The remaining balance participates in distributions with, and has a liquidation value equal to, that of the OP Units. The Series A Units are redeemable at the option of the holder, which redemption obligation may be satisfied, at the Company’s option, in cash or shares of its common stock. On June 25, 2007, the Operating Partnership loaned the holders of the Series A Units $100,000 . The note receivable bears interest at 4.85% . During 2013, a loan amendment was signed extending the maturity date to September 1, 2020. The loan is secured by the borrower’s Series A Units. The holders of the Series A Units could redeem up to 114,500 Series A Units prior to the maturity date of the loan. If any redemption in excess of 114,500 Series A Units occurs prior to the maturity date, the holder of the Series A Units is required to repay the loan as of the date of that redemption. On October 3, 2014, the holders of the Series A Units redeemed 114,500 Series A Units for $4,794 in cash and 280,331 shares of common stock. No additional redemption of Series A Units can be made without repayment of the loan. The Series A Units are shown on the balance sheet net of the $100,000 loan because the borrower under the loan receivable is also the holder of the Series A Units. Series B Redeemable Preferred Units On April 3, 2014, the Operating Partnership completed the purchase of a store located in Georgia. This store was acquired in exchange for $15,158 of cash and 333,360 Series B Units valued at $8,334 . On August 29, 2013, the Operating Partnership completed the purchase of 19 out of 20 stores affiliated with All Aboard Mini Storage, all of which are located in California. On September 26, 2013, the Operating Partnership completed the purchase of the remaining store. These stores were acquired in exchange for $100,876 of cash (including $98,960 of debt assumed and immediately defeased at closing), 1,342,727 Series B Units valued at $33,568 , and 1,448,108 OP Units valued at $62,341 . The Partnership Agreement provides for the designation and issuance of the Series B Units. The Series B Units rank junior to the Series A Units, on parity with the Series C Units and Series D Units, and senior to all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The outstanding Series B Units have a liquidation value of $25.00 per unit for a fixed liquidation value of $41,902 . Holders of the Series B Units receive distributions at an annual rate of 6.0% . These distributions are cumulative. The Series B Units became redeemable at the option of the holder on the first anniversary of the date of issuance, which redemption obligation may be satisfied at the Company’s option in cash or shares of its common stock. Series C Convertible Redeemable Preferred Units The Company completed the purchase of twelve stores in California between December 2013 and May 2014. The Company previously held 35% interests in five of these stores and a 40% interest in one store through six separate joint ventures. These stores were acquired in exchange for a total of approximately $45,722 of cash, the assumption of $37,532 in existing debt, and the issuance of 704,016 Series C Units valued at $30,960 . The Partnership Agreement provides for the designation and issuance of the Series C Units. The Series C Units rank junior to the Series A Units, on parity with the Series B Units and Series D Units, and senior to all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The outstanding Series C Units have a liquidation value of $42.10 per unit for a fixed liquidation value of $29,639 . From issuance to the fifth anniversary of issuance, each Series C Unit holder will receive quarterly distributions equal to the quarterly distribution per OP Unit plus $0.18 . Beginning on the fifth anniversary of issuance, each Series C Unit holder will receive a fixed quarterly distribution equal to the aggregate quarterly distribution payable in respect of such Series C Unit during the four quarters immediately preceding the fifth anniversary of issuance, divided by four. These distributions are cumulative. The Series C Units became redeemable at the option of the holder one year from the date of issuance, which redemption obligation may be satisfied at the Company’s option in cash or shares of its common stock. The Series C Units are convertible into OP Units at the option of the holder at a rate of 0.9145 OP Units per Series C Unit converted. This conversion option expires upon the fifth anniversary of the date of issuance. In December 2014, the Operating Partnership loaned certain holders of the Series C Units $20,230 . The notes receivable, which are collateralized by the Series C Units, bear interest at 5.0% per annum and mature on December 15, 2024 . The Series C Units are shown on the balance sheet net of the $20,230 loan because the borrower under the loan receivable is also the holder of the Series C Units. Series D Redeemable Preferred Units On November 8, 2016, the Operating Partnership completed the acquisition of a store located in Illinois. This store was acquired in exchange for 486,244 Series D-4 Preferred Units ("D-4 Units") valued at $12,156 . On June 10, 2016, the Operating Partnership completed the acquisition of four stores located in Illinois. These stores were acquired in exchange for 2,201,467 Series D-3 Preferred Units ("D-3 Units") valued at $ 55,037 . In December 2014, the Operating Partnership completed the acquisition of a store located in Florida. This store was acquired in exchange for $5,621 in cash and 548,390 Series D-1 Preferred Units ("D-1 Units," and together with the D-3 Units and D-4 Units, "Series D Units") valued at $13,710 . The Partnership Agreement provides for the designation and issuance of the Series D Units. The Series D Units rank junior to the Series A Units, on parity with the Series B Units and Series C Units, and senior to all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series D Units have a liquidation value of $25.00 per unit, for a fixed liquidation value of $80,903 . Holders of the Series D Units receive distributions at an annual rate between 3.5% to 5.0% . These distributions are cumulative. The Series D Units become redeemable at the option of the holder on the first anniversary of the date of issuance, which redemption obligation may be satisfied at the Company’s option in cash or shares of its common stock. In addition, the D-3 Units are convertible into OP Units at the option of the holder until the tenth anniversary of the date of issuance, with the number of OP Units to be issued equal to $25.00 per D-3 Unit, divided by the value of a share of common stock as of the exchange date.

Noncontrolling Interest in Oper

Noncontrolling Interest in Operating Partnership	3 Months Ended
	Mar. 31, 2017
Common Operating Partnership [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest in Operating Partnership	NONCONTROLLING INTEREST IN OPERATING PARTNERSHIP The Company’s interest in its stores is held through the Operating Partnership. ESS Holding Business Trust I, a wholly-owned subsidiary of the Company, is the sole general partner of the Operating Partnership. ESS Holding Business Trust II, also a wholly-owned subsidiary of the Company, is a limited partner of the Operating Partnership. Between its general partner and limited partner interests, the Company held a 91.2% ownership interest in the Operating Partnership as of March 31, 2017 . The remaining ownership interests in the Operating Partnership (including Preferred Operating Partnership units) of 8.8% are held by certain former owners of assets acquired by the Operating Partnership. The noncontrolling interest in the Operating Partnership represents OP Units that are not owned by the Company. In conjunction with the formation of the Company, and as a result of subsequent acquisitions, certain persons and entities contributing interests in stores to the Operating Partnership received limited partnership interests in the form of OP Units. Limited partners who received OP Units in the formation transactions or in exchange for contributions for interests in stores have the right to require the Operating Partnership to redeem part or all of their OP Units for cash based upon the fair market value of an equivalent number of shares of the Company’s common stock (based on the ten -day average trading price) at the time of the redemption. Alternatively, the Company may, in its sole discretion, elect to acquire those OP Units in exchange for shares of its common stock on a one-for-one basis , subject to anti-dilution adjustments provided in the Partnership Agreement. The ten-day average closing stock price at March 31, 2017 was $74.84 and there were 5,584,242 OP Units outstanding. Assuming that all of the OP Unit holders exercised their right to redeem all of their OP Units on March 31, 2017 and the Company elected to pay the OP Unit holders cash, the Company would have paid $417,925 in cash consideration to redeem the units. During the quarter, 23,796 OP Units were redeemed for $1,754 in cash. GAAP requires a company to present ownership interests in subsidiaries held by parties other than the company in the consolidated financial statements within the equity section, but separate from the company’s equity. It also requires the amount of consolidated net income attributable to the parent and to the noncontrolling interest to be clearly identified and presented on the face of the consolidated statement of operations, and requires changes in ownership interest to be accounted for similarly as equity transactions. If noncontrolling interests are determined to be redeemable, they are to be carried at their redemption value as of the balance sheet date and reported as temporary equity. The Company has evaluated the terms of the OP Units and classifies the noncontrolling interest represented by the OP Units as stockholders’ equity in the accompanying condensed consolidated balance sheets. The Company will periodically evaluate individual noncontrolling interests for the ability to continue to recognize the noncontrolling amount as permanent equity in the condensed consolidated balance sheets. Any noncontrolling interests that fail to qualify as permanent equity will be reclassified as temporary equity and adjusted to the greater of (1) the carrying amount and (2) the redemption value as of the end of the period in which the determination is made.

Other Noncontrolling Interests

Other Noncontrolling Interests	3 Months Ended
	Mar. 31, 2017
Other Noncontrolling Interests [Member]
Noncontrolling Interest [Line Items]
Other Noncontrolling Interests	OTHER NONCONTROLLING INTERESTS Other noncontrolling interests represent the ownership interests of a third party in one consolidated joint venture as of March 31, 2017 . This joint venture owns an operating store in Texas. The voting interests of the third-party owner are 20.0% .

Equity in Earnings of Unconsoli

Equity in Earnings of Unconsolidated Real Estate Ventures - Gain on Sale of Real Estate and Purchase of Joint Venture Partner's Interest	3 Months Ended
	Mar. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Equity in Earnings of Unconsolidated Real Estate Ventures - Gain on Sale of Real Estate and Purchase of Joint Venture Partner's Interest	EQUITY IN EARNINGS OF UNCONSOLIDATED REAL ESTATE VENTURES—GAIN ON SALE OF REAL ESTATE AND PURCHASE OF JOINT VENTURE PARTNER'S INTEREST On February 2, 2016, the Company acquired six stores from its VRS Self Storage LLC joint venture (“VRS”) in a step acquisition. These stores are located in Florida, Maryland, Nevada, New York, and Tennessee. The Company owns 45.04% of VRS, with the other 54.96% owned by affiliates of Prudential Global Investment Management ("Prudential"). VRS created a new subsidiary, Extra Space Properties 122 LLC (“ESP 122”) and transferred six stores into ESP 122. VRS then distributed ESP 122 to the Company and Prudential on a pro rata basis. This distribution was accounted for as a spinoff, and was therefore recorded at the net carrying amount of the stores of $17,261 . Immediately after the distribution, the Company acquired Prudential’s 54.96% interest in ESP 122 for $53,940 , resulting in 100% ownership of ESP 122 and the related six stores. Based on the purchase price of Prudential’s share of ESP 122, the Company determined that the fair value of its investment in ESP 122 immediately prior to the acquisition of Prudential’s share was $44,184 , and the Company recorded a gain of $26,923 during the three months ended March 31, 2016 as a result of remeasuring to fair value its existing equity interest in ESP 122. This gain is included in equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of joint venture partner's interest on the Company’s condensed consolidated statements of operations. The Company recorded fixed assets related to this acquisition of $98,082 , which includes total cash paid, the investment in ESP 122, and the step acquisition gain, less net assets acquired.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION The Company operates in three distinct segments: (1) rental operations; (2) tenant reinsurance; and (3) property management, acquisition and development. Management fees collected for wholly-owned stores are eliminated in consolidation. Financial information for the Company’s business segments is presented below: March 31, 2017 December 31, 2016 Balance Sheet Investment in unconsolidated real estate ventures Rental operations $ 79,385 $ 79,570 Total assets Rental operations $ 6,729,670 $ 6,731,292 Tenant reinsurance 33,611 44,524 Property management, acquisition and development 271,076 315,630 $ 7,034,357 $ 7,091,446 For the Three Months Ended March 31, 2017 2016 Statement of Operations Total revenues Rental operations $ 231,493 $ 199,488 Tenant reinsurance 22,855 20,555 Property management, acquisition and development 8,660 9,360 263,008 229,403 Operating expenses, including depreciation and amortization Rental operations 115,357 101,698 Tenant reinsurance 3,920 4,311 Property management, acquisition and development 19,528 29,766 138,805 135,775 Income (loss) from operations Rental operations 116,136 97,790 Tenant reinsurance 18,935 16,244 Property management, acquisition and development (10,868 ) (20,406 ) 124,203 93,628 Loss on earnout from prior acquisition Property management, acquisition and development — (1,544 ) Interest expense Rental operations (34,821 ) (30,565 ) Property management, acquisition and development (1,149 ) (794 ) (35,970 ) (31,359 ) Non-cash interest expense related to the amortization of discount on equity component of exchangeable senior notes Property management, acquisition and development (1,269 ) (1,233 ) Interest income Property management, acquisition and development 1,102 1,714 Interest income on note receivable from Preferred Operating Partnership unit holder Property management, acquisition and development 1,213 1,213 Equity in earnings of unconsolidated real estate ventures Rental operations 3,579 2,830 Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of joint venture partner's interest Property management, acquisition and development — 26,923 Income tax (expense) benefit Rental operations (463 ) (845 ) Tenant reinsurance (3,263 ) (2,663 ) Property management, acquisition and development 602 743 (3,124 ) (2,765 ) Net income (loss) Rental operations 84,431 69,210 Tenant reinsurance 15,672 13,581 Property management, acquisition and development (10,369 ) 6,616 $ 89,734 $ 89,407 For the Three Months Ended March 31, 2017 2016 Depreciation and amortization expense Rental operations $ 48,712 $ 40,586 Property management, acquisition and development 720 2,311 $ 49,432 $ 42,897 Statement of Cash Flows Acquisition of real estate assets Property management, acquisition and development $ (39,136 ) $ (234,820 ) Development and redevelopment of real estate assets Property management, acquisition and development $ (5,246 ) $ (6,543 )

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES As of March 31, 2017 , the Company is involved in various legal proceedings and is subject to various claims and complaints arising in the ordinary course of business. Because litigation is inherently unpredictable, the outcome of these matters cannot presently be determined with any degree of certainty. In accordance with applicable accounting guidance, management establishes an accrued liability for litigation when those matters present loss contingencies that are both probable and reasonably estimable. In such cases, there may be an exposure to loss in excess of any amounts accrued. The estimated loss, if any, is based upon currently available information and is subject to significant judgment, a variety of assumptions, and known and unknown uncertainties. Therefore, any estimate(s) of loss disclosed below represents what management believes to be an estimate of loss only for certain matters meeting these criteria and does not represent the Company’s maximum loss exposure. The Company could in the future incur judgments or enter into settlements of claims that could have a material adverse effect on its results of operations in any particular period, notwithstanding the fact that the Company is currently vigorously defending any legal proceedings against it. The Company currently has a legal proceeding pending against it that includes causes of action alleging wrongful foreclosure, violations of various state specific self-storage statutes, and violations of various consumer fraud acts. As a result of this litigation matter, the Company has a liability of $5,600 at March 31, 2017 , which is included in other liabilities on the condensed consolidated balance sheet. As of March 31, 2017 , the Company was under agreement to acquire two operating stores and 13 stores to be acquired upon the completion of construction. The total purchase price of all stores with commitments was $165,581 . Of these stores, six are scheduled to close in 2017. The remaining stores will close upon completion of construction, expected to occur on various dates in 2018 and 2019. Additionally, the Company is under agreement to acquire 23 stores with joint venture partners, for a total purchase price of $141,887 . Eleven of these stores are scheduled to close in 2017, while the remaining twelve stores are expected to close in 2018. Although there can be no assurance, the Company is not aware of any material environmental liability, for which it believes it will be ultimately responsible, that could have a material adverse effect on its financial condition or results of operations. However, changes in applicable environmental laws and regulations, the uses and conditions of properties in the vicinity of the Company’s stores, the activities of its tenants and other environmental conditions of which the Company is unaware with respect to its stores could result in future material environmental liabilities.

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Recently Issued Accounting Standards	Recently Issued Accounting Standards In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, “ Revenue from Contracts with Customers, ” which amends the guidance for revenue recognition to replace numerous, industry-specific requirements and converges areas under this topic with those of the International Financial Reporting Standards. ASU 2014-09 outlines a five-step process for customer contract revenue recognition that focuses on transfer of control, as opposed to transfer of risk and rewards. The amendment also requires enhanced disclosures regarding the nature, amount, timing and uncertainty of revenues and cash flows from contracts with customers. The new standard will become effective for annual and interim periods beginning after December 15, 2017 with early adoption permitted. The Company has determined that its property rental revenue and tenant reinsurance revenue will not be subject to the guidance in ASU 2014-09, as they qualify as lease contracts and insurance contracts, which are excluded from its scope. The Company's management fee revenue will be included in the scope of the standard. However, based on the Company's initial assessment, it appears that revenue recognized under the standard will not differ materially from revenue recognized under existing guidance. The Company continues to assess the potential impacts of ASU 2014-09. The Company anticipates adopting the standard using the modified retrospective transition method as of January 1, 2018. In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842),” which modifies the accounting for leases, intending to increase transparency and comparability of organizations by requiring balance sheet presentation of leased assets and increased financial statement disclosure of leasing arrangements. ASU 2016-02 will require entities to recognize a liability for their lease obligations and a corresponding asset representing the right to use the underlying asset over the lease term. Lease obligations are to be measured at their present value and accounted for using the effective interest method. The accounting for the leased asset will differ slightly depending on whether the agreement is deemed to be a financing or operating lease. For financing leases, the leased asset is depreciated on a straight-line basis and depreciation expense is recorded separately from the interest expense in the statements of operations, resulting in higher expense in the earlier part of the lease term. For operating leases, the depreciation and interest expense components are combined, recognized evenly over the term of the lease, and presented as a reduction to operating income. ASU 2016-02 requires that assets and liabilities be presented or disclosed separately, and requires additional disclosure of certain qualitative and quantitative information related to these lease agreements. ASU 2016-02 is effective for annual and interim periods beginning after December 15, 2018. The Company is currently assessing the impact of the adoption of ASU 2016-02 on the Company’s consolidated financial statements. In March 2016, the FASB issued ASU 2016-05, "Derivatives and Hedging (Topic 815): Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships." ASU 2016-05 clarifies that a change in the counterparty to a derivative instrument that has been designated as a hedging instrument does not, in and of itself, require re-designation of that hedging relationship provided that all other hedge accounting criteria continue to be met. The Company adopted this guidance on January 1, 2017. The adoption of ASU 2016-05 did not have a material impact on the Company's consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, “ Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting .” ASU 2016-09 simplifies several aspects of the accounting for employee share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. This ASU is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. The Company adopted this guidance prospectively on January 1, 2017, and prior periods have not been adjusted. As a result of the adoption of this guidance, the Company no longer presents the tax effects from vesting of restricted stock grants and stock option exercises on its condensed consolidated statement of noncontrolling interests and equity. In August 2016, the FASB issued ASU 2016-15, "Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments." ASU 2016-15 provides guidance on several specific cash flow issues, including the classification of debt prepayment or debt extinguishment costs, contingent consideration payments, and distributions received from equity method investees. This guidance is effective for fiscal years beginning after December 15, 2017. The Company is currently evaluating the new guidance to determine the impact it may have on its consolidated financial statements. In October 2016, the FASB issued ASU 2016-18, " Statement of Cash Flows (Topic 230)," which requires that a statement of cash flows explains the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. This guidance is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the new guidance to determine the impact it may have on its consolidated financial statements.
Fair Value Disclosures	Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Long-lived assets held for use are evaluated for impairment when events or circumstances indicate there may be impairment. The Company reviews each store at least annually to determine if any such events or circumstances have occurred or exist. The Company focuses on stores where occupancy and/or rental income have decreased by a significant amount. For these stores, the Company determines whether the decrease is temporary or permanent, and whether the store will likely recover the lost occupancy and/or revenue in the short term. In addition, the Company carefully reviews stores in the lease-up stage and compares actual operating results to original projections. When the Company determines that an event that may indicate impairment has occurred, the Company compares the carrying value of the related long-lived assets to the undiscounted future net operating cash flows attributable to the assets. An impairment loss is recorded if the net carrying value of the assets exceeds the undiscounted future net operating cash flows attributable to the assets. The impairment loss recognized equals the excess of net carrying value over the related fair value of the assets. When real estate assets are identified by management as held for sale, the Company discontinues depreciating the assets and estimates the fair value of the assets, net of selling costs. If the estimated fair value, net of selling costs, of the assets that have been identified as held for sale is less than the net carrying value of the assets, the Company would recognize a loss on the assets held for sale. The operations of assets held for sale or sold during the period are presented as part of normal operations for all periods presented. As of March 31, 2017 , the Company had one parcel of undeveloped land and 36 operating stores classified as held for sale. The estimated fair value less selling costs of each of these assets is greater than the carrying value of the assets, and therefore no loss has been recorded. The Company assesses whether there are any indicators that the value of the Company’s investments in unconsolidated real estate ventures may be impaired annually and when events or circumstances indicate that there may be impairment. An investment is impaired if management’s estimate of the fair value of the investment is less than its carrying value. To the extent impairment has occurred, and is considered to be other than temporary, the loss is measured as the excess of the carrying amount of the investment over the fair value of the investment. In connection with the Company’s acquisition of stores, the purchase price is allocated to the tangible and intangible assets and liabilities acquired based on their relative fair values, which are estimated using significant unobservable inputs. The value of the tangible assets, consisting of land and buildings, is determined as if vacant. Intangible assets, which represent the value of existing tenant relationships, are recorded at their fair values based on the avoided cost to replace the current leases. The Company measures the value of tenant relationships 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 stores. Debt assumed as part of an acquisition is recorded at fair value based on current interest rates compared to contractual rates. Acquisition-related transaction costs, for those qualifying as asset acquisitions, are capitalized as a component of the cost of the assets acquired. Fair Value of Financial Instruments The carrying values of cash and cash equivalents, restricted cash, receivables, other financial instruments included in other assets, accounts payable and accrued expenses, variable-rate notes payable, lines of credit and other liabilities reflected in the condensed consolidated balance sheets at March 31, 2017 and December 31, 2016 approximate fair value. The fair values of the Company’s notes receivable from Preferred Operating Partnership unit holders and other fixed rate notes receivable were based on the discounted estimated future cash flows of the notes (categorized within Level 3 of the fair value hierarchy); the discount rate used approximated the current market rate for loans with similar maturities and credit quality. The fair values of the Company’s fixed-rate notes payable and notes payable to trusts were estimated using the discounted estimated future cash payments to be made on such debt (categorized within Level 3 of the fair value hierarchy); the discount rates used approximated current market rates for loans, or groups of loans, with similar maturities and credit quality. The fair value of the Company’s exchangeable senior notes was estimated using an average market price for similar securities obtained from a third party. Derivative Financial Instruments Currently, the Company uses interest rate swaps to manage its interest rate risk. The valuation of these instruments is determined using widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves. The fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash payments and the discounted expected variable cash receipts. The variable cash receipts are based on an expectation of future interest rates (forward curves) derived from observable market interest rate forward curves. The Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts and guarantees. In conjunction with the FASB’s fair value measurement guidance, the Company made an accounting policy election to measure the credit risk of its derivative financial instruments that are subject to master netting agreements on a net basis by counterparty portfolio. Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by the Company and its counterparties. However, as of March 31, 2017 , the Company had assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and determined that the credit valuation adjustments were not significant to the overall valuation of its derivatives. As a result, the Company determined that its derivative valuations in their entirety were classified in Level 2 of the fair value hierarchy.
Earnings Per Common Share	EARNINGS PER COMMON SHARE Basic earnings per common share is computed using the two-class method by dividing net income attributable to common stockholders by the weighted average number of common shares outstanding during the period. All outstanding unvested restricted stock awards contain rights to non-forfeitable dividends and participate in undistributed earnings with common stockholders; accordingly, they are considered participating securities that are included in the two-class method. Diluted earnings per common share measures the performance of the Company over the reporting period while giving effect to all potential common shares that were dilutive and outstanding during the period. The denominator includes the weighted average number of basic shares and the number of additional common shares that would have been outstanding if the potential common shares that were dilutive had been issued, and is calculated using either the two-class, treasury stock or as if-converted method, whichever is most dilutive. Potential common shares are securities (such as options, convertible debt, Series A Participating Redeemable Preferred Units (“Series A Units”), Series B Redeemable Preferred Units (“Series B Units”), Series C Convertible Redeemable Preferred Units (“Series C Units”), Series D Redeemable Preferred Units (“Series D Units”) and common Operating Partnership units (“OP Units”)) that do not have a current right to participate in earnings of the Company but could do so in the future by virtue of their option, redemption or conversion right. In computing the dilutive effect of convertible securities, net income is adjusted to add back any changes in earnings in the period associated with the convertible security. The numerator also is adjusted for the effects of any other non-discretionary changes in income or loss that would result from the assumed conversion of those potential common shares. In computing diluted earnings per common share, only potential common shares that are dilutive (those that reduce earnings per common share) are included.
Derivatives	The Company is exposed to certain risks arising from both its business operations and economic conditions. The Company principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company manages economic risks, including interest rate, liquidity and credit risk, primarily by managing the amount, sources and duration of its debt funding and by using derivative financial instruments. Specifically, the Company enters into derivative financial instruments to manage exposure that arises from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. The Company’s derivative financial instruments are used to manage differences in the amount, timing and duration of the Company’s known or expected cash receipts and its known or expected cash payments principally related to the Company’s investments and borrowings.
Convertible Debt	GAAP requires entities with convertible debt instruments that may be settled entirely or partially in cash upon conversion to separately account for the liability and equity components of the instrument in a manner that reflects the issuer’s economic interest cost. The Company therefore accounts for the liability and equity components of the 2013 Notes and 2015 Notes separately. The equity components are included in paid-in capital in stockholders’ equity in the condensed consolidated balance sheets, and the value of the equity components are treated as original issue discount for purposes of accounting for the debt components. The discounts are being amortized as interest expense over the remaining period of the debt through its first redemption date: July 1, 2018 for the 2013 Notes, and October 1, 2020 for the 2015 Notes. The effective interest rate on the liability components of both the 2013 Notes and the 2015 Notes is 4.0% , which approximated the market rate of interest of similar debt without exchange features (i.e. nonconvertible debt) at the time of issuance.

Fair Value Disclosures (Tables)

Fair Value Disclosures (Tables)	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	The table below presents the Company’s assets and liabilities measured at fair value on a recurring basis as of March 31, 2017 , aggregated by the level in the fair value hierarchy within which those measurements fall. Fair Value Measurements at Reporting Date Using Description March 31, 2017 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Other assets - Cash Flow Hedge Swap Agreements $ 28,744 $ — $ 28,744 $ — Other liabilities - Cash Flow Hedge Swap Agreements $ (1,073 ) $ — $ (1,073 ) $ —
Schedule of Fair Value of Financial Instruments	The fair values of the Company’s fixed-rate assets and liabilities were as follows for the periods indicated: March 31, 2017 December 31, 2016 Fair Carrying Fair Carrying Notes receivable from Preferred Operating Partnership unit holders $ 124,837 $ 120,230 $ 125,642 $ 120,230 Fixed rate notes receivable $ 21,649 $ 20,608 $ 53,450 $ 52,201 Fixed rate notes payable and notes payable to trusts $ 2,329,582 $ 2,360,128 $ 2,404,996 $ 2,417,558 Exchangeable senior notes $ 691,554 $ 638,170 $ 706,827 $ 638,170

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Schedule of Antidilutive Shares Excluded from Computation of Earnings Per Share	The following table presents the number of Preferred Operating Partnership units, and the potential common shares, that were excluded from the computation of earnings per share as their effect would have been anti-dilutive. For the Three Months Ended March 31, 2017 2016 Equivalent Shares (if converted) Equivalent Shares (if converted) Series B Units 555,216 482,133 Series C Units 392,727 341,032 Series D Units 1,071,983 157,747 2,019,926 980,912
Schedule of Computation of Earnings Per Common Share	The computation of earnings per common share was as follows for the periods presented: For the Three Months Ended March 31, 2017 2016 Net income attributable to common stockholders $ 82,282 $ 82,592 Earnings and dividends allocated to participating securities (197 ) (165 ) Earnings for basic computations 82,085 82,427 Income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units) and Operating Partnership 4,049 5,474 Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units) (1,271 ) (1,271 ) Net income for diluted computations $ 84,863 $ 86,630 Weighted average common shares outstanding: Average number of common shares outstanding - basic 125,605,403 124,754,174 OP Units 5,596,191 5,621,470 Series A Units 875,480 875,480 Shares related to exchangeable senior notes and dilutive stock options 541,570 704,970 Average number of common shares outstanding - diluted 132,618,644 131,956,094 Earnings per common share Basic $ 0.65 $ 0.66 Diluted $ 0.64 $ 0.66

Store Acquisitions (Tables)

Store Acquisitions (Tables)	3 Months Ended
	Mar. 31, 2017
Business Combinations [Abstract]
Schedule of Operating Properties Acquired	The following table shows the Company’s acquisitions of operating stores for the three months ended March 31, 2017 . The table excludes purchases of raw land or improvements made to existing assets. Consideration Paid Total Property Location Number of Stores Date of Acquisition Cash Paid Net Liabilities/(Assets) Assumed Real estate assets Illinois 1 2/1/2017 $ 9,020 $ 8 $ 9,028 Georgia 1 1/6/2017 16,521 7 16,528 2017 Totals 2 $ 25,541 $ 15 $ 25,556

Variable Interests (Tables)

Variable Interests (Tables)	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Assets and Liabilities and Maximum Exposure to Loss Related to Trusts	Following is a tabular comparison of the assets and liabilities the Company has recorded as a result of its involvement with the Trusts to the maximum exposure to loss the Company is subject to as a result of such involvement as of March 31, 2017 : Notes payable Investment Maximum Difference Trust $ 36,083 $ 1,083 $ 35,000 $ — Trust II 42,269 1,269 41,000 — Trust III 41,238 1,238 40,000 — 119,590 $ 3,590 $ 116,000 — Unamortized debt issuance costs (2,238 ) $ 117,352

Derivatives (Tables)

Derivatives (Tables)	3 Months Ended
	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Balance Sheet Classification and Fair Value of Entity's Derivative Financial Instruments	The table below presents the fair value of the Company’s derivative financial instruments as well as their classification on the condensed consolidated balance sheets: Asset (Liability) Derivatives March 31, 2017 December 31, 2016 Derivatives designated as hedging instruments: Fair Value Other assets $ 28,744 $ 23,844 Other liabilities $ (1,073 ) $ (2,447 )
Schedule of Information Relating to Gain (Loss) Recognized on Swap Agreements	The tables below present the effect of the Company’s derivative financial instruments on the condensed consolidated statements of operations for the periods presented. No tax effect has been presented as the derivative instruments are held by the Company: Gain (loss) recognized in OCI Location of amounts reclassified from OCI into income Gain (loss) reclassified from OCI Type 2017 2016 2017 2016 Swap Agreements $ 3,006 $ (34,960 ) Interest expense $ (3,330 ) $ (4,454 )

Exchangeable Senior Notes (Tabl

Exchangeable Senior Notes (Tables)	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Schedule of Information about Total Carrying Amounts of Equity Components, Principal Amounts of Liability Components, Unamortized Discounts and Net Carrying Amounts for Notes	Information about the Company’s 2013 Notes and 2015 Notes, including the total carrying amounts of the equity components, the principal amounts of the liability components, the unamortized discounts and the net carrying amounts was as follows for the periods indicated: March 31, 2017 December 31, 2016 Carrying amount of equity component - 2013 Notes $ — $ — Carrying amount of equity component - 2015 Notes 22,597 22,597 Carrying amount of equity components $ 22,597 $ 22,597 Principal amount of liability component - 2013 Notes $ 63,170 $ 63,170 Principal amount of liability component - 2015 Notes 575,000 575,000 Unamortized discount - equity component - 2013 Notes (992 ) (1,187 ) Unamortized discount - equity component - 2015 Notes (16,281 ) (17,355 ) Unamortized cash discount - 2013 Notes (234 ) (281 ) Unamortized debt issuance costs (8,430 ) (9,033 ) Net carrying amount of liability components $ 612,233 $ 610,314
Summary of Amount of Interest Cost Recognized Relating to Contractual Interest Rates and Amortization of Discounts on Liability Components of Notes	The amount of interest cost recognized relating to the contractual interest rates and the amortization of the discounts on the liability components of the Notes were as follows for the periods indicated: For the Three Months Ended March 31, 2017 2016 Contractual interest $ 4,867 $ 4,882 Amortization of discount 1,269 1,233 Total interest expense recognized $ 6,136 $ 6,115
Summary of Repurchase of Debt	Information about the repurchases is as follows: February 2016 Principal amount repurchased $ 19,639 Amount allocated to: Extinguishment of liability component $ 18,887 Reacquisition of equity component 12,132 Total consideration paid for repurchase $ 31,019 Exchangeable senior notes repurchased $ 19,639 Extinguishment of liability component (18,887 ) Discount on exchangeable senior notes (716 ) Related debt issuance costs (36 ) Gain/(loss) on repurchase $ —

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Schedule of Financial Information of Business Segments	Financial information for the Company’s business segments is presented below: March 31, 2017 December 31, 2016 Balance Sheet Investment in unconsolidated real estate ventures Rental operations $ 79,385 $ 79,570 Total assets Rental operations $ 6,729,670 $ 6,731,292 Tenant reinsurance 33,611 44,524 Property management, acquisition and development 271,076 315,630 $ 7,034,357 $ 7,091,446 For the Three Months Ended March 31, 2017 2016 Statement of Operations Total revenues Rental operations $ 231,493 $ 199,488 Tenant reinsurance 22,855 20,555 Property management, acquisition and development 8,660 9,360 263,008 229,403 Operating expenses, including depreciation and amortization Rental operations 115,357 101,698 Tenant reinsurance 3,920 4,311 Property management, acquisition and development 19,528 29,766 138,805 135,775 Income (loss) from operations Rental operations 116,136 97,790 Tenant reinsurance 18,935 16,244 Property management, acquisition and development (10,868 ) (20,406 ) 124,203 93,628 Loss on earnout from prior acquisition Property management, acquisition and development — (1,544 ) Interest expense Rental operations (34,821 ) (30,565 ) Property management, acquisition and development (1,149 ) (794 ) (35,970 ) (31,359 ) Non-cash interest expense related to the amortization of discount on equity component of exchangeable senior notes Property management, acquisition and development (1,269 ) (1,233 ) Interest income Property management, acquisition and development 1,102 1,714 Interest income on note receivable from Preferred Operating Partnership unit holder Property management, acquisition and development 1,213 1,213 Equity in earnings of unconsolidated real estate ventures Rental operations 3,579 2,830 Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of joint venture partner's interest Property management, acquisition and development — 26,923 Income tax (expense) benefit Rental operations (463 ) (845 ) Tenant reinsurance (3,263 ) (2,663 ) Property management, acquisition and development 602 743 (3,124 ) (2,765 ) Net income (loss) Rental operations 84,431 69,210 Tenant reinsurance 15,672 13,581 Property management, acquisition and development (10,369 ) 6,616 $ 89,734 $ 89,407 For the Three Months Ended March 31, 2017 2016 Depreciation and amortization expense Rental operations $ 48,712 $ 40,586 Property management, acquisition and development 720 2,311 $ 49,432 $ 42,897 Statement of Cash Flows Acquisition of real estate assets Property management, acquisition and development $ (39,136 ) $ (234,820 ) Development and redevelopment of real estate assets Property management, acquisition and development $ (5,246 ) $ (6,543 )

Organization - Additional Infor

Organization - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2017segmentstorestate
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of operating storage facilities in which the entity has equity interests (in stores)	1,020
Number of stores owned by franchisees and third parties	421
Number of operating stores owned and/or managed	1,441
Number of states in which operating storage facilities are located | state	38
Number of reportable segments | segment	3
Rental Revenue [Member] | Customer Concentration Risk [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Percentage of rental income accounted for by any single tenant (no more than)	5.00%

Fair Value Disclosures - Schedu

Fair Value Disclosures - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - Recurring Basis [Member] $ in Thousands	Mar. 31, 2017USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets - Cash Flow Hedge Swap Agreements	$ 28,744
Other liabilities - Cash Flow Hedge Swap Agreements	(1,073)
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets - Cash Flow Hedge Swap Agreements	0
Other liabilities - Cash Flow Hedge Swap Agreements	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets - Cash Flow Hedge Swap Agreements	28,744
Other liabilities - Cash Flow Hedge Swap Agreements	(1,073)
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets - Cash Flow Hedge Swap Agreements	0
Other liabilities - Cash Flow Hedge Swap Agreements	$ 0

Fair Value Disclosures - Sche34

Fair Value Disclosures - Schedule of Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Value of Financial Instruments [Line Items]
Notes receivable from Preferred Operating Partnership unit holders	$ 120,230	$ 120,230
Fixed rate notes payable and notes payable to trusts	3,198,870	3,213,588
Exchangeable senior notes	612,233	610,314
Fair Value [Member]
Fair Value of Financial Instruments [Line Items]
Notes receivable from Preferred Operating Partnership unit holders	124,837	125,642
Fixed rate notes receivable	21,649	53,450
Fixed rate notes payable and notes payable to trusts	2,329,582	2,404,996
Exchangeable senior notes	691,554	706,827
Carrying Value [Member]
Fair Value of Financial Instruments [Line Items]
Notes receivable from Preferred Operating Partnership unit holders	120,230	120,230
Fixed rate notes receivable	20,608	52,201
Fixed rate notes payable and notes payable to trusts	2,360,128	2,417,558
Exchangeable senior notes	$ 638,170	$ 638,170

Fair Value Disclosures - Additi

Fair Value Disclosures - Additional Information (Detail)	Mar. 31, 2017land_parcelstore
Fair Value Disclosures [Abstract]
Number of parcels of undeveloped land classified as held for sale | land_parcel	1
Number of operating stores held for sale | store	36

Earnings Per Common Share - Sch

Earnings Per Common Share - Schedule of Antidilutive Shares Excluded from Computation of Earnings Per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent shares (if converted) (in shares)	2,019,926	980,912
Series B Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent shares (if converted) (in shares)	555,216	482,133
Series C Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent shares (if converted) (in shares)	392,727	341,032
Series D Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent shares (if converted) (in shares)	1,071,983	157,747

Earnings Per Common Share - S37

Earnings Per Common Share - Schedule of Computation of Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Line Items]
Net income attributable to common stockholders	$ 82,282	$ 82,592
Earnings and dividends allocated to participating securities	(197)	(165)
Earnings for basic computations	82,085	82,427
Income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units) and Operating Partnership	4,049	5,474
Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units)	(1,271)	(1,271)
Net income for diluted computations	$ 84,863	$ 86,630
Weighted average common shares outstanding:
Average number of common shares outstanding - basic (in shares)	125,605,403	124,754,174
OP Units (in shares)	5,596,191	5,621,470
Shares related to exchangeable senior notes and dilutive stock options (in shares)	541,570	704,970
Average number of common shares outstanding - diluted (in shares)	132,618,644	131,956,094
Earnings per common share
Basic (in dollars per share)	$ 0.65	$ 0.66
Diluted (in dollars per share)	$ 0.64	$ 0.66
Series A Units [Member]
Weighted average common shares outstanding:
Preferred series units (in shares)	875,480	875,480

Earnings Per Common Share - Add

Earnings Per Common Share - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Feb. 29, 2016	Sep. 30, 2015	Jun. 21, 2013
Earnings Per Share [Line Items]
Average share price (in dollars per share)	$ 75.47	$ 86.91
Principal amount of notes outstanding	$ 612,233,000		$ 610,314,000
Series A Units [Member]
Earnings Per Share [Line Items]
Exchangeable preferred operating partnership units settled in cash, minimum	115,000,000
Operating Partnership [Member] | Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes) [Member]
Earnings Per Share [Line Items]
Principal amount of notes outstanding	$ 63,170,000		63,170,000	$ 19,639,000
Interest rate	2.375%					2.375%
Exchange price (in dollars per share)	$ 53.81
Shares related to the Notes included in the computation for diluted earnings per share (in shares)	336,848	441,598
Operating Partnership [Member] | Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes) [Member]
Earnings Per Share [Line Items]
Principal amount of notes outstanding	$ 575,000,000		$ 575,000,000
Interest rate	3.125%				3.125%
Exchange price (in dollars per share)	$ 94.47
Shares related to the Notes included in the computation for diluted earnings per share (in shares)	0	0
Stock Options [Member]
Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per common share (in shares)	103,854	67,812

Store Acquisitions - Schedule o

Store Acquisitions - Schedule of Operating Properties Acquired (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)store
Property Acquisitions [Line Items]
Number of Stores | store	2
Cash Paid	$ 25,541
Net Liabilities/(Assets) Assumed	15
Fair value, real estate assets	$ 25,556
Illinois Property 2/1/2017 [Member]
Property Acquisitions [Line Items]
Number of Stores | store	1
Cash Paid	$ 9,020
Net Liabilities/(Assets) Assumed	8
Fair value, real estate assets	$ 9,028
Georgia Property 1/6/2017 [Member]
Property Acquisitions [Line Items]
Number of Stores | store	1
Cash Paid	$ 16,521
Net Liabilities/(Assets) Assumed	7
Fair value, real estate assets	$ 16,528

Variable Interests - Schedule o

Variable Interests - Schedule of Assets and Liabilities and Maximum Exposure to Loss Related to Trusts (Detail) - Operating Partnership [Member] - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Unamortized debt issuance costs	$ (8,430,000)	$ (9,033,000)
Net carrying amount of liability components	612,233,000	$ 610,314,000
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investment Balance
Maximum exposure to loss
Difference
Variable Interest Entity, Not Primary Beneficiary [Member] | Notes Payable to Trusts [Member]
Variable Interest Entity [Line Items]
Unamortized debt issuance costs	(2,238,000)
Net carrying amount of liability components	117,352,000
Variable Interest Entity, Not Primary Beneficiary [Member] | Trust I [Member]
Variable Interest Entity [Line Items]
Investment Balance	1,083,000
Maximum exposure to loss	35,000,000
Difference	0
Variable Interest Entity, Not Primary Beneficiary [Member] | Trust I [Member] | Notes Payable to Trusts [Member]
Variable Interest Entity [Line Items]
Notes payable to Trusts	36,083,000
Variable Interest Entity, Not Primary Beneficiary [Member] | Trust II [Member]
Variable Interest Entity [Line Items]
Investment Balance	1,269,000
Maximum exposure to loss	41,000,000
Difference	0
Variable Interest Entity, Not Primary Beneficiary [Member] | Trust II [Member] | Notes Payable to Trusts [Member]
Variable Interest Entity [Line Items]
Notes payable to Trusts	42,269,000
Variable Interest Entity, Not Primary Beneficiary [Member] | Trust III [Member]
Variable Interest Entity [Line Items]
Investment Balance	1,238,000
Maximum exposure to loss	40,000,000
Difference	0
Variable Interest Entity, Not Primary Beneficiary [Member] | Trust III [Member] | Notes Payable to Trusts [Member]
Variable Interest Entity [Line Items]
Notes payable to Trusts	41,238,000
Variable Interest Entity, Not Primary Beneficiary [Member] | Subtotal [Member]
Variable Interest Entity [Line Items]
Investment Balance	3,590,000
Maximum exposure to loss	116,000,000
Difference	0
Variable Interest Entity, Not Primary Beneficiary [Member] | Subtotal [Member] | Notes Payable to Trusts [Member]
Variable Interest Entity [Line Items]
Notes payable to Trusts	$ 119,590,000

Variable Interests - Additional

Variable Interests - Additional Information (Detail)	Mar. 31, 2017joint_venturesubsidiary
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of wholly-owned unconsolidated subsidiaries | subsidiary	3
Number of interests in consolidated VIE joint ventures | joint_venture	0

Derivatives - Schedule of Balan

Derivatives - Schedule of Balance Sheet Classification and Fair Value of Entity's Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Other Assets [Member]
Derivative [Line Items]
Other assets	$ 28,744	$ 23,844
Other Liabilities [Member]
Derivative [Line Items]
Other liabilities	$ (1,073)	$ (2,447)

Derivatives - Schedule of Infor

Derivatives - Schedule of Information Relating to Gain (Loss) Recognized on Swap Agreements (Detail) - Cash Flow Hedging [Member] - Interest Rate Swap [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Derivative [Line Items]
Swap agreements gain (loss) recognized in OCI	$ 3,006	$ (34,960)
Swap agreements gain (loss) reclassified from OCI - Interest expense	$ (3,330)	$ (4,454)

Derivatives - Additional Inform

Derivatives - Additional Information (Detail) $ in Thousands	Mar. 31, 2017USD ($)derivative
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Estimated amount of unrealized gains or losses expected to be reclassified as interest expense in next fiscal year	$ 4,209
Number of derivative financial instruments | derivative	28
Combined notional amount	$ 2,052,010
Credit risk derivative, fair value of derivatives in a net liability position	1,361
Estimated termination value on settlement	$ 1,361

Exchangeable Senior Notes - Sch

Exchangeable Senior Notes - Schedule of Information about Total Carrying Amounts of Equity Components, Principal Amounts of Liability Components, Unamortized Discounts and Net Carrying Amounts for Notes (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Feb. 29, 2016	Sep. 30, 2015	Jun. 21, 2013
Debt Instrument [Line Items]
Principal amount of liability components	$ 612,233	$ 610,314
Operating Partnership [Member]
Debt Instrument [Line Items]
Carrying amount of equity components	22,597	22,597
Unamortized debt issuance costs	(8,430)	(9,033)
Net carrying amount of liability components	612,233	610,314
Operating Partnership [Member] | Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes) [Member]
Debt Instrument [Line Items]
Carrying amount of equity components	0	0
Principal amount of liability components	63,170	63,170	$ 19,639
Unamortized discount - equity components	(992)	(1,187)
Unamortized cash discount - 2013 Notes	(234)	(281)	(716)		$ (3,750)
Unamortized debt issuance costs			$ (36)		$ (1,672)
Operating Partnership [Member] | Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes) [Member]
Debt Instrument [Line Items]
Carrying amount of equity components	22,597	22,597
Principal amount of liability components	575,000	575,000
Unamortized discount - equity components	$ (16,281)	$ (17,355)
Unamortized debt issuance costs				$ (11,992)

Exchangeable Senior Notes - Sum

Exchangeable Senior Notes - Summary of Amount of Interest Cost Recognized Relating to Contractual Interest Rates and Amortization of Discounts on Liability Components of Notes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Debt Disclosure [Abstract]
Contractual interest	$ 4,867	$ 4,882
Amortization of discount	1,269	1,233
Total interest expense recognized	$ 6,136	$ 6,115

Exchangeable Senior Notes - S47

Exchangeable Senior Notes - Summary of Repurchase of Debt (Detail) - USD ($) $ in Thousands	Feb. 29, 2016	Mar. 31, 2017	Dec. 31, 2016	Jun. 21, 2013
Debt Instrument [Line Items]
Exchangeable senior notes repurchased		$ 612,233	$ 610,314
Operating Partnership [Member]
Debt Instrument [Line Items]
Related debt issuance costs		8,430	9,033
Operating Partnership [Member] | Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes) [Member]
Debt Instrument [Line Items]
Principal amount repurchased	$ 19,639
Extinguishment of liability component	(18,887)
Reacquisition of equity component	12,132
Total consideration paid for repurchase	31,019
Exchangeable senior notes repurchased	19,639	63,170	63,170
Extinguishment of liability component	(18,887)
Discount on exchangeable senior notes	(716)	$ (234)	$ (281)	$ (3,750)
Related debt issuance costs	36			$ 1,672
Gain/(loss) on repurchase	$ 0

Exchangeable Senior Notes - Add

Exchangeable Senior Notes - Additional Information (Detail)	Jun. 21, 2013USD ($)	Feb. 29, 2016USD ($)shares	Sep. 30, 2015USD ($)	Mar. 31, 2017USD ($)d	Dec. 31, 2016USD ($)
Par Value [Member]
Debt Instrument [Line Items]
Shares issued for value of notes in excess of principal amount | shares		130,909
Value of notes in excess of principal amount		$ 11,380,000
Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes) [Member]
Debt Instrument [Line Items]
Effective interest rate on the liability component				4.00%
Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes) [Member]
Debt Instrument [Line Items]
Notes exchange, threshold percentage				130.00%
Notes exchange, threshold trading days | d				20
Notes exchange, threshold consecutive trading days				30 days
Effective interest rate on the liability component				4.00%
Operating Partnership [Member]
Debt Instrument [Line Items]
Related debt issuance costs				$ 8,430,000	$ 9,033,000
Operating Partnership [Member] | Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes) [Member]
Debt Instrument [Line Items]
Principal amount of notes issued			$ 575,000,000
Interest rate			3.125%	3.125%
Underwriting fee percentage			2.00%
Amortization period			5 years
Conversion ratio, number of shares per $1,000 principal amount, numerator				10.58
Principal amount used for debt instrument conversion ratio				$ 1,000
Redemption price as percentage of principal amount of notes plus accrued and unpaid interest			100.00%
Redemption price as percentage of principal amount of notes at request of debt holders and upon occurrence of designated event			100.00%
Related debt issuance costs			$ 11,992,000
Operating Partnership [Member] | Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes) [Member] | Minimum [Member]
Debt Instrument [Line Items]
Number of days of written notice to holders of notes required for redemption			30 days
Operating Partnership [Member] | Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes) [Member] | Maximum [Member]
Debt Instrument [Line Items]
Number of days of written notice to holders of notes required for redemption			60 days
Operating Partnership [Member] | Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes) [Member]
Debt Instrument [Line Items]
Principal amount of notes issued	$ 250,000,000
Interest rate	2.375%			2.375%
Conversion ratio, number of shares per $1,000 principal amount, numerator				18.58
Principal amount used for debt instrument conversion ratio				$ 1,000
Redemption price as percentage of principal amount of notes plus accrued and unpaid interest	100.00%
Redemption price as percentage of principal amount of notes at request of debt holders and upon occurrence of designated event	100.00%
Discount rate	1.50%
Unamortized cash discount	$ 3,750,000	716,000		$ 234,000	$ 281,000
Related debt issuance costs	$ 1,672,000	36,000
Amortization period	5 years
Principal amount repurchased		$ 19,639,000
Operating Partnership [Member] | Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes) [Member] | Minimum [Member]
Debt Instrument [Line Items]
Number of days of written notice to holders of notes required for redemption	30 days
Operating Partnership [Member] | Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes) [Member] | Maximum [Member]
Debt Instrument [Line Items]
Number of days of written notice to holders of notes required for redemption	60 days

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - At the Market Equity Distribution Agreement [Member]	May 06, 2016USD ($)sales_agent	Mar. 31, 2017USD ($)shares
Changes In Equity And Comprehensive Income Line Items [Line Items]
Aggregate offering price of common share	$ 400,000,000
Number of sales agents | sales_agent	5
Shares, issued | shares		0
Value of stock available for issuance under ATM		$ 349,375,000

Noncontrolling Interest Repre50

Noncontrolling Interest Represented by Preferred Operating Partnership Units - Additional Information (Details) $ / shares in Units, $ in Thousands

Nov. 04, 2016USD ($)shares

May 21, 2016USD ($)storeshares

Oct. 03, 2014USD ($)shares

Apr. 03, 2014USD ($)storeshares

Nov. 19, 2013store

Sep. 26, 2013USD ($)storeshares

Aug. 29, 2013store

Jun. 25, 2007USD ($)shares

Jun. 15, 2007storeshares

Dec. 31, 2014USD ($)storeshares

Mar. 31, 2017USD ($)sharesstore$ / shares

Mar. 31, 2016USD ($)

May 31, 2014USD ($)storeshares

Dec. 31, 2016USD ($)

Jun. 15, 2016USD ($)

Noncontrolling Interest [Line Items]

Note receivable from noncontrolling interest represented by Preferred Operating Partnership units

$ 120,230

$ 120,230

Redemption of Operating Partnership units held by noncontrolling interests

$ 1,754

$ 0

Number of stores acquired | store

2

Series B Redeemable Preferred Units [Member] | Series B Units [Member]

Noncontrolling Interest [Line Items]

Liquidation value (in dollars per share) | $ / shares

$ 25

Fixed liquidation value

$ 41,902

Annual rate of return (as a percent)

6.00%

Series B Redeemable Preferred Units [Member] | Series B Units [Member] | Georgia, 1 Property Acquired 4/3/2014 [Member]

Noncontrolling Interest [Line Items]

Preferred units issued as part of acquisition (in units) | shares

333,360

Preferred units issued as part of acquisition

$ 8,334

Series C Convertible Redeemable Preferred Units [Member] | California, Properties Acquired December 2013 [Member]

Noncontrolling Interest [Line Items]

Number of stores acquired | store

12

Ownership interests in five stores through joint ventures prior to the acquisition

35.00%

Number of stores in which ownership interest was held prior to acquisition of remaining properties | store

5

Ownership interest in one store through joint ventures prior to the acquisition

40.00%

Number of stores in which ownership interest was held prior to acquisition | store

1

Series C Convertible Redeemable Preferred Units [Member] | Series C Units [Member]

Noncontrolling Interest [Line Items]

Note receivable from noncontrolling interest represented by Preferred Operating Partnership units

$ 20,230

Note receivable interest rate

5.00%

Liquidation value (in dollars per share) | $ / shares

$ 42.10

Fixed liquidation value

$ 29,639

Quarterly distribution per preferred OP unit payable above quarterly distribution for common OP Unit (in dollars per share) | $ / shares

$ 0.18

Number of months immediately preceding the fifth anniversary of issuance for which distribution is payable

12 months

Period from date of issuance after which preferred OP units will become redeemable at the option of the holder

1 year

Preferred OP units conversion ratio | shares

0.9145

Note receivable maturity date

Dec. 15, 2024

Series D Redeemable Preferred Units [Member] | Series D Units [Member]

Noncontrolling Interest [Line Items]

Liquidation value (in dollars per share) | $ / shares

$ 25

Fixed liquidation value

$ 80,903

Series D Redeemable Preferred Units [Member] | D-1 Units[Member] | Minimum [Member]

Noncontrolling Interest [Line Items]

Annual rate of return (as a percent)

3.50%

Series D Redeemable Preferred Units [Member] | D-1 Units[Member] | Maximum [Member]

Noncontrolling Interest [Line Items]

Annual rate of return (as a percent)

5.00%

Operating Partnership [Member] | Illinois Property Acquired 5/21/2016 [Member]

Noncontrolling Interest [Line Items]

Number of stores acquired | store

4

Operating Partnership [Member] | Series A Participating Redeemable Preferred Units [Member]

Noncontrolling Interest [Line Items]

Number of stores acquired | store

10

Operating Partnership [Member] | Series A Participating Redeemable Preferred Units [Member] | Series A Units [Member]

Noncontrolling Interest [Line Items]

Preferred units issued as part of acquisition (in units) | shares

989,980

Fixed priority return on preferred OP units, amount

$ 115,000

Fixed priority return on preferred OP units, stated return rate

5.00%

Fixed priority return on preferred OP units, liquidation value

$ 115,000

Operating Partnership [Member] | Series B Redeemable Preferred Units [Member] | Georgia, 1 Property Acquired 4/3/2014 [Member]

Noncontrolling Interest [Line Items]

Number of stores acquired | store

1

Cash portion of payment for acquisition

$ 15,158

Operating Partnership [Member] | Series B Redeemable Preferred Units [Member] | California, 20 Properties Acquired 2013-September [Member]

Noncontrolling Interest [Line Items]

Number of stores acquired | store

1

19

Cash portion of payment for acquisition

$ 100,876

Number of stores acquired as part of portfolio acquisition | store

20

Debt assumed

$ 98,960

Number of common units issued as part of acquisition (in units) | shares

1,448,108

OP units issued as part of the acquisition

$ 62,341

Operating Partnership [Member] | Series B Redeemable Preferred Units [Member] | Series B Units [Member] | California, 20 Properties Acquired 2013-September [Member]

Noncontrolling Interest [Line Items]

Preferred units issued as part of acquisition (in units) | shares

1,342,727

Preferred units issued as part of acquisition

$ 33,568

Operating Partnership [Member] | Series C Convertible Redeemable Preferred Units [Member] | California, Properties Acquired December 2013 [Member]

Noncontrolling Interest [Line Items]

Cash portion of payment for acquisition

$ 45,722

Debt assumed

$ 37,532

Number of stores acquired | store

6

Operating Partnership [Member] | Series C Convertible Redeemable Preferred Units [Member] | Series C Units [Member] | California, Properties Acquired December 2013 [Member]

Noncontrolling Interest [Line Items]

Preferred units issued as part of acquisition (in units) | shares

704,016

Preferred units issued as part of acquisition

$ 30,960

Operating Partnership [Member] | Series D Redeemable Preferred Units [Member] | Self Storage Facility in Florida [Member]

Noncontrolling Interest [Line Items]

Number of stores acquired | store

1

Cash portion of payment for acquisition

$ 5,621

Operating Partnership [Member] | Series D Redeemable Preferred Units [Member] | D-4 Preferred Units [Member] | Illinois Property Acquired 5/21/2016 [Member]

Noncontrolling Interest [Line Items]

Number of OP units issued for store acquisition (in units) | shares

486,244

Operating Partnership units issued

$ 12,156

Operating Partnership [Member] | Series D Redeemable Preferred Units [Member] | D-3 Units [Member] | Illinois Property Acquired 5/21/2016 [Member]

Noncontrolling Interest [Line Items]

Number of OP units issued for store acquisition (in units) | shares

2,201,467

Operating Partnership units issued

$ 55,037

Operating Partnership [Member] | Series D Redeemable Preferred Units [Member] | Series D Units [Member] | Self Storage Facility in Florida [Member]

Noncontrolling Interest [Line Items]

Preferred units issued as part of acquisition (in units) | shares

548,390

Preferred units issued as part of acquisition

$ 13,710

Operating Partnership Holders of A Units [Member] | Series A Participating Redeemable Preferred Units [Member]

Noncontrolling Interest [Line Items]

Note receivable from noncontrolling interest represented by Preferred Operating Partnership units

$ 100,000

Note receivable interest rate

4.85%

Maximum number of preferred OP units converted prior to the maturity date of the loan (in units) | shares

114,500

A units redeemed | shares

114,500

Redemption of Operating Partnership units held by noncontrolling interests

$ 4,794

Common shares issued in Preferred Unit redemption (in shares) | shares

280,331

Additional units redeemed (in units) | shares

0

Noncontrolling Interest in Op51

Noncontrolling Interest in Operating Partnership - Additional Information (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)$ / sharesshares
Noncontrolling Interest [Line Items]
Period used as a denomination to determine the average closing price of common stock	10 days
OP units conversion basis	one-for-one basis
OP units conversion ratio	1
Ten day average closing stock price (in dollars per share) | $ / shares	$ 74.84
Consideration to be paid on redemption of common OP units | $	$ 1,754
Number of OP units issued for remaining interest in joint venture (in units) | shares	23,796
Operating Partnership [Member]
Noncontrolling Interest [Line Items]
Ownership interest held by entity	91.20%
Ownership percentage in joint venture	8.80%
OP units outstanding (in units) | shares	5,584,242
Consideration to be paid on redemption of common OP units | $	$ 417,925

Other Noncontrolling Interests

Other Noncontrolling Interests - Additional Information (Detail) - Other [Member]	Mar. 31, 2017joint_venture
Noncontrolling Interest [Line Items]
Number of consolidated joint ventures	1
Voting interests of third-party owners	20.00%

Equity in Earnings of Unconso53

Equity in Earnings of Unconsolidated Real Estate Ventures - Gain on Sale of Real Estate and Purchase of Joint Venture Partner's Interest - Additional Information (Detail) $ in Thousands	Feb. 02, 2016USD ($)store	Mar. 31, 2016USD ($)	Mar. 31, 2017USD ($)
Schedule Of Results Related To Equity Accounted Investees [Line Items]
Fair value, real estate assets			$ 25,556
VRS [Member]
Schedule Of Results Related To Equity Accounted Investees [Line Items]
Number of stores acquired | store	6
Ownership interest percentage	45.04%
Extra Space Properties One Two Two LLC [Member]
Schedule Of Results Related To Equity Accounted Investees [Line Items]
Number of stores acquired | store	6
Number of transferred stores | store	6
Net carrying amount of properties distributed	$ 17,261
Business combination, step acquisition, equity interest in acquiree, including subsequent acquisition, percentage	100.00%
Business combination, step acquisition, equity interest in acquiree, fair value	$ 44,184
Equity interest fair value remeasurement non-cash gain		$ 26,923
Prudential Real Estate and Affiliates [Member] | VRS [Member]
Schedule Of Results Related To Equity Accounted Investees [Line Items]
Business acquisition, percentage of voting interests acquired	54.96%
Prudential Real Estate and Affiliates [Member] | Extra Space Properties One Two Two LLC [Member]
Schedule Of Results Related To Equity Accounted Investees [Line Items]
Business acquisition, percentage of voting interests acquired	54.96%
Business combination amount paid to acquire joint venture partner's interest	$ 53,940
Various States Properties Feb 2, 2016 [Member]
Schedule Of Results Related To Equity Accounted Investees [Line Items]
Fair value, real estate assets	$ 98,082

Segment Information - Schedule

Segment Information - Schedule of Financial Information of Business Segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Investment in unconsolidated real estate ventures	$ 79,385		$ 79,570
Total assets	7,034,357		7,091,446
Total revenues	263,008	$ 229,403
Operating expenses, including depreciation and amortization	138,805	135,775
Income (loss) from operations	124,203	93,628
Loss on earnout from prior acquisition	0	(1,544)
Interest expense	(35,970)	(31,359)
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	(1,269)	(1,233)
Interest income	1,102	1,714
Interest income on note receivable from Preferred Operating Partnership unit holder	1,213	1,213
Equity in earnings of unconsolidated real estate ventures	3,579	2,830
Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of joint venture partner's interest	0	26,923
Income tax (expense) benefit	(3,124)	(2,765)
Net income (loss)	89,734	89,407
Depreciation and amortization expense	49,432	42,897
Acquisition of real estate assets	(39,136)	(234,820)
Development and redevelopment of real estate assets	(5,246)	(6,543)
Rental Operations [Member]
Segment Reporting Information [Line Items]
Investment in unconsolidated real estate ventures	79,385		79,570
Total assets	6,729,670		6,731,292
Total revenues	231,493	199,488
Operating expenses, including depreciation and amortization	115,357	101,698
Income (loss) from operations	116,136	97,790
Interest expense	(34,821)	(30,565)
Equity in earnings of unconsolidated real estate ventures	3,579	2,830
Income tax (expense) benefit	(463)	(845)
Net income (loss)	84,431	69,210
Depreciation and amortization expense	48,712	40,586
Tenant Reinsurance [Member]
Segment Reporting Information [Line Items]
Total assets	33,611		44,524
Total revenues	22,855	20,555
Operating expenses, including depreciation and amortization	3,920	4,311
Income (loss) from operations	18,935	16,244
Income tax (expense) benefit	(3,263)	(2,663)
Net income (loss)	15,672	13,581
Property Management, Acquisition and Development [Member]
Segment Reporting Information [Line Items]
Total assets	271,076		$ 315,630
Total revenues	8,660	9,360
Operating expenses, including depreciation and amortization	19,528	29,766
Income (loss) from operations	(10,868)	(20,406)
Loss on earnout from prior acquisition	0	(1,544)
Interest expense	(1,149)	(794)
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	(1,269)	(1,233)
Interest income	1,102	1,714
Interest income on note receivable from Preferred Operating Partnership unit holder	1,213	1,213
Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of joint venture partner's interest	0	26,923
Income tax (expense) benefit	602	743
Net income (loss)	(10,369)	6,616
Depreciation and amortization expense	720	2,311
Acquisition of real estate assets	(39,136)	(234,820)
Development and redevelopment of real estate assets	$ (5,246)	$ (6,543)

Segment Information - Additiona

Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2017segment
Segment Reporting [Abstract]
Number of reportable segments	3

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)store
Commitments And Contingencies [Line Items]
Litigation liability recorded | $	$ 5,600
Commitment to acquire retail space [Member]
Commitments And Contingencies [Line Items]
Number of real estate properties to be acquired	2
Purchase price | $	$ 165,581
Number of stores scheduled to be closed	6
Commitment to acquire retail space [Member] | Construction in progress [Member]
Commitments And Contingencies [Line Items]
Number of real estate properties to be acquired	13
Commitment to acquire real estate with joint venture partners [Member]
Commitments And Contingencies [Line Items]
Number of real estate properties to be acquired	23
Purchase price | $	$ 141,887
Number of stores scheduled to be closed	11
Number of stores expected to be closed	12