Extra Space Storage (EXR) 10-Q 5 Aug 21 2021 Q2 Quarterly report Financial data

Cover

Cover - shares	6 Months Ended
	Jun. 30, 2021	Aug. 02, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	001-32269
Entity Registrant Name	EXTRA SPACE STORAGE INC.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	20-1076777
Entity Address, Address Line One	2795 East Cottonwood Parkway, Suite 300
Entity Address, City or Town	Salt Lake City
Entity Address, State or Province	UT
Entity Address, Postal Zip Code	84121
City Area Code	801
Local Phone Number	365-4600
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	EXR
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		133,807,322
Amendment Flag	false
Entity Central Index Key	0001289490
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets:
Real estate assets, net	$ 8,113,074	$ 7,893,802
Real estate assets - operating lease right-of-use assets	233,929	252,172
Investments in unconsolidated real estate entities	361,228	397,444
Investments in debt securities and notes receivable	568,781	593,810
Cash and cash equivalents	56,006	109,124
Restricted cash	3,743	18,885
Other assets, net	126,331	130,611
Total assets	9,463,092	9,395,848
Liabilities, Noncontrolling Interests and Equity:
Notes payable, net	5,109,882	4,797,303
Revolving lines of credit	261,000	949,000
Operating lease liabilities	238,411	263,485
Cash distributions in unconsolidated real estate ventures	62,704	47,126
Accounts payable and accrued expenses	150,091	130,012
Other liabilities	280,049	272,798
Total liabilities	6,102,137	6,459,724
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, 133,791,109 and 131,357,961 shares issued and outstanding at June 30, 2021 and December 31, 2020, respectively	1,337	1,314
Additional paid-in capital	3,288,852	3,000,458
Accumulated other comprehensive loss	(71,830)	(99,093)
Accumulated deficit	(250,271)	(354,900)
Total Extra Space Storage Inc. stockholders' equity	2,968,088	2,547,779
Noncontrolling interest represented by Preferred Operating Partnership units, net	172,902	172,052
Noncontrolling interests in Operating Partnership, net and other noncontrolling interests	219,965	216,293
Total noncontrolling interests and equity	3,360,955	2,936,124
Total liabilities, noncontrolling interests and equity	$ 9,463,092	$ 9,395,848

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value (dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	50,000,000	50,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	500,000,000	500,000,000
Common stock, issued (in shares)	133,791,109	131,357,961
Common stock, outstanding (in shares)	133,791,109	131,357,961

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Property rental	$ 321,500	$ 279,312	$ 625,093	$ 566,015
Tenant reinsurance	42,334	35,078	81,953	68,691
Management fees and other income	14,796	12,856	30,441	24,992
Total revenues	378,630	327,246	737,487	659,698
Expenses:
Property operations	89,155	89,040	181,522	179,337
Tenant reinsurance	6,735	6,858	13,896	13,536
General and administrative	26,341	25,337	49,881	48,348
Depreciation and amortization	59,570	56,018	118,169	111,293
Total expenses	181,801	177,253	363,468	352,514
Gain on real estate transactions	0	0	63,883	0
Income from operations	196,829	149,993	437,902	307,184
Interest expense	(40,240)	(41,039)	(80,935)	(85,397)
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	0	(1,233)	0	(2,442)
Interest income	12,838	1,669	25,142	3,343
Income before equity in earnings and dividend income from unconsolidated real estate ventures and income tax expense	169,427	109,390	382,109	222,688
Equity in earnings and dividend income from unconsolidated real estate entities	8,322	5,044	15,278	10,087
Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of joint venture partner's interest	6,251	0	6,251	0
Income tax expense	(5,421)	(3,177)	(9,558)	(5,356)
Net income	178,579	111,257	394,080	227,419
Net income allocated to Preferred Operating Partnership noncontrolling interests	(3,438)	(3,139)	(7,118)	(6,250)
Net income allocated to Operating Partnership and other noncontrolling interests	(7,193)	(5,207)	(16,016)	(10,079)
Net income attributable to common stockholders	$ 167,948	$ 102,911	$ 370,946	$ 211,090
Earnings per common share
Basic (in dollars per share)	$ 1.25	$ 0.80	$ 2.79	$ 1.63
Diluted (in dollars per share)	$ 1.25	$ 0.80	$ 2.79	$ 1.63
Weighted average number of shares
Basic (in shares)	133,756,610	128,932,152	132,886,933	129,110,131
Diluted (in shares)	140,407,195	129,082,468	140,428,558	129,285,675
Cash dividends paid per common share (in dollars per share)	$ 1	$ 0.90	$ 2	$ 1.80

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 178,579	$ 111,257	$ 394,080	$ 227,419
Other comprehensive income (loss):
Change in fair value of interest rate swaps	5,617	(5,728)	28,630	(94,972)
Total comprehensive income	184,196	105,529	422,710	132,447
Less: comprehensive income attributable to noncontrolling interests	10,898	8,034	24,501	11,647
Comprehensive income attributable to common stockholders	$ 173,298	$ 97,495	$ 398,209	$ 120,800

Condensed Consolidated Statem_3

Condensed Consolidated Statement of Noncontrolling Interests and Equity - USD ($) $ in Thousands	Total	Redemption of Operating Partnership units for stock	Redemption of Operating Partnership units for cash	Noncontrolling Interest - Preferred Operating Partnership	Noncontrolling Interest - Operating Partnership	Noncontrolling Interest - Operating PartnershipRedemption of Operating Partnership units for stock	Noncontrolling Interest - Operating PartnershipRedemption of Operating Partnership units for cash	Noncontrolling Interest - Other	Common Stock	Common StockRedemption of Operating Partnership units for stock	Additional Paid-in Capital	Additional Paid-in CapitalRedemption of Operating Partnership units for stock	Additional Paid-in CapitalRedemption of Operating Partnership units for cash	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance, beginning of period at Dec. 31, 2019	$ 2,921,694			$ 175,948	$ 205,419			$ 366	$ 1,295		$ 2,868,681			$ (28,966)	$ (301,049)
Balance, beginning of period (in shares) at Dec. 31, 2019									129,534,407
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)									77,400
Issuance of common stock upon the exercise of options	944								$ 1		943
Issuance of common stock in connection with share based compensation (in shares)									73,602
Issuance of common stock in connection with share based compensation	2,980								$ 1		2,979
Restricted stock grants cancelled (in shares)									(1,767)
Buyback of common stock, net of offering costs (in shares)									(653,597)
Buyback of common stock, net of offering costs	(52,204)								$ (7)						(52,197)
Redemption of Operating Partnership units					(330)						330
Redemption of Operating Partnership units for stock (in shares)									8,862
Net income (loss)	116,162			3,112	4,877			(6)							108,179
Other comprehensive income (loss)	(89,244)			(563)	(3,807)									(84,874)
Distributions to Operating Partnership units held by noncontrolling interests	(8,505)			(3,178)	(5,327)
Dividends paid on common stock	(117,197)														(117,197)
Balance, end of period at Mar. 31, 2020	2,774,630			175,319	200,832			360	$ 1,290		2,872,933			(113,840)	(362,264)
Balance, end of period (in shares) at Mar. 31, 2020									129,038,907
Balance, beginning of period at Dec. 31, 2019	2,921,694			175,948	205,419			366	$ 1,295		2,868,681			(28,966)	(301,049)
Balance, beginning of period (in shares) at Dec. 31, 2019									129,534,407
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	227,419
Balance, end of period at Jun. 30, 2020	2,745,518			172,542	196,867			419	$ 1,291		2,884,940			(119,256)	(391,285)
Balance, end of period (in shares) at Jun. 30, 2020									129,069,555
Balance, beginning of period at Mar. 31, 2020	2,774,630			175,319	200,832			360	$ 1,290		2,872,933			(113,840)	(362,264)
Balance, beginning of period (in shares) at Mar. 31, 2020									129,038,907
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)									13,610
Issuance of common stock upon the exercise of options	726										726
Issuance of common stock in connection with share based compensation (in shares)									60,032
Issuance of common stock in connection with share based compensation	4,884								$ 1		4,883
Restricted stock grants cancelled (in shares)									(889)
Buyback of common stock, net of offering costs (in shares)									(172,600)
Buyback of common stock, net of offering costs	(15,615)								$ (1)						(15,614)
Redemption of Operating Partnership units					(3,675)				$ 1		3,674
Redemption of Operating Partnership units for stock (in shares)									100,000
Redemption of Preferred D Units in the Operating Partnership for Stock				(2,724)							2,724
Redemption of Preferred D Units in the Operating Partnership for stock (in shares)									30,495
Noncontrolling interest in consolidated joint venture	68							68
Net income (loss)	111,257			3,139	5,216			(9)							102,911
Other comprehensive income (loss)	(5,728)			(41)	(271)									(5,416)
Distributions to Operating Partnership units held by noncontrolling interests	(8,386)			(3,151)	(5,235)
Dividends paid on common stock	(116,318)														(116,318)
Balance, end of period at Jun. 30, 2020	2,745,518			172,542	196,867			419	$ 1,291		2,884,940			(119,256)	(391,285)
Balance, end of period (in shares) at Jun. 30, 2020									129,069,555
Balance, beginning of period at Dec. 31, 2020	$ 2,936,124			172,052	215,892			401	$ 1,314		3,000,458			(99,093)	(354,900)
Balance, beginning of period (in shares) at Dec. 31, 2020	131,357,961								131,357,961
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)									56,722
Issuance of common stock upon the exercise of options	$ 4,254										4,254
Issuance of common stock in connection with share based compensation (in shares)									89,793
Issuance of common stock in connection with share based compensation	3,652										3,652
Restricted stock grants cancelled (in shares)									(2,499)
Offering costs associated with previous stock issuance	273,720								$ 22		273,698				0
Issuance of common stock, net of offering costs (in shares)									2,185,685
Redemption of Operating Partnership units					(193)						193
Redemption of Operating Partnership units for stock (in shares)									5,000
Noncontrolling interest in consolidated joint venture	(50)							(50)
Net income (loss)	215,501			3,680	8,828			(5)							202,998
Other comprehensive income (loss)	23,013			144	956									21,913
Distributions to Operating Partnership units held by noncontrolling interests	(9,025)			(3,224)	(5,801)
Dividends paid on common stock	(132,540)														(132,540)
Balance, end of period at Mar. 31, 2021	3,314,649			172,652	219,682			346	$ 1,336		3,282,255			(77,180)	(284,442)
Balance, end of period (in shares) at Mar. 31, 2021									133,692,662
Balance, beginning of period at Dec. 31, 2020	$ 2,936,124			172,052	215,892			401	$ 1,314		3,000,458			(99,093)	(354,900)
Balance, beginning of period (in shares) at Dec. 31, 2020	131,357,961								131,357,961
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Buyback of common stock, net of offering costs (in shares)	0
Net income (loss)	$ 394,080
Balance, end of period at Jun. 30, 2021	$ 3,360,955			172,902	219,466			499	$ 1,337		3,288,852			(71,830)	(250,271)
Balance, end of period (in shares) at Jun. 30, 2021	133,791,109								133,791,109
Balance, beginning of period at Mar. 31, 2021	$ 3,314,649			172,652	219,682			346	$ 1,336		3,282,255			(77,180)	(284,442)
Balance, beginning of period (in shares) at Mar. 31, 2021									133,692,662
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with share based compensation (in shares)									44,990
Issuance of common stock in connection with share based compensation	4,983										4,983
Restricted stock grants cancelled (in shares)									(4,972)
Offering costs associated with previous stock issuance	(211)										(211)
Redemption of Operating Partnership units		$ 0	$ (472)			$ (2,185)	$ (113)			$ 1		$ 2,184	$ (359)
Redemption of Operating Partnership units for stock (in shares)										58,429
Repayment of receivable with Operating Partnership units pledged as collateral	411				411
Noncontrolling interest in consolidated joint venture	150							150
Net income (loss)	178,579			3,438	7,190			3							167,948
Other comprehensive income (loss)	5,617			35	232									5,350
Distributions to Operating Partnership units held by noncontrolling interests	(8,974)			(3,223)	(5,751)
Dividends paid on common stock	(133,777)														(133,777)
Balance, end of period at Jun. 30, 2021	$ 3,360,955			$ 172,902	$ 219,466			$ 499	$ 1,337		$ 3,288,852			$ (71,830)	$ (250,271)
Balance, end of period (in shares) at Jun. 30, 2021	133,791,109								133,791,109

Condensed Consolidated Statem_4

Condensed Consolidated Statement of Noncontrolling Interests and Equity (Parenthetical) - $ / shares	3 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Dividends paid on common stock (in dollars per share)	$ 1	$ 1	$ 0.90	$ 0.90

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income	$ 394,080	$ 227,419
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	118,169	111,293
Amortization of deferred financing costs	4,869	4,946
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	0	2,442
Non-cash lease expense	945	430
Compensation expense related to stock-based awards	8,635	7,864
Accrual of interest income added to principal of debt securities and notes receivable	(17,312)	0
Gain on real estate transactions	(63,883)	0
Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of joint venture partner's interest	(6,251)	0
Distributions from unconsolidated real estate ventures in excess of earnings	3,026	4,254
Changes in operating assets and liabilities:
Other assets	5,519	(10,185)
Accounts payable and accrued expenses	19,063	19,963
Other liabilities	(3,172)	23,647
Net cash provided by operating activities	463,688	392,073
Cash flows from investing activities:
Acquisition of real estate assets	(375,209)	(45,246)
Development and redevelopment of real estate assets	(25,782)	(29,991)
Proceeds from sale of real estate assets	194,205	0
Investment in unconsolidated real estate entities	(7,174)	(9,541)
Return of investment in unconsolidated real estate ventures	31,534	0
Issuance and purchase of notes receivable	(68,523)	(24,325)
Principal payments received from notes receivable	20,426	0
Proceeds from sale of notes receivable	87,298	0
Purchase of equipment and fixtures	(2,077)	(2,765)
Net cash used in investing activities	(145,302)	(111,868)
Cash flows from financing activities:
Proceeds from the sale of common stock, net of offering costs	273,509	0
Proceeds from notes payable and revolving lines of credit	2,372,000	594,000
Principal payments on notes payable and revolving lines of credit	(3,193,025)	(566,689)
Proceeds from issuance of public bonds, net	446,396	0
Deferred financing costs	(5,403)	(12)
Net proceeds from exercise of stock options	4,254	1,670
Repurchase of common stock	0	(67,819)
Redemption of Operating Partnership units held by noncontrolling interests	(472)	0
Proceeds from principal payments on note receivable collateralized by OP Units	411	0
Contributions from noncontrolling interests	0	68
Dividends paid on common stock	(266,317)	(233,515)
Distributions to noncontrolling interests	(17,999)	(16,890)
Net cash used in financing activities	(386,646)	(289,187)
Net decrease in cash, cash equivalents, and restricted cash	(68,260)	(8,982)
Cash, cash equivalents, and restricted cash, beginning of the period	128,009	70,733
Cash, cash equivalents, and restricted cash, end of the period	59,749	61,751
Supplemental schedule of cash flow information
Interest paid	76,289	81,950
Income taxes paid	16,749	1,792
Redemption of Operating Partnership units held by noncontrolling interests for common stock
Noncontrolling interests in Operating Partnership	(2,378)	(4,005)
Common stock and paid-in capital	2,378	4,005
Establishment of operating lease right of use assets and lease liabilities
Real estate assets - operating lease right-of-use assets	2,493	6,779
Operating lease liabilities	(2,493)	(6,779)
Acquisitions of real estate assets
Real estate assets, net	2,673	0
Investment in unconsolidated real estate ventures	(2,673)	0
Accrued construction costs and capital expenditures
Acquisition of real estate assets	1,016	912
Accounts payable and accrued expenses	(1,016)	(912)
Redemption of Preferred Operating Partnership units for common stock
Preferred Operating Partnership units	0	(2,724)
Additional paid-in capital	0	2,724
Establishment of finance lease assets and lease liabilities
Real estate assets, net	40,993	8,514
Other liabilities	(40,993)	(8,514)
Investment in unconsolidated real estate ventures received on sale of stores to joint venture
Investment in unconsolidated real estate ventures	33,878	0
Real estate assets	$ (33,878)	$ 0

Organization

Organization	6 Months Ended
	Jun. 30, 2021
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 self-storage properties ("stores") located throughout the United States. The Company was formed to continue the business of Extra Space Storage LLC and its subsidiaries, which had engaged in the self-storage business since 1977. The Company’s interest 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 invests in stores by acquiring wholly-owned stores or by acquiring an equity interest in real estate entities. At June 30, 2021, the Company had direct and indirect equity interests in 1,205 stores. In addition, the Company managed 768 stores for third parties, bringing the total number of stores which it owns and/or manages to 1,973. These stores are located in 40 states and Washington, D.C. The Company also offers tenant reinsurance at its owned and managed stores that insures the value of goods in the storage units.

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2021
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 and six months ended June 30, 2021 are not necessarily indicative of results that may be expected for the year ending December 31, 2021. The condensed consolidated balance sheet as of December 31, 2020 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, 2020, as filed with the Securities and Exchange Commission. Recently Issued Accounting Standards In March 2020, the Financial Accounting Standards Board ("FASB") issued ASU 2020-04, " Reference Rate Reform (Topic 848) ." ASU 2020-04 and subsequent amendments contain practical expedients for reference rate reform related activities that impact debt, leases, derivatives and other contracts. The guidance in ASU 2020-04 is optional and may be elected over time as reference rate reform activities occur through December 31, 2022. The Company continues to evaluate the impact of the guidance and may apply other elections as applicable as additional changes in the market occur. In August 2020, the FASB issued ASU 2020-06, " Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) ." ASU 2020-06 simplifies the accounting for convertible instruments and contracts in an entity's own equity, and amended related earnings per share guidance. The guidance in ASU 2020-06 becomes effective for fiscal years beginning after December 15, 2021. Early adoption is permitted no earlier than the fiscal years beginning after December 15, 2020. The guidance may be adopted on a modified or fully retrospective basis. The Company is currently assessing the impact of the adoption of ASU 2020-06 on its consolidated financial statements.

Fair Value Disclosures

Fair Value Disclosures	6 Months Ended
	Jun. 30, 2021
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 June 30, 2021, the Company 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 has 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 June 30, 2021, aggregated by the level in the fair value hierarchy within which those measurements fall. Fair Value Measurements at Reporting Date Using Description Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other assets - Cash flow hedge swap agreements $ — $ — $ — Other liabilities - Cash flow hedge swap agreements $ — $ 69,551 $ — The Company did not have any significant assets or liabilities that are re-measured on a recurring basis using significant unobservable inputs as of June 30, 2021 or December 31, 2020. 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 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 an impairment loss on the assets held for sale. The operations of assets held for sale or sold during the period is presented as part of normal operations for all periods presented. As of June 30, 2021, the Company had 17 operating stores classified as held for sale which are included in real estate assets, net. The Company assesses annually 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. Any 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 are capitalized as part of the purchase price. 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 June 30, 2021 and December 31, 2020 approximate fair value. Restricted cash is comprised of funds deposited with financial institutions located throughout the United States primarily relating to earnest money deposits on potential acquisitions. The fair values of the Company’s notes receivable from Preferred and Common 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 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 values of the Company’s fixed-rate assets and liabilities were as follows for the periods indicated: June 30, 2021 December 31, 2020 Fair Carrying Fair Carrying Notes receivable from Preferred and Common Operating Partnership unit holders $ 100,458 $ 101,900 $ 102,333 $ 102,311 Fixed rate notes receivable $ 107,454 $ 104,000 $ 114,145 $ 104,000 Fixed rate notes payable $ 4,001,843 $ 3,925,841 $ 3,816,530 $ 3,637,220

Earnings Per Common Share

Earnings Per Common Share	6 Months Ended
	Jun. 30, 2021
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 D Redeemable Preferred Units (“Series D Units” and, together with the Series A Units and Series B Units, the “Preferred OP 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 (i.e. those that reduce earnings per common share) are included. For the three and six months ended June 30, 2021 and 2020, there were no anti-dilutive options. 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 June 30, 2021 and 2020 was $149.81 and $92.95, 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 June 30, For the Six Months Ended June 30, 2021 2020 2021 2020 Equivalent Shares (if converted) Equivalent Shares (if converted) Equivalent Shares (if converted) Equivalent Shares (if converted) Common OP Units — 5,876,356 — 5,898,029 Series A Units (Variable Only) — 875,480 — 875,480 Series B Units 273,027 450,803 301,483 425,446 Series D Units 783,406 1,282,322 — 1,214,732 1,056,433 8,484,961 301,483 8,413,687 As of June 30, 2021, the Operating Partnership had no exchangeable senior notes issued or outstanding. The Operating Partnership had $575,000 of its 3.125% Exchangeable Senior Notes due 2035 (the “2015 Notes”) issued and outstanding as of June 30, 2020. In October and November 2020, a portion of the 2015 Notes were exchanged for cash and shares of the Company’s common stock and the remaining 2015 Notes were redeemed for cash. The 2015 Notes could potentially have had a dilutive impact on the Company’s earnings per share calculations. The 2015 Notes were 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 Company had 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 had retained the right to satisfy the exchange obligation in excess of the accreted principal amount of the 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 the exchange obligation in excess of the accreted principal amount, 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 and six months ended June 30, 2021 and 2020, zero and 121,283 shares, respectively, related to the 2015 Notes were included in the computation for diluted earnings per share. 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 $101,700 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 $101,700 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 $101,700 amount. The computation of earnings per common share is as follows for the periods presented: For the Three Months Ended June 30, For the Six Months Ended June 30, 2021 2020 2021 2020 Net income attributable to common stockholders $ 167,948 $ 102,911 $ 370,946 $ 211,090 Earnings and dividends allocated to participating securities (232) (173) (541) (336) Earnings for basic computations 167,716 102,738 370,405 210,754 Income allocated to noncontrolling interest - Preferred Operating Partnership Units and Operating Partnership Units 8,833 — 21,889 — Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units) (572) — (1,144) — Net income for diluted computations $ 175,977 $ 102,738 $ 391,150 $ 210,754 Weighted average common shares outstanding: Average number of common shares outstanding - basic 133,756,610 128,932,152 132,886,933 129,110,131 OP Units 5,767,460 — 5,784,003 — Series A Units 875,480 — 875,480 — Series D Units — — 865,056 — Shares related to exchangeable senior notes and dilutive stock options 7,645 150,316 17,086 175,544 Average number of common shares outstanding - diluted 140,407,195 129,082,468 140,428,558 129,285,675 Earnings per common share Basic $ 1.25 $ 0.80 $ 2.79 $ 1.63 Diluted $ 1.25 $ 0.80 $ 2.79 $ 1.63

Store Acquisitions and Disposit

Store Acquisitions and Dispositions	6 Months Ended
	Jun. 30, 2021
Real Estate [Abstract]
Store Acquisitions and Dispositions	STORE ACQUISITIONS AND DISPOSITIONS Store Acquisitions The following table shows the Company’s acquisitions of stores for the three and six months ended June 30, 2021 and 2020. The table excludes purchases of raw land and improvements made to existing assets. All acquisitions are considered asset acquisitions under ASU 2017-01, " Business Combinations (Topic 805): Clarifying the Definition of a Business ." Consideration Paid Total Quarter Number of Stores Total Cash Paid Investments in Real Estate Ventures Net Liabilities/ (Assets) Assumed Real estate assets Q2 2021 15 (1) $ 193,783 $ 190,729 $ 2,673 $ 381 $ 193,783 Q1 2021 9 151,884 148,940 — 2,944 151,884 24 $ 345,667 $ 339,669 $ 2,673 $ 3,325 $ 345,667 Q2 2020 — $ — $ — $ — $ — $ — Q1 2020 2 19,399 19,354 — 45 19,399 2 $ 19,399 $ 19,354 $ — $ 45 $ 19,399 (1) Store acquisitions for the three months ended June 30, 2021 include the acquisition of two stores previously held in joint ventures where the Company held a noncontrolling interest. The Company purchased its partners' equity interests in these joint ventures, and the properties owned by the joint ventures became wholly owned by the Company. No gain or loss was recognized as a result of these acquisitions. Store Dispositions On March 1, 2021, the Company sold 16 stores that had been classified as held for sale to a newly established unconsolidated joint venture. The Company received cash of $132,759 and maintained a 55% interest in the new joint venture valued at $33,878. The Company recognized a gain of $64,804 related to the sale of these properties.

Investments in Unconsolidated R

Investments in Unconsolidated Real Estate Entities	6 Months Ended
	Jun. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
Investments in Unconsolidated Real Estate Entities	INVESTMENTS IN UNCONSOLIDATED REAL ESTATE ENTITIES Investments in unconsolidated real estate entities and cash distributions in unconsolidated real estate ventures represent the Company's interest in preferred stock of SmartStop Self Storage REIT, Inc. ("SmartStop") and the Company's noncontrolling interest in real estate joint ventures that own stores. The Company accounts for its investment in SmartStop preferred stock, which does not have a readily determinable fair value, at the transaction price less impairment, if any. The Company accounts for its investments in joint ventures using the equity method of accounting. The Company initially records these investments at cost and subsequently adjusts for cash contributions, distributions and net equity in income or loss, which is allocated in accordance with the provisions of the applicable partnership or joint venture agreement. In these joint ventures, the Company and the joint venture partner generally receive a preferred return on their invested capital. To the extent that cash or profits in excess of these preferred returns are generated through operations or capital transactions, the Company would receive a higher percentage of the excess cash or profits than its equity interest. The Company separately reports investments with net equity less than zero in cash distributions in unconsolidated real estate ventures in the condensed consolidated balance sheets. The net equity of certain joint ventures is less than zero because distributions have exceeded the Company's investment in and share of income from these joint ventures. This is generally the result of financing distributions, capital events or operating distributions that are usually greater than net income, as net income includes non-cash charges for depreciation and amortization while distributions do not. Net investments in unconsolidated real estate ventures and cash distributions in unconsolidated real estate ventures consist of the following: Number of Stores Equity Ownership % Excess Profit % (1) June 30, December 31, 2021 2020 PR EXR Self Storage, LLC 5 25% 40% $ 59,865 $ 60,092 WICNN JV LLC — 10% 35% — 36,032 ESS-CA TIVS JV LP (2) 16 55% 60% 34,000 — GFN JV, LLC — 10% 30% — 18,397 ESS-NYFL JV LP 11 16% 24% 12,025 12,211 PRISA Self Storage LLC 85 4% 4% 8,717 8,815 Alan Jathoo JV LLC 9 10% 10% 7,689 7,780 Storage Portfolio IV JV LLC 5 10% 30% 6,909 — Storage Portfolio III JV LLC 5 10% 30% 5,649 5,726 ESS Bristol Investments LLC 8 10% 30% 2,743 2,810 Extra Space Northern Properties Six LLC 10 10% 35% (2,737) (2,541) Storage Portfolio II JV LLC 36 10% 30% (5,771) (5,441) VRS Self Storage, LLC 16 45% 54% (14,499) 17,186 Storage Portfolio I LLC 24 34% 49% (39,697) (39,144) Other minority owned stores 17 10-50% 19-50% 23,631 28,395 SmartStop Self Storage REIT, Inc. Preferred Stock (3) n/a n/a n/a 200,000 200,000 Net Investments in and Cash distributions in unconsolidated real estate entities 247 $ 298,524 $ 350,318 (1) Includes pro-rata equity ownership share and maximum potential promoted interest. (2) The Company sold 16 operating stores to this newly formed joint venture in March 2021. The Company received cash of $132,759 and an interest in the new joint venture valued at $33,878. This joint venture is unconsolidated and the Company accounts for its investment under the equity method of accounting as the Company does not have voting control but does exercise significant influence over the joint venture. (3) The Company invested in shares of convertible preferred stock of SmartStop. The dividend rate for the preferred shares is 6.25% per annum, subject to increase after five years. The preferred shares are generally not redeemable for five years, except in the case of a change of control or initial listing of SmartStop. Dividend income from this investment is included on the equity in earnings and dividend income from unconsolidated real estate entities line on the Company's condensed consolidated statements of operations. During the six months ended June 30, 2021, the Company contributed a total of $7,174 of cash to its joint ventures, including its pro-rata portion of the purchase price of five operating stores and other capital contributions related to cash flow requirements for lease up stores. In June 2021, the Company sold its interest in two unconsolidated joint ventures to its joint venture partner. The Company received proceeds of $1,888 in cash, and recorded a gain of $525 which 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 in the Company's condensed consolidated statements of operations. The Company also purchased its joint venture partners' interests in two unconsolidated joint ventures. In June 2021, the WICNN JV LLC and GFN JV, LLC joint ventures sold all 17 of the stores owned by the joint ventures to a third party. Subsequent to the sales, these joint ventures were dissolved. As a result of these transactions, the Company recorded a gain of $5,739, which 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 in the Company's condensed consolidated statements of operations.

Investments in Debt Securities

Investments in Debt Securities and Notes Receivable	6 Months Ended
	Jun. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Investments in Debt Securities and Notes Receivable	INVESTMENTS IN DEBT SECURITIES AND NOTES RECEIVABLE Investments in debt securities and notes receivable consists of the Company's investment in mandatorily redeemable preferred stock of Jernigan Capital, Inc. ("JCAP") in connection with JCAP's acquisition by affiliates of NexPoint Advisors, L.P. ("NexPoint Investment") and receivables due to the Company under its bridge loan program. Information about these balances is as follows: June 30, 2021 December 31, 2020 Debt securities - NexPoint Series A Preferred Stock $ 200,000 $ 200,000 Debt securities - NexPoint Series B Preferred Stock 100,000 100,000 Notes Receivable-Bridge Loans 145,581 187,368 Notes Receivable-Senior Mezzanine Loan, net 101,830 101,553 Dividends Receivable 21,370 4,889 $ 568,781 $ 593,810 In November 2020, the Company invested $300,000 in the preferred stock of JCAP in connection with the acquisition of JCAP by affiliates of NexPoint Advisors, L.P. This investment consists of 200,000 Series A Preferred Shares valued at a total of $200,000, and 100,000 Series B Preferred Shares valued at a total of $100,000. The JCAP preferred stock is mandatorily redeemable after five years, with two one-year extension options. NexPoint may redeem the Preferred Shares at any time, subject to certain prepayment penalties. The Company accounts for the JCAP preferred stock as a held to maturity debt security at amortized cost. The Series A Preferred Shares and the Series B Preferred Shares have initial dividend rates of 10.0% and 12.0%, respectively. If the investment is not retired after five years, the preferred dividends increase annually. In July 2020, the Company purchased a senior mezzanine note receivable with a principal amount of $103,000. This note receivable bears interest at 5.5%, matures in December 2023 and is collateralized through an equity interest in which it or its subsidiaries wholly own 62 storage facilities. The Company paid cash of $101,142 for the loan receivable and accounts for the discount at amortized cost. The discount is being amortized over the term of the loan receivable.

Notes Payable, Net

Notes Payable, Net	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Notes Payable, Net	NOTES PAYABLE, NETIn May 2021, the Operating Partnership executed its initial public bond issuance by selling $450.0 million principal amount of 2.550% Senior Notes due 2031 (the "Notes"). Interest on the Notes is paid semi-annually in arrears on June 1 and December 1 of each year. The Notes will mature on June 1, 2031, and the Operating Partnership may redeem the Notes at its option and sole discretion at any time prior to March 31, 2031 for cash equal to the outstanding principal amount plus the present value of the remaining scheduled interest payments, plus any accrued but unpaid interest. The Notes are unsecured, and are fully and unconditionally guaranteed by the Company, ESS Holdings Business Trust I, and ESS Holdings Business Trust II (the "Guarantors," and together with the Operating Partnership, the "Obligated Group"), on a joint and several basis. The guarantee of the Notes will be a senior unsecured obligation of each Guarantor. The Guarantors have no material operations separate from the operation of the Operating Partnership and no material assets, other than their respective investments directly or indirectly in the Operating Partnership, and therefore the assets, liabilities, and results of operations of the Obligated Group are not materially different than those reported in the Company's financial statements.

Derivatives

Derivatives	6 Months Ended
	Jun. 30, 2021
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 and six months ended June 30, 2021 and 2020, 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 $35,455 will be reclassified and increase interest expense. The Company held 20 derivative financial instruments which had a total combined notional amount of $1,989,896 as of June 30, 2021. 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 Derivatives designated as hedging instruments: June 30, 2021 December 31, 2020 Other assets $ — $ — Other liabilities $ 69,551 $ 98,325 Effect of Derivative Instruments The table below presents 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 For the Three Months Ended June 30, Location of amounts reclassified from OCI into income Gain (loss) reclassified from OCI For the Three Months Ended June 30, Type 2021 2020 2021 2020 Swap Agreements $ (3,124) $ (13,350) Interest expense $ (8,747) $ (7,639) Gain (loss) recognized in OCI For the Six Months Ended June 30, Location of amounts reclassified from OCI into income Gain (loss) reclassified from OCI For the Six Months Ended June 30, Type 2021 2020 2021 2020 Swap Agreements $ 11,052 $ (103,060) Interest expense $ (17,592) $ (8,202) 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 June 30, 2021, 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 $71,694. As of June 30, 2021, the Company had not posted any collateral related to these agreements. If the Company had breached any of these provisions as of June 30, 2021, it could have been required to cash settle its obligations under the agreements at their termination value of $71,694, including accrued interest.

Exchangeable Senior Notes

Exchangeable Senior Notes	6 Months Ended
	Jun. 30, 2021
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 were amortized as an adjustment to interest expense over five years, which represented the estimated term based on the first available redemption date, and are included in exchangeable senior notes, net, in the condensed consolidated balance sheets. Prior to the full redemption of the 2015 Notes in November 2020 as described below, the 2015 Notes were general unsecured senior obligations of the Operating Partnership and were fully guaranteed by the Company. Interest was 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 bore interest at 3.125% per annum and contained an exchange settlement feature, which provided that the 2015 Notes could have been, under certain circumstances, 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. 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 accounted for the liability and equity components of the 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 were amortized as interest expense over the remaining period of the debt through its first redemption date of October 1, 2020. The effective interest rate on the liability components of the 2015 Notes was 4.0%, which approximated the market rate of interest of similar debt without exchange features (i.e. nonconvertible debt) at the time of issuance. The amount of interest cost recognized relating to the contractual interest rate and the amortization of the discount on the liability component of the Notes were as follows for the periods indicated: For the Three Months Ended June 30, For the Six Months Ended June 30, 2021 2020 2021 2020 Contractual interest $ — $ 4,492 $ — $ 8,984 Amortization of discount — 1,233 — 2,442 Total interest expense recognized $ — $ 5,725 $ — $ 11,426

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2021
Stockholders' Equity Note [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY On May 15, 2019, the Company filed its $500,000 "at the market" equity program with the Securities and Exchange Commission using a shelf registration statement on Form S-3, and entered into separate equity distribution agreements with nine sales agents. During the six months ended June 30, 2021, the Company sold 585,685 shares of common stock under its "at the market" equity program resulting in net proceeds of $66,937. As of June 30, 2021, the Company did not have an active ATM program, and anticipates filing a new plan in the third quarter of 2021. On March 23, 2021, the Company sold 1,600,000 shares of its common stock in a registered offering structured as a bought deal at a price of $129.13 per share resulting in net proceeds of $206,573.

Noncontrolling Interest Represe

Noncontrolling Interest Represented by Preferred Operating Partnership Units	6 Months Ended
	Jun. 30, 2021
Noncontrolling Interest [Abstract]
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. At June 30, 2021 and December 31, 2020, the noncontrolling interests represented by the Preferred OP Units qualified for classification as permanent equity on the Company's condensed consolidated balance sheets. The partnership agreement of the Operating Partnership (as amended, the "Partnership Agreement") provides for the designation and issuance of the OP Units. As of June 30, 2021 and December 31, 2020, noncontrolling interests in Preferred OP Units were presented net of notes receivable from Preferred OP Unit holders of $100,000 as more fully described below. The balances for each of the specific Preferred OP Units as presented in the Statement of Noncontrolling Interests and Equity as of the periods indicated is as follows: June 30, 2021 December 31, 2020 Series A Units $ 14,638 $ 13,788 Series B Units 40,902 40,902 Series D Units 117,362 117,362 $ 172,902 $ 172,052 Series A Participating Redeemable Preferred Units The Partnership Agreement provides for the designation and issuance of the Series A Units. The Series A Units have priority over all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series A Units were issued in June 2007. Series A Units in the amount of $101,700 bear a fixed priority return of 2.3% and originally had 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. As a result of the redemption of 114,500 Series A Units in October 2014, the remaining fixed liquidation value was reduced to $101,700, which represents 875,480 Series A Units. On June 25, 2007, the Operating Partnership loaned the holder of the Series A Units $100,000. The loan bears interest at 2.1%. The loan is secured by the borrower’s Series A Units. No future redemption of Series A Units can be made unless the loan secured by the Series A Units is also repaid. 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 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 Series B Units were issued in 2013 and 2014 and have a liquidation value of $25.00 per unit for a fixed liquidation value of $40,902, which represents 1,636,087 Series B Units. 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 Partnership Agreement provides for the designation and issuance of the Series C Units. The Series C Units ranked 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 Series C Units were issued in 2013 and 2014 and had a liquidation value of $42.10 per unit. The Series C Units became redeemable at the option of the holder one year from the date of issuance, which redemption obligation could be satisfied at the Company’s option in cash or shares of its common stock. The Series C Units were 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 expired 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 loan receivable, which was collateralized by the Series C Units, bears interest at 5.0% per annum and matures on December 15, 2024. The Series C Units were shown on the balance sheet net of the loan balance because the borrower under the loan receivable was also the holder of the Series C Units. On December 1, 2018, certain holders of the Series C Units converted their Series C Units into OP Units, with a total of 407,996 Series C Units being converted into a total of 373,113 OP Units. On April 25, 2019, the remaining 296,020 Series C Units were converted into 270,709 OP Units. The remaining outstanding balance of the loan receivable of $1,900 is shown as a reduction of the noncontrolling interests related to the OP Units as of June 30, 2021 and December 31, 2020. See footnote 13 for further discussion of noncontrolling interests. Series D Redeemable Preferred Units 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 been issued at various times from 2014 to 2019. The Series D Units have a liquidation value of $25.00 per unit, for a fixed liquidation value of $117,362, which represents 4,694,485 Series D Units. Holders of the Series D Units receive distributions at an annual rate between 3.0% and 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, certain of the Series D Units are exchangeable for 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 Series D Unit, divided by the value of a share of common stock as of the exchange date. Noncontrolling Interest in Operating Partnership The Company’s interest in its stores is held through the Operating Partnership. Between its general partner and limited partner interests, the Company held a 94.6% ownership interest in the Operating Partnership as of June 30, 2021. The remaining ownership interests in the Operating Partnership (including Preferred OP Units) of 5.4% are held by certain former owners of assets acquired by the Operating Partnership. As of June 30, 2021 and December 31, 2020, the noncontrolling interests in the Operating Partnership are shown on the balance sheet net of notes receivable of $1,900 and $2,311, respectively, because the borrowers under the loan receivable are also holders of OP Units (Note 12). This loan receivable bears interest at 5.0% per annum and matures on December 15, 2024. The noncontrolling interest in the Operating Partnership represents OP Units that are not owned by the Company. OP Units are redeemable at the option of the holder, which redemption may be satisfied at the Company's option in 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, or shares of the Company's common stock on a one-for-one basis, subject to anti-dilution adjustments provided in the Partnership Agreement. As of June 30, 2021, the ten-day average closing price of the Company's common stock was $163.63 and there were 5,734,356 OP Units outstanding. Assuming that all of the OP Unit holders exercised their right to redeem all of their OP Units on June 30, 2021 and the Company elected to pay the OP Unit holders cash, the Company would have paid $938,313 in cash consideration to redeem the units. OP Unit activity is summarized as follows for the periods presented: For the Six Months Ended June 30, 2021 2020 OP Units redeemed for common stock 63,429 108,862 OP Units redeemed for cash 3,000 — Cash paid for OP Units redeemed $ 472 $ — 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

Noncontrolling Interest in Oper

Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests	6 Months Ended
	Jun. 30, 2021
Noncontrolling Interest [Abstract]
Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests	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. At June 30, 2021 and December 31, 2020, the noncontrolling interests represented by the Preferred OP Units qualified for classification as permanent equity on the Company's condensed consolidated balance sheets. The partnership agreement of the Operating Partnership (as amended, the "Partnership Agreement") provides for the designation and issuance of the OP Units. As of June 30, 2021 and December 31, 2020, noncontrolling interests in Preferred OP Units were presented net of notes receivable from Preferred OP Unit holders of $100,000 as more fully described below. The balances for each of the specific Preferred OP Units as presented in the Statement of Noncontrolling Interests and Equity as of the periods indicated is as follows: June 30, 2021 December 31, 2020 Series A Units $ 14,638 $ 13,788 Series B Units 40,902 40,902 Series D Units 117,362 117,362 $ 172,902 $ 172,052 Series A Participating Redeemable Preferred Units The Partnership Agreement provides for the designation and issuance of the Series A Units. The Series A Units have priority over all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series A Units were issued in June 2007. Series A Units in the amount of $101,700 bear a fixed priority return of 2.3% and originally had 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. As a result of the redemption of 114,500 Series A Units in October 2014, the remaining fixed liquidation value was reduced to $101,700, which represents 875,480 Series A Units. On June 25, 2007, the Operating Partnership loaned the holder of the Series A Units $100,000. The loan bears interest at 2.1%. The loan is secured by the borrower’s Series A Units. No future redemption of Series A Units can be made unless the loan secured by the Series A Units is also repaid. 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 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 Series B Units were issued in 2013 and 2014 and have a liquidation value of $25.00 per unit for a fixed liquidation value of $40,902, which represents 1,636,087 Series B Units. 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 Partnership Agreement provides for the designation and issuance of the Series C Units. The Series C Units ranked 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 Series C Units were issued in 2013 and 2014 and had a liquidation value of $42.10 per unit. The Series C Units became redeemable at the option of the holder one year from the date of issuance, which redemption obligation could be satisfied at the Company’s option in cash or shares of its common stock. The Series C Units were 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 expired 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 loan receivable, which was collateralized by the Series C Units, bears interest at 5.0% per annum and matures on December 15, 2024. The Series C Units were shown on the balance sheet net of the loan balance because the borrower under the loan receivable was also the holder of the Series C Units. On December 1, 2018, certain holders of the Series C Units converted their Series C Units into OP Units, with a total of 407,996 Series C Units being converted into a total of 373,113 OP Units. On April 25, 2019, the remaining 296,020 Series C Units were converted into 270,709 OP Units. The remaining outstanding balance of the loan receivable of $1,900 is shown as a reduction of the noncontrolling interests related to the OP Units as of June 30, 2021 and December 31, 2020. See footnote 13 for further discussion of noncontrolling interests. Series D Redeemable Preferred Units 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 been issued at various times from 2014 to 2019. The Series D Units have a liquidation value of $25.00 per unit, for a fixed liquidation value of $117,362, which represents 4,694,485 Series D Units. Holders of the Series D Units receive distributions at an annual rate between 3.0% and 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, certain of the Series D Units are exchangeable for 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 Series D Unit, divided by the value of a share of common stock as of the exchange date. Noncontrolling Interest in Operating Partnership The Company’s interest in its stores is held through the Operating Partnership. Between its general partner and limited partner interests, the Company held a 94.6% ownership interest in the Operating Partnership as of June 30, 2021. The remaining ownership interests in the Operating Partnership (including Preferred OP Units) of 5.4% are held by certain former owners of assets acquired by the Operating Partnership. As of June 30, 2021 and December 31, 2020, the noncontrolling interests in the Operating Partnership are shown on the balance sheet net of notes receivable of $1,900 and $2,311, respectively, because the borrowers under the loan receivable are also holders of OP Units (Note 12). This loan receivable bears interest at 5.0% per annum and matures on December 15, 2024. The noncontrolling interest in the Operating Partnership represents OP Units that are not owned by the Company. OP Units are redeemable at the option of the holder, which redemption may be satisfied at the Company's option in 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, or shares of the Company's common stock on a one-for-one basis, subject to anti-dilution adjustments provided in the Partnership Agreement. As of June 30, 2021, the ten-day average closing price of the Company's common stock was $163.63 and there were 5,734,356 OP Units outstanding. Assuming that all of the OP Unit holders exercised their right to redeem all of their OP Units on June 30, 2021 and the Company elected to pay the OP Unit holders cash, the Company would have paid $938,313 in cash consideration to redeem the units. OP Unit activity is summarized as follows for the periods presented: For the Six Months Ended June 30, 2021 2020 OP Units redeemed for common stock 63,429 108,862 OP Units redeemed for cash 3,000 — Cash paid for OP Units redeemed $ 472 $ — 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

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION The Company’s segment disclosures present the measure used by the chief operating decision makers ("CODMs") for purposes of assessing each segment’s performance. The Company’s CODMs are comprised of several members of its executive management team who use net operating income ("NOI") to assess the performance of the business for the Company’s reportable operating segments. NOI for the Company's self-storage operations represents total property revenue less direct property operating expenses. NOI for the Company's tenant reinsurance segment represents tenant reinsurance revenues less tenant reinsurance expense. The Company has two reportable segments: (1) self-storage operations and (2) tenant reinsurance. The self-storage operations activities include rental operations of wholly-owned stores. The Company's consolidated revenues equal total segment revenues plus property management fees and other income. Tenant reinsurance activities include the reinsurance of risks relating to the loss of goods stored by tenants in the stores operated by the Company. Excluded from segment revenues and net operating income is property management fees and other income. For all periods presented, substantially all of the Company's real estate assets, intangible assets, other assets, and accrued and other liabilities are associated with the self-storage operations segment. Financial information for the Company’s business segments is set forth below: For the Three Months Ended June 30, For the Six Months Ended June 30, 2021 2020 2021 2020 Revenues: Self-Storage Operations $ 321,500 $ 279,312 $ 625,093 $ 566,015 Tenant Reinsurance 42,334 35,078 81,953 68,691 Total segment revenues $ 363,834 $ 314,390 $ 707,046 $ 634,706 Operating expenses: Self-Storage Operations $ 89,155 $ 89,040 $ 181,522 $ 179,337 Tenant Reinsurance 6,735 6,858 13,896 13,536 Total segment operating expenses $ 95,890 $ 95,898 $ 195,418 $ 192,873 Net operating income: Self-Storage Operations $ 232,345 $ 190,272 $ 443,571 $ 386,678 Tenant Reinsurance 35,599 28,220 68,057 55,155 Total segment net operating income: $ 267,944 $ 218,492 $ 511,628 $ 441,833 Other components of net income: Management fees and other income $ 14,796 $ 12,856 $ 30,441 $ 24,992 General and administrative expense (26,341) (25,337) (49,881) (48,348) Depreciation and amortization expense (59,570) (56,018) (118,169) (111,293) Gain on real estate transactions — — 63,883 — Interest expense (40,240) (41,039) (80,935) (85,397) Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes — (1,233) — (2,442) Interest income 12,838 1,669 25,142 3,343 Equity in earnings and dividend income from unconsolidated real estate entities 8,322 5,044 15,278 10,087 Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of joint venture partner's interest 6,251 — 6,251 — Income tax expense (5,421) (3,177) (9,558) (5,356) Net income $ 178,579 $ 111,257 $ 394,080 $ 227,419

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES As of June 30, 2021, the Company was involved in various legal proceedings and was 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. 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. As of June 30, 2021, the Company was under agreement to acquire three stores at a total purchase price of $28,850. All three stores are scheduled to close in 2021. Additionally, the Company is under agreement to acquire seven stores with joint venture partners, for a total investment of $9,890. These stores are also expected to close in 2021. 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)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
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 and six months ended June 30, 2021 are not necessarily indicative of results that may be expected for the year ending December 31, 2021. The condensed consolidated balance sheet as of December 31, 2020 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, 2020, as filed with the Securities and Exchange Commission.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In March 2020, the Financial Accounting Standards Board ("FASB") issued ASU 2020-04, " Reference Rate Reform (Topic 848) ." ASU 2020-04 and subsequent amendments contain practical expedients for reference rate reform related activities that impact debt, leases, derivatives and other contracts. The guidance in ASU 2020-04 is optional and may be elected over time as reference rate reform activities occur through December 31, 2022. The Company continues to evaluate the impact of the guidance and may apply other elections as applicable as additional changes in the market occur. In August 2020, the FASB issued ASU 2020-06, " Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) ." ASU 2020-06 simplifies the accounting for convertible instruments and contracts in an entity's own equity, and amended related earnings per share guidance. The guidance in ASU 2020-06 becomes effective for fiscal years beginning after December 15, 2021. Early adoption is permitted no earlier than the fiscal years beginning after December 15, 2020. The guidance may be adopted on a modified or fully retrospective basis. The Company is currently assessing the impact of the adoption of ASU 2020-06 on its consolidated financial statements.

Fair Value Disclosures (Tables)

Fair Value Disclosures (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The table below presents the Company’s assets and liabilities measured at fair value on a recurring basis as of June 30, 2021, aggregated by the level in the fair value hierarchy within which those measurements fall. Fair Value Measurements at Reporting Date Using Description Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other assets - Cash flow hedge swap agreements $ — $ — $ — Other liabilities - Cash flow hedge swap agreements $ — $ 69,551 $ —
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: June 30, 2021 December 31, 2020 Fair Carrying Fair Carrying Notes receivable from Preferred and Common Operating Partnership unit holders $ 100,458 $ 101,900 $ 102,333 $ 102,311 Fixed rate notes receivable $ 107,454 $ 104,000 $ 114,145 $ 104,000 Fixed rate notes payable $ 4,001,843 $ 3,925,841 $ 3,816,530 $ 3,637,220

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	6 Months Ended
	Jun. 30, 2021
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 June 30, For the Six Months Ended June 30, 2021 2020 2021 2020 Equivalent Shares (if converted) Equivalent Shares (if converted) Equivalent Shares (if converted) Equivalent Shares (if converted) Common OP Units — 5,876,356 — 5,898,029 Series A Units (Variable Only) — 875,480 — 875,480 Series B Units 273,027 450,803 301,483 425,446 Series D Units 783,406 1,282,322 — 1,214,732 1,056,433 8,484,961 301,483 8,413,687
Schedule of Computation of Earnings Per Common Share	The computation of earnings per common share is as follows for the periods presented: For the Three Months Ended June 30, For the Six Months Ended June 30, 2021 2020 2021 2020 Net income attributable to common stockholders $ 167,948 $ 102,911 $ 370,946 $ 211,090 Earnings and dividends allocated to participating securities (232) (173) (541) (336) Earnings for basic computations 167,716 102,738 370,405 210,754 Income allocated to noncontrolling interest - Preferred Operating Partnership Units and Operating Partnership Units 8,833 — 21,889 — Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units) (572) — (1,144) — Net income for diluted computations $ 175,977 $ 102,738 $ 391,150 $ 210,754 Weighted average common shares outstanding: Average number of common shares outstanding - basic 133,756,610 128,932,152 132,886,933 129,110,131 OP Units 5,767,460 — 5,784,003 — Series A Units 875,480 — 875,480 — Series D Units — — 865,056 — Shares related to exchangeable senior notes and dilutive stock options 7,645 150,316 17,086 175,544 Average number of common shares outstanding - diluted 140,407,195 129,082,468 140,428,558 129,285,675 Earnings per common share Basic $ 1.25 $ 0.80 $ 2.79 $ 1.63 Diluted $ 1.25 $ 0.80 $ 2.79 $ 1.63

Store Acquisitions and Dispos_2

Store Acquisitions and Dispositions (Tables)	6 Months Ended
	Jun. 30, 2021
Real Estate [Abstract]
Schedule of Operating Properties Acquired	The following table shows the Company’s acquisitions of stores for the three and six months ended June 30, 2021 and 2020. The table excludes purchases of raw land and improvements made to existing assets. All acquisitions are considered asset acquisitions under ASU 2017-01, " Business Combinations (Topic 805): Clarifying the Definition of a Business ." Consideration Paid Total Quarter Number of Stores Total Cash Paid Investments in Real Estate Ventures Net Liabilities/ (Assets) Assumed Real estate assets Q2 2021 15 (1) $ 193,783 $ 190,729 $ 2,673 $ 381 $ 193,783 Q1 2021 9 151,884 148,940 — 2,944 151,884 24 $ 345,667 $ 339,669 $ 2,673 $ 3,325 $ 345,667 Q2 2020 — $ — $ — $ — $ — $ — Q1 2020 2 19,399 19,354 — 45 19,399 2 $ 19,399 $ 19,354 $ — $ 45 $ 19,399 (1) Store acquisitions for the three months ended June 30, 2021 include the acquisition of two stores previously held in joint ventures where the Company held a noncontrolling interest. The Company purchased its partners' equity interests in these joint ventures, and the properties owned by the joint ventures became wholly owned by the Company. No gain or loss was recognized as a result of these acquisitions.

Investments in Unconsolidated_2

Investments in Unconsolidated Real Estate Entities (Tables)	6 Months Ended
	Jun. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
Schedule of investments in unconsolidated real estate ventures	Net investments in unconsolidated real estate ventures and cash distributions in unconsolidated real estate ventures consist of the following: Number of Stores Equity Ownership % Excess Profit % (1) June 30, December 31, 2021 2020 PR EXR Self Storage, LLC 5 25% 40% $ 59,865 $ 60,092 WICNN JV LLC — 10% 35% — 36,032 ESS-CA TIVS JV LP (2) 16 55% 60% 34,000 — GFN JV, LLC — 10% 30% — 18,397 ESS-NYFL JV LP 11 16% 24% 12,025 12,211 PRISA Self Storage LLC 85 4% 4% 8,717 8,815 Alan Jathoo JV LLC 9 10% 10% 7,689 7,780 Storage Portfolio IV JV LLC 5 10% 30% 6,909 — Storage Portfolio III JV LLC 5 10% 30% 5,649 5,726 ESS Bristol Investments LLC 8 10% 30% 2,743 2,810 Extra Space Northern Properties Six LLC 10 10% 35% (2,737) (2,541) Storage Portfolio II JV LLC 36 10% 30% (5,771) (5,441) VRS Self Storage, LLC 16 45% 54% (14,499) 17,186 Storage Portfolio I LLC 24 34% 49% (39,697) (39,144) Other minority owned stores 17 10-50% 19-50% 23,631 28,395 SmartStop Self Storage REIT, Inc. Preferred Stock (3) n/a n/a n/a 200,000 200,000 Net Investments in and Cash distributions in unconsolidated real estate entities 247 $ 298,524 $ 350,318 (1) Includes pro-rata equity ownership share and maximum potential promoted interest. (2) The Company sold 16 operating stores to this newly formed joint venture in March 2021. The Company received cash of $132,759 and an interest in the new joint venture valued at $33,878. This joint venture is unconsolidated and the Company accounts for its investment under the equity method of accounting as the Company does not have voting control but does exercise significant influence over the joint venture. (3) The Company invested in shares of convertible preferred stock of SmartStop. The dividend rate for the preferred shares is 6.25% per annum, subject to increase after five years. The preferred shares are generally not redeemable for five years, except in the case of a change of control or initial listing of SmartStop. Dividend income from this investment is included on the equity in earnings and dividend income from unconsolidated real estate entities line on the Company's condensed consolidated statements of operations.

Investments in Debt Securitie_2

Investments in Debt Securities and Notes Receivable (Tables)	6 Months Ended
	Jun. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Investments in Debt Securities and Bridge Loans Receivable	Information about these balances is as follows: June 30, 2021 December 31, 2020 Debt securities - NexPoint Series A Preferred Stock $ 200,000 $ 200,000 Debt securities - NexPoint Series B Preferred Stock 100,000 100,000 Notes Receivable-Bridge Loans 145,581 187,368 Notes Receivable-Senior Mezzanine Loan, net 101,830 101,553 Dividends Receivable 21,370 4,889 $ 568,781 $ 593,810

Derivatives (Tables)

Derivatives (Tables)	6 Months Ended
	Jun. 30, 2021
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 Derivatives designated as hedging instruments: June 30, 2021 December 31, 2020 Other assets $ — $ — Other liabilities $ 69,551 $ 98,325
Schedule of information relating to gain (loss) recognized on swap agreements	The table below presents 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 For the Three Months Ended June 30, Location of amounts reclassified from OCI into income Gain (loss) reclassified from OCI For the Three Months Ended June 30, Type 2021 2020 2021 2020 Swap Agreements $ (3,124) $ (13,350) Interest expense $ (8,747) $ (7,639) Gain (loss) recognized in OCI For the Six Months Ended June 30, Location of amounts reclassified from OCI into income Gain (loss) reclassified from OCI For the Six Months Ended June 30, Type 2021 2020 2021 2020 Swap Agreements $ 11,052 $ (103,060) Interest expense $ (17,592) $ (8,202)

Exchangeable Senior Notes (Tabl

Exchangeable Senior Notes (Tables)	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
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 rate and the amortization of the discount on the liability component of the Notes were as follows for the periods indicated: For the Three Months Ended June 30, For the Six Months Ended June 30, 2021 2020 2021 2020 Contractual interest $ — $ 4,492 $ — $ 8,984 Amortization of discount — 1,233 — 2,442 Total interest expense recognized $ — $ 5,725 $ — $ 11,426

Noncontrolling Interest (Tables

Noncontrolling Interest (Tables)	6 Months Ended
	Jun. 30, 2021
Noncontrolling Interest [Abstract]
Balances of OP Units	balances for each of the specific Preferred OP Units as presented in the Statement of Noncontrolling Interests and Equity as of the periods indicated is as follows: June 30, 2021 December 31, 2020 Series A Units $ 14,638 $ 13,788 Series B Units 40,902 40,902 Series D Units 117,362 117,362 $ 172,902 $ 172,052

Noncontrolling Interest in Op_2

Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests (Tables)	6 Months Ended
	Jun. 30, 2021
Noncontrolling Interest [Abstract]
Redeemable Noncontrolling Interest	OP Unit activity is summarized as follows for the periods presented: For the Six Months Ended June 30, 2021 2020 OP Units redeemed for common stock 63,429 108,862 OP Units redeemed for cash 3,000 — Cash paid for OP Units redeemed $ 472 $ —

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Schedule of Financial Information of Business Segments	Financial information for the Company’s business segments is set forth below: For the Three Months Ended June 30, For the Six Months Ended June 30, 2021 2020 2021 2020 Revenues: Self-Storage Operations $ 321,500 $ 279,312 $ 625,093 $ 566,015 Tenant Reinsurance 42,334 35,078 81,953 68,691 Total segment revenues $ 363,834 $ 314,390 $ 707,046 $ 634,706 Operating expenses: Self-Storage Operations $ 89,155 $ 89,040 $ 181,522 $ 179,337 Tenant Reinsurance 6,735 6,858 13,896 13,536 Total segment operating expenses $ 95,890 $ 95,898 $ 195,418 $ 192,873 Net operating income: Self-Storage Operations $ 232,345 $ 190,272 $ 443,571 $ 386,678 Tenant Reinsurance 35,599 28,220 68,057 55,155 Total segment net operating income: $ 267,944 $ 218,492 $ 511,628 $ 441,833 Other components of net income: Management fees and other income $ 14,796 $ 12,856 $ 30,441 $ 24,992 General and administrative expense (26,341) (25,337) (49,881) (48,348) Depreciation and amortization expense (59,570) (56,018) (118,169) (111,293) Gain on real estate transactions — — 63,883 — Interest expense (40,240) (41,039) (80,935) (85,397) Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes — (1,233) — (2,442) Interest income 12,838 1,669 25,142 3,343 Equity in earnings and dividend income from unconsolidated real estate entities 8,322 5,044 15,278 10,087 Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of joint venture partner's interest 6,251 — 6,251 — Income tax expense (5,421) (3,177) (9,558) (5,356) Net income $ 178,579 $ 111,257 $ 394,080 $ 227,419

Organization (Detail)

Organization (Detail)	Jun. 30, 2021storestate
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating storage facilities in which the entity has equity interests (in stores)	1,205
Number of stores owned by franchisees and third parties	768
Number of operating stores owned and/or managed	1,973
Number of states in which operating storage facilities are located | state	40

Fair Value Disclosures - Assets

Fair Value Disclosures - Assets and Liabilities on a Recurring Basis (Detail) - Recurring Basis $ in Thousands	Jun. 30, 2021USD ($)
Quoted Prices in Active Markets for Identical Assets (Level 1)
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)
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	69,551
Significant Unobservable Inputs (Level 3)
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 - Additi

Fair Value Disclosures - Additional Information (Detail)	Jun. 30, 2021store
Fair Value Disclosures [Abstract]
Number of operating stores held-for-sale	17

Fair Value Disclosures - Schedu

Fair Value Disclosures - Schedule of Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair Value
Fair Value of Financial Instruments [Line Items]
Notes receivable from Preferred and Common Operating Partnership unit holders	$ 100,458	$ 102,333
Fixed rate notes receivable	107,454	114,145
Fixed rate notes payable	4,001,843	3,816,530
Carrying Value
Fair Value of Financial Instruments [Line Items]
Notes receivable from Preferred and Common Operating Partnership unit holders	101,900	102,311
Fixed rate notes receivable	104,000	104,000
Fixed rate notes payable	$ 3,925,841	$ 3,637,220

Earnings Per Common Share - Add

Earnings Per Common Share - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per common share (in shares)	1,056,433	8,484,961	301,483	8,413,687
Average share price (in dollars per share)	$ 149.81	$ 92.95
Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Principal amount of notes issued		$ 575,000,000		$ 575,000,000
Debt stated interest rate		3.125%		3.125%
Shares related to the Notes included in the computation for diluted earnings per share (in shares)	0	121,283	0	121,283
Series A Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Exchangeable preferred operating partnership units settled in cash, minimum	$ 101,700,000		$ 101,700,000
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per common share (in shares)	0	0	0	0

Earnings Per Common Share - Ant

Earnings Per Common Share - Antidilutive Shares (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per common share (in shares)	1,056,433	8,484,961	301,483	8,413,687
Common OP Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per common share (in shares)	0	5,876,356	0	5,898,029
Series A Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per common share (in shares)	0	875,480	0	875,480
Series B Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per common share (in shares)	273,027	450,803	301,483	425,446
Series D Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per common share (in shares)	783,406	1,282,322	0	1,214,732

Earnings Per Common Share - Sch

Earnings Per Common Share - Schedule of Computation (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income attributable to common stockholders	$ 167,948	$ 102,911	$ 370,946	$ 211,090
Earnings and dividends allocated to participating securities	(232)	(173)	(541)	(336)
Earnings for basic computations	167,716	102,738	370,405	210,754
Income allocated to noncontrolling interest - Preferred Operating Partnership Units and Operating Partnership Units	8,833	0	21,889	0
Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units)	(572)	0	(1,144)	0
Net income for diluted computations	$ 175,977	$ 102,738	$ 391,150	$ 210,754
Weighted average common shares outstanding:
Average number of common shares outstanding - basic (in shares)	133,756,610	128,932,152	132,886,933	129,110,131
OP Units (in shares)	5,767,460	0	5,784,003	0
Shares related to exchangeable senior notes and dilutive stock options (in shares)	7,645	150,316	17,086	175,544
Average number of common shares outstanding - diluted (in shares)	140,407,195	129,082,468	140,428,558	129,285,675
Earnings per common share
Basic (in dollars per share)	$ 1.25	$ 0.80	$ 2.79	$ 1.63
Diluted (in dollars per share)	$ 1.25	$ 0.80	$ 2.79	$ 1.63
Series A Units
Weighted average common shares outstanding:
Preferred Units (in shares)	875,480	0	875,480	0
Series D Units
Weighted average common shares outstanding:
Preferred Units (in shares)	0	0	865,056	0

Store Acquisitions and Dispos_3

Store Acquisitions and Dispositions (Detail) $ in Thousands	Mar. 01, 2021USD ($)store	Jun. 30, 2021USD ($)store	Mar. 31, 2021USD ($)store	Jun. 30, 2020USD ($)store	Mar. 31, 2020USD ($)store	Jun. 30, 2021USD ($)store	Jun. 30, 2020USD ($)store
Real Estate [Abstract]
Number of Stores | store		15	9	0	2	24	2
Total Consideration Paid		$ 193,783	$ 151,884	$ 0	$ 19,399	$ 345,667	$ 19,399
Cash Paid		190,729	148,940	0	19,354	339,669	19,354
Investments in Real Estate Ventures		2,673	0	0		2,673	0
Net Liabilities/ (Assets) Assumed		$ 381	$ 2,944	$ 0	$ 45	$ 3,325	$ 45
Number of stores acquired, previously held in joint ventures | store		2
Number of stores sold | store	16
Proceeds from sale of real estate assets	$ 132,759
Equity Ownership %	55.00%
Real estate exchanged for interest in joint venture	$ 33,878
Gain on sale	$ 64,804

Investments in Unconsolidated_3

Investments in Unconsolidated Real Estate Entities (Details) $ in Thousands	Mar. 01, 2021USD ($)store	Jun. 30, 2021USD ($)propertyjoint_venturestore	Jun. 30, 2021USD ($)property	Jun. 30, 2021USD ($)propertystore	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		247	247	247
Equity Ownership %	55.00%
Investment balance		$ 298,524	$ 298,524	$ 298,524		$ 350,318
Number of stores sold | store	16
Proceeds from sale of real estate assets	$ 132,759
Real estate exchanged for interest in joint venture	$ 33,878
Amount invested				$ 7,174	$ 9,541
Number of joint venture stores purchased | store				5
Number of joint ventures sold | joint_venture		2
Proceeds from sale of joint ventures		$ 1,888
Gain on sale of joint ventures		$ 525
Number of joint ventures purchased | joint_venture		2
Minimum
Schedule of Equity Method Investments [Line Items]
Equity Ownership %		10.00%	10.00%	10.00%
Excess Profit %		19.00%	19.00%	19.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Equity Ownership %		50.00%	50.00%	50.00%
Excess Profit %		50.00%	50.00%	50.00%
PR EXR Self Storage, LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		5	5	5
Equity Ownership %		25.00%	25.00%	25.00%
Excess Profit %		40.00%	40.00%	40.00%
Investment balance		$ 59,865	$ 59,865	$ 59,865		60,092
WICNN JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		0	0	0
Equity Ownership %		10.00%	10.00%	10.00%
Excess Profit %		35.00%	35.00%	35.00%
Investment balance		$ 0	$ 0	$ 0		36,032
ESS-CA TIVS JV LP
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		16	16	16
Equity Ownership %		55.00%	55.00%	55.00%
Excess Profit %		60.00%	60.00%	60.00%
Investment balance		$ 34,000	$ 34,000	$ 34,000		0
GFN JV, LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		0	0	0
Equity Ownership %		10.00%	10.00%	10.00%
Excess Profit %		30.00%	30.00%	30.00%
Investment balance		$ 0	$ 0	$ 0		18,397
ESS-NYFL JV LP
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		11	11	11
Equity Ownership %		16.00%	16.00%	16.00%
Excess Profit %		24.00%	24.00%	24.00%
Investment balance		$ 12,025	$ 12,025	$ 12,025		12,211
PRISA Self Storage LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		85	85	85
Equity Ownership %		4.00%	4.00%	4.00%
Excess Profit %		4.00%	4.00%	4.00%
Investment balance		$ 8,717	$ 8,717	$ 8,717		8,815
Alan Jathoo JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		9	9	9
Equity Ownership %		10.00%	10.00%	10.00%
Excess Profit %		10.00%	10.00%	10.00%
Investment balance		$ 7,689	$ 7,689	$ 7,689		7,780
Storage Portfolio IV JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		5	5	5
Equity Ownership %		10.00%	10.00%	10.00%
Excess Profit %		30.00%	30.00%	30.00%
Investment balance		$ 6,909	$ 6,909	$ 6,909		0
Storage Portfolio III JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		5	5	5
Equity Ownership %		10.00%	10.00%	10.00%
Excess Profit %		30.00%	30.00%	30.00%
Investment balance		$ 5,649	$ 5,649	$ 5,649		5,726
ESS Bristol Investments LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		8	8	8
Equity Ownership %		10.00%	10.00%	10.00%
Excess Profit %		30.00%	30.00%	30.00%
Investment balance		$ 2,743	$ 2,743	$ 2,743		2,810
Extra Space Northern Properties Six LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		10	10	10
Equity Ownership %		10.00%	10.00%	10.00%
Excess Profit %		35.00%	35.00%	35.00%
Investment balance		$ (2,737)	$ (2,737)	$ (2,737)		(2,541)
Storage Portfolio II JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		36	36	36
Equity Ownership %		10.00%	10.00%	10.00%
Excess Profit %		30.00%	30.00%	30.00%
Investment balance		$ (5,771)	$ (5,771)	$ (5,771)		(5,441)
VRS Self Storage, LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		16	16	16
Equity Ownership %		45.00%	45.00%	45.00%
Excess Profit %		54.00%	54.00%	54.00%
Investment balance		$ (14,499)	$ (14,499)	$ (14,499)		17,186
Storage Portfolio I LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		24	24	24
Equity Ownership %		34.00%	34.00%	34.00%
Excess Profit %		49.00%	49.00%	49.00%
Investment balance		$ (39,697)	$ (39,697)	$ (39,697)		(39,144)
Other minority owned stores
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		17	17	17
Investment balance		$ 23,631	$ 23,631	$ 23,631		28,395
SmartStop Self Storage REIT, Inc. Preferred Stock
Schedule of Equity Method Investments [Line Items]
Investment balance		$ 200,000	200,000	$ 200,000		$ 200,000
Investment, preferred dividend rate				6.25%
Period after which preferred stock dividend is subject to increase				5 years
Investment redemption restriction period				5 years
WICNN JV LLC and GFN JV, LLC
Schedule of Equity Method Investments [Line Items]
Gain on sale of joint ventures			$ 5,739
Number of joint venture stores sold | store		17

Investments in Debt Securitie_3

Investments in Debt Securities and Notes Receivable - Schedule (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Dividends Receivable	$ 21,370	$ 4,889
Investments in debt securities and notes receivable	568,781	593,810
Notes Receivable-Bridge Loans
Schedule of Held-to-maturity Securities [Line Items]
Notes receivable	145,581	187,368
Notes Receivable-Senior Mezzanine Loan
Schedule of Held-to-maturity Securities [Line Items]
Notes receivable	101,830	101,553
JCAP Series A Preferred Stock
Schedule of Held-to-maturity Securities [Line Items]
Debt securities	200,000	200,000
JCAP Series B Preferred Stock
Schedule of Held-to-maturity Securities [Line Items]
Debt securities	$ 100,000	$ 100,000

Investments in Debt Securitie_4

Investments in Debt Securities and Notes Receivable - Additional Information (Details) $ in Thousands	1 Months Ended		6 Months Ended
	Nov. 30, 2020USD ($)extension_optionshares	Jul. 31, 2020USD ($)facility	Jun. 30, 2021USD ($)extension_option	Jun. 30, 2020USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Investment in debt securities	$ 300,000
Debt securities, term	5 years
Debt securities, extension option | extension_option	2
Debt securities, extension term	1 year
Debt securities, period after which preferred dividends increase annually	5 years
Payments for issuance/purchase of notes receivable			$ 68,523	$ 24,325
Bridge loans, extension option | extension_option			2
Bridge loans, extension term			1 year
Proceeds from sale of notes receivable			$ 87,298	$ 0
Notes Receivable-Senior Mezzanine Loan
Schedule of Held-to-maturity Securities [Line Items]
Purchase of note receivable		$ 103,000
Note receivable interest rate		5.50%
Collateral, number of facilities | facility		62
Payments for issuance/purchase of notes receivable		$ 101,142
Notes Receivable-Bridge Loans
Schedule of Held-to-maturity Securities [Line Items]
Bridge loans, original maturities			3 years
Principal amount of notes sold			$ 87,812
Proceeds from sale of notes receivable			$ 87,298
JCAP Series A Preferred Stock
Schedule of Held-to-maturity Securities [Line Items]
Investment in debt securities	$ 200,000
Investment in debt securities (in shares) | shares	200,000
Debt securities, dividend rate	10.00%
JCAP Series B Preferred Stock
Schedule of Held-to-maturity Securities [Line Items]
Investment in debt securities	$ 100,000
Investment in debt securities (in shares) | shares	100,000
Debt securities, dividend rate	12.00%

Notes Payable, Net (Details)

Notes Payable, Net (Details) - Senior Notes	May 31, 2021USD ($)
Debt Instrument [Line Items]
Principal amount of notes issued	$ 450,000,000
Debt stated interest rate	2.55%

Derivatives - Additional Inform

Derivatives - Additional Information (Detail) $ in Thousands	Jun. 30, 2021USD ($)derivative
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Estimated amount of unrealized gains (losses) expected to be reclassified as interest expense in next fiscal year	$ 35,455
Number of derivative financial instruments | derivative	20
Combined notional amount	$ 1,989,896
Fair value - net liability position	71,694
Contingent cash settlement value	$ 71,694

Derivatives - Schedule of Balan

Derivatives - Schedule of Balance Sheet Classification and Fair Value of Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Other assets
Derivative [Line Items]
Other assets - Cash flow hedge swap agreements	$ 0	$ 0
Other liabilities
Derivative [Line Items]
Derivative liability, fair value	$ 69,551	$ 98,325

Derivatives - Gain (Loss) Recog

Derivatives - Gain (Loss) Recognized on Swap Agreements (Detail) - Swap Agreements - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative [Line Items]
Gain (loss) recognized in OCI	$ (3,124)	$ (13,350)	$ 11,052	$ (103,060)
Gain (loss) reclassified from OCI	$ (8,747)	$ (7,639)	$ (17,592)	$ (8,202)

Exchangeable Senior Notes - Add

Exchangeable Senior Notes - Additional Information (Detail) - USD ($)	Nov. 02, 2020	Oct. 01, 2020	Sep. 30, 2015	Jun. 30, 2020
Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Repurchase of exchangeable senior notes		$ 71,513,000
Repurchase of exchangeable senior notes with common stock (in shares)		124,819
Repurchase of exchangeable senior notes with common stock		$ 13,495,000
Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Repurchase of exchangeable senior notes	$ 503,487,000
Repurchase of exchangeable senior notes with common stock (in shares)	1,198,962
Repurchase of exchangeable senior notes with common stock	$ 138,900,000
Principal amount exchanged	503,432,000
Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Repurchase of exchangeable senior notes	$ 55,000
Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes)
Debt Instrument [Line Items]
Principal amount of notes issued				$ 575,000,000
Debt stated interest rate				3.125%
Related debt issuance costs			$ 11,992,000
Underwriting fee percentage			2.00%
Amortization period			5 years
Effective interest rate on the liability component			4.00%

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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Disclosure [Abstract]
Contractual interest	$ 0	$ 4,492	$ 0	$ 8,984
Amortization of discount	0	1,233	0	2,442
Total interest expense recognized	$ 0	$ 5,725	$ 0	$ 11,426

Stockholders' Equity (Detail)

Stockholders' Equity (Detail)	Mar. 23, 2021USD ($)$ / sharesshares	May 15, 2019USD ($)sales_agent	Jun. 30, 2021USD ($)shares	Oct. 15, 2020USD ($)
Class of Stock [Line Items]
Number of sales agents | sales_agent		9
Shares issued (in shares) | shares	1,600,000
Net proceeds	$ 206,573,000
Average sales price (in dollars per share) | $ / shares	$ 129.13
Share repurchase program, authorized amount				$ 400,000,000
Repurchase of common stock (in shares) | shares			0
At the Market Equity Distribution Agreement
Class of Stock [Line Items]
Aggregate offering price of common shares		$ 500,000,000
Shares issued (in shares) | shares			585,685
Net proceeds			$ 66,937,000

Noncontrolling Interest Repre_2

Noncontrolling Interest Represented by Preferred Operating Partnership Units (Details) $ / shares in Units, $ in Thousands	Apr. 25, 2019shares	Dec. 01, 2018shares	Jun. 25, 2007USD ($)	Dec. 31, 2014USD ($)$ / shares	Oct. 31, 2014USD ($)shares	Jun. 30, 2007USD ($)	Jun. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2014$ / shares	Dec. 31, 2020USD ($)
Noncontrolling Interest [Line Items]
Loans and notes to affiliates							$ 100,000		$ 100,000
Preferred units outstanding (in shares) | shares							5,734,356
Note receivable interest rate				5.00%
Loan to affiliates				$ 20,230
Series A Units
Noncontrolling Interest [Line Items]
Fixed priority return on preferred OP units, amount						$ 101,700
Fixed priority return on preferred OP units, stated return rate						2.30%
Fixed priority return on preferred OP units, liquidation value					$ 101,700	$ 115,000
Preferred units outstanding (in shares) | shares					875,480
Series B Units
Noncontrolling Interest [Line Items]
Preferred units outstanding (in shares) | shares							1,636,087
Liquidation value (in dollars per share) | $ / shares							$ 25
Fixed liquidation value							$ 40,902
Annual rate of return percentage							6.00%
Series C Units
Noncontrolling Interest [Line Items]
Liquidation value (in dollars per share) | $ / shares				$ 42.10				$ 42.10
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								0.9145
Shares converted (in shares) | shares	296,020	407,996
Series D Units
Noncontrolling Interest [Line Items]
Preferred units outstanding (in shares) | shares							4,694,485
Liquidation value (in dollars per share) | $ / shares							$ 25
Fixed liquidation value							$ 117,362
Series D Units | Minimum
Noncontrolling Interest [Line Items]
Annual rate of return percentage							3.00%
Series D Units | Maximum
Noncontrolling Interest [Line Items]
Annual rate of return percentage							5.00%
Operating Partnership Holders of A Units | Series A Units
Noncontrolling Interest [Line Items]
Loans and notes to affiliates			$ 100,000
Maximum number of preferred OP units converted prior to the maturity date of the loan (in shares) | shares					114,500
Note receivable interest rate			2.10%
Noncontrolling Interest - Operating Partnership
Noncontrolling Interest [Line Items]
Issuance of units upon conversion (in shares) | shares	270,709	373,113
Loan receivable, reduction of noncontrolling interests							$ 1,900		$ 2,311

Noncontrolling Interest Repre_3

Noncontrolling Interest Represented by Preferred Operating Partnership Units - Balances of OP Units (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Noncontrolling Interest [Line Items]
Preferred OP Units	$ 172,902	$ 172,052
Series A Units
Noncontrolling Interest [Line Items]
Preferred OP Units	14,638	13,788
Series B Units
Noncontrolling Interest [Line Items]
Preferred OP Units	40,902	40,902
Series D Units
Noncontrolling Interest [Line Items]
Preferred OP Units	$ 117,362	$ 117,362

Noncontrolling Interest in Op_3

Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests - Additional Information (Details) $ / shares in Units, $ in Thousands	1 Months Ended	6 Months Ended
	Dec. 31, 2014	Jun. 30, 2021USD ($)propertyjoint_venture$ / sharesshares	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Noncontrolling Interest [Line Items]
Note receivable interest rate	5.00%
Period used as a denomination to determine the average closing price of common stock		10 days
Ten day average closing stock price (in dollars per share) | $ / shares		$ 163.63
Preferred units outstanding (in shares) | shares		5,734,356
Consideration to be paid on redemption of common OP units		$ 938,313
Real estate assets associated with finance lease		40,993	$ 8,514
Noncontrolling Interest - Operating Partnership
Noncontrolling Interest [Line Items]
Loan receivable, reduction of noncontrolling interests		$ 1,900		$ 2,311
Common Stock
Noncontrolling Interest [Line Items]
OP units conversion ratio		1
Noncontrolling Interest - Operating Partnership
Noncontrolling Interest [Line Items]
Ownership interest held		94.60%
Ownership interest held by joint venture partner		5.40%
Other noncontrolling interests
Noncontrolling Interest [Line Items]
Number of consolidated joint ventures | joint_venture		3
Other noncontrolling interests | Minimum
Noncontrolling Interest [Line Items]
Ownership interest held by joint venture partner		5.00%
Other noncontrolling interests | Maximum
Noncontrolling Interest [Line Items]
Ownership interest held by joint venture partner		20.00%
Joint Venture 1 | Other noncontrolling interests
Noncontrolling Interest [Line Items]
Number of operating stores owned | property		4
Joint Venture 2 | Other noncontrolling interests
Noncontrolling Interest [Line Items]
Number of operating stores owned | property		2

Noncontrolling Interest in Op_4

Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests - Schedule of OP Unit Activity (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Noncontrolling Interest [Abstract]
OP Units redeemed for common stock (in units)	63,429	108,862
OP Units redeemed for cash (in units)	3,000	0
Cash paid for OP Units redeemed	$ 472	$ 0

Segment Information - Additiona

Segment Information - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2021segment
Segment Reporting [Abstract]
Number of reportable segments	2

Segment Information - Schedule

Segment Information - Schedule of Financial Information (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Revenues:	$ 378,630		$ 327,246		$ 737,487	$ 659,698
Operating expenses:	181,801		177,253		363,468	352,514
Net operating income:	196,829		149,993		437,902	307,184
Management fees and other income	14,796		12,856		30,441	24,992
General and administrative expense	(26,341)		(25,337)		(49,881)	(48,348)
Depreciation and amortization expense	(59,570)		(56,018)		(118,169)	(111,293)
Gain on real estate transactions	0		0		63,883	0
Interest expense	(40,240)		(41,039)		(80,935)	(85,397)
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	0		(1,233)		0	(2,442)
Interest income	12,838		1,669		25,142	3,343
Equity in earnings and dividend income from unconsolidated real estate entities	8,322		5,044		15,278	10,087
Equity in earnings of unconsolidated real estate ventures - gain on sale of real estate assets and purchase of joint venture partner's interest	6,251		0		6,251	0
Income tax expense	(5,421)		(3,177)		(9,558)	(5,356)
Net income	178,579	$ 215,501	111,257	$ 116,162	394,080	227,419
Operating Segments
Segment Reporting Information [Line Items]
Revenues:	363,834		314,390		707,046	634,706
Operating expenses:	95,890		95,898		195,418	192,873
Net operating income:	267,944		218,492		511,628	441,833
Self-Storage Operations | Operating Segments
Segment Reporting Information [Line Items]
Revenues:	321,500		279,312		625,093	566,015
Operating expenses:	89,155		89,040		181,522	179,337
Net operating income:	232,345		190,272		443,571	386,678
Tenant Reinsurance | Operating Segments
Segment Reporting Information [Line Items]
Revenues:	42,334		35,078		81,953	68,691
Operating expenses:	6,735		6,858		13,896	13,536
Net operating income:	$ 35,599		$ 28,220		$ 68,057	$ 55,155

Commitments and Contingencies (

Commitments and Contingencies (Detail) $ in Thousands	Jun. 30, 2021USD ($)store
Commitment to acquire stores
Other Commitments [Line Items]
Number of real estate properties to be acquired | store	3
Purchase price | $	$ 28,850
Commitment to acquire stores with joint venture partners
Other Commitments [Line Items]
Number of real estate properties to be acquired | store	7
Purchase price | $	$ 9,890