Extra Space Storage (EXR) 10-K 26 Feb 21 2020 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 19, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Smaller Reporting Company	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 11,637,515,440
Entity Common Stock, Shares Outstanding		132,033,131
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement to be issued in connection with the registrant’s annual stockholders’ meeting to be held in 2021 are incorporated by reference into Part III of this Annual Report on Form 10-K.
Amendment Flag	false
Entity Central Index Key	0001289490
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets:
Real estate assets, net	$ 7,893,802	$ 7,696,864
Real estate assets - operating lease right-of-use assets	252,172	264,643
Investments in unconsolidated real estate entities	397,444	338,054
Investments in debt securities and notes receivable	593,810	43,586
Cash and cash equivalents	109,124	65,746
Restricted cash	18,885	4,987
Other assets, net	130,611	118,497
Total assets	9,395,848	8,532,377
Liabilities, Noncontrolling Interests and Equity:
Notes payable, net	4,797,303	4,318,973
Exchangeable senior notes, net	0	569,513
Revolving lines of credit	949,000	158,000
Operating lease liabilities	263,485	274,783
Cash distributions in unconsolidated real estate ventures	47,126	45,264
Accounts payable and accrued expenses	130,012	111,382
Other liabilities	272,798	132,768
Total liabilities	6,459,724	5,610,683
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, 131,357,961 and 129,534,407 shares issued and outstanding at December 31, 2020 and 2019, respectively	1,314	1,295
Additional paid-in capital	3,000,458	2,868,681
Accumulated other comprehensive loss	(99,093)	(28,966)
Accumulated deficit	(354,900)	(301,049)
Total Extra Space Storage Inc. stockholders' equity	2,547,779	2,539,961
Noncontrolling interest represented by Preferred Operating Partnership units, net	172,052	175,948
Noncontrolling interests in Operating Partnership, net and other noncontrolling interests	216,293	205,785
Total noncontrolling interests and equity	2,936,124	2,921,694
Total liabilities, noncontrolling interests and equity	$ 9,395,848	$ 8,532,377

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
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)	131,357,961	129,534,407
Common stock, outstanding (in shares)	131,357,961	129,534,407

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Property rental	$ 1,157,522	$ 1,130,177	$ 1,039,340
Tenant reinsurance	146,561	128,387	115,507
Management fees and other income	52,129	49,890	41,757
Total revenues	1,356,212	1,308,454	1,196,604
Expenses:
Property operations	360,615	336,050	291,695
Tenant reinsurance	26,494	29,376	25,707
General and administrative	96,594	89,418	81,256
Depreciation and amortization	224,444	219,857	209,050
Total expenses	708,147	674,701	607,708
Gain on real estate transactions	18,075	1,205	30,807
Income from operations	666,140	634,958	619,703
Interest expense	(168,626)	(186,526)	(178,436)
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	(3,675)	(4,742)	(4,687)
Interest income	15,192	7,467	5,292
Income before equity in earnings of unconsolidated real estate ventures and income tax expense	509,031	451,157	441,872
Equity in earnings and dividend income from unconsolidated real estate entities	22,361	11,274	14,452
Income tax expense	(13,810)	(11,308)	(9,244)
Net income	517,582	451,123	447,080
Net income allocated to Preferred Operating Partnership noncontrolling interests	(12,882)	(12,492)	(13,995)
Net income allocated to Operating Partnership and other noncontrolling interests	(22,921)	(18,664)	(17,796)
Net income attributable to common stockholders	$ 481,779	$ 419,967	$ 415,289
Earnings per common share
Basic (in dollars per share)	$ 3.71	$ 3.27	$ 3.29
Diluted (in dollars per share)	$ 3.71	$ 3.24	$ 3.27
Weighted average number of shares
Basic (in shares)	129,541,531	128,203,568	126,087,487
Diluted (in shares)	129,584,829	136,433,769	133,159,033

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 517,582	$ 451,123	$ 447,080
Other comprehensive income (loss):
Change in fair value of interest rate swaps	(73,686)	(66,843)	1,430
Total comprehensive income	443,896	384,280	448,510
Less: comprehensive income attributable to noncontrolling interests	32,244	27,929	31,861
Comprehensive income attributable to common stockholders	$ 411,652	$ 356,351	$ 416,649

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Redemption of units for stockSeries D Units	Redemption of units for cash	Redemption of units for cashSeries B Units	Preferred Operating Partnership	Preferred Operating PartnershipRedemption of units for stockSeries D Units	Preferred Operating PartnershipRedemption of units for cashSeries B Units	Operating Partnership	Operating PartnershipRedemption of units for stock	Operating PartnershipRedemption of units for cash	Other	Common Stock	Common StockRedemption of units for stock	Common StockRedemption of units for stockSeries D Units	Additional Paid-in Capital	Additional Paid-in CapitalRedemption of units for stock	Additional Paid-in CapitalRedemption of units for stockSeries D Units	Additional Paid-in CapitalRedemption of units for cash	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance at Dec. 31, 2017	$ 2,723,807				$ 159,636			$ 213,301			$ 119	$ 1,260			$ 2,569,485				$ 33,290	$ (253,284)
Beginning balance (in shares) at Dec. 31, 2017												126,007,091
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon the exercise of options	$ 1,169														1,169
Issuance of common stock upon the exercise of options (in shares)	54,575											54,575
Restricted stock grants issued	$ 1											$ 1
Restricted stock grants issued (in shares)												85,066
Restricted stock grants cancelled (in shares)												(11,771)
Issuance of common stock, net of offering costs	90,231											$ 10			90,221
Issuance of common stock, net of offering costs (in shares)												933,789
Compensation expense related to stock-based awards	11,176														11,176
Repayment of receivable for preferred operating units pledged as collateral on loan	495				495
Issuance of Operating Partnership units in conjunction with acquisitions	1,877							1,877
Redemption of noncontrolling interests	0		$ (2,558)						$ (1,337)	$ (1,126)						$ 1,337		$ (1,432)
Redemption of noncontrolling interests (in shares)													35,000
Conversion of Preferred C Units in the Operating Partnership for Common Operating Partnership Units	0				(6,851)			6,851
Noncontrolling interest in consolidated joint venture	122										122
Repurchase of equity portion of 2013 exchangeable senior notes	(31,251)														(31,251)
Net income (loss)	447,080				13,995			17,797			(1)									415,289
Other comprehensive income (loss)	1,430				12			58											1,360
Distributions to Operating Partnership units held by noncontrolling interests	(33,250)				(14,191)			(19,059)
Dividends paid on common stock	(424,907)																			(424,907)
Ending balance at Dec. 31, 2018	2,785,422				153,096			218,362			240	$ 1,271			2,640,705				34,650	(262,902)
Ending balance (in shares) at Dec. 31, 2018												127,103,750
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon the exercise of options	$ 3,063											$ 3			3,060
Issuance of common stock upon the exercise of options (in shares)	211,057											211,057
Restricted stock grants issued	$ 2											$ 2
Restricted stock grants issued (in shares)												109,081
Restricted stock grants cancelled (in shares)												(8,863)
Issuance of common stock, net of offering costs	198,827											$ 19			198,808
Issuance of common stock, net of offering costs (in shares)												1,779,200
Compensation expense related to stock-based awards	13,051														13,051
Repayment of receivable for preferred operating units pledged as collateral on loan	1,211							1,211
Issuance of Operating Partnership units in conjunction with acquisitions	28,022				28,022
Redemption of noncontrolling interests	0								(13,057)							13,057
Redemption of noncontrolling interests (in shares)													340,182
Conversion of Preferred C Units in the Operating Partnership for Common Operating Partnership Units	0				(4,374)			4,374
Noncontrolling interest in consolidated joint venture	173										173
Net income (loss)	451,123				12,492			18,711			(47)									419,967
Other comprehensive income (loss)	(66,843)				(407)			(2,820)											(63,616)
Distributions to Operating Partnership units held by noncontrolling interests	(34,243)				(12,881)			(21,362)
Dividends paid on common stock	(458,114)																			(458,114)
Ending balance at Dec. 31, 2019	$ 2,921,694				175,948			205,419			366	$ 1,295			2,868,681				(28,966)	(301,049)
Ending balance (in shares) at Dec. 31, 2019	129,534,407											129,534,407
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon the exercise of options	$ 4,759											$ 1			4,758
Issuance of common stock upon the exercise of options (in shares)	134,930											134,930
Issuance of common stock in connection with share based compensation (in shares)												143,187
Issuance of common stock in connection with share based compensation	$ 16,281											$ 1			16,280
Restricted stock grants cancelled (in shares)												(5,083)
Issuance of common stock, net of offering costs	103,468											$ 9			103,459
Issuance of common stock, net of offering costs (in shares)												899,048
Buyback of common stock, net of offering costs	(67,873)											$ (8)								(67,865)
Buyback of common stock, net of offering costs (in shares)												(826,797)
Repayment of receivable for preferred operating units pledged as collateral on loan	16,213							16,213
Redemption of noncontrolling interests	0	$ 0		$ (1,000)		$ (2,724)	$ (1,000)		$ (4,572)				$ 1	$ 1		4,571	$ 2,723
Redemption of noncontrolling interests (in shares)				40,000									123,993	30,495
Repurchase of equity portion of 2015 exchangeable senior notes	0												$ 14			$ (14)
Repurchase of equity portion of 2015 exchangeable senior notes (in shares)													1,323,781
Noncontrolling interest in consolidated joint venture	66										66
Net income (loss)	517,582				12,882			22,952			(31)									481,779
Other comprehensive income (loss)	(73,686)				(456)			(3,103)											(70,127)
Distributions to Operating Partnership units held by noncontrolling interests	(33,615)				(12,598)			(21,017)
Dividends paid on common stock	(467,765)																			(467,765)
Ending balance at Dec. 31, 2020	$ 2,936,124				$ 172,052			$ 215,892			$ 401	$ 1,314			$ 3,000,458				$ (99,093)	$ (354,900)
Ending balance (in shares) at Dec. 31, 2020	131,357,961											131,357,961

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends paid on common stock (in dollars per share)	$ 0.90	$ 3.56	$ 3.36

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 517,582	$ 451,123	$ 447,080
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	224,444	219,857	209,050
Amortization of deferred financing costs	9,386	11,989	14,286
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	3,675	4,742	4,687
Non-cash lease expense	1,173	1,064
Compensation expense related to stock-based awards	16,281	13,051	11,176
Accrual of interest income added to principal of debt securities and notes receivable	(8,059)	0	0
Gain on real estate transactions	(18,075)	(1,205)	(30,807)
Distributions from unconsolidated real estate ventures in excess of earnings	6,893	6,358	6,867
Changes in operating assets and liabilities:
Other assets	(19,674)	(12,482)	(1,664)
Accounts payable and accrued expenses	17,974	15,522	2,736
Other liabilities	19,632	(2,333)	14,384
Net cash provided by operating activities	771,232	707,686	677,795
Cash flows from investing activities:
Acquisition of real estate assets	(320,148)	(349,494)	(426,388)
Development and redevelopment of real estate assets	(67,300)	(53,717)	(60,677)
Proceeds from sale of real estate assets	44,024	11,254	52,458
Investment in unconsolidated real estate entities	(64,792)	(197,759)	(65,500)
Return of investment in unconsolidated real estate ventures	371	3,982	49,130
Issuance and purchase of notes receivable	(313,355)	(185,993)	(13,850)
Investment in debt securities	(300,000)	0	0
Proceeds from sale of notes receivable	62,764	0	0
Principal payments received from notes receivable	10,102	157,861	25,226
Purchase of equipment and fixtures	(7,093)	(7,764)	(4,297)
Net cash used in investing activities	(955,427)	(621,630)	(443,898)
Cash flows from financing activities:
Proceeds from the sale of common stock, net of offering costs	103,468	198,827	90,231
Proceeds from notes payable and revolving lines of credit	3,281,000	2,214,000	1,413,030
Principal payments on notes payable and revolving lines of credit	(2,014,730)	(1,977,805)	(1,109,854)
Principal payments on notes payable to trusts	0	(30,928)	(88,662)
Deferred financing costs	(4,052)	(2,986)	(12,302)
Repurchase of exchangeable senior notes	(575,000)	0	(80,270)
Net proceeds from exercise of stock options	4,759	3,063	1,169
Repurchase of common stock	(67,873)	0	0
Proceeds from principal payments on note receivable collateralized by Preferred OP Units	16,213	0	0
Redemption of Operating Partnership units held by noncontrolling interests	(1,000)	0	(2,558)
Contributions from noncontrolling interests	66	173	122
Dividends paid on common stock	(467,765)	(458,114)	(424,907)
Distributions to noncontrolling interests	(33,615)	(34,243)	(33,250)
Net cash provided by (used in) financing activities	241,471	(88,013)	(247,251)
Net increase (decrease) in cash, cash equivalents, and restricted cash	57,276	(1,957)	(13,354)
Cash, cash equivalents, and restricted cash, beginning of the period	70,733	72,690	86,044
Cash, cash equivalents, and restricted cash, end of the period	128,009	70,733	72,690
Supplemental schedule of cash flow information
Interest paid	159,597	174,155	159,474
Income taxes paid	5,181	10,359	730
Redemption of Operating Partnership units held by noncontrolling interests for common stock
Noncontrolling interests in Operating Partnership	(4,005)	(13,057)	(1,337)
Common stock and paid-in capital	4,005	13,057	1,337
Establishment of operating lease right of use assets and lease liabilities
Real estate assets - operating lease right-of-use assets	8,014	277,557
Operating lease liabilities	(8,014)	(286,914)
Accounts payable and accrued expenses	0	9,357
Acquisitions of real estate assets
Real estate assets, net	(41,491)	21,066	88,842
Value of Operating Partnership units issued	0	0	(1,877)
Notes payable assumed	0	(17,157)	(87,500)
Investment in unconsolidated real estate ventures	0	(2,780)	535
Finance lease liability	41,491	0	0
Net liabilities assumed	0	(1,129)	0
Accrued construction costs and capital expenditures
Acquisition of real estate assets	656	2,203	778
Development and redevelopment of real estate assets	0	1,601	554
Accounts payable and accrued expenses	(656)	(3,804)	(1,332)
Contribution of Preferred OP Units to unconsolidated real estate venture
Investments in unconsolidated real estate ventures	0	(28,022)	0
Value of Preferred Operating Partnership units issued	0	28,022	0
Redemption of Preferred Operating Partnership units for common stock
Noncontrolling interests in Operating Partnership	(2,724)	0	0
Common stock and paid-in capital	2,724	0	0
Issuance of Preferred OP Units for additional investment in unconsolidated real estate venture
Conversion of Preferred Operating Units to Common Units	$ 0	$ 4,374	$ 6,851

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS	DESCRIPTION OF BUSINESS Extra Space Storage Inc. (the “Company”) is a fully integrated, self-administered and self-managed real estate investment trust (“REIT”), formed as a Maryland corporation on April 30, 2004, to own, operate, manage, acquire, develop and redevelop professionally managed self-storage properties 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 December 31, 2020, the Company had direct and indirect equity interests in 1,197 storage facilities. In addition, the Company managed 724 stores for third parties bringing the total number of stores which it owns and/or manages to 1,921. These stores are located in 40 states, Washington, D.C. and Puerto Rico. The Company also offers tenant reinsurance at its owned and managed stores that insures the value of goods in the storage units.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The consolidated financial statements are presented on the accrual basis of accounting in accordance with U.S. generally accepted accounting principles (“GAAP”) and include the accounts of the Company and its wholly- or majority-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Variable Interest Entities The Company accounts for arrangements that are not controlled through voting or similar rights as variable interest entities (“VIEs”). An enterprise is required to consolidate a VIE if it is the primary beneficiary of the VIE. A VIE is created when (i) the equity investment at risk is not sufficient to permit the entity to finance its activities without additional subordinated financial support from other parties, or (ii) the entity’s equity holders as a group either: (a) lack the power, through voting or similar rights, to direct the activities of the entity that most significantly impact the entity’s economic performance, (b) are not obligated to absorb expected losses of the entity if they occur, or (c) do not have the right to receive expected residual returns of the entity if they occur. If an entity is deemed to be a VIE, the enterprise that is deemed to have a variable interest, or combination of variable interests, that provides the enterprise with a controlling financial interest in the VIE, is considered the primary beneficiary and must consolidate the VIE. The Company has concluded that under certain circumstances when the Company enters into arrangements for the formation of joint ventures or when entering into a new bridge loan agreement, a VIE may be created under condition (i), (ii) (b) or (c) of the previous paragraph. For each VIE created, the Company has performed a qualitative analysis, including considering which party, if any, has the power to direct the activities most significant to the economic performance of each VIE and whether that party has the obligation to absorb losses of the VIE or the right to receive benefits from the VIE that could be significant to the VIE. If the Company is determined to be the primary beneficiary of the VIE, the assets, liabilities and operations of the VIE are consolidated with the Company’s financial statements. As of December 31, 2020 and 2019, the Company had no consolidated VIEs. The Company’s investments in real estate joint ventures, where the Company has significant influence, but not control, and joint ventures which are VIEs in which the Company is not the primary beneficiary, are recorded under the equity method of accounting on the accompanying consolidated financial statements. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. 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 Financial Accounting Standard Board’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 itself and its counterparties. However, as of December 31, 2020, the Company has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivatives. As a result, the Company has determined that its derivative valuations in their entirety are 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 December 31, 2020, aggregated by the level in the fair value hierarchy within which those measurements fall. Fair Value Measurements at Reporting Date Using Description December 31, 2020 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 $ 98,325 $ — $ 98,325 $ — There were no transfers of assets and liabilities between Level 1 and Level 2 during the year ended December 31, 2020. The Company did not have any significant assets or liabilities that are re-measured on a recurring basis using significant unobservable inputs as of December 31, 2020 or 2019. 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. The Company compares the carrying value of the related long-lived assets to the undiscounted future net operating cash flows attributable to the assets (categorized within Level 3 of the fair value hierarchy). If the estimated fair value, net of selling costs, of the assets that have been identified as held for sale is less than the net carrying value of the assets, the Company would recognize a loss on the assets held for sale. The operations of assets held for sale or sold during the period are presented as part of normal operations for all periods presented. The Company assesses annually whether there are any indicators that the value of the Company’s investments in unconsolidated real estate entities may be impaired 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. As of December 31, 2020 and 2019, the Company did not have any assets or liabilities measured at fair value on a nonrecurring basis. 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, investments in debt securities and notes receivable, revolving lines of credit and other liabilities reflected in the consolidated balance sheets at December 31, 2020 and 2019, approximate fair value. The fair values of the Company’s notes receivable and notes receivable from Preferred Operating Partnership unit holders were based on the discounted estimated future cash flow 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 value of the Company’s exchangeable senior notes was estimated using an average market price for similar securities obtained from a third party. The fair values of the Company’s fixed-rate assets and liabilities were as follows for the periods indicated: December 31, 2020 December 31, 2019 Fair Carrying Fair Carrying Notes receivable from Preferred and Common Operating Partnership unit holders $ 102,333 $ 102,311 $ 116,184 $ 118,524 Fixed rate notes receivable $ 114,145 $ 104,000 $ — $ — Fixed rate notes payable $ 3,816,530 $ 3,637,220 $ 3,511,151 $ 3,417,928 Exchangeable senior notes $ — $ — $ 673,831 $ 575,000 Real Estate Assets Real estate assets are stated at cost, less accumulated depreciation. Direct and allowable internal costs associated with the development, construction, renovation, and improvement of real estate assets are capitalized. Interest, property taxes, and other costs associated with development incurred during the construction period are capitalized. The construction period begins when expenditures for the real estate assets have been made and activities that are necessary to prepare the asset for its intended use are in progress. The construction period ends when the asset is substantially complete and ready for its intended use. Expenditures for maintenance and repairs are charged to expense as incurred. Major replacements and betterments that improve or extend the life of the asset are capitalized and depreciated over their estimated useful lives. Depreciation is computed using the straight-line method over the estimated useful lives of the buildings and improvements, which are generally between five The purchase of stores are considered asset acquisitions. As such, the purchase price is allocated to the real estate assets 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 relative 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 the acquisition is recorded at fair value based on current interest rates compared to contractual rates. Acquisition-related transactions costs are capitalized as part of the purchase price. Intangible lease rights represent: (1) purchase price amounts allocated to leases on three stores that cannot be classified as ground or building leases; these rights are amortized to expense over the life of the leases and (2) intangibles related to ground leases on eight stores where the leases were assumed by the Company at rates that were lower than the current market rates for similar leases. The values associated with these assumed leases were recorded as intangibles, which will be amortized over the lease terms. Real Estate Sales In general, sales of real estate and related profits/losses are recognized when all consideration has changed hands and risks and rewards of ownership have been transferred. Certain types of continuing involvement preclude sale treatment and related profit recognition; other forms of continuing involvement allow for sale recognition but require deferral of profit recognition. Investments in Unconsolidated Real Estate Entities Investments in unconsolidated real estate entities and cash distributions in unconsolidated real estate ventures represent the Company's noncontrolling interest in real estate joint ventures that own stores and the Company's interest in preferred stock of SmartStop Self Storage REIT, Inc. ("SmartStop"). The Company’s investments in real estate joint ventures, where the Company has significant influence, but not control and joint ventures which are VIEs in which the Company is not the primary beneficiary, are recorded under the equity method of accounting in the accompanying consolidated financial statements. Under the equity method, the Company’s investment in real estate ventures is stated at cost and adjusted for the Company’s share of net earnings or losses and reduced by distributions. Equity in earnings of real estate ventures is generally recognized based on the Company’s ownership interest in the earnings of each of the unconsolidated real estate ventures. For the purposes of presentation in the statement of cash flows, the Company follows the “nature of distribution” approach for classification of distributions from joint ventures. Under this approach, cash flows are classified on the basis of the nature of the activity or activities of the investee that generated the distribution as either a return on investment (classified as a cash inflow from operating activities) or a return of investment (classified as a cash inflow from investing activities). The Company evaluated its investments in preferred stock of non-public real estate entities and determined it did not have significant influence over the entity, and the investment in preferred stock does not have a readily determinable fair value, therefore it has been recorded at the transaction price. The Company periodically evaluates the investment for impairment. No impairment indicators were noted as of December 31, 2020. Investments in Debt Securities and Notes Receivable The Company accounts for its investment in debt securities and loans receivable at amortized cost. The Company recognizes interest income related to the debt securities and notes receivable using the effective interest method, with deferred fees and costs amortized over the lives of the related loans as yield adjustment. Additionally, the discount related to purchased notes receivable is being amortized to interest income over the remaining period of the notes. Cash and Cash Equivalents The Company’s cash is deposited with financial institutions located throughout the United States and at times may exceed federally insured limits. The Company considers all highly liquid debt instruments with a maturity date of three months or less to be cash equivalents. Restricted Cash Restricted cash is comprised of escrowed funds deposited with financial institutions located throughout the United States relating to earnest money deposits on potential acquisitions, real estate taxes, loan collateral, operating reserves and insurance and capital expenditures. Other Assets Other assets consist of equipment and fixtures, capitalized software, rents receivable from our tenants, other receivables, other intangible assets, deferred tax assets, prepaid expenses and the fair value of interest rate swaps. Depreciation of equipment and fixtures is computed on a straight-line basis over three Derivative Instruments and Hedging Activities The Company records all derivatives on the balance sheet at fair value. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether the Company has elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. Derivatives designated and qualifying as a hedge of the exposure to changes in the fair value of an asset, liability or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Derivatives designated and qualifying as a hedge of the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Hedge accounting generally provides for the matching of the timing of gain or loss recognition on the hedging instrument with the recognition of the changes in the fair value of the hedged asset or liability that are attributable to the hedged risk in a fair value hedge or the earnings effect of the hedged forecasted transactions in a cash flow hedge. The Company may enter into derivative contracts that are intended to economically hedge certain of its risk, even though hedge accounting does not apply or the Company elects not to apply hedge accounting. 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. Risk Management and Use of Financial Instruments In the normal course of its ongoing business operations, the Company encounters economic risk. There are three main components of economic risk: interest rate risk, credit risk and market risk. The Company is subject to interest rate risk on its interest-bearing liabilities. Credit risk is the risk of inability or unwillingness of tenants to make contractually required payments. Market risk is the risk of declines in the value of stores due to changes in rental rates, interest rates or other market factors affecting the value of stores held by the Company. The Company has entered into interest rate swap agreements to manage a portion of its interest rate risk. Exchange of Common Operating Partnership Units Redemption of common Operating Partnership units for shares of common stock, when redeemed under the original provisions of the Operating Partnership agreement, are accounted for by reclassifying the underlying net book value of the units from noncontrolling interest to the Company’s equity. Revenue and Expense Recognition Rental revenues are recognized as earned based upon amounts that are currently due from tenants. Leases are generally on month-to-month terms. Prepaid rents are recognized on a straight-line basis over the term of the leases. Promotional discounts are recognized as a reduction to rental income over the promotional period. Late charges, administrative fees and merchandise sales are recognized as income when earned. Equity in earnings of unconsolidated real estate ventures is recognized based on the Company's ownership interest in the earnings of each of the unconsolidated real estate entities. Interest income is recognized as earned. The Company's management fees are earned subject to the terms of the related management services agreements ("MSAs"). These MSAs provide that the Company will perform management services, which include leasing and operating the property and providing accounting, marketing, banking, maintenance and other services. These services are provided in exchange for monthly management fees, which are based on a percentage of revenues collected from stores owned by third parties and unconsolidated joint ventures. MSAs generally have original terms from three The Company accounts for the management services provided to a customer as a single performance obligation which are rendered over time each month. The total amount of consideration from the contract is variable as it is based on monthly revenues, which are influenced by multiple factors, some of which are outside the Company's control. Therefore, the Company recognizes the revenue at the end of each month once the uncertainty is resolved. Due to the standardized terms of the MSAs, the Company accounts for all MSAs in a similar, consistent manner. Therefore, no disaggregated information relating to MSAs is presented. Property expenses, including utilities, property taxes, repairs and maintenance and other costs to manage the facilities are recognized as incurred. The Company accrues for property tax expense based upon invoice amounts and estimates. If these estimates are incorrect, the timing of expense recognition could be affected. Tenant reinsurance premiums are recognized as revenue over the period of insurance coverage. The Company records an unpaid claims liability at the end of each period based on existing unpaid claims and historical claims payment history. The unpaid claims liability represents an estimate of the ultimate cost to settle all unpaid claims as of each period end, including both reported but unpaid claims and claims that may have been incurred but have not been reported. The Company uses a third party claims administrator to adjust all tenant reinsurance claims received. The administrator evaluates each claim to determine the ultimate claim loss and includes an estimate for claims that may have been incurred but not reported. Annually, a third party actuary evaluates the adequacy of the unpaid claims liability. Prior year claim reserves are adjusted as experience develops or new information becomes known. The impact of such adjustments is included in the current period operations. The unpaid claims liability is not discounted to its present value. Each tenant chooses the amount of insurance coverage they want through the tenant reinsurance program. Tenants can purchase policies in amounts of 2,000 dollars to 10,000 dollars of insurance coverage in exchange for a monthly fee. As of December 31, 2020, the average insurance coverage for tenants was approximately 3,100 dollars. The Company’s exposure per claim is limited by the maximum amount of coverage chosen by each tenant. The Company purchases reinsurance for losses exceeding a set amount for any one event. The Company does not currently have any amounts recoverable under the reinsurance arrangements. For the years ended December 31, 2020, 2019 and 2018, the number of individual claims made were 8,890, 7,911 and 8,088, respectively (claim numbers not in thousands). The following table presents information on the portion of the Company’s unpaid claims liability, which is included in other liabilities on the Company's consolidated balance sheets, that relates to tenant insurance for the periods indicated: For the Year Ended December 31, Tenant Reinsurance Claims: 2020 2019 2018 Unpaid claims liability at beginning of year $ 8,109 $ 7,326 $ 5,167 Claims and claim adjustment expense for claims incurred in the current year 14,534 16,280 15,800 Claims and claim adjustment expense (benefit) for claims incurred in the prior years (1,351) 98 107 Payments for current year claims (9,697) (11,352) (11,010) Payments for prior year claims (3,301) (4,243) (2,738) Unpaid claims liability at the end of the year $ 8,294 $ 8,109 $ 7,326 Advertising Costs The Company incurs advertising costs primarily attributable to digital and other advertising. These costs are expensed as incurred. The Company recognized $28,336, $25,106 and $16,153 in advertising expense for the years ended December 31, 2020, 2019 and 2018, respectively, which are included in property operating expenses on the Company’s consolidated statements of operations. Income Taxes The Company has elected to be treated as a REIT under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended (the "Internal Revenue Code"). In order to maintain its qualification as a REIT, among other things, the Company is required to distribute at least 90% of its REIT taxable income to its stockholders and meet certain tests regarding the nature of its income and assets. As a REIT, the Company is not subject to U.S. federal income tax with respect to that portion of its income which meets certain criteria and is distributed annually to stockholders. The Company plans to continue to operate so that it meets the requirements for taxation as a REIT. Many of these requirements, however, are highly technical and complex. For any taxable year that the Company fails to qualify as a REIT and for which applicable statutory relief provisions did not apply, the Company would be subject to U.S. federal corporate income tax on all of its taxable income for at least that year and the ensuing four years. The Company is subject to certain state and local taxes. Provision for such taxes has been included in income tax expense on the Company’s consolidated statements of operations. For the year ended December 31, 2020, 0% (unaudited) of all distributions to stockholders qualified as a return of capital. The Company owns and may acquire direct or indirect interests in entities that have elected or will elect to be taxed as REITs under the Internal Revenue Code (each, a “Subsidiary REIT ”). A Subsidiary REIT is subject to the various REIT qualification requirements and other limitations described herein that are applicable to the Company. If a Subsidiary REIT were to fail to qualify as a REIT, then (i) that Subsidiary REIT would become subject to U.S. federal income tax, (ii) shares in such Subsidiary REIT would cease to be qualifying assets for purposes of the asset tests applicable to REITs, and (iii) it is possible that the Company would fail certain of the asset tests applicable to REITs, in which event the Company would fail to qualify as a REIT unless it could avail itself of certain relief provisions. The Company has elected to treat certain corporate subsidiaries, including Extra Space Management, Inc. (“ESMI”), as a taxable REIT subsidiary (“TRS”). In general, a TRS may perform additional services for tenants and may engage in any real estate or non-real estate related business. A TRS is subject to U.S. federal corporate income tax and may also be subject to state and local income taxes. ESM Reinsurance Limited, a wholly-owned subsidiary of ESMI, generates income from insurance premiums that are subject to U.S. federal corporate income tax and state insurance premiums tax. Deferred tax assets and liabilities are determined based on differences between financial reporting and tax bases of assets and liabilities. At December 31, 2020 and 2019, there were no material unrecognized tax benefits. Interest and penalties relating to uncertain tax positions will be recognized in income tax expense when incurred. As of December 31, 2020 and 2019, the Company had no interest or penalties related to uncertain tax provisions. Stock-Based Compensation The measurement and recognition of compensation expense for all share-based payment awards to employees and directors are based on estimated fair values. Awards granted are valued at fair value and any compensation expense is recognized over the service periods of each award. Earnings Per Common Share Basic earnings per common share is computed using the two-class method by dividing net income attributable to common stockholders by the weighted average number of common shares outstanding during the period. All outstanding unvested restricted stock awards contain rights to non-forfeitable dividends and participate in undistributed earnings with common stockholders; accordingly, they are considered participating securities that are included in the two-class method. Diluted earnings per common share measures the performance of the Company over the reporting period while giving effect to all potential common shares that were dilutive and outstanding during the period. The denominator includes the weighted average number of basic shares and the number of additional common shares that would have been outstanding if the potential common shares that were dilutive had been issued, and is calculated using either the two-class, treasury stock or as if-converted method, whichever is most dilutive. Potential common shares are securities (such as options, convertible debt, Series A Participating Redeemable Preferred Units (“Series A Units”), Series B Redeemable Preferred Units (“Series B Units”), Series C Convertible Redeemable Preferred Units (“Series C Units”), Series D Redeemable Preferred Units (“Series D Units” and together with the Series A Units, Series B Units and Series C 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 (those that reduce earnings per common share) are included. For the years ended December 31, 2020 and 2019, there were no anti-dilutive shares outstanding. For the year ended December 31, 2018, options to purchase approximately 36,075 shares of common stock were excluded from the computation of earnings per share as their effect would have been anti-dilutive. For the purposes of computing the diluted impact of the potential exchange of the Preferred OP 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 liquidation value of the Preferred OP Units by the average share price of $103.62 for the year ended December 31, 2020. The following table presents the number of weighted OP Units and Preferred OP 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 Year Ended December 31, 2020 2019 2018 Equivalent Shares (if converted) Equivalent Shares (if converted) Equivalent Shares (if converted) Common OP Units 5,853,814 — — Series A Units (Variable Only) 875,480 — — Series B Units 400,771 393,189 464,033 Series C Units (1) — — 312,075 Series D Units 1,143,547 1,081,369 1,019,524 8,273,612 1,474,558 1,795,632 (1) The remainder of the Series C Units were converted to OP Units on April 25, 2019. The Operating Partnership had $575,000 of its 3.125% Exchangeable Senior Notes due 2035 (the “2015 Notes”) issued and outstanding prior to their redemption in November 2020. 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 ob

Real Estate Assets

Real Estate Assets	12 Months Ended
	Dec. 31, 2020
Real Estate [Abstract]
Real Estate Assets	REAL ESTATE ASSETS The components of real estate assets are summarized as follows: December 31, 2020 December 31, 2019 Land - operating $ 1,952,097 $ 1,935,551 Land - development 3,372 3,372 Buildings, improvements and other intangibles 7,357,033 7,047,654 Right of use asset - finance lease 58,148 8,050 Intangible assets - tenant relationships 124,695 122,489 Intangible lease rights 12,443 12,443 9,507,788 9,129,559 Less: accumulated depreciation and amortization (1,681,429) (1,473,852) Net operating real estate assets 7,826,359 7,655,707 Real estate under development/redevelopment 67,443 41,157 Net real estate assets $ 7,893,802 $ 7,696,864 Real estate assets held for sale included in net real estate assets $ 103,624 $ 2,947 As of December 31, 2020, the Company had 16 stores classified as held for sale. The estimated fair value less selling costs of these assets is greater than the carrying value of the assets, and therefore no loss has been recorded related to these assets. Assets held for sale are included in the self-storage operations segment of the Company’s segment information. The Company amortizes to expense intangible assets—tenant relationships on a straight-line basis over the average period that a tenant is expected to utilize the facility (currently estimated at 18 months). The Company amortizes to expense the intangible lease rights over the terms of the related leases. Amortization related to the tenant relationships and lease rights was $2,258, $6,614, and $9,050 for the years ended December 31, 2020, 2019 and 2018, respectively. The remaining balance of the unamortized lease rights will be amortized over the next eight

Property Acquisitions and Dispo

Property Acquisitions and Dispositions	12 Months Ended
	Dec. 31, 2020
Real Estate [Abstract]
Property Acquisitions and Dispositions	PROPERTY ACQUISITIONS AND DISPOSITIONS The following table shows the Company’s acquisitions of stores for the years ended December 31, 2020 and 2019. The table excludes purchases of raw land or improvements made to existing assets. Consideration Paid Total Quarter Number of Stores Total Cash Paid Loan Assumed Finance Lease Liability Investments in Real Estate Ventures Net Liabilities/ (Assets) Assumed Real estate assets Total 2020 23 $ 296,725 $ 254,111 $ — $ 41,491 $ — $ 1,123 $ 296,725 Total 2019 21 $ 300,379 $ 279,313 $ 17,157 $ — $ 2,780 $ 1,129 $ 300,379 (1) Store acquisitions during the year ended December 31, 2020 include the acquisition of three stores that were subject to finance land leases. The right-of-use assets associated with these leases are included in real estate assets above. (2) Store acquisitions during the year ended December 31, 2019 include the acquisition of 12 stores previously held in joint ventures where the Company held a noncontrolling interest. The Company purchased its partners' remaining equity interests in the 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 Disposals On December 18, 2020, the Company sold four stores located in Florida that had been classified as held for sale for a total sale price of $46,592. The Company recorded a gain on the sale of $19,600. On April 11, 2019, the Company sold a store located in New York that had been classified as held for sale for $11,272 in cash. The Company recorded a gain on the sale of $1,205. On August 16, 2018, the Company sold a store located in California that had been classified as held for sale for $40,235 in cash. The Company recorded a gain on the sale of $30,671.

Investments in Unconsolidated R

Investments in Unconsolidated Real Estate Entities	12 Months Ended
	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Investments in Unconsolidated Real Estate Entities	INVESTMENTS IN UNCONSOLIDATED REAL ESTATE ENTITIESInvestments 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, as applicable, 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 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 entities and cash distributions in unconsolidated real estate ventures consist of the following: Number of Stores Equity Ownership % Excess Profit % (1) December 31, 2020 2019 PR EXR Self Storage, LLC 5 25% 40% $ 60,092 $ 59,391 WICNN JV LLC (3) 10 10% 35% 36,032 36,552 VRS Self Storage, LLC 16 45% 54% 17,186 17,639 ESS-NYFL JV LP 11 16% 26% 12,211 13,320 GFN JV, LLC (3) 7 10% 30% 18,397 12,168 PRISA Self Storage LLC 85 4% 4% 8,815 9,133 Alan Jathoo JV LLC 9 10% 10% 7,780 7,977 Storage Portfolio III JV LLC 5 10% 30% 5,726 3,995 ESS Bristol Investments LLC 8 10% 30% 2,810 3,046 Extra Space Northern Properties Six LLC 10 10% 35% (2,541) (2,091) Storage Portfolio II JV LLC 36 10% 30% (5,441) (4,827) Storage Portfolio I LLC 24 34% 49% (39,144) (38,345) Other minority owned stores 21 10-50% 19-50% 28,395 24,832 SmartStop Self Storage REIT, Inc. Preferred Stock (2) n/a n/a n/a 200,000 150,000 Net Investments in and Cash distributions in unconsolidated real estate entities 247 350,318 292,790 (1) Includes pro-rata equity ownership share and promoted interest. (2) In October 2019, the Company invested $150,000 in shares of newly issued convertible preferred stock of SmartStop, with an additional commitment to purchase up to $50,000 of the preferred shares over the 12 months after the original purchase. In October 2020 the Company purchased the additional $50,000 in SmartStop convertible preferred stock that was previously committed. 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 in equity in earnings and dividend income from unconsolidated real estate entities on the Company's consolidated statements of operations. (3) The Company had $31,500 and $15,450 of preferred equity in the WICNN JV LLC and GFN JV, LLC joint ventures, respectively, as of December 31, 2020. The Company earns an 8.0% return on its preferred equity in these joint ventures, which has priority over other distributions. In accordance with ASC 810, the Company reviews all of its joint venture relationships annually to ensure that there are no entities that require consolidation. As of December 31, 2020, there were no previously unconsolidated entities that were required to be consolidated as a result of this review. The Company entered into several new unconsolidated real estate ventures during the years ended December 31, 2019 and 2018. The Company did not enter into any new joint ventures during the year ended December 31, 2020. The Company accounts for its investment in the following ventures under the equity method of accounting. Information about these real estate ventures is summarized as follows: Number of Stores Equity ownership % Total initial investment For the Year Ended December 31, 2019 16 10.0% - 50.0% $ 19,663 For the Year Ended December 31, 2018 28 10.0% - 25.0% $ 63,723 During the year ended December 31, 2020, the Company contributed a total of $14,792 to its existing joint ventures primarily relating to the purchase of one operating store and five stores acquired at the issuance of certificate of occupancy as well as for other operational and capital needs. In January 2019, the Company purchased its joint venture partners' interests in the Extra Space West One LLC and Extra Space West Two LLC joint ventures, which owned a total of 12 stores. The Company paid $172,505 of cash to acquire the equity interests, and subsequent to this acquisition, the Company owned 100.0% of the joint ventures and the related stores. On April 30, 2018, the Company acquired its partner's interest in the WCOT Self Storage LLC joint venture. The Company paid cash of $115,797 and assumed a loan of $87,500. The 14 properties owned by this joint venture became wholly-owned properties of the Company subsequent to this acquisition. Equity in earnings and dividend income from unconsolidated real estate entities consists of the following: For the Year Ended December 31, 2020 2019 2018 Dividend income from SmartStop preferred stock $ 9,968 $ 1,636 $ — Equity in earnings of PRISA Self Storage LLC 2,229 2,327 2,338 Equity in earnings of Storage Portfolio II JV LLC 559 291 79 Equity in earnings of Storage Portfolio I LLC 1,636 1,809 1,886 Equity in earnings of VRS Self Storage, LLC 3,509 3,583 3,640 Equity in earnings of ESS-NYFL JV LLC (331) (96) — Equity in earnings of WICNN JV LLC 1,878 1,373 622 Equity in earnings of Extra Space Northern Properties Six LLC 1,088 1,091 1,014 Equity in earnings of Alan Jathoo JV LLC 57 (47) (12) Equity in earnings of Bristol Investments LLC (67) (262) (152) Equity in earnings of GFN JV, LLC 788 450 22 Equity in earnings of PR EXR Self Storage, LLC (211) (443) (75) Equity in earnings of WCOT Self Storage LLC — — 359 Equity in earnings of Extra Space West Two LLC — — 1,042 Equity in earnings of Extra Space West One LLC — — 2,526 Equity in earnings of other minority owned stores 1,258 (438) 1,163 $ 22,361 $ 11,274 $ 14,452 Equity in earnings of certain of our joint ventures includes the amortization of the Company’s excess purchase price of $25,251 of these equity investments over its original basis. The excess basis is amortized over forty years. The Company provides management services to joint ventures for a fee. Management fee revenues for affiliated real estate joint ventures for the years ended December 31, 2020, 2019 and 2018 were $15,657, $14,624 and $12,650, respectively.

Investments in Debt Securities

Investments in Debt Securities and Notes Receivable	12 Months Ended
	Dec. 31, 2020
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: December 31, 2020 December 31, 2019 Debt securities - NexPoint Series A Preferred Stock $ 200,000 $ — Debt securities - NexPoint Series B Preferred Stock 100,000 — Notes Receivable-Bridge Loans 187,368 43,586 Notes Receivable-Senior Mezzanine Loan 101,553 — Dividends Receivable 4,889 — $ 593,810 $ 43,586 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 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 isn't retired after five years, the preferred dividends increase annually. The Company provides bridge loan financing to third-party self-storage operators. These notes receivable consist of primary mortgage and mezzanine loans receivable, collateralized by self-storage properties. These notes receivable typically have a term of three years with two one year extensions, and have variable interest rates. The Company intends to sell the majority of the mortgage receivables and keep the mezzanine receivables to maturity. During the year ended December 31, 2020, the Company sold a total principal amount of $63,088 of its mortgage bridge loans receivable to third parties for a total of $62,764 in cash. Subsequent to December 31, 2020, the Company sold a total of $76,241 principal amount of mortgage bridge loans to third parties for total cash of $75,707. 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%, and matures in December 2023. 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 and Revolving Lin

Notes Payable and Revolving Lines of Credit	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Notes Payable and Revolving Lines of Credit	NOTES PAYABLE AND REVOLVING LINES OF CREDIT The components of notes payable are summarized as follows: Notes Payable December 31, 2020 December 31, 2019 Fixed Rate Variable Rate Basis Rate (2) Maturity Dates Secured fixed rate notes payable (1) $ 1,112,220 $ 1,365,408 2.53% - 5.85% February 2021 - February 2030 Secured variable rate notes payable (1) 1,081,551 878,093 1.39% - 2.20% Libor plus 1.3% - 2.0% April 2021 - August 2028 Unsecured fixed rate notes payable 2,525,000 2,052,521 2.80% - 4.39% October 2023 - October 2030 Unsecured variable rate notes payable 100,000 47,480 1.04% Libor plus 0.9% Dec 2021 Total 4,818,771 4,343,502 Less: unamortized debt issuance costs (21,468) (24,529) Total $ 4,797,303 $ 4,318,973 (1) The loans are collateralized by mortgages on real estate assets and the assignment of rents. (2) 30-day USD LIBOR At December 31, 2020, the terms of the credit agreement originally entered into on October 14, 2016 (the "Credit Agreement") and amended and restated on December 7, 2018, July 1, 2019, and December 20, 2019, are as follows: Debt Capacity Maturity Date Revolving Credit Facility $ 650,000 January 2023 Tranche 1 Term Loan Facility (1) 480,000 January 2024 Tranche 2 Term Loan Facility (1) 220,000 October 2023 Tranche 3 Term Loan Facility (1) 245,000 January 2025 Tranche 4 Term Loan Facility (1) 255,000 June 2026 $ 1,850,000 (1) The term loan amounts have been fully drawn as of December 31, 2020. The Company may request an extension of the term of the Revolving Credit Facility for up to two additional periods of six months each, after satisfying certain conditions. As of December 31, 2020, amounts outstanding under the Revolving Credit Facility bore interest at floating rates, at the Company’s option, equal to either (i) LIBOR plus the applicable Eurodollar rate margin or (ii) the applicable base rate which is the applicable margin plus the highest of (a) 0.0%, (b) the federal funds rate plus 0.50%, (c) U.S. Bank’s prime rate or (d) the Eurodollar rate plus 1.00%. Per the Credit Agreement, the applicable Eurodollar rate margin and applicable base rate margin are based on the Company’s achieved debt rating pursuant to the ‘Investment Grade Election,’ with the Eurodollar rate margin ranging from 0.75% to 2.25% per annum and the applicable base rate margin ranging from 0.00% to 1.25% per annum. The Credit Agreement is guaranteed by the Company and is not secured by any assets of the Company. The Company's unsecured debt is subject to certain financial covenants. As of December 31, 2020, the Company was in compliance with all of its financial covenants. The following table summarizes the scheduled maturities of notes payable, excluding available extensions, at December 31, 2020: 2021 $ 459,557 2022 584,865 2023 762,925 2024 705,153 2025 524,827 Thereafter 1,781,444 $ 4,818,771 Real estate assets are pledged as collateral for the secured loans. Of the Company’s $4,818,771 principal amount of notes payable outstanding at December 31, 2020, $1,969,323 was recourse due to guarantees or other security provisions. All of the Company’s lines of credit are guaranteed by the Company. The following table presents information on the Company’s lines of credit, the proceeds of which are used to repay debt and for general corporate purposes, for the periods indicated: As of December 31, 2020 Revolving Lines of Credit Amount Drawn Capacity Interest Rate Origination Date Maturity Basis Rate (1) Credit Line 1 (2) $ 102,000 $ 140,000 1.6% 6/4/2010 7/1/2021 LIBOR plus 1.45% Credit Line 2 (3)(4) 487,000 650,000 1.0% 12/7/2018 1/29/2023 LIBOR plus 0.9% Credit Line 3 (4)(5) $ 360,000 $ 400,000 1.5% 6/17/2020 6/17/2021 LIBOR plus 1.2% $ 949,000 $ 1,190,000 (1) 30-day USD LIBOR (2) Secured by mortgages on certain real estate assets. One two (3) Unsecured. Two six (4) Basis Rate as of December 31, 2020. Rate is subject to change based on our investment grade rating. (5) Unsecured. One twelve 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 were included in exchangeable senior notes, net, in the consolidated balance sheets. 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. The Notes bore interest at 3.125% per annum and contained an exchange settlement feature, which provided that the 2015 Notes could, under certain circumstances, be exchangeable for cash (for the principal amount of the 2015 Notes) and, with respect to any excess exchange value, for cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock, at the Company’s option. The Operating Partnership could redeem the 2015 Notes at any time to preserve the Company’s status as a REIT. In addition, on or after October 5, 2020, the Operating Partnership could redeem the 2015 Notes for cash, in whole or in part, at 100% of the principal amount plus accrued and unpaid interest, upon at least 30 days but not more than 60 days prior written notice to the holders of the 2015 Notes. The holders of the 2015 Notes had the right to require the Operating Partnership to repurchase the 2015 Notes for cash, in whole or in part, on October 1 of the years 2020, 2025 and 2030, (unless the Operating Partnership had called the 2015 Notes for redemption), and upon the occurrence of certain designated events, in each case for a repurchase price equal to 100% of the principal amount of the 2015 Notes plus accrued and unpaid interest. Additionally, the 2015 Notes could have been exchanged during any calendar quarter, if the last reported sale price of the common stock of the Company was greater than or equal to 130% of the exchange price for at least 20 trading days during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter. The Company redeemed all outstanding 2015 Notes on November 2, 2020. On June 21, 2013, the Operating Partnership issued $250,000 of its 2013 Notes at a 1.5% discount, or $3,750. Costs incurred to issue the 2013 Notes were approximately $1,672. 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. The 2013 Notes bore interest at 2.375% per annum and contained an exchange settlement feature. The Operating Partnership redeemed all remaining outstanding 2013 Notes on July 5, 2018. 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 component of the 2015 Notes separately. The equity components were included in paid-in capital in stockholders’ equity in the consolidated balance sheets, and the value of the equity components were treated as original issue discount for purposes of accounting for the debt components. The discount was amortized as interest expense over the remaining period of the debt through its first redemption date, October 1, 2020 for the 2015 Notes. The effective interest rate on the liability components of the 2015 Notes was 4.0%, which approximates the market rate of interest of similar debt without exchange features (i.e. nonconvertible debt) at the time of issuance. Information about the 2015 Notes, including the total carrying amounts of the equity component, the principal amount of the liability component, the unamortized discount and net carrying amount, was as follows for the periods indicated: December 31, 2020 December 31, 2019 Carrying amount of equity component $ — $ 22,597 Principal amount of liability component $ — $ 575,000 Unamortized discount - equity component — (3,675) Unamortized debt issuance costs — (1,812) Net carrying amount of liability component $ — $ 569,513 The amount of interest cost recognized relating to the contractual interest rate and the amortization of the discount on the liability component for the Notes were as follows for the periods indicated: For the Year Ended December 31, 2020 2019 2018 Contractual interest $ 13,476 $ 17,968 $ 18,106 Amortization of discount 3,675 4,742 4,687 Total interest expense recognized $ 17,151 $ 22,710 $ 22,793 Repurchase of 2013 Notes During the year ended December 31, 2018, the Company repurchased a total principal amount of $49,259 of the 2013 Notes, which represented all of the remaining principal amount outstanding. The Company paid cash of $80,270 for the total of the principal amount and the exchange value in excess of the principal amount. Repurchase of 2015 Notes On October 1, 2020, the holders of $71,513 principal amount of the 2015 Notes exchanged their Notes. The Company paid cash of $71,513 for the principal amount and issued 124,819 shares of common stock with a value of $13,495 for the exchange value in excess of the principal amount. On November 2, 2020, the holders of an additional $503,432 principal amount of the 2015 Notes exchanged their Notes. The Company paid cash of $503,432 for the principal amount and issued 1,198,962 shares of common stock with a value of $138,900 for the exchange value in excess of the principal amount. Also on November 2, 2020, the Company redeemed the remaining $55 of outstanding principal amount of the 2015 Notes for cash. The Company allocated the value of the consideration paid to repurchase the 2013 Notes and the 2015 Notes (1) to the extinguishment of the liability component and (2) to the reacquisition of the equity component. The amount allocated to the extinguishment of the liability component is equal to the fair value of that component immediately prior to extinguishment. The difference between the consideration attributed to the extinguishment of the liability component and the sum of (a) the net carrying amount of the repurchased liability component, and (b) the related unamortized debt issuance costs, is recognized as a gain on debt extinguishment. The remaining settlement consideration is allocated to the reacquisition of the equity component of the repurchased 2013 Notes and 2015 Notes and recognized as a reduction of stockholders’ equity. Information about the repurchases is as follows: For the Year Ended December 31, 2020 2019 2018 Principal amount repurchased $ 575,000 $ — $ 49,259 Amount allocated to: Extinguishment of liability component $ 575,000 $ — $ 49,019 Reacquisition of equity component — — 31,251 Total consideration paid for repurchase $ 575,000 $ — $ 80,270 Exchangeable senior notes repurchased $ 575,000 $ — $ 49,259 Extinguishment of liability component (575,000) — (49,019) Discount on exchangeable senior notes — — (230) Related debt issuance costs — — (10) Gain/(loss) on repurchase $ — $ — $ —

Derivatives

Derivatives	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	DERIVATIVESThe Company is exposed to certain risk 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 the use of derivative financial instruments. Specifically, the Company enters into derivative financial instruments to manage exposures that arise 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 this objective, 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 years ended December 31, 2020, 2019 and 2018, such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt. During 2021, the Company estimates that $35,080 will be reclassified as an increase to interest expense. The following table summarizes the terms of the Company’s 22 derivative financial instruments, which have a total combined notional amount of $2,091,270 as of December 31, 2020: Hedge Product Range of Notional Amounts Strike Effective Dates Maturity Dates Swap Agreements $33,681 - $238,139 1.07% - 3.87% 7/8/2015 - 3/30/2020 4/1/2021 - 6/29/2026 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 consolidated balance sheets: Asset / Liability Derivatives December 31, 2020 December 31, 2019 Derivatives designated as hedging instruments: Fair Value Other assets $ — $ 6,214 Other liabilities $ 98,325 $ 31,400 Effect of Derivative Instruments The tables below present the effect of the Company’s derivative financial instruments on the 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 Year Ended December 31, Location of amounts reclassified from OCI into income Gain (loss) reclassified from OCI For the Year Ended December 31, Type 2020 2019 2020 2019 2018 Swap Agreements $ (100,352) $ (54,680) Interest expense $ (26,794) $ 12,322 $ 8,258 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.

Notes Payable to Trusts

Notes Payable to Trusts	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Notes Payable to Trusts	NOTES PAYABLE TO TRUSTS The Operating Partnership had three wholly-owned unconsolidated subsidiaries (“Trust", “Trust II”, “Trust III,” together, the "Trusts") that had issued trust preferred securities to third parties and common securities to the Operating Partnership during 2005. The Trusts loaned proceeds from the sale of the preferred and common securities to the Operating Partnership in the form of notes. The Trusts were VIEs because the holders of the equity investment at risk (that is the Trusts' preferred securities) did not have the power to direct the activities of the entities that most significantly affected the entities’ economic performance due to their lack of voting or similar rights. Because the Operating Partnership’s investment in the Trusts’ common securities was financed directly by the Trusts as a result of its loan of the proceeds to the Operating Partnership, that investment was not considered an equity investment at risk. The Operating Partnership’s investment in the Trusts was not a variable interest because equity interests are variable interests only to the extent that the investment is considered to be at risk, and therefore the Operating Partnership was not the primary beneficiary of the Trusts. Since the Company was not the primary beneficiary of the Trusts, they were not consolidated. A debt obligation was recorded in the form of notes for the proceeds as discussed above, which were owed to the Trusts. The Company had also included its investment in the Trusts’ common securities in other assets on the Company's consolidated balance sheets. During the year ended December 31, 2018, the Company repaid a total principal amount of $88,662 of the notes payable to Trusts, representing all of the notes payable to Trust III, all of the notes payable to Trust II, and all but $30,928 of the notes payable to Trust. The Trusts used the proceeds from these repayments to redeem their preferred and common securities. In January 2019, the Company repaid the remaining balance of $30,928 of notes payable to Trust. During the time the notes were outstanding, the Company did not provide financing or other support during the periods presented to the Trusts that it was not previously contractually obligated to provide. The Company’s maximum exposure to loss as a result of its involvement with the Trusts was equal to the total amount of the notes discussed above less the amounts of the Company’s investments in the Trusts’ common securities. The net amount was equal to the notes payable that the Trusts owed to third parties for their investments in the Trusts’ preferred securities.

Exchangeable Senior Notes

Exchangeable Senior Notes	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Exchangeable Senior Notes	NOTES PAYABLE AND REVOLVING LINES OF CREDIT The components of notes payable are summarized as follows: Notes Payable December 31, 2020 December 31, 2019 Fixed Rate Variable Rate Basis Rate (2) Maturity Dates Secured fixed rate notes payable (1) $ 1,112,220 $ 1,365,408 2.53% - 5.85% February 2021 - February 2030 Secured variable rate notes payable (1) 1,081,551 878,093 1.39% - 2.20% Libor plus 1.3% - 2.0% April 2021 - August 2028 Unsecured fixed rate notes payable 2,525,000 2,052,521 2.80% - 4.39% October 2023 - October 2030 Unsecured variable rate notes payable 100,000 47,480 1.04% Libor plus 0.9% Dec 2021 Total 4,818,771 4,343,502 Less: unamortized debt issuance costs (21,468) (24,529) Total $ 4,797,303 $ 4,318,973 (1) The loans are collateralized by mortgages on real estate assets and the assignment of rents. (2) 30-day USD LIBOR At December 31, 2020, the terms of the credit agreement originally entered into on October 14, 2016 (the "Credit Agreement") and amended and restated on December 7, 2018, July 1, 2019, and December 20, 2019, are as follows: Debt Capacity Maturity Date Revolving Credit Facility $ 650,000 January 2023 Tranche 1 Term Loan Facility (1) 480,000 January 2024 Tranche 2 Term Loan Facility (1) 220,000 October 2023 Tranche 3 Term Loan Facility (1) 245,000 January 2025 Tranche 4 Term Loan Facility (1) 255,000 June 2026 $ 1,850,000 (1) The term loan amounts have been fully drawn as of December 31, 2020. The Company may request an extension of the term of the Revolving Credit Facility for up to two additional periods of six months each, after satisfying certain conditions. As of December 31, 2020, amounts outstanding under the Revolving Credit Facility bore interest at floating rates, at the Company’s option, equal to either (i) LIBOR plus the applicable Eurodollar rate margin or (ii) the applicable base rate which is the applicable margin plus the highest of (a) 0.0%, (b) the federal funds rate plus 0.50%, (c) U.S. Bank’s prime rate or (d) the Eurodollar rate plus 1.00%. Per the Credit Agreement, the applicable Eurodollar rate margin and applicable base rate margin are based on the Company’s achieved debt rating pursuant to the ‘Investment Grade Election,’ with the Eurodollar rate margin ranging from 0.75% to 2.25% per annum and the applicable base rate margin ranging from 0.00% to 1.25% per annum. The Credit Agreement is guaranteed by the Company and is not secured by any assets of the Company. The Company's unsecured debt is subject to certain financial covenants. As of December 31, 2020, the Company was in compliance with all of its financial covenants. The following table summarizes the scheduled maturities of notes payable, excluding available extensions, at December 31, 2020: 2021 $ 459,557 2022 584,865 2023 762,925 2024 705,153 2025 524,827 Thereafter 1,781,444 $ 4,818,771 Real estate assets are pledged as collateral for the secured loans. Of the Company’s $4,818,771 principal amount of notes payable outstanding at December 31, 2020, $1,969,323 was recourse due to guarantees or other security provisions. All of the Company’s lines of credit are guaranteed by the Company. The following table presents information on the Company’s lines of credit, the proceeds of which are used to repay debt and for general corporate purposes, for the periods indicated: As of December 31, 2020 Revolving Lines of Credit Amount Drawn Capacity Interest Rate Origination Date Maturity Basis Rate (1) Credit Line 1 (2) $ 102,000 $ 140,000 1.6% 6/4/2010 7/1/2021 LIBOR plus 1.45% Credit Line 2 (3)(4) 487,000 650,000 1.0% 12/7/2018 1/29/2023 LIBOR plus 0.9% Credit Line 3 (4)(5) $ 360,000 $ 400,000 1.5% 6/17/2020 6/17/2021 LIBOR plus 1.2% $ 949,000 $ 1,190,000 (1) 30-day USD LIBOR (2) Secured by mortgages on certain real estate assets. One two (3) Unsecured. Two six (4) Basis Rate as of December 31, 2020. Rate is subject to change based on our investment grade rating. (5) Unsecured. One twelve 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 were included in exchangeable senior notes, net, in the consolidated balance sheets. 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. The Notes bore interest at 3.125% per annum and contained an exchange settlement feature, which provided that the 2015 Notes could, under certain circumstances, be exchangeable for cash (for the principal amount of the 2015 Notes) and, with respect to any excess exchange value, for cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock, at the Company’s option. The Operating Partnership could redeem the 2015 Notes at any time to preserve the Company’s status as a REIT. In addition, on or after October 5, 2020, the Operating Partnership could redeem the 2015 Notes for cash, in whole or in part, at 100% of the principal amount plus accrued and unpaid interest, upon at least 30 days but not more than 60 days prior written notice to the holders of the 2015 Notes. The holders of the 2015 Notes had the right to require the Operating Partnership to repurchase the 2015 Notes for cash, in whole or in part, on October 1 of the years 2020, 2025 and 2030, (unless the Operating Partnership had called the 2015 Notes for redemption), and upon the occurrence of certain designated events, in each case for a repurchase price equal to 100% of the principal amount of the 2015 Notes plus accrued and unpaid interest. Additionally, the 2015 Notes could have been exchanged during any calendar quarter, if the last reported sale price of the common stock of the Company was greater than or equal to 130% of the exchange price for at least 20 trading days during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter. The Company redeemed all outstanding 2015 Notes on November 2, 2020. On June 21, 2013, the Operating Partnership issued $250,000 of its 2013 Notes at a 1.5% discount, or $3,750. Costs incurred to issue the 2013 Notes were approximately $1,672. 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. The 2013 Notes bore interest at 2.375% per annum and contained an exchange settlement feature. The Operating Partnership redeemed all remaining outstanding 2013 Notes on July 5, 2018. 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 component of the 2015 Notes separately. The equity components were included in paid-in capital in stockholders’ equity in the consolidated balance sheets, and the value of the equity components were treated as original issue discount for purposes of accounting for the debt components. The discount was amortized as interest expense over the remaining period of the debt through its first redemption date, October 1, 2020 for the 2015 Notes. The effective interest rate on the liability components of the 2015 Notes was 4.0%, which approximates the market rate of interest of similar debt without exchange features (i.e. nonconvertible debt) at the time of issuance. Information about the 2015 Notes, including the total carrying amounts of the equity component, the principal amount of the liability component, the unamortized discount and net carrying amount, was as follows for the periods indicated: December 31, 2020 December 31, 2019 Carrying amount of equity component $ — $ 22,597 Principal amount of liability component $ — $ 575,000 Unamortized discount - equity component — (3,675) Unamortized debt issuance costs — (1,812) Net carrying amount of liability component $ — $ 569,513 The amount of interest cost recognized relating to the contractual interest rate and the amortization of the discount on the liability component for the Notes were as follows for the periods indicated: For the Year Ended December 31, 2020 2019 2018 Contractual interest $ 13,476 $ 17,968 $ 18,106 Amortization of discount 3,675 4,742 4,687 Total interest expense recognized $ 17,151 $ 22,710 $ 22,793 Repurchase of 2013 Notes During the year ended December 31, 2018, the Company repurchased a total principal amount of $49,259 of the 2013 Notes, which represented all of the remaining principal amount outstanding. The Company paid cash of $80,270 for the total of the principal amount and the exchange value in excess of the principal amount. Repurchase of 2015 Notes On October 1, 2020, the holders of $71,513 principal amount of the 2015 Notes exchanged their Notes. The Company paid cash of $71,513 for the principal amount and issued 124,819 shares of common stock with a value of $13,495 for the exchange value in excess of the principal amount. On November 2, 2020, the holders of an additional $503,432 principal amount of the 2015 Notes exchanged their Notes. The Company paid cash of $503,432 for the principal amount and issued 1,198,962 shares of common stock with a value of $138,900 for the exchange value in excess of the principal amount. Also on November 2, 2020, the Company redeemed the remaining $55 of outstanding principal amount of the 2015 Notes for cash. The Company allocated the value of the consideration paid to repurchase the 2013 Notes and the 2015 Notes (1) to the extinguishment of the liability component and (2) to the reacquisition of the equity component. The amount allocated to the extinguishment of the liability component is equal to the fair value of that component immediately prior to extinguishment. The difference between the consideration attributed to the extinguishment of the liability component and the sum of (a) the net carrying amount of the repurchased liability component, and (b) the related unamortized debt issuance costs, is recognized as a gain on debt extinguishment. The remaining settlement consideration is allocated to the reacquisition of the equity component of the repurchased 2013 Notes and 2015 Notes and recognized as a reduction of stockholders’ equity. Information about the repurchases is as follows: For the Year Ended December 31, 2020 2019 2018 Principal amount repurchased $ 575,000 $ — $ 49,259 Amount allocated to: Extinguishment of liability component $ 575,000 $ — $ 49,019 Reacquisition of equity component — — 31,251 Total consideration paid for repurchase $ 575,000 $ — $ 80,270 Exchangeable senior notes repurchased $ 575,000 $ — $ 49,259 Extinguishment of liability component (575,000) — (49,019) Discount on exchangeable senior notes — — (230) Related debt issuance costs — — (10) Gain/(loss) on repurchase $ — $ — $ —

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY The Company’s charter provides that it can issue up to 500,000,000 shares of common stock, $0.01 par value per share and 50,000,000 shares of preferred stock, $0.01 par value per share. As of December 31, 2020, 131,357,961 shares of common stock were issued and outstanding, and no shares of preferred stock were issued or outstanding. All holders of the Company's common stock are entitled to receive dividends and to one vote on all matters submitted to a vote of stockholders. The transfer agent and registrar for the Company’s common stock is American Stock Transfer & Trust Company. On May 15, 2019, the Company filed its current $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. Under the terms of the current equity distribution agreements, the Company may from time to time offer and sell shares of common stock, up to the aggregate offering price of $500,000, through its sales agents. During the year ended December 31, 2020, the Company sold 899,048 shares of common stock under its "at the market" equity program at an average sales price of $116.42 per share, resulting in net proceeds of $103,468. At December 31, 2020, the Company had $193,951 available for issuance under the current equity distribution agreements. Subsequent to year end, the Company sold 585,685 shares of common stock at an average sales price of $115.90, resulting in net proceeds of $67,204. During the year ended December 31, 2019, the Company sold 1,779,200 shares of common stock at an average sales price of $113.19 per share, resulting in net proceeds of $198,827.

Noncontrolling Interest Represe

Noncontrolling Interest Represented By Preferred Operating Partnership Units	12 Months Ended
	Dec. 31, 2020
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 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 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, or (2) its redemption value as of the end of the period in which the determination is made. At December 31, 2020 and 2019, the noncontrolling interests represented by the Preferred OP Units qualified for classification as permanent equity on the Company's 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. Noncontrolling interests in Preferred OP Units were presented net of notes receivable from preferred Operating Partnership unit holders of $100,000 as of December 31, 2020 and 2019, respectively, as more fully described below. Series A Participating Redeemable Preferred Units 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 common OP Units. The Series A Units became redeemable at the option of the holder on September 1, 2008, 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 April 18, 2017, the holder of the Series A Units and the Operating Partnership agreed to reduce the fixed priority return on the Series A Units from 5.0% to 2.3% in exchange for a reduction in the interest rate of the related loan, as more fully described below. 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. On June 25, 2007, the Operating Partnership loaned the holders of the Series A Units $100,000. The note receivable bears interest at 2.1%. On April 18, 2017, a loan amendment was signed modifying the maturity date of the loan to the later of the death of the Series A Unit holder or his spouse and also lowering the interest rate of the loan from 4.9% to 2.1%. The loan amendment was determined to be a loan modification under GAAP, and therefore no change in value was recognized. 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 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 current 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 are redeemable at the option of the holder on the first anniversary of the date of issuance, which redemption obligations may be satisfied at the Company’s option in cash or shares of its common stock. 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. On August 17, 2020, 40,000 Series B Units were redeemed for a total of $1,000 in cash. Series C Convertible Redeemable Preferred Units The Partnership Agreement provides for the designation and issuance of the Series C Units. The Series C Units rank junior to the Series A Units, on parity with the Series B Units and Series D Units, and senior to all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series C Units were issued in 2013 and 2014 and had a liquidation value of $42.10 per unit. From issuance to the fifth anniversary of issuance, each Series C Unit holder received quarterly distributions equal to the quarterly distribution for common OP Unit plus $0.18. These distributions were cumulative. 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 common OP Units at the option of the holder one year from the date of issuance, at a rate of 0.9145 common 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 holders of the Series C Units $20,230. The note receivable, which was collateralized by the Series C Units, bears interest at 5.0% and matures on December 15, 2024. The Series C Units were shown on the balance sheet net of the loan 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 common OP Units, with a total of 407,996 Series C Units being converted into a total of 373,113 common OP Units. As part of this conversion, the holders of the Series C Units agreed to pledge the common OP Units received in the conversion as collateral on the loan receivable to replace the Series C Units that were converted. As of December 31, 2018, the total outstanding balance of the loan receivable was $19,735, of which $8,644 was shown as a reduction of the noncontrolling interests related to the Series C Units and $11,091 was shown as a reduction of the noncontrolling interests related to the common OP Units on the Company's consolidated balance sheets. 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 $2,311 and $18,524 is shown as a reduction of the noncontrolling interests related to the OP Units as of December 31, 2020 and December 31, 2019, respectively. 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 interest of the Operating Partnership with respect to distributions and liquidation. The Series D Units have been issued at various times from 2014 to 2019. During the year ended December 31, 2019, the Operating Partnership issued a total of 1,120,924 Series D Units valued at $28,022 in conjunction with joint venture acquisitions. 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 94.2% majority ownership interest therein as of December 31, 2020. The remaining ownership interests in the Operating Partnership (including Preferred OP Units) of 5.8% are held by certain former owners of assets acquired by the Operating Partnership. The noncontrolling interest in the Operating Partnership represents OP Units that are not owned by the Company. 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. Alternatively, the Company may, at its sole discretion, elect to acquire those OP Units in exchange for shares of its common stock on a one-for-one basis, subject to anti-dilution adjustments provided in the Operating Partnership agreement. The ten-day average closing stock price at December 31, 2020, was $114.15 and there were 5,800,785 OP Units outstanding. Assuming that all of the OP Unit holders exercised their right to redeem all of their OP Units on December 31, 2020 and the Company elected to pay the OP Unit holders cash, the Company would have paid $662,160 in cash consideration to redeem the units. OP Unit activity is summarized as follows for the periods presented: For the Year Ended December 31, 2020 2019 2018 OP Units redeemed for common stock 123,993 340,182 35,000 OP Units redeemed for cash — — 30,000 Cash paid for OP Units redeemed $ — $ — $ 2,558 OP Units issued in conjunction with acquisitions — — 21,768 Value of OP Units issued in conjunction with acquisitions $ — $ — $ 1,877 OP Units issued upon redemption of Series C Units — 270,709 373,113 On December 1, 2018, 373,113 common OP Units were issued in the conversion of 407,996 Series C Units. These newly issued OP Units were pledged as collateral on the existing loan receivable to the Series C Unit holders. As a result, noncontrolling interests in the Operating Partnership was reported net of $11,091 of the loan receivable as of December 31, 2018, which represents the portion of the note receivable that is collateralized by the OP Units. The remaining 296,020 Series C Units were converted into 270,709 OP Units on April 25, 2019 and the remainder of the loan receivable was reported net with the OP Units. The remaining total outstanding balance of the loan receivable of $2,311 and $18,524 is shown as a reduction of the noncontrolling interests related to the OP Units as of December 31, 2020 and 2019, respectively. 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 common OP Units and classifies the noncontrolling interest represented by the common OP Units as stockholders’ equity in the accompanying 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 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, or (2) its redemption value as of the end of the period in which the determination is made. Other Noncontrolling Interests

Noncontrolling Interests In Ope

Noncontrolling Interests In Operating Partnership and Other Noncontrolling Interests	12 Months Ended
	Dec. 31, 2020
Noncontrolling Interest [Abstract]
Noncontrolling Interests 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 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 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, or (2) its redemption value as of the end of the period in which the determination is made. At December 31, 2020 and 2019, the noncontrolling interests represented by the Preferred OP Units qualified for classification as permanent equity on the Company's 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. Noncontrolling interests in Preferred OP Units were presented net of notes receivable from preferred Operating Partnership unit holders of $100,000 as of December 31, 2020 and 2019, respectively, as more fully described below. Series A Participating Redeemable Preferred Units 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 common OP Units. The Series A Units became redeemable at the option of the holder on September 1, 2008, 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 April 18, 2017, the holder of the Series A Units and the Operating Partnership agreed to reduce the fixed priority return on the Series A Units from 5.0% to 2.3% in exchange for a reduction in the interest rate of the related loan, as more fully described below. 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. On June 25, 2007, the Operating Partnership loaned the holders of the Series A Units $100,000. The note receivable bears interest at 2.1%. On April 18, 2017, a loan amendment was signed modifying the maturity date of the loan to the later of the death of the Series A Unit holder or his spouse and also lowering the interest rate of the loan from 4.9% to 2.1%. The loan amendment was determined to be a loan modification under GAAP, and therefore no change in value was recognized. 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 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 current 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 are redeemable at the option of the holder on the first anniversary of the date of issuance, which redemption obligations may be satisfied at the Company’s option in cash or shares of its common stock. 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. On August 17, 2020, 40,000 Series B Units were redeemed for a total of $1,000 in cash. Series C Convertible Redeemable Preferred Units The Partnership Agreement provides for the designation and issuance of the Series C Units. The Series C Units rank junior to the Series A Units, on parity with the Series B Units and Series D Units, and senior to all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series C Units were issued in 2013 and 2014 and had a liquidation value of $42.10 per unit. From issuance to the fifth anniversary of issuance, each Series C Unit holder received quarterly distributions equal to the quarterly distribution for common OP Unit plus $0.18. These distributions were cumulative. 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 common OP Units at the option of the holder one year from the date of issuance, at a rate of 0.9145 common 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 holders of the Series C Units $20,230. The note receivable, which was collateralized by the Series C Units, bears interest at 5.0% and matures on December 15, 2024. The Series C Units were shown on the balance sheet net of the loan 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 common OP Units, with a total of 407,996 Series C Units being converted into a total of 373,113 common OP Units. As part of this conversion, the holders of the Series C Units agreed to pledge the common OP Units received in the conversion as collateral on the loan receivable to replace the Series C Units that were converted. As of December 31, 2018, the total outstanding balance of the loan receivable was $19,735, of which $8,644 was shown as a reduction of the noncontrolling interests related to the Series C Units and $11,091 was shown as a reduction of the noncontrolling interests related to the common OP Units on the Company's consolidated balance sheets. 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 $2,311 and $18,524 is shown as a reduction of the noncontrolling interests related to the OP Units as of December 31, 2020 and December 31, 2019, respectively. 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 interest of the Operating Partnership with respect to distributions and liquidation. The Series D Units have been issued at various times from 2014 to 2019. During the year ended December 31, 2019, the Operating Partnership issued a total of 1,120,924 Series D Units valued at $28,022 in conjunction with joint venture acquisitions. 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 94.2% majority ownership interest therein as of December 31, 2020. The remaining ownership interests in the Operating Partnership (including Preferred OP Units) of 5.8% are held by certain former owners of assets acquired by the Operating Partnership. The noncontrolling interest in the Operating Partnership represents OP Units that are not owned by the Company. 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. Alternatively, the Company may, at its sole discretion, elect to acquire those OP Units in exchange for shares of its common stock on a one-for-one basis, subject to anti-dilution adjustments provided in the Operating Partnership agreement. The ten-day average closing stock price at December 31, 2020, was $114.15 and there were 5,800,785 OP Units outstanding. Assuming that all of the OP Unit holders exercised their right to redeem all of their OP Units on December 31, 2020 and the Company elected to pay the OP Unit holders cash, the Company would have paid $662,160 in cash consideration to redeem the units. OP Unit activity is summarized as follows for the periods presented: For the Year Ended December 31, 2020 2019 2018 OP Units redeemed for common stock 123,993 340,182 35,000 OP Units redeemed for cash — — 30,000 Cash paid for OP Units redeemed $ — $ — $ 2,558 OP Units issued in conjunction with acquisitions — — 21,768 Value of OP Units issued in conjunction with acquisitions $ — $ — $ 1,877 OP Units issued upon redemption of Series C Units — 270,709 373,113 On December 1, 2018, 373,113 common OP Units were issued in the conversion of 407,996 Series C Units. These newly issued OP Units were pledged as collateral on the existing loan receivable to the Series C Unit holders. As a result, noncontrolling interests in the Operating Partnership was reported net of $11,091 of the loan receivable as of December 31, 2018, which represents the portion of the note receivable that is collateralized by the OP Units. The remaining 296,020 Series C Units were converted into 270,709 OP Units on April 25, 2019 and the remainder of the loan receivable was reported net with the OP Units. The remaining total outstanding balance of the loan receivable of $2,311 and $18,524 is shown as a reduction of the noncontrolling interests related to the OP Units as of December 31, 2020 and 2019, respectively. 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 common OP Units and classifies the noncontrolling interest represented by the common OP Units as stockholders’ equity in the accompanying 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 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, or (2) its redemption value as of the end of the period in which the determination is made. Other Noncontrolling Interests

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	LEASES The Company adopted ASC 842, "Leases," effective January 1, 2019 on a modified retrospective basis as allowed under the standard and thus prior periods have not been restated. The Company elected the package of transition practical expedients, and has therefore (1) not reassessed whether any expired or existing contracts are or contain leases, (2) not reassessed the lease classification for any expired or existing leases, and (3) not reassessed initial direct costs for any expired or existing leases. Lessee Accounting The Company recognized right-of-use assets related to operating leases totaling $95,506 and lease liabilities of $104,863 as of the adoption date, January 1, 2019. These are presented as “Operating lease liabilities” and “Real estate assets-operating lease right-of-use assets” on the Company’s consolidated balance sheets. Right-of-use assets associated with finance leases are included in real estate assets, net and finance lease liabilities are included in other liabilities During the year ended December 31, 2020, the Company recorded new finance lease right-of-use assets and finance lease liabilities totaling $41,491 associated with the acquisition of three stores with land leases. The Company also recorded finance lease right-of-use assets and finance lease liabilities of $8,605 upon the completion of construction of a store with a land lease. In June and August 2019, the Company entered into new triple-net lease agreements to lease land and buildings at 22 and five operating stores, respectively. These leases are categorized as operating leases, and have contractual lease terms of 25 years, but have termination options after 10 years that result in lease terms of 10 years under ASC 842. The Company recorded new operating lease right-of-use assets and operating lease liabilities of $127,532 and $52,224, respectively, in conjunction with these new lease agreements. The Company is lessee under several types of lease agreements. Generally, these leases fall into the following categories: • Leases of real estate at 53 stores classified as wholly-owned or in consolidated joint ventures. These leases generally have original lease terms between 10-99 years. Under these leases, the Company typically has the option to extend the lease term for additional terms of 5-35 years. • Leases of its corporate offices and call center. These leases have original lease terms between 5.3 and 12.1 years, with no extension options. Subsequent to year-end the Company modified and extended the lease of its corporate offices to add additional space and extend the lease until 2034. • Leases of 13 regional offices. These leases have original lease terms between three three • Leases of small district offices. These leases generally have terms of 12 months or less. The Company has made an election to account for these under the short-term lease exception outlined under ASC 842. Therefore, no lease assets or liabilities are recorded related to these leases. The Company has included lease extension options in the lease term for calculations of its right-of-use assets and liabilities related to the real estate asset leases at its stores when it is reasonably certain that the Company plans to extend the lease terms as the options arise. Several of the leases of real estate at the Company’s stores include escalation clauses based on an index or rate, such as the Consumer Price Index (CPI). The Company included these lease payments in its calculations of right-of-use assets and liabilities based on the prevailing index or rate as of the adoption date. The Company will recognize changes to these variable lease payments in earnings in the period of change. One of the real estate leases includes variable lease payments that are based upon a percentage of gross revenues. Certain other leases include additional variable payments relating to a percentage of sales in excess of a specified amount, common area maintenance, property taxes, and similar items. These payments are variable lease payments that do not depend on an index or rate and are excluded from the measurement of the lease liabilities and right-of-use-assets for these leases. The Company will recognize costs from these variable lease payments in the period in which the obligation for those payments is incurred. The Company has a signed lease agreement for a store in California. The store is under construction by the lessor, and the Company will take possession of the leased asset upon completion of construction, which is estimated to be completed in mid- 2021. The lease term is 15 years from the lease commencement date, with three 10-year extension options and one 5-year extension option. The Company has not recorded right-of-use asset or lease liability related to this lease as of December 31, 2020 as the lease term has not yet commenced. The lease commencement date will occur when the Company takes possession of the leased asset, and the Company will recognize a lease liability and right-of-use asset relating to the lease at that time. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available surrounding the Company’s unsecured borrowing rates and implied secured spread at the lease commencement date in determining the present value of lease payments. These discount rates vary depending on the term of the specific leases. Following is information on our total lease costs as of the period indicated: For the Year Ended December 31, 2020 2019 Finance lease cost: Amortization of finance lease right-of-use assets $ 400 $ 168 Interest expense related to finance lease liabilities 712 290 Operating lease cost 28,709 20,268 Variable lease cost 9,056 5,068 Short-term lease cost 80 164 Total lease cost $ 38,957 $ 25,958 Cash paid for amounts included in the measurement of lease liabilities Operating cash outflows for finance lease payments $ 712 $ 231 Operating cash outflows for operating lease payments 25,037 19,226 Total cash flows for lease liability measurement $ 25,749 $ 19,457 Right-of-use assets obtained in exchange for new operating lease liabilities $ 8,014 $ 277,557 Right-of-use assets obtained in exchange for new finance lease liabilities $ 50,096 $ 8,050 Weighted average remaining lease term - finance leases (years) 78.48 46.86 Weighted average remaining lease term - operating leases (years) 13.99 14.68 Weighted average discount rate - finance leases 3.47 % 6.07 % Weighted average discount rate - operating leases 3.66 % 3.65 % The Company recorded lease expense of $8,229 related to operating leases in the years ended December 31, 2018. The following table presents information about the Company’s undiscounted cash flows on an annual basis for operating and finance leases, including a reconciliation of the undiscounted cash flows to the finance lease and operating lease liabilities recognized in the Company’s consolidated balance sheets: Operating Finance Total 2021 $ 29,565 $ 1,284 $ 30,849 2022 29,591 1,485 31,076 2023 29,642 1,496 31,138 2024 30,008 1,508 31,516 2025 30,485 1,537 32,022 Thereafter 199,168 222,529 421,697 Total $ 348,459 $ 229,839 $ 578,298 Present value adjustments (84,974) (174,836) (259,810) Lease liabilities $ 263,485 $ 55,003 $ 318,488 The Company elected the package of practical expedients upon adoption of ASC 842, which allows for the application of the standard solely to the transition period in 2019 and does not require application to prior fiscal comparative periods resented. Disclosures required under the previous leasing standard are presented for prior years.
Leases	LEASES The Company adopted ASC 842, "Leases," effective January 1, 2019 on a modified retrospective basis as allowed under the standard and thus prior periods have not been restated. The Company elected the package of transition practical expedients, and has therefore (1) not reassessed whether any expired or existing contracts are or contain leases, (2) not reassessed the lease classification for any expired or existing leases, and (3) not reassessed initial direct costs for any expired or existing leases. Lessee Accounting The Company recognized right-of-use assets related to operating leases totaling $95,506 and lease liabilities of $104,863 as of the adoption date, January 1, 2019. These are presented as “Operating lease liabilities” and “Real estate assets-operating lease right-of-use assets” on the Company’s consolidated balance sheets. Right-of-use assets associated with finance leases are included in real estate assets, net and finance lease liabilities are included in other liabilities During the year ended December 31, 2020, the Company recorded new finance lease right-of-use assets and finance lease liabilities totaling $41,491 associated with the acquisition of three stores with land leases. The Company also recorded finance lease right-of-use assets and finance lease liabilities of $8,605 upon the completion of construction of a store with a land lease. In June and August 2019, the Company entered into new triple-net lease agreements to lease land and buildings at 22 and five operating stores, respectively. These leases are categorized as operating leases, and have contractual lease terms of 25 years, but have termination options after 10 years that result in lease terms of 10 years under ASC 842. The Company recorded new operating lease right-of-use assets and operating lease liabilities of $127,532 and $52,224, respectively, in conjunction with these new lease agreements. The Company is lessee under several types of lease agreements. Generally, these leases fall into the following categories: • Leases of real estate at 53 stores classified as wholly-owned or in consolidated joint ventures. These leases generally have original lease terms between 10-99 years. Under these leases, the Company typically has the option to extend the lease term for additional terms of 5-35 years. • Leases of its corporate offices and call center. These leases have original lease terms between 5.3 and 12.1 years, with no extension options. Subsequent to year-end the Company modified and extended the lease of its corporate offices to add additional space and extend the lease until 2034. • Leases of 13 regional offices. These leases have original lease terms between three three • Leases of small district offices. These leases generally have terms of 12 months or less. The Company has made an election to account for these under the short-term lease exception outlined under ASC 842. Therefore, no lease assets or liabilities are recorded related to these leases. The Company has included lease extension options in the lease term for calculations of its right-of-use assets and liabilities related to the real estate asset leases at its stores when it is reasonably certain that the Company plans to extend the lease terms as the options arise. Several of the leases of real estate at the Company’s stores include escalation clauses based on an index or rate, such as the Consumer Price Index (CPI). The Company included these lease payments in its calculations of right-of-use assets and liabilities based on the prevailing index or rate as of the adoption date. The Company will recognize changes to these variable lease payments in earnings in the period of change. One of the real estate leases includes variable lease payments that are based upon a percentage of gross revenues. Certain other leases include additional variable payments relating to a percentage of sales in excess of a specified amount, common area maintenance, property taxes, and similar items. These payments are variable lease payments that do not depend on an index or rate and are excluded from the measurement of the lease liabilities and right-of-use-assets for these leases. The Company will recognize costs from these variable lease payments in the period in which the obligation for those payments is incurred. The Company has a signed lease agreement for a store in California. The store is under construction by the lessor, and the Company will take possession of the leased asset upon completion of construction, which is estimated to be completed in mid- 2021. The lease term is 15 years from the lease commencement date, with three 10-year extension options and one 5-year extension option. The Company has not recorded right-of-use asset or lease liability related to this lease as of December 31, 2020 as the lease term has not yet commenced. The lease commencement date will occur when the Company takes possession of the leased asset, and the Company will recognize a lease liability and right-of-use asset relating to the lease at that time. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available surrounding the Company’s unsecured borrowing rates and implied secured spread at the lease commencement date in determining the present value of lease payments. These discount rates vary depending on the term of the specific leases. Following is information on our total lease costs as of the period indicated: For the Year Ended December 31, 2020 2019 Finance lease cost: Amortization of finance lease right-of-use assets $ 400 $ 168 Interest expense related to finance lease liabilities 712 290 Operating lease cost 28,709 20,268 Variable lease cost 9,056 5,068 Short-term lease cost 80 164 Total lease cost $ 38,957 $ 25,958 Cash paid for amounts included in the measurement of lease liabilities Operating cash outflows for finance lease payments $ 712 $ 231 Operating cash outflows for operating lease payments 25,037 19,226 Total cash flows for lease liability measurement $ 25,749 $ 19,457 Right-of-use assets obtained in exchange for new operating lease liabilities $ 8,014 $ 277,557 Right-of-use assets obtained in exchange for new finance lease liabilities $ 50,096 $ 8,050 Weighted average remaining lease term - finance leases (years) 78.48 46.86 Weighted average remaining lease term - operating leases (years) 13.99 14.68 Weighted average discount rate - finance leases 3.47 % 6.07 % Weighted average discount rate - operating leases 3.66 % 3.65 % The Company recorded lease expense of $8,229 related to operating leases in the years ended December 31, 2018. The following table presents information about the Company’s undiscounted cash flows on an annual basis for operating and finance leases, including a reconciliation of the undiscounted cash flows to the finance lease and operating lease liabilities recognized in the Company’s consolidated balance sheets: Operating Finance Total 2021 $ 29,565 $ 1,284 $ 30,849 2022 29,591 1,485 31,076 2023 29,642 1,496 31,138 2024 30,008 1,508 31,516 2025 30,485 1,537 32,022 Thereafter 199,168 222,529 421,697 Total $ 348,459 $ 229,839 $ 578,298 Present value adjustments (84,974) (174,836) (259,810) Lease liabilities $ 263,485 $ 55,003 $ 318,488 The Company elected the package of practical expedients upon adoption of ASC 842, which allows for the application of the standard solely to the transition period in 2019 and does not require application to prior fiscal comparative periods resented. Disclosures required under the previous leasing standard are presented for prior years.
Leases	LEASES The Company adopted ASC 842, "Leases," effective January 1, 2019 on a modified retrospective basis as allowed under the standard and thus prior periods have not been restated. The Company elected the package of transition practical expedients, and has therefore (1) not reassessed whether any expired or existing contracts are or contain leases, (2) not reassessed the lease classification for any expired or existing leases, and (3) not reassessed initial direct costs for any expired or existing leases. Lessee Accounting The Company recognized right-of-use assets related to operating leases totaling $95,506 and lease liabilities of $104,863 as of the adoption date, January 1, 2019. These are presented as “Operating lease liabilities” and “Real estate assets-operating lease right-of-use assets” on the Company’s consolidated balance sheets. Right-of-use assets associated with finance leases are included in real estate assets, net and finance lease liabilities are included in other liabilities During the year ended December 31, 2020, the Company recorded new finance lease right-of-use assets and finance lease liabilities totaling $41,491 associated with the acquisition of three stores with land leases. The Company also recorded finance lease right-of-use assets and finance lease liabilities of $8,605 upon the completion of construction of a store with a land lease. In June and August 2019, the Company entered into new triple-net lease agreements to lease land and buildings at 22 and five operating stores, respectively. These leases are categorized as operating leases, and have contractual lease terms of 25 years, but have termination options after 10 years that result in lease terms of 10 years under ASC 842. The Company recorded new operating lease right-of-use assets and operating lease liabilities of $127,532 and $52,224, respectively, in conjunction with these new lease agreements. The Company is lessee under several types of lease agreements. Generally, these leases fall into the following categories: • Leases of real estate at 53 stores classified as wholly-owned or in consolidated joint ventures. These leases generally have original lease terms between 10-99 years. Under these leases, the Company typically has the option to extend the lease term for additional terms of 5-35 years. • Leases of its corporate offices and call center. These leases have original lease terms between 5.3 and 12.1 years, with no extension options. Subsequent to year-end the Company modified and extended the lease of its corporate offices to add additional space and extend the lease until 2034. • Leases of 13 regional offices. These leases have original lease terms between three three • Leases of small district offices. These leases generally have terms of 12 months or less. The Company has made an election to account for these under the short-term lease exception outlined under ASC 842. Therefore, no lease assets or liabilities are recorded related to these leases. The Company has included lease extension options in the lease term for calculations of its right-of-use assets and liabilities related to the real estate asset leases at its stores when it is reasonably certain that the Company plans to extend the lease terms as the options arise. Several of the leases of real estate at the Company’s stores include escalation clauses based on an index or rate, such as the Consumer Price Index (CPI). The Company included these lease payments in its calculations of right-of-use assets and liabilities based on the prevailing index or rate as of the adoption date. The Company will recognize changes to these variable lease payments in earnings in the period of change. One of the real estate leases includes variable lease payments that are based upon a percentage of gross revenues. Certain other leases include additional variable payments relating to a percentage of sales in excess of a specified amount, common area maintenance, property taxes, and similar items. These payments are variable lease payments that do not depend on an index or rate and are excluded from the measurement of the lease liabilities and right-of-use-assets for these leases. The Company will recognize costs from these variable lease payments in the period in which the obligation for those payments is incurred. The Company has a signed lease agreement for a store in California. The store is under construction by the lessor, and the Company will take possession of the leased asset upon completion of construction, which is estimated to be completed in mid- 2021. The lease term is 15 years from the lease commencement date, with three 10-year extension options and one 5-year extension option. The Company has not recorded right-of-use asset or lease liability related to this lease as of December 31, 2020 as the lease term has not yet commenced. The lease commencement date will occur when the Company takes possession of the leased asset, and the Company will recognize a lease liability and right-of-use asset relating to the lease at that time. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available surrounding the Company’s unsecured borrowing rates and implied secured spread at the lease commencement date in determining the present value of lease payments. These discount rates vary depending on the term of the specific leases. Following is information on our total lease costs as of the period indicated: For the Year Ended December 31, 2020 2019 Finance lease cost: Amortization of finance lease right-of-use assets $ 400 $ 168 Interest expense related to finance lease liabilities 712 290 Operating lease cost 28,709 20,268 Variable lease cost 9,056 5,068 Short-term lease cost 80 164 Total lease cost $ 38,957 $ 25,958 Cash paid for amounts included in the measurement of lease liabilities Operating cash outflows for finance lease payments $ 712 $ 231 Operating cash outflows for operating lease payments 25,037 19,226 Total cash flows for lease liability measurement $ 25,749 $ 19,457 Right-of-use assets obtained in exchange for new operating lease liabilities $ 8,014 $ 277,557 Right-of-use assets obtained in exchange for new finance lease liabilities $ 50,096 $ 8,050 Weighted average remaining lease term - finance leases (years) 78.48 46.86 Weighted average remaining lease term - operating leases (years) 13.99 14.68 Weighted average discount rate - finance leases 3.47 % 6.07 % Weighted average discount rate - operating leases 3.66 % 3.65 % The Company recorded lease expense of $8,229 related to operating leases in the years ended December 31, 2018. The following table presents information about the Company’s undiscounted cash flows on an annual basis for operating and finance leases, including a reconciliation of the undiscounted cash flows to the finance lease and operating lease liabilities recognized in the Company’s consolidated balance sheets: Operating Finance Total 2021 $ 29,565 $ 1,284 $ 30,849 2022 29,591 1,485 31,076 2023 29,642 1,496 31,138 2024 30,008 1,508 31,516 2025 30,485 1,537 32,022 Thereafter 199,168 222,529 421,697 Total $ 348,459 $ 229,839 $ 578,298 Present value adjustments (84,974) (174,836) (259,810) Lease liabilities $ 263,485 $ 55,003 $ 318,488 The Company elected the package of practical expedients upon adoption of ASC 842, which allows for the application of the standard solely to the transition period in 2019 and does not require application to prior fiscal comparative periods resented. Disclosures required under the previous leasing standard are presented for prior years.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION As of December 31, 2020 , 1,239,557 shares were available for issuance under the Company’s 2015 Incentive Award Plan (the “Plan”). Options are exercisable once vested. Options are exercisable at such times and subject to such terms as deter mined by the Compensation Committee, but under no circumstances may be exercised if such exercise would cause a violation of the ownership limit in the Company’s charter. Options expire 10 years from the date of grant. Beginning in 2017, the CNG Committee decided to the replace stock options granted to executives with performance based stock units for executive compensation. See the "Performance-Based Stock Units" section below. Also as defined under the terms of the Plan, restricted stock grants may be awarded. The stock grants are subject to a vesting period over which the restrictions are released and the stock certificates are given to the grantee. During the vesting period, the grantee is not permitted to sell, transfer, pledge, encumber or assign shares of restricted stock granted under the Plan; however, the grantee has the ability to vote the shares and receive nonforfeitable dividends paid on shares. Unless otherwise determined by the Compensation Committee at the time of grant, the forfeiture and transfer restrictions on the shares lapse over a four-year period beginning on the date of grant. For actions taken prior to July 2020, references to the Compensation Committee refer to its predecessor, the CNG Committee; the Board split the CNG Committee into two committees, the Compensation Committee and the Nominating and Governance Committee, effective July 1, 2020. Option Grants A summary of stock option activity is as follows: Options Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value as of December 31, 2020 Outstanding at December 31, 2017 472,156 $ 30.41 Exercised (54,575) 21.45 Outstanding at December 31, 2018 417,581 $ 31.58 Exercised (211,057) 14.65 Outstanding at December 31, 2019 206,524 $ 48.88 Exercised (134,930) 35.26 Outstanding at December 31, 2020 71,594 $ 74.54 4.61 $1,823 Vested and Expected to Vest 71,594 $ 74.54 4.61 $1,823 Ending Exercisable 71,594 $ 74.54 4.61 $1,823 The aggregate intrinsic value in the table above represents the total value (the difference between the Company’s closing stock price on the last trading day of 2020 and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their options on December 31, 2020. The amount of aggregate intrinsic value will change based on the fair market value of the Company’s stock. The total intrinsic value of options exercised for the years ended December 31, 2020, 2019 and 2018 was $10,016, $18,089 and $3,693, respectively. There have been no options granted since 2016. The fair value of each option grant was estimated on the date of grant using the Black-Scholes option-pricing model. The Black-Scholes model incorporates assumptions to value stock-based awards. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of the grant for the estimated life of the option. The Company uses actual historical data to calculate the expected price volatility, dividend yield and average expected term. The forfeiture rate, which is estimated at a weighted-average of 7.4% of unvested options outstanding as of December 31, 2020, is adjusted periodically based on the extent to which actual forfeitures differ, or are expected to differ, from the previous estimates. A summary of stock options outstanding and exercisable as of December 31, 2020, is as follows: Options Outstanding Options Exercisable Exercise Price Shares Weighted Average Remaining Contractual Life Weighted Average Exercise Price Shares Weighted Average Exercise Price $47.50 - $47.50 2,700 3.13 $ 47.50 2,700 $ 47.50 $65.36 - $65.36 1,582 4.15 65.36 1,582 65.36 $65.45 - $65.45 2,900 4.13 65.45 2,900 65.45 $73.52 - $73.52 50,000 4.58 73.52 50,000 73.52 $85.99 - $85.99 14,412 5.15 85.99 14,412 85.99 71,594 4.61 $ 74.54 71,594 $ 74.54 The Company recorded compensation expense relating to outstanding options of $27, $364 and $570 in general and administrative expense for the years ended December 31, 2020, 2019 and 2018, respectively. Net proceeds received for the years ended December 31, 2020, 2019 and 2018, related to option exercises was $4,759, $3,063 and $1,169, respectively. At December 31, 2020, there was no unrecognized compensation expense related to non-vested stock options under the Plan. Common Stock Granted to Employees and Directors The Company recorded $9,244, $9,173 and $8,733 of expense in general and administrative expense in its statement of operations related to restricted stock awards granted to employees and directors for the years ended December 31, 2020, 2019 and 2018, respectively. The forfeiture rate, which is estimated at a weighted-average of 10.0% of unvested awards outstanding as of December 31, 2020, is adjusted periodically based on the extent to which actual forfeitures differ, or are expected to differ, from the previous estimates. At December 31, 2020 there was $11,638 of total unrecognized compensation expense related to non-vested restricted stock awards under the Plan. That cost is expected to be recognized over a weighted-average period of 2.04 years. The fair value of common stock awards is determined based on the closing trading price of the Company’s common stock on the grant date. A summary of the Company’s employee and director share grant activity is as follows: Restricted Stock Grants Shares Weighted-Average Grant-Date Fair Value Unreleased at December 31, 2017 266,475 $ 74.76 Granted 85,066 86.14 Released (116,656) 72.38 Cancelled (11,771) 80.96 Unreleased at December 31, 2018 223,114 $ 80.02 Granted 109,081 101.52 Released (110,724) 79.58 Cancelled (8,863) 90.11 Unreleased at December 31, 2019 212,608 $ 91.62 Granted 95,671 98.81 Released (94,164) 89.43 Cancelled (5,083) 93.16 Unreleased at December 31, 2020 209,032 $ 95.86 Performance-based Stock Units In 2017, the CNG Committee changed its compensation for executives to issue performance-based stock units (the "PSUs") as a replacement for stock option awards. The PSUs granted to executives represent the right to earn shares of the Company's common stock. These awards have two financial performance components: (1) the Company's core FFO performance ("FFO Target"), and (2) the Company's total stockholder return relative to the performance of a defined group of peers ("TSR Target"). Each of these performance components are weighted 50% and are measured over the performance period, which is defined as the three-year period ending December 31 from the year of grant. At the end of the performance period, the financial performance components are reviewed to determine the number of shares actually granted to executives, which can be as low as zero shares and up to a maximum of two shares issued for each PSU. A summary of the PSU activity is as follows: Performance-Based Stock Units Units Weighted-Average Grant-Date Fair Value Unvested at December 31, 2017 30,071 $ 83.84 Granted 28,735 96.19 Unvested at December 31, 2018 58,806 $ 89.87 Granted 49,334 103.18 Unvested at December 31, 2019 108,140 $ 95.94 Granted 45,242 129.38 Released (47,516) $ 112.16 Unvested at December 31, 2020 105,866 $ 102.95 The Company recorded $7,048, $3,514 and $1,873 of expense in general and administrative expense in its statement of operations related to PSUs granted to employees and directors for the years ended December 31, 2020, 2019 and 2018, respectively. The Company estimated the fair value of the PSUs as of the grant date, using the closing trading price of the Company's common stock on the grant date to value the FFO Target portion. A Monte Carlo simulation model was used to calculate the fair value of the TSR Target portion of the PSUs, using the following assumptions: For the Year Ended December 31, 2020 2019 2018 Intrinsic value $12,266 $6,211 $5,321 Risk-free rate 1.42% 2.53% 2.37% Volatility 18.4% 20.7% 22.6% Expected term (in years) 2.9 2.8 2.9 Dividend yield —% —% —% Unrecognized compensation cost $6,406 $4,315 $2,739 Term over which compensation cost recognized (in years) 3 3 3 Under the terms of the PSUs, dividends for the entire measurement period are paid in cash when the shares are released, so a dividend yield of zero was used. The valuation model applied in this calculation utilizes subjective assumptions that could potentially change over time, including the probabilities associated with achieving the FFO Targets (categorized within Level 3 of the fair value hierarchy). Therefore, the amount of unrecognized compensation expense at December 31, 2020 noted above does not necessarily represent the expense that will ultimately be realized by the Company in the statement of operations.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Employee Benefit Plan	EMPLOYEE BENEFIT PLANThe Company has a retirement savings plan under Section 401(k) of the Internal Revenue Code under which eligible employees can contribute up to 60% of their annual salary, subject to a statutory prescribed annual limit. For the years ended December 31, 2020, 2019 and 2018, the Company made matching contributions to the plan of $3,980, $3,355 and $2,833, respectively, based on 100% of the first 3% and up to 50% of the next 2% of an employee’s compensation.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES As a REIT, the Company is generally not subject to U.S. federal income tax with respect to that portion of its income which is distributed annually to its stockholders. However, the Company has elected to treat certain of its corporate subsidiaries, including Extra Space Management, Inc., as a TRS. In general, a TRS may perform additional services for tenants and generally may engage in any real estate or non-real estate related business. A TRS is subject to U.S. federal corporate income tax and may be subject to state and local income taxes. The Company accounts for income taxes in accordance with the provisions of ASC 740, “Income Taxes.” Deferred tax assets and liabilities are determined based on differences between financial reporting and tax bases of assets and liabilities. The Company has elected to use the Tax-Law-Ordering approach to determine when excess tax benefits will be realized. The income tax provision for the years ended December 31, 2020, 2019 and 2018, is comprised of the following components: For the Year Ended December 31, 2020 Federal State Total Current expense $ 15,553 $ 3,347 $ 18,900 Tax credits/true-up (5,610) (135) (5,745) Change in deferred expense/(benefit) 594 61 655 Total tax expense $ 10,537 $ 3,273 $ 13,810 For the Year Ended December 31, 2019 Federal State Total Current expense $ 10,164 $ 2,936 $ 13,100 Tax credits/true-up (3,633) (30) (3,663) Change in deferred expense 1,787 84 1,871 Total tax expense $ 8,318 $ 2,990 $ 11,308 For the Year Ended December 31, 2018 Federal State Total Current expense $ 9,136 $ 2,426 $ 11,562 Tax credits/true-up (5,841) (175) (6,016) Change in deferred benefit 3,730 (32) 3,698 Total tax expense $ 7,025 $ 2,219 $ 9,244 A reconciliation of the statutory income tax provisions to the effective income tax provisions for the periods indicated is as follows: For the Year Ended December 31, 2020 2019 2018 Expected tax at statutory rate $ 111,760 21.0 % $ 97,110 21.0 % $ 95,828 21.0 % Non-taxable REIT income (94,270) (17.7) % (82,717) (17.9) % (83,022) (18.2) % State and local tax expense - net of federal benefit 3,075 0.6 % 2,837 0.6 % 2,385 0.5 % Change in valuation allowance (363) (0.1) % (207) — % (1,052) (0.2) % Tax credits/true-up (5,745) (1.1) % (3,663) (0.8) % (6,016) (1.3) % Miscellaneous (647) (0.1) % (2,052) (0.4) % 1,121 0.2 % Total provision $ 13,810 2.6 % $ 11,308 2.5 % $ 9,244 2.0 % The major sources of temporary differences stated at their deferred tax effects are as follows: December 31, 2020 December 31, 2019 Deferred tax liabilities: Fixed assets $ (27,374) $ (23,805) Operating lease right-of-use assets (2,223) (2,475) Other (72) (84) State deferred taxes (3,210) (3,405) Total deferred tax liabilities (32,879) (29,769) Deferred tax assets: Captive insurance subsidiary 378 312 Accrued liabilities 2,325 2,006 Stock compensation 2,635 2,118 Operating lease liabilities 2,232 2,478 SmartStop TRS 219 219 Other 1,554 50 State deferred taxes 6,725 7,250 Total deferred tax assets 16,068 14,433 Valuation allowance (3,302) (3,665) Net deferred income tax liabilities $ (20,113) $ (19,001) The state income tax net operating losses expire between 2021 and 2038. The valuation allowance is associated with the state income tax net operating losses. The tax years 2016 through 2019 remain open related to the state returns, and 2017 through 2019 for the federal returns.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2020
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 our self-storage operations represents total property revenue less direct property operating expenses. NOI for our tenant reinsurance segment represents tenant reinsurance revenues less tenant reinsurance expense. The Company’s segments are comprised of 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 our 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: Year Ended December 31, 2020 2019 2018 Revenues: Self-Storage Operations $ 1,157,522 $ 1,130,177 $ 1,039,340 Tenant Reinsurance 146,561 128,387 115,507 Total segment revenues $ 1,304,083 $ 1,258,564 $ 1,154,847 Operating expenses: Self-Storage Operations $ 360,615 $ 336,050 $ 291,695 Tenant Reinsurance 26,494 29,376 25,707 Total segment operating expenses $ 387,109 $ 365,426 $ 317,402 Net operating income: Self-Storage Operations $ 796,907 $ 794,127 $ 747,645 Tenant Reinsurance 120,067 99,011 89,800 Total segment net operating income: $ 916,974 $ 893,138 $ 837,445 Total segment net operating income $ 916,974 $ 893,138 $ 837,445 Other components of net income (loss): Property management fees and other income 52,129 49,890 41,757 General and administrative expense (96,594) (89,418) (81,256) Depreciation and amortization expense (224,444) (219,857) (209,050) Gain on real estate transactions 18,075 1,205 30,807 Interest expense (168,626) (186,526) (178,436) Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes (3,675) (4,742) (4,687) Interest income 15,192 7,467 5,292 Equity in earnings and dividend income from unconsolidated real estate entities 22,361 11,274 14,452 Income tax expense (13,810) (11,308) (9,244) Net income $ 517,582 $ 451,123 $ 447,080

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES As of December 31, 2020, the Company was under agreement to acquire ten stores at a total purchase price of $165,500. Of these stores, all ten are scheduled to close in 2021. Additionally, the Company is under agreement to acquire one store in 2021 with a joint venture partner, for a total investment of $1,600. The Company is involved in various legal proceedings and is subject to various claims and complaints arising in the ordinary course of business. Because litigation is inherently unpredictable, the outcome of these matters cannot presently be determined with any degree of certainty. In accordance with applicable accounting guidance, management establishes an accrued liability for litigation when those matters present loss contingencies that are both probable and reasonably estimable. In such cases, there may be an exposure to loss in excess of any amounts accrued. The estimated loss, if any, is based upon currently available information and is subject to significant judgment, a variety of assumptions, and known and unknown uncertainties. 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 December 31, 2020, the Company was involved in various legal proceedings and was subject to various claims and complaints arising in the ordinary course of business. In the opinion of management, such litigation, claims and complaints are not expected to have a material adverse effect on the Company’s financial condition or results of operations. 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 properties, the activities of its tenants and other environmental conditions of which the Company is unaware with respect to its properties could result in future material environmental liabilities.

Schedule III - Real Estate and

Schedule III - Real Estate and Accumulated Depreciation	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Schedule III - Real Estate and Accumulated Depreciation	Building and Improvements Initial Cost Adjustments and Costs to Land and Building Subsequent to Acquisition Gross carrying amount at December 31, 2020 Self - Storage Facilities by State: Store Count Land Initial Cost Building and Improvements Accumulated Depreciation Debt Land Total AL 9 $ 30,450 $ 8,766 $ 53,158 $ 4,026 $ 8,767 $ 57,183 $ 65,950 $ 9,689 AZ 23 21,885 27,535 117,304 10,218 27,533 127,524 155,057 28,011 CA 168 514,047 539,355 1,191,333 124,766 540,043 1,315,411 1,855,454 302,214 CO 17 29,605 17,224 81,144 16,619 17,942 97,045 114,987 22,571 CT 7 23,583 9,875 50,966 5,402 9,874 56,369 66,243 11,638 FL 92 270,055 161,339 624,568 57,728 161,465 682,170 843,635 145,939 GA 66 86,912 87,450 436,339 34,164 87,434 470,519 557,953 73,133 HI 13 30,484 17,663 133,870 6,664 17,663 140,534 158,197 29,660 IL 39 44,694 48,723 248,347 30,362 48,176 279,256 327,432 51,032 IN 15 10,825 12,447 58,247 6,521 12,447 64,768 77,215 13,688 KS 1 — 366 1,897 1,080 366 2,977 3,343 1,206 KY 11 34,289 8,640 68,679 18,858 9,412 86,765 96,177 14,883 LA 2 — 6,114 8,541 4,787 6,115 13,327 19,442 4,541 MA 46 103,569 73,544 270,243 55,023 73,725 325,085 398,810 90,473 MD 31 107,272 97,772 275,357 28,895 97,180 304,844 402,024 79,171 MI 7 5,690 9,583 51,359 3,984 9,583 55,343 64,926 7,338 MN 6 — 8,666 59,483 589 8,666 60,072 68,738 3,978 MO 5 — 4,129 15,444 4,407 4,086 19,894 23,980 8,055 MS 3 — 2,420 20,849 1,575 2,420 22,424 24,844 3,294 NC 19 27,881 31,969 104,104 8,479 31,967 112,585 144,552 14,470 NH 2 5,853 754 4,054 1,300 817 5,291 6,108 2,552 NJ 60 159,385 142,291 560,512 46,254 137,258 611,799 749,057 147,109 NM 11 17,387 32,252 71,142 5,916 32,252 77,058 109,310 11,655 NV 14 37,829 15,252 74,376 5,202 15,252 79,578 94,830 12,733 NY 28 43,510 121,945 237,795 38,200 122,679 275,261 397,940 67,681 OH 17 33,744 17,788 50,493 8,043 17,787 58,537 76,324 15,166 OR 6 29,642 7,906 39,576 2,094 7,906 41,670 49,576 8,729 PA 19 34,051 25,518 155,095 13,573 24,810 169,376 194,186 29,247 RI 2 11,621 3,191 6,926 1,333 3,191 8,259 11,450 3,210 SC 24 34,036 38,684 143,826 11,228 38,685 155,053 193,738 27,087 TN 20 46,809 29,806 125,653 9,950 29,806 135,603 165,409 21,279 TX 102 195,522 171,687 666,970 65,514 171,539 732,632 904,171 133,990 UT 10 23,225 9,008 39,295 2,634 9,008 41,929 50,937 11,201 VA 46 162,806 139,318 414,335 22,410 139,319 436,744 576,063 81,436 WA 8 19,936 12,528 47,645 3,403 12,530 51,046 63,576 12,843 DC 1 8,475 14,394 18,172 462 14,394 18,634 33,028 2,344 Other corporate assets — — 656 163,815 — 164,471 164,471 48,232 Intangible tenant relationships and lease rights — — 134,932 2,206 — 137,138 137,138 129,385 Construction in Progress/Undeveloped Land — 5,447 — 65,368 3,372 67,443 70,815 — Right of use asset - finance lease — — — 58,145 — 58,145 58,145 566 Totals (1) 950 $ 2,205,072 $ 1,961,349 $ 6,662,685 $ 951,197 $ 1,955,469 $ 7,619,762 $ 9,575,231 $ 1,681,429 (1) No right-of-use assets related to operating leases are included in the ending net real estate assets information above. Activity in real estate facilities during the years ended December 31, 2020, 2019 and 2018 is as follows: 2020 2019 2018 Operating facilities Balance at beginning of year $ 9,129,558 $ 8,709,315 $ 8,158,741 Acquisitions 255,235 303,588 459,223 Improvements 66,693 68,459 64,336 Transfers from construction in progress 40,988 59,614 49,449 Dispositions and other 15,314 (11,418) (22,434) Balance at end of year $ 9,507,788 $ 9,129,558 $ 8,709,315 Accumulated depreciation: Balance at beginning of year $ 1,473,851 $ 1,262,438 $ 1,060,060 Depreciation expense 217,364 212,202 203,030 Dispositions and other (9,786) (789) (652) Balance at end of year $ 1,681,429 $ 1,473,851 $ 1,262,438 Real estate under development/redevelopment: Balance at beginning of year $ 41,157 $ 44,954 $ 33,750 Current development 67,274 55,817 60,677 Transfers to operating facilities (40,988) (59,614) (49,449) Dispositions and other — — (24) Balance at end of year $ 67,443 $ 41,157 $ 44,954 Net non-lease real estate assets $ 7,893,802 $ 7,696,864 $ 7,491,831 (1) No right-of-use assets related to operating leases are included in the ending net real estate assets information above. As of December 31, 2020, the aggregate cost of real estate for U.S. federal income tax purposes was $7,817,038.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements are presented on the accrual basis of accounting in accordance with U.S. generally accepted accounting principles (“GAAP”) and include the accounts of the Company and its wholly- or majority-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Variable Interest Entities	Variable Interest Entities The Company accounts for arrangements that are not controlled through voting or similar rights as variable interest entities (“VIEs”). An enterprise is required to consolidate a VIE if it is the primary beneficiary of the VIE. A VIE is created when (i) the equity investment at risk is not sufficient to permit the entity to finance its activities without additional subordinated financial support from other parties, or (ii) the entity’s equity holders as a group either: (a) lack the power, through voting or similar rights, to direct the activities of the entity that most significantly impact the entity’s economic performance, (b) are not obligated to absorb expected losses of the entity if they occur, or (c) do not have the right to receive expected residual returns of the entity if they occur. If an entity is deemed to be a VIE, the enterprise that is deemed to have a variable interest, or combination of variable interests, that provides the enterprise with a controlling financial interest in the VIE, is considered the primary beneficiary and must consolidate the VIE. The Company has concluded that under certain circumstances when the Company enters into arrangements for the formation of joint ventures or when entering into a new bridge loan agreement, a VIE may be created under condition (i), (ii) (b) or (c) of the previous paragraph. For each VIE created, the Company has performed a qualitative analysis, including considering which party, if any, has the power to direct the activities most significant to the economic performance of each VIE and whether that party has the obligation to absorb losses of the VIE or the right to receive benefits from the VIE that could be significant to the VIE. If the Company is determined to be the primary beneficiary of the VIE, the assets, liabilities and operations of the VIE are consolidated with the Company’s financial statements. As of December 31, 2020 and 2019, the Company had no consolidated VIEs. The Company’s investments in real estate joint ventures, where the Company has significant influence, but not control, and joint ventures which are VIEs in which the Company is not the primary beneficiary, are recorded under the equity method of accounting on the accompanying consolidated financial statements.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
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 Financial Accounting Standard Board’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 itself and its counterparties. However, as of December 31, 2020, the Company has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivatives. As a result, the Company has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. 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. The Company compares the carrying value of the related long-lived assets to the undiscounted future net operating cash flows attributable to the assets (categorized within Level 3 of the fair value hierarchy). If the estimated fair value, net of selling costs, of the assets that have been identified as held for sale is less than the net carrying value of the assets, the Company would recognize a loss on the assets held for sale. The operations of assets held for sale or sold during the period are presented as part of normal operations for all periods presented. The Company assesses annually whether there are any indicators that the value of the Company’s investments in unconsolidated real estate entities may be impaired 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. As of December 31, 2020 and 2019, the Company did not have any assets or liabilities measured at fair value on a nonrecurring basis. 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, investments in debt securities and notes receivable, revolving lines of credit and other liabilities reflected in the consolidated balance sheets at December 31, 2020 and 2019, approximate fair value. The fair values of the Company’s notes receivable and notes receivable from Preferred Operating Partnership unit holders were based on the discounted estimated future cash flow 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 value of the Company’s exchangeable senior notes was estimated using an average market price for similar securities obtained from a third party.
Real Estate Assets and Sales	Real Estate Assets Real estate assets are stated at cost, less accumulated depreciation. Direct and allowable internal costs associated with the development, construction, renovation, and improvement of real estate assets are capitalized. Interest, property taxes, and other costs associated with development incurred during the construction period are capitalized. The construction period begins when expenditures for the real estate assets have been made and activities that are necessary to prepare the asset for its intended use are in progress. The construction period ends when the asset is substantially complete and ready for its intended use. Expenditures for maintenance and repairs are charged to expense as incurred. Major replacements and betterments that improve or extend the life of the asset are capitalized and depreciated over their estimated useful lives. Depreciation is computed using the straight-line method over the estimated useful lives of the buildings and improvements, which are generally between five The purchase of stores are considered asset acquisitions. As such, the purchase price is allocated to the real estate assets 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 relative 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 the acquisition is recorded at fair value based on current interest rates compared to contractual rates. Acquisition-related transactions costs are capitalized as part of the purchase price. Intangible lease rights represent: (1) purchase price amounts allocated to leases on three stores that cannot be classified as ground or building leases; these rights are amortized to expense over the life of the leases and (2) intangibles related to ground leases on eight stores where the leases were assumed by the Company at rates that were lower than the current market rates for similar leases. The values associated with these assumed leases were recorded as intangibles, which will be amortized over the lease terms. Real Estate Sales In general, sales of real estate and related profits/losses are recognized when all consideration has changed hands and risks and rewards of ownership have been transferred. Certain types of continuing involvement preclude sale treatment and related profit recognition; other forms of continuing involvement allow for sale recognition but require deferral of profit recognition.
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 noncontrolling interest in real estate joint ventures that own stores and the Company's interest in preferred stock of SmartStop Self Storage REIT, Inc. ("SmartStop"). The Company’s investments in real estate joint ventures, where the Company has significant influence, but not control and joint ventures which are VIEs in which the Company is not the primary beneficiary, are recorded under the equity method of accounting in the accompanying consolidated financial statements. Under the equity method, the Company’s investment in real estate ventures is stated at cost and adjusted for the Company’s share of net earnings or losses and reduced by distributions. Equity in earnings of real estate ventures is generally recognized based on the Company’s ownership interest in the earnings of each of the unconsolidated real estate ventures. For the purposes of presentation in the statement of cash flows, the Company follows the “nature of distribution” approach for classification of distributions from joint ventures. Under this approach, cash flows are classified on the basis of the nature of the activity or activities of the investee that generated the distribution as either a return on investment (classified as a cash inflow from operating activities) or a return of investment (classified as a cash inflow from investing activities).
Investments in Debt Securities and Notes Receivable	Investments in Debt Securities and Notes Receivable The Company accounts for its investment in debt securities and loans receivable at amortized cost. The Company recognizes interest income related to the debt securities and notes receivable using the effective interest method, with deferred fees and costs amortized over the lives of the related loans as yield adjustment. Additionally, the discount related to purchased notes receivable is being amortized to interest income over the remaining period of the notes.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company’s cash is deposited with financial institutions located throughout the United States and at times may exceed federally insured limits. The Company considers all highly liquid debt instruments with a maturity date of three months or less to be cash equivalents.
Restricted Cash	Restricted Cash Restricted cash is comprised of escrowed funds deposited with financial institutions located throughout the United States relating to earnest money deposits on potential acquisitions, real estate taxes, loan collateral, operating reserves and insurance and capital expenditures.
Other Assets	Other AssetsOther assets consist of equipment and fixtures, capitalized software, rents receivable from our tenants, other receivables, other intangible assets, deferred tax assets, prepaid expenses and the fair value of interest rate swaps. Depreciation of equipment and fixtures is computed on a straight-line basis over three
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities The Company records all derivatives on the balance sheet at fair value. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether the Company has elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. Derivatives designated and qualifying as a hedge of the exposure to changes in the fair value of an asset, liability or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Derivatives designated and qualifying as a hedge of the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Hedge accounting generally provides for the matching of the timing of gain or loss recognition on the hedging instrument with the recognition of the changes in the fair value of the hedged asset or liability that are attributable to the hedged risk in a fair value hedge or the earnings effect of the hedged forecasted transactions in a cash flow hedge. The Company may enter into derivative contracts that are intended to economically hedge certain of its risk, even though hedge accounting does not apply or the Company elects not to apply hedge accounting. 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.
Risk Management and Use of Financial Instruments	Risk Management and Use of Financial Instruments In the normal course of its ongoing business operations, the Company encounters economic risk. There are three main components of economic risk: interest rate risk, credit risk and market risk. The Company is subject to interest rate risk on its interest-bearing liabilities. Credit risk is the risk of inability or unwillingness of tenants to make contractually required payments. Market risk is the risk of declines in the value of stores due to changes in rental rates, interest rates or other market factors affecting the value of stores held by the Company. The Company has entered into interest rate swap agreements to manage a portion of its interest rate risk.
Exchange of Common Operating Partnership Units	Exchange of Common Operating Partnership Units Redemption of common Operating Partnership units for shares of common stock, when redeemed under the original provisions of the Operating Partnership agreement, are accounted for by reclassifying the underlying net book value of the units from noncontrolling interest to the Company’s equity.
Revenue and Expense Recognition	Revenue and Expense Recognition Rental revenues are recognized as earned based upon amounts that are currently due from tenants. Leases are generally on month-to-month terms. Prepaid rents are recognized on a straight-line basis over the term of the leases. Promotional discounts are recognized as a reduction to rental income over the promotional period. Late charges, administrative fees and merchandise sales are recognized as income when earned. Equity in earnings of unconsolidated real estate ventures is recognized based on the Company's ownership interest in the earnings of each of the unconsolidated real estate entities. Interest income is recognized as earned. The Company's management fees are earned subject to the terms of the related management services agreements ("MSAs"). These MSAs provide that the Company will perform management services, which include leasing and operating the property and providing accounting, marketing, banking, maintenance and other services. These services are provided in exchange for monthly management fees, which are based on a percentage of revenues collected from stores owned by third parties and unconsolidated joint ventures. MSAs generally have original terms from three The Company accounts for the management services provided to a customer as a single performance obligation which are rendered over time each month. The total amount of consideration from the contract is variable as it is based on monthly revenues, which are influenced by multiple factors, some of which are outside the Company's control. Therefore, the Company recognizes the revenue at the end of each month once the uncertainty is resolved. Due to the standardized terms of the MSAs, the Company accounts for all MSAs in a similar, consistent manner. Therefore, no disaggregated information relating to MSAs is presented. Property expenses, including utilities, property taxes, repairs and maintenance and other costs to manage the facilities are recognized as incurred. The Company accrues for property tax expense based upon invoice amounts and estimates. If these estimates are incorrect, the timing of expense recognition could be affected. Tenant reinsurance premiums are recognized as revenue over the period of insurance coverage. The Company records an unpaid claims liability at the end of each period based on existing unpaid claims and historical claims payment history. The unpaid claims liability represents an estimate of the ultimate cost to settle all unpaid claims as of each period end, including both reported but unpaid claims and claims that may have been incurred but have not been reported. The Company uses a third party claims administrator to adjust all tenant reinsurance claims received. The administrator evaluates each claim to determine the ultimate claim loss and includes an estimate for claims that may have been incurred but not reported. Annually, a third party actuary evaluates the adequacy of the unpaid claims liability. Prior year claim reserves are adjusted as experience develops or new information becomes known. The impact of such adjustments is included in the current period operations. The unpaid claims liability is not discounted to its present value. Each tenant chooses the amount of insurance coverage they want through the tenant reinsurance program. Tenants can purchase policies in amounts of 2,000 dollars to 10,000 dollars of insurance coverage in exchange for a monthly fee. As of December 31, 2020, the average insurance coverage for tenants was approximately 3,100 dollars. The Company’s exposure per claim is limited by the maximum amount of coverage chosen by each tenant. The Company purchases reinsurance for losses exceeding a set amount for any one event. The Company does not currently have any amounts recoverable under the reinsurance arrangements.
Advertising Costs	Advertising Costs The Company incurs advertising costs primarily attributable to digital and other advertising. These costs are expensed as incurred. The Company recognized $28,336, $25,106 and $16,153 in advertising expense for the years ended December 31, 2020, 2019 and 2018, respectively, which are included in property operating expenses on the Company’s consolidated statements of operations.
Income Taxes	Income Taxes The Company has elected to be treated as a REIT under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended (the "Internal Revenue Code"). In order to maintain its qualification as a REIT, among other things, the Company is required to distribute at least 90% of its REIT taxable income to its stockholders and meet certain tests regarding the nature of its income and assets. As a REIT, the Company is not subject to U.S. federal income tax with respect to that portion of its income which meets certain criteria and is distributed annually to stockholders. The Company plans to continue to operate so that it meets the requirements for taxation as a REIT. Many of these requirements, however, are highly technical and complex. For any taxable year that the Company fails to qualify as a REIT and for which applicable statutory relief provisions did not apply, the Company would be subject to U.S. federal corporate income tax on all of its taxable income for at least that year and the ensuing four years. The Company is subject to certain state and local taxes. Provision for such taxes has been included in income tax expense on the Company’s consolidated statements of operations. For the year ended December 31, 2020, 0% (unaudited) of all distributions to stockholders qualified as a return of capital. The Company owns and may acquire direct or indirect interests in entities that have elected or will elect to be taxed as REITs under the Internal Revenue Code (each, a “Subsidiary REIT ”). A Subsidiary REIT is subject to the various REIT qualification requirements and other limitations described herein that are applicable to the Company. If a Subsidiary REIT were to fail to qualify as a REIT, then (i) that Subsidiary REIT would become subject to U.S. federal income tax, (ii) shares in such Subsidiary REIT would cease to be qualifying assets for purposes of the asset tests applicable to REITs, and (iii) it is possible that the Company would fail certain of the asset tests applicable to REITs, in which event the Company would fail to qualify as a REIT unless it could avail itself of certain relief provisions. The Company has elected to treat certain corporate subsidiaries, including Extra Space Management, Inc. (“ESMI”), as a taxable REIT subsidiary (“TRS”). In general, a TRS may perform additional services for tenants and may engage in any real estate or non-real estate related business. A TRS is subject to U.S. federal corporate income tax and may also be subject to state and local income taxes. ESM Reinsurance Limited, a wholly-owned subsidiary of ESMI, generates income from insurance premiums that are subject to U.S. federal corporate income tax and state insurance premiums tax. Deferred tax assets and liabilities are determined based on differences between financial reporting and tax bases of assets and liabilities. At December 31, 2020 and 2019, there were no material unrecognized tax benefits. Interest and penalties relating
Stock-Based Compensation	Stock-Based Compensation The measurement and recognition of compensation expense for all share-based payment awards to employees and directors are based on estimated fair values. Awards granted are valued at fair value and any compensation expense is recognized over the service periods of each award.
Earnings Per Common Share	Earnings Per Common Share Basic earnings per common share is computed using the two-class method by dividing net income attributable to common stockholders by the weighted average number of common shares outstanding during the period. All outstanding unvested restricted stock awards contain rights to non-forfeitable dividends and participate in undistributed earnings with common stockholders; accordingly, they are considered participating securities that are included in the two-class method. Diluted earnings per common share measures the performance of the Company over the reporting period while giving effect to all potential common shares that were dilutive and outstanding during the period. The denominator includes the weighted average number of basic shares and the number of additional common shares that would have been outstanding if the potential common shares that were dilutive had been issued, and is calculated using either the two-class, treasury stock or as if-converted method, whichever is most dilutive. Potential common shares are securities (such as options, convertible debt, Series A Participating Redeemable Preferred Units (“Series A Units”), Series B Redeemable Preferred Units (“Series B Units”), Series C Convertible Redeemable Preferred Units (“Series C Units”), Series D Redeemable Preferred Units (“Series D Units” and together with the Series A Units, Series B Units and Series C 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 (those that reduce earnings per common share) are included. For the years ended December 31, 2020 and 2019, there were no anti-dilutive shares outstanding. For the year ended December 31, 2018, options to purchase approximately 36,075 shares of common stock were excluded from the computation of earnings per share as their effect would have been anti-dilutive. For the purposes of computing the diluted impact of the potential exchange of the Preferred OP 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 liquidation value of the Preferred OP Units by the average share price of $103.62 for the year ended December 31, 2020. The following table presents the number of weighted OP Units and Preferred OP 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 Year Ended December 31, 2020 2019 2018 Equivalent Shares (if converted) Equivalent Shares (if converted) Equivalent Shares (if converted) Common OP Units 5,853,814 — — Series A Units (Variable Only) 875,480 — — Series B Units 400,771 393,189 464,033 Series C Units (1) — — 312,075 Series D Units 1,143,547 1,081,369 1,019,524 8,273,612 1,474,558 1,795,632 (1) The remainder of the Series C Units were converted to OP Units on April 25, 2019. The Operating Partnership had $575,000 of its 3.125% Exchangeable Senior Notes due 2035 (the “2015 Notes”) issued and outstanding prior to their redemption in November 2020. 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. Though the Company has retained that right, 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 year ended December 31, 2020, the Company had repaid the principal and accrued interest of its 2015 Notes, and therefore, no shares relating to the 2015 Notes were included in the computation of diluted earnings per share. For the years ended December 31, 2019 and 2018, 993,114 and zero shares, respectively, related to the 2015 Notes were included in the computation of 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.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In February 2016, the Financial Accounting Standards Board ("FASB") issued ASU 2016-02, "Leases (Topic 842)," which modifies the accounting for leases, intending to increase transparency and comparability of organizations by requiring balance sheet presentation of leased assets and increased financial statement disclosure of leasing arrangements. ASU 2016-02 requires entities to recognize a liability for their lease obligations and a corresponding asset representing the right to use the underlying asset over the lease term. ASU 2016-02 became effective for annual and interim periods beginning after December 15, 2018. The Company adopted the standard using the modified retrospective approach as of January 1, 2019. The Company elected the package of practical expedients upon adoption, which allows for the application of the standard solely to the transition period in 2019 but does not require application to prior fiscal comparative periods presented. The Company also elected the practical expedient provided in a subsequent amendment to ASU 2016-02 that removed the requirement to separate lease and non-lease components. The Company did not record a significant cumulative catch-up adjustment upon the adoption of ASC 2016-02. The primary impact was related to the Company's 22 operating ground leases and two corporate facility leases under which it served as lessee as of the adoption date. The Company recognized lease liabilities totaling $104,863 and right-of-use assets related to operating leases totaling $95,506 as of the adoption date. Refer to footnote 14 for further discussion of the Company's leases. In June 2016, the FASB issued ASU 2016-13, " Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments." ASU 2016-13 changes how entities measure credit losses for most financial assets. This standard requires an entity to estimate its lifetime "expected credit loss" and record an allowance that, when deducted from the amortized cost basis of the financial asset, presents the net amount expected to be collected on the financial asset. In November 2018, the FASB issued ASU 2018-19, "Codification Improvements to Topic 326, Financial Instruments - Credit Losses," which clarified that receivables arising from operating leases are within the scope of the leasing standard (ASU 2016-02), and not within the scope of ASU 2016-13. This new standard became effective for the Company on January 1, 2020. The adoption of this standard by the Company did not have a material impact on the Company's consolidated financial statements. In March 2020, the FASB issued ASU 2020-04, "Reference Rate Reform (Topic 848)." ASU 2020-04 contains 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. The Company continues to evaluate the impact of the guidance and may apply other elections as applicable as additional changes in the market occur.
Convertible Debt	GAAP requires entities with convertible debt instruments that may be settled entirely or partially in cash upon conversion to separately account for the liability and equity components of the instrument in a manner that reflects the issuer’s economic interest cost. The Company therefore accounted for the liability and equity component of the 2015 Notes separately. The equity components were included in paid-in capital in stockholders’ equity in the consolidated balance sheets, and the value of the equity components were treated as original issue discount for purposes of accounting for the debt components. The discount was amortized as interest expense over the remaining period of the debt through its first redemption date, October 1, 2020 for the 2015 Notes. The effective interest rate on the liability components of the 2015 Notes was 4.0%, which approximates the market rate of interest of similar debt without exchange features (i.e. nonconvertible debt) at the time of issuance.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	The table below presents the Company’s assets and liabilities measured at fair value on a recurring basis as of December 31, 2020, aggregated by the level in the fair value hierarchy within which those measurements fall. Fair Value Measurements at Reporting Date Using Description December 31, 2020 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 $ 98,325 $ — $ 98,325 $ —
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: December 31, 2020 December 31, 2019 Fair Carrying Fair Carrying Notes receivable from Preferred and Common Operating Partnership unit holders $ 102,333 $ 102,311 $ 116,184 $ 118,524 Fixed rate notes receivable $ 114,145 $ 104,000 $ — $ — Fixed rate notes payable $ 3,816,530 $ 3,637,220 $ 3,511,151 $ 3,417,928 Exchangeable senior notes $ — $ — $ 673,831 $ 575,000
Schedule of Unpaid Claims Liability	The following table presents information on the portion of the Company’s unpaid claims liability, which is included in other liabilities on the Company's consolidated balance sheets, that relates to tenant insurance for the periods indicated: For the Year Ended December 31, Tenant Reinsurance Claims: 2020 2019 2018 Unpaid claims liability at beginning of year $ 8,109 $ 7,326 $ 5,167 Claims and claim adjustment expense for claims incurred in the current year 14,534 16,280 15,800 Claims and claim adjustment expense (benefit) for claims incurred in the prior years (1,351) 98 107 Payments for current year claims (9,697) (11,352) (11,010) Payments for prior year claims (3,301) (4,243) (2,738) Unpaid claims liability at the end of the year $ 8,294 $ 8,109 $ 7,326
Schedule of Antidilutive Shares Excluded from Computation of Earnings Per Share	The following table presents the number of weighted OP Units and Preferred OP 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 Year Ended December 31, 2020 2019 2018 Equivalent Shares (if converted) Equivalent Shares (if converted) Equivalent Shares (if converted) Common OP Units 5,853,814 — — Series A Units (Variable Only) 875,480 — — Series B Units 400,771 393,189 464,033 Series C Units (1) — — 312,075 Series D Units 1,143,547 1,081,369 1,019,524 8,273,612 1,474,558 1,795,632 (1) The remainder of the Series C Units were converted to OP Units on April 25, 2019.
Schedule of Computation of Earnings Per Common Share	The computation of earnings per share is as follows for the periods presented: For the Year Ended December 31, 2020 2019 2018 Net income attributable to common stockholders $ 481,779 $ 419,967 $ 415,289 Earnings and dividends allocated to participating securities (706) (680) (723) Earnings for basic computations 481,073 419,287 414,566 Earnings and dividends allocated to participating securities — 680 723 Income allocated to noncontrolling interest - Preferred Operating Partnership Units and Operating Partnership Units — 23,727 22,831 Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units) — (2,288) (2,288) Net income for diluted computations $ 481,073 $ 441,406 $ 435,832 Weighted average common shares outstanding: Average number of common shares outstanding - basic 129,541,531 128,203,568 126,087,487 OP Units — 6,006,114 5,675,547 Series A Units — 875,480 875,480 Unvested restricted stock awards included for treasury stock method — 212,402 244,215 Shares related to exchangeable senior notes and dilutive stock options 43,298 1,136,205 276,304 Average number of common shares outstanding - diluted 129,584,829 136,433,769 133,159,033 Earnings per common share Basic $ 3.71 $ 3.27 $ 3.29 Diluted $ 3.71 $ 3.24 $ 3.27

Real Estate Assets (Tables)

Real Estate Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Real Estate [Abstract]
Schedule of Components of Real Estate Assets	The components of real estate assets are summarized as follows: December 31, 2020 December 31, 2019 Land - operating $ 1,952,097 $ 1,935,551 Land - development 3,372 3,372 Buildings, improvements and other intangibles 7,357,033 7,047,654 Right of use asset - finance lease 58,148 8,050 Intangible assets - tenant relationships 124,695 122,489 Intangible lease rights 12,443 12,443 9,507,788 9,129,559 Less: accumulated depreciation and amortization (1,681,429) (1,473,852) Net operating real estate assets 7,826,359 7,655,707 Real estate under development/redevelopment 67,443 41,157 Net real estate assets $ 7,893,802 $ 7,696,864 Real estate assets held for sale included in net real estate assets $ 103,624 $ 2,947

Property Acquisitions and Dis_2

Property Acquisitions and Dispositions (Tables)	12 Months Ended
	Dec. 31, 2020
Real Estate [Abstract]
Schedule of Operating Properties Acquired	The following table shows the Company’s acquisitions of stores for the years ended December 31, 2020 and 2019. The table excludes purchases of raw land or improvements made to existing assets. Consideration Paid Total Quarter Number of Stores Total Cash Paid Loan Assumed Finance Lease Liability Investments in Real Estate Ventures Net Liabilities/ (Assets) Assumed Real estate assets Total 2020 23 $ 296,725 $ 254,111 $ — $ 41,491 $ — $ 1,123 $ 296,725 Total 2019 21 $ 300,379 $ 279,313 $ 17,157 $ — $ 2,780 $ 1,129 $ 300,379 (1) Store acquisitions during the year ended December 31, 2020 include the acquisition of three stores that were subject to finance land leases. The right-of-use assets associated with these leases are included in real estate assets above.

Investments in Unconsolidated_2

Investments in Unconsolidated Real Estate Entities (Tables)	12 Months Ended
	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Investments in Unconsolidated Real Estate Entities	Net Investments in unconsolidated real estate entities and cash distributions in unconsolidated real estate ventures consist of the following: Number of Stores Equity Ownership % Excess Profit % (1) December 31, 2020 2019 PR EXR Self Storage, LLC 5 25% 40% $ 60,092 $ 59,391 WICNN JV LLC (3) 10 10% 35% 36,032 36,552 VRS Self Storage, LLC 16 45% 54% 17,186 17,639 ESS-NYFL JV LP 11 16% 26% 12,211 13,320 GFN JV, LLC (3) 7 10% 30% 18,397 12,168 PRISA Self Storage LLC 85 4% 4% 8,815 9,133 Alan Jathoo JV LLC 9 10% 10% 7,780 7,977 Storage Portfolio III JV LLC 5 10% 30% 5,726 3,995 ESS Bristol Investments LLC 8 10% 30% 2,810 3,046 Extra Space Northern Properties Six LLC 10 10% 35% (2,541) (2,091) Storage Portfolio II JV LLC 36 10% 30% (5,441) (4,827) Storage Portfolio I LLC 24 34% 49% (39,144) (38,345) Other minority owned stores 21 10-50% 19-50% 28,395 24,832 SmartStop Self Storage REIT, Inc. Preferred Stock (2) n/a n/a n/a 200,000 150,000 Net Investments in and Cash distributions in unconsolidated real estate entities 247 350,318 292,790 (1) Includes pro-rata equity ownership share and promoted interest. (2) In October 2019, the Company invested $150,000 in shares of newly issued convertible preferred stock of SmartStop, with an additional commitment to purchase up to $50,000 of the preferred shares over the 12 months after the original purchase. In October 2020 the Company purchased the additional $50,000 in SmartStop convertible preferred stock that was previously committed. 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 in equity in earnings and dividend income from unconsolidated real estate entities on the Company's consolidated statements of operations.
Equity Method Investments	Information about these real estate ventures is summarized as follows: Number of Stores Equity ownership % Total initial investment For the Year Ended December 31, 2019 16 10.0% - 50.0% $ 19,663 For the Year Ended December 31, 2018 28 10.0% - 25.0% $ 63,723
Schedule of Equity in Earnings of Unconsolidated Real Estate Ventures	Equity in earnings and dividend income from unconsolidated real estate entities consists of the following: For the Year Ended December 31, 2020 2019 2018 Dividend income from SmartStop preferred stock $ 9,968 $ 1,636 $ — Equity in earnings of PRISA Self Storage LLC 2,229 2,327 2,338 Equity in earnings of Storage Portfolio II JV LLC 559 291 79 Equity in earnings of Storage Portfolio I LLC 1,636 1,809 1,886 Equity in earnings of VRS Self Storage, LLC 3,509 3,583 3,640 Equity in earnings of ESS-NYFL JV LLC (331) (96) — Equity in earnings of WICNN JV LLC 1,878 1,373 622 Equity in earnings of Extra Space Northern Properties Six LLC 1,088 1,091 1,014 Equity in earnings of Alan Jathoo JV LLC 57 (47) (12) Equity in earnings of Bristol Investments LLC (67) (262) (152) Equity in earnings of GFN JV, LLC 788 450 22 Equity in earnings of PR EXR Self Storage, LLC (211) (443) (75) Equity in earnings of WCOT Self Storage LLC — — 359 Equity in earnings of Extra Space West Two LLC — — 1,042 Equity in earnings of Extra Space West One LLC — — 2,526 Equity in earnings of other minority owned stores 1,258 (438) 1,163 $ 22,361 $ 11,274 $ 14,452

Investments in Debt Securitie_2

Investments in Debt Securities and Notes Receivable (Tables)	12 Months Ended
	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Investments in Debt Securities and Bridge Loans Receivable	Information about these balances is as follows: December 31, 2020 December 31, 2019 Debt securities - NexPoint Series A Preferred Stock $ 200,000 $ — Debt securities - NexPoint Series B Preferred Stock 100,000 — Notes Receivable-Bridge Loans 187,368 43,586 Notes Receivable-Senior Mezzanine Loan 101,553 — Dividends Receivable 4,889 — $ 593,810 $ 43,586

Notes Payable and Revolving L_2

Notes Payable and Revolving Lines of Credit (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of Components of Notes Payable	The components of notes payable are summarized as follows: Notes Payable December 31, 2020 December 31, 2019 Fixed Rate Variable Rate Basis Rate (2) Maturity Dates Secured fixed rate notes payable (1) $ 1,112,220 $ 1,365,408 2.53% - 5.85% February 2021 - February 2030 Secured variable rate notes payable (1) 1,081,551 878,093 1.39% - 2.20% Libor plus 1.3% - 2.0% April 2021 - August 2028 Unsecured fixed rate notes payable 2,525,000 2,052,521 2.80% - 4.39% October 2023 - October 2030 Unsecured variable rate notes payable 100,000 47,480 1.04% Libor plus 0.9% Dec 2021 Total 4,818,771 4,343,502 Less: unamortized debt issuance costs (21,468) (24,529) Total $ 4,797,303 $ 4,318,973 (1) The loans are collateralized by mortgages on real estate assets and the assignment of rents. (2) 30-day USD LIBOR
Schedule of Information on Lines of Credit	At December 31, 2020, the terms of the credit agreement originally entered into on October 14, 2016 (the "Credit Agreement") and amended and restated on December 7, 2018, July 1, 2019, and December 20, 2019, are as follows: Debt Capacity Maturity Date Revolving Credit Facility $ 650,000 January 2023 Tranche 1 Term Loan Facility (1) 480,000 January 2024 Tranche 2 Term Loan Facility (1) 220,000 October 2023 Tranche 3 Term Loan Facility (1) 245,000 January 2025 Tranche 4 Term Loan Facility (1) 255,000 June 2026 $ 1,850,000 (1) The term loan amounts have been fully drawn as of December 31, 2020. As of December 31, 2020 Revolving Lines of Credit Amount Drawn Capacity Interest Rate Origination Date Maturity Basis Rate (1) Credit Line 1 (2) $ 102,000 $ 140,000 1.6% 6/4/2010 7/1/2021 LIBOR plus 1.45% Credit Line 2 (3)(4) 487,000 650,000 1.0% 12/7/2018 1/29/2023 LIBOR plus 0.9% Credit Line 3 (4)(5) $ 360,000 $ 400,000 1.5% 6/17/2020 6/17/2021 LIBOR plus 1.2% $ 949,000 $ 1,190,000 (1) 30-day USD LIBOR (2) Secured by mortgages on certain real estate assets. One two (3) Unsecured. Two six (4) Basis Rate as of December 31, 2020. Rate is subject to change based on our investment grade rating. (5) Unsecured. One twelve
Schedule of Maturities of Notes Payable	The following table summarizes the scheduled maturities of notes payable, excluding available extensions, at December 31, 2020: 2021 $ 459,557 2022 584,865 2023 762,925 2024 705,153 2025 524,827 Thereafter 1,781,444 $ 4,818,771

Derivatives (Tables)

Derivatives (Tables)	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule Summarizing Terms of Entity's Derivative Financial Instruments	The following table summarizes the terms of the Company’s 22 derivative financial instruments, which have a total combined notional amount of $2,091,270 as of December 31, 2020: Hedge Product Range of Notional Amounts Strike Effective Dates Maturity Dates Swap Agreements $33,681 - $238,139 1.07% - 3.87% 7/8/2015 - 3/30/2020 4/1/2021 - 6/29/2026
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 consolidated balance sheets: Asset / Liability Derivatives December 31, 2020 December 31, 2019 Derivatives designated as hedging instruments: Fair Value Other assets $ — $ 6,214 Other liabilities $ 98,325 $ 31,400
Schedule of Information Relating to Gain (Loss) Recognized on Swap Agreements	The tables below present the effect of the Company’s derivative financial instruments on the 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 Year Ended December 31, Location of amounts reclassified from OCI into income Gain (loss) reclassified from OCI For the Year Ended December 31, Type 2020 2019 2020 2019 2018 Swap Agreements $ (100,352) $ (54,680) Interest expense $ (26,794) $ 12,322 $ 8,258

Exchangeable Senior Notes (Tabl

Exchangeable Senior Notes (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of Information about Carrying Amount of Equity Component, Principal Amount of Liability Component, Unamortized Discount and Net Carrying Amount for Notes	Information about the 2015 Notes, including the total carrying amounts of the equity component, the principal amount of the liability component, the unamortized discount and net carrying amount, was as follows for the periods indicated: December 31, 2020 December 31, 2019 Carrying amount of equity component $ — $ 22,597 Principal amount of liability component $ — $ 575,000 Unamortized discount - equity component — (3,675) Unamortized debt issuance costs — (1,812) Net carrying amount of liability component $ — $ 569,513
Summary of Amount of Interest Cost Recognized Relating to Contractual Interest Rate and Amortization of Discount on Liability Component of Notes	The amount of interest cost recognized relating to the contractual interest rate and the amortization of the discount on the liability component for the Notes were as follows for the periods indicated: For the Year Ended December 31, 2020 2019 2018 Contractual interest $ 13,476 $ 17,968 $ 18,106 Amortization of discount 3,675 4,742 4,687 Total interest expense recognized $ 17,151 $ 22,710 $ 22,793
Summary of Repurchase of Debt	Information about the repurchases is as follows: For the Year Ended December 31, 2020 2019 2018 Principal amount repurchased $ 575,000 $ — $ 49,259 Amount allocated to: Extinguishment of liability component $ 575,000 $ — $ 49,019 Reacquisition of equity component — — 31,251 Total consideration paid for repurchase $ 575,000 $ — $ 80,270 Exchangeable senior notes repurchased $ 575,000 $ — $ 49,259 Extinguishment of liability component (575,000) — (49,019) Discount on exchangeable senior notes — — (230) Related debt issuance costs — — (10) Gain/(loss) on repurchase $ — $ — $ —

Noncontrolling Interests In O_2

Noncontrolling Interests In Operating Partnership and Other Noncontrolling Interests (Tables)	12 Months Ended
	Dec. 31, 2020
Noncontrolling Interest [Abstract]
Redeemable Noncontrolling Interest	OP Unit activity is summarized as follows for the periods presented: For the Year Ended December 31, 2020 2019 2018 OP Units redeemed for common stock 123,993 340,182 35,000 OP Units redeemed for cash — — 30,000 Cash paid for OP Units redeemed $ — $ — $ 2,558 OP Units issued in conjunction with acquisitions — — 21,768 Value of OP Units issued in conjunction with acquisitions $ — $ — $ 1,877 OP Units issued upon redemption of Series C Units — 270,709 373,113

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Lease Costs	Following is information on our total lease costs as of the period indicated: For the Year Ended December 31, 2020 2019 Finance lease cost: Amortization of finance lease right-of-use assets $ 400 $ 168 Interest expense related to finance lease liabilities 712 290 Operating lease cost 28,709 20,268 Variable lease cost 9,056 5,068 Short-term lease cost 80 164 Total lease cost $ 38,957 $ 25,958 Cash paid for amounts included in the measurement of lease liabilities Operating cash outflows for finance lease payments $ 712 $ 231 Operating cash outflows for operating lease payments 25,037 19,226 Total cash flows for lease liability measurement $ 25,749 $ 19,457 Right-of-use assets obtained in exchange for new operating lease liabilities $ 8,014 $ 277,557 Right-of-use assets obtained in exchange for new finance lease liabilities $ 50,096 $ 8,050 Weighted average remaining lease term - finance leases (years) 78.48 46.86 Weighted average remaining lease term - operating leases (years) 13.99 14.68 Weighted average discount rate - finance leases 3.47 % 6.07 % Weighted average discount rate - operating leases 3.66 % 3.65 %
Undiscounted Cash Flows on an Annual Basis, Operating Leases	The following table presents information about the Company’s undiscounted cash flows on an annual basis for operating and finance leases, including a reconciliation of the undiscounted cash flows to the finance lease and operating lease liabilities recognized in the Company’s consolidated balance sheets: Operating Finance Total 2021 $ 29,565 $ 1,284 $ 30,849 2022 29,591 1,485 31,076 2023 29,642 1,496 31,138 2024 30,008 1,508 31,516 2025 30,485 1,537 32,022 Thereafter 199,168 222,529 421,697 Total $ 348,459 $ 229,839 $ 578,298 Present value adjustments (84,974) (174,836) (259,810) Lease liabilities $ 263,485 $ 55,003 $ 318,488
Undiscounted Cash Flows on an Annual Basis, Financing Leases	The following table presents information about the Company’s undiscounted cash flows on an annual basis for operating and finance leases, including a reconciliation of the undiscounted cash flows to the finance lease and operating lease liabilities recognized in the Company’s consolidated balance sheets: Operating Finance Total 2021 $ 29,565 $ 1,284 $ 30,849 2022 29,591 1,485 31,076 2023 29,642 1,496 31,138 2024 30,008 1,508 31,516 2025 30,485 1,537 32,022 Thereafter 199,168 222,529 421,697 Total $ 348,459 $ 229,839 $ 578,298 Present value adjustments (84,974) (174,836) (259,810) Lease liabilities $ 263,485 $ 55,003 $ 318,488

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Summary of Stock Option Activity	A summary of stock option activity is as follows: Options Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value as of December 31, 2020 Outstanding at December 31, 2017 472,156 $ 30.41 Exercised (54,575) 21.45 Outstanding at December 31, 2018 417,581 $ 31.58 Exercised (211,057) 14.65 Outstanding at December 31, 2019 206,524 $ 48.88 Exercised (134,930) 35.26 Outstanding at December 31, 2020 71,594 $ 74.54 4.61 $1,823 Vested and Expected to Vest 71,594 $ 74.54 4.61 $1,823 Ending Exercisable 71,594 $ 74.54 4.61 $1,823
Schedule of Stock Options Outstanding and Exercisable	A summary of stock options outstanding and exercisable as of December 31, 2020, is as follows: Options Outstanding Options Exercisable Exercise Price Shares Weighted Average Remaining Contractual Life Weighted Average Exercise Price Shares Weighted Average Exercise Price $47.50 - $47.50 2,700 3.13 $ 47.50 2,700 $ 47.50 $65.36 - $65.36 1,582 4.15 65.36 1,582 65.36 $65.45 - $65.45 2,900 4.13 65.45 2,900 65.45 $73.52 - $73.52 50,000 4.58 73.52 50,000 73.52 $85.99 - $85.99 14,412 5.15 85.99 14,412 85.99 71,594 4.61 $ 74.54 71,594 $ 74.54
Summary of Company's Employee and Director Share Grant Activity	A summary of the Company’s employee and director share grant activity is as follows: Restricted Stock Grants Shares Weighted-Average Grant-Date Fair Value Unreleased at December 31, 2017 266,475 $ 74.76 Granted 85,066 86.14 Released (116,656) 72.38 Cancelled (11,771) 80.96 Unreleased at December 31, 2018 223,114 $ 80.02 Granted 109,081 101.52 Released (110,724) 79.58 Cancelled (8,863) 90.11 Unreleased at December 31, 2019 212,608 $ 91.62 Granted 95,671 98.81 Released (94,164) 89.43 Cancelled (5,083) 93.16 Unreleased at December 31, 2020 209,032 $ 95.86
Schedule of Nonvested Performance-based Units Activity	A summary of the PSU activity is as follows: Performance-Based Stock Units Units Weighted-Average Grant-Date Fair Value Unvested at December 31, 2017 30,071 $ 83.84 Granted 28,735 96.19 Unvested at December 31, 2018 58,806 $ 89.87 Granted 49,334 103.18 Unvested at December 31, 2019 108,140 $ 95.94 Granted 45,242 129.38 Released (47,516) $ 112.16 Unvested at December 31, 2020 105,866 $ 102.95
Schedule of Weighted Average Assumptions Used to Estimate Fair Value of Awards	A Monte Carlo simulation model was used to calculate the fair value of the TSR Target portion of the PSUs, using the following assumptions: For the Year Ended December 31, 2020 2019 2018 Intrinsic value $12,266 $6,211 $5,321 Risk-free rate 1.42% 2.53% 2.37% Volatility 18.4% 20.7% 22.6% Expected term (in years) 2.9 2.8 2.9 Dividend yield —% —% —% Unrecognized compensation cost $6,406 $4,315 $2,739 Term over which compensation cost recognized (in years) 3 3 3

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Summarized Statement of Components of Income Tax Provision	The income tax provision for the years ended December 31, 2020, 2019 and 2018, is comprised of the following components: For the Year Ended December 31, 2020 Federal State Total Current expense $ 15,553 $ 3,347 $ 18,900 Tax credits/true-up (5,610) (135) (5,745) Change in deferred expense/(benefit) 594 61 655 Total tax expense $ 10,537 $ 3,273 $ 13,810 For the Year Ended December 31, 2019 Federal State Total Current expense $ 10,164 $ 2,936 $ 13,100 Tax credits/true-up (3,633) (30) (3,663) Change in deferred expense 1,787 84 1,871 Total tax expense $ 8,318 $ 2,990 $ 11,308 For the Year Ended December 31, 2018 Federal State Total Current expense $ 9,136 $ 2,426 $ 11,562 Tax credits/true-up (5,841) (175) (6,016) Change in deferred benefit 3,730 (32) 3,698 Total tax expense $ 7,025 $ 2,219 $ 9,244
Schedule of Reconciliation of Statutory Income Tax Provisions to the Effective Income Tax Provisions	A reconciliation of the statutory income tax provisions to the effective income tax provisions for the periods indicated is as follows: For the Year Ended December 31, 2020 2019 2018 Expected tax at statutory rate $ 111,760 21.0 % $ 97,110 21.0 % $ 95,828 21.0 % Non-taxable REIT income (94,270) (17.7) % (82,717) (17.9) % (83,022) (18.2) % State and local tax expense - net of federal benefit 3,075 0.6 % 2,837 0.6 % 2,385 0.5 % Change in valuation allowance (363) (0.1) % (207) — % (1,052) (0.2) % Tax credits/true-up (5,745) (1.1) % (3,663) (0.8) % (6,016) (1.3) % Miscellaneous (647) (0.1) % (2,052) (0.4) % 1,121 0.2 % Total provision $ 13,810 2.6 % $ 11,308 2.5 % $ 9,244 2.0 %
Schedule of Major Sources of Temporary Differences Stated at their Deferred Tax Effects	The major sources of temporary differences stated at their deferred tax effects are as follows: December 31, 2020 December 31, 2019 Deferred tax liabilities: Fixed assets $ (27,374) $ (23,805) Operating lease right-of-use assets (2,223) (2,475) Other (72) (84) State deferred taxes (3,210) (3,405) Total deferred tax liabilities (32,879) (29,769) Deferred tax assets: Captive insurance subsidiary 378 312 Accrued liabilities 2,325 2,006 Stock compensation 2,635 2,118 Operating lease liabilities 2,232 2,478 SmartStop TRS 219 219 Other 1,554 50 State deferred taxes 6,725 7,250 Total deferred tax assets 16,068 14,433 Valuation allowance (3,302) (3,665) Net deferred income tax liabilities $ (20,113) $ (19,001)

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Schedule of Financial Information of Business Segments	Financial information for the Company’s business segments is set forth below: Year Ended December 31, 2020 2019 2018 Revenues: Self-Storage Operations $ 1,157,522 $ 1,130,177 $ 1,039,340 Tenant Reinsurance 146,561 128,387 115,507 Total segment revenues $ 1,304,083 $ 1,258,564 $ 1,154,847 Operating expenses: Self-Storage Operations $ 360,615 $ 336,050 $ 291,695 Tenant Reinsurance 26,494 29,376 25,707 Total segment operating expenses $ 387,109 $ 365,426 $ 317,402 Net operating income: Self-Storage Operations $ 796,907 $ 794,127 $ 747,645 Tenant Reinsurance 120,067 99,011 89,800 Total segment net operating income: $ 916,974 $ 893,138 $ 837,445 Total segment net operating income $ 916,974 $ 893,138 $ 837,445 Other components of net income (loss): Property management fees and other income 52,129 49,890 41,757 General and administrative expense (96,594) (89,418) (81,256) Depreciation and amortization expense (224,444) (219,857) (209,050) Gain on real estate transactions 18,075 1,205 30,807 Interest expense (168,626) (186,526) (178,436) Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes (3,675) (4,742) (4,687) Interest income 15,192 7,467 5,292 Equity in earnings and dividend income from unconsolidated real estate entities 22,361 11,274 14,452 Income tax expense (13,810) (11,308) (9,244) Net income $ 517,582 $ 451,123 $ 447,080

Description of Business (Detail

Description of Business (Details)	Dec. 31, 2020storestate
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of storage facilities in which the entity had equity interests	1,197
Number of stores managed for third parties	724
Number of stores owned and/or managed	1,921
Number of states in which storage facilities are located | state	40

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Recurring $ in Thousands	Dec. 31, 2020USD ($)
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	98,325
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	98,325
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

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value
Fair Value of Financial Instruments [Line Items]
Notes receivable from Preferred and Common Operating Partnership unit holders	$ 102,333	$ 116,184
Fixed rate notes receivable	114,145	0
Fixed rate notes payable	3,816,530	3,511,151
Exchangeable senior notes	0	673,831
Carrying Value
Fair Value of Financial Instruments [Line Items]
Notes receivable from Preferred and Common Operating Partnership unit holders	102,311	118,524
Fixed rate notes receivable	104,000	0
Fixed rate notes payable	3,637,220	3,417,928
Exchangeable senior notes	$ 0	$ 575,000

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Real Estate Assets (Details)	12 Months Ended
	Dec. 31, 2020store
Property, Plant and Equipment [Line Items]
Number of properties whereby leases cannot be classified as ground or building leases	3
Number of properties whereby leases have been assumed at rates lower than the current market rates	8
Buildings, improvements and other intangibles | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Buildings, improvements and other intangibles | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	39 years

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Other Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Amortization expense	$ 224,444	$ 219,857	$ 209,050
Equipment and fixtures | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Equipment and fixtures | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Software development
Property, Plant and Equipment [Line Items]
Unamortized software costs	$ 22,708	$ 22,354
Amortization expense	$ 1,571

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Risk Management and Use of Financial Instruments (Details)	12 Months Ended
	Dec. 31, 2020item
Accounting Policies [Abstract]
Number of main components of economic risk	3

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Revenue and Expense Recognition (Details)	12 Months Ended
	Dec. 31, 2020USD ($)claim	Dec. 31, 2019claim	Dec. 31, 2018claim
Disaggregation of Revenue [Line Items]
Minimum amount of insurance coverage	$ 2,000
Maximum amount of insurance coverage	10,000
Average amount of insurance coverage	$ 3,100
Number of claims made | claim	8,890	7,911	8,088
Management Services Agreements (MSA) | Minimum
Disaggregation of Revenue [Line Items]
Contract term	3 years
Management Services Agreements (MSA) | Maximum
Disaggregation of Revenue [Line Items]
Contract term	5 years

Summary of Significant Accou_10

Summary of Significant Accounting Policies - Schedule of Unpaid Claims Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Tenant Reinsurance Claims:
Unpaid claims liability at beginning of year	$ 8,109	$ 7,326	$ 5,167
Claims and claim adjustment expense for claims incurred in the current year	14,534	16,280	15,800
Claims and claim adjustment expense (benefit) for claims incurred in the prior years	(1,351)	98	107
Payments for current year claims	(9,697)	(11,352)	(11,010)
Payments for prior year claims	(3,301)	(4,243)	(2,738)
Unpaid claims liability at the end of the year	$ 8,294	$ 8,109	$ 7,326

Summary of Significant Accou_11

Summary of Significant Accounting Policies - Advertising Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Advertising expense	$ 28,336	$ 25,106	$ 16,153

Summary of Significant Accou_12

Summary of Significant Accounting Policies - Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Percentage of all distributions to stockholders which qualified as a return of capital	0.00%
Unrecognized tax benefits	$ 0	$ 0
Interest or penalties related to uncertain tax provisions	$ 0	$ 0

Summary of Significant Accou_13

Summary of Significant Accounting Policies - Earnings Per Common Share (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2016	Jun. 21, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per common share (in shares)	8,273,612	1,474,558	1,795,632
Average share price (in dollars per share)	$ 103.62
Exchangeable senior notes	$ 0	$ 569,513,000
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)	875,480	0	0
Instruments to be settled in cash (at least)	$ 101,700,000
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	36,075
2015 Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Exchangeable senior notes	$ 575,000,000
Fixed interest rate	3.125%			3.125%
Shares related to the Notes included in the computation for diluted earnings per share (in shares)		993,114	993,114
2013 Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Fixed interest rate					2.375%
Shares related to the Notes included in the computation for diluted earnings per share (in shares)	0	0

Summary of Significant Accou_14

Summary of Significant Accounting Policies - Schedule of Antidilutive Shares Excluded from Computation of Earnings Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent Shares (if converted) (in shares)	8,273,612	1,474,558	1,795,632
Series A Units (Variable Only)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent Shares (if converted) (in shares)	875,480	0	0
Common OP Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent Shares (if converted) (in shares)	5,853,814	0	0
Series B Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent Shares (if converted) (in shares)	400,771	393,189	464,033
Series C Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent Shares (if converted) (in shares)	0	0	312,075
Series D Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent Shares (if converted) (in shares)	1,143,547	1,081,369	1,019,524

Summary of Significant Accou_15

Summary of Significant Accounting Policies - Schedule of Computation of Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Net income attributable to common stockholders	$ 481,779	$ 419,967	$ 415,289
Earnings and dividends allocated to participating securities	(706)	(680)	(723)
Earnings for basic computations	481,073	419,287	414,566
Earnings and dividends allocated to participating securities	0	680	723
Income allocated to noncontrolling interest - Preferred Operating Partnership Units and Operating Partnership Units	0	23,727	22,831
Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units)	0	(2,288)	(2,288)
Net income for diluted computations	$ 481,073	$ 441,406	$ 435,832
Weighted average common shares outstanding:
Average number of common shares outstanding - basic (in shares)	129,541,531	128,203,568	126,087,487
OP Units (in shares)	0	6,006,114	5,675,547
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Unvested restricted stock awards included for treasury stock method (in shares)	0	212,402	244,215
Shares related to exchangeable senior notes and dilutive stock options (in shares)	43,298	1,136,205	276,304
Average number of common shares outstanding - diluted (in shares)	129,584,829	136,433,769	133,159,033
Earnings per common share
Basic (in dollars per share)	$ 3.71	$ 3.27	$ 3.29
Diluted (in dollars per share)	$ 3.71	$ 3.24	$ 3.27
Series A Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Series A Units (in shares)	0	875,480	875,480

Summary of Significant Accou_16

Summary of Significant Accounting Policies - Recently Issued Accounting Standards (Details) $ in Thousands	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Jan. 01, 2019USD ($)lease
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Real estate assets - operating lease right-of-use assets	$ 252,172	$ 264,643
Operating lease liabilities	$ 263,485	$ 274,783
Operating ground leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of operating ground leases | lease			22
Corporate facility leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of operating ground leases | lease			2
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Real estate assets - operating lease right-of-use assets			$ 104,863
Operating lease liabilities			$ 95,506

Real Estate Assets - Schedule o

Real Estate Assets - Schedule of Components of Real Estate Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Real Estate [Abstract]
Land - operating	$ 1,952,097	$ 1,935,551
Land - development	3,372	3,372
Buildings, improvements and other intangibles	7,357,033	7,047,654
Right of use asset - finance lease	58,148	8,050
Intangible assets - tenant relationships	124,695	122,489
Intangible lease rights	12,443	12,443
Gross operating real estate assets	9,507,788	9,129,559
Less: accumulated depreciation and amortization	(1,681,429)	(1,473,852)
Net operating real estate assets	7,826,359	7,655,707
Real estate under development/redevelopment	67,443	41,157
Net real estate assets	7,893,802	7,696,864
Real estate assets held for sale included in net real estate assets	$ 103,624	$ 2,947

Real Estate Assets - Additional

Real Estate Assets - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)store	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Real Estate [Abstract]
Number of stores classified as held for sale | store	16
Average period that a tenant is expected to utilize the facility	18 months
Amortization related to the tenant relationships and lease rights	$ 2,258	$ 6,614	$ 9,050
Real Estate Properties [Line Items]
Intangible assets, accumulated amortization	$ 129,385	$ 127,712
Minimum
Real Estate Properties [Line Items]
Remaining amortization period	8 years
Maximum
Real Estate Properties [Line Items]
Remaining amortization period	41 years

Property Acquisitions and Dis_3

Property Acquisitions and Dispositions - Acquisitions of Operating Stores (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)store	Dec. 31, 2019USD ($)store	Dec. 31, 2018USD ($)
Real Estate [Abstract]
Number of Stores | store	23	21
Total Real Estate Assets Acquired	$ 296,725	$ 300,379
Cash Paid	254,111	279,313
Loan Assumed	0	17,157	$ 87,500
Finance Lease Liability	41,491	0
Investments in Real Estate Ventures	0	2,780	$ (535)
Net Liabilities/ (Assets) Assumed	$ 1,123	$ 1,129
Number of stores acquired, subject to finance lease | store	3
Number of stores acquired, previously held noncontrolling interest | store		12

Property Acquisitions and Dis_4

Property Acquisitions and Dispositions - Additional Information (Details) - Disposal Group, Disposed of by Sale, Not Discontinued Operations $ in Thousands	Dec. 18, 2020USD ($)store	Apr. 11, 2019USD ($)	Aug. 16, 2018USD ($)
Disposal of Florida Stores
Property Acquisitions [Line Items]
Number of stores sold | store	4
Proceeds from sale of real estate assets	$ 46,592
Gain (loss) on disposition of assets	$ 19,600
Disposal of New York Store
Property Acquisitions [Line Items]
Proceeds from sale of real estate assets		$ 11,272
Gain (loss) on disposition of assets		$ 1,205
Disposal of California Store
Property Acquisitions [Line Items]
Proceeds from sale of real estate assets			$ 40,235
Gain (loss) on disposition of assets			$ 30,671

Investments in Unconsolidated_3

Investments in Unconsolidated Real Estate Entities - Schedule of Investments in Unconsolidated Real Estate Ventures (Details) $ in Thousands	1 Months Ended		12 Months Ended
	Oct. 31, 2020USD ($)	Oct. 31, 2019USD ($)	Dec. 31, 2020USD ($)property	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			247
Investment balance			$ 350,318	$ 292,790
Amount invested			$ 64,792	$ 197,759	$ 65,500
Minimum
Schedule of Equity Method Investments [Line Items]
Equity Ownership %				10.00%	10.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Equity Ownership %				50.00%	25.00%
PR EXR Self Storage, LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			5
Equity Ownership %			25.00%
Excess Profit %			40.00%
Investment balance			$ 60,092	$ 59,391
WICNN JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			10
Equity Ownership %			10.00%
Excess Profit %			35.00%
Investment balance			$ 36,032	36,552
Joint venture preferred equity investment			$ 31,500
Joint venture preferred equity investment return percentage			8.00%
VRS Self Storage, LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			16
Equity Ownership %			45.00%
Excess Profit %			54.00%
Investment balance			$ 17,186	17,639
ESS-NYFL JV LP
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			11
Equity Ownership %			16.00%
Excess Profit %			26.00%
Investment balance			$ 12,211	13,320
GFN JV, LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			7
Equity Ownership %			10.00%
Excess Profit %			30.00%
Investment balance			$ 18,397	12,168
Joint venture preferred equity investment			$ 15,450
PRISA Self Storage LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			85
Equity Ownership %			4.00%
Excess Profit %			4.00%
Investment balance			$ 8,815	9,133
Alan Jathoo JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			9
Equity Ownership %			10.00%
Excess Profit %			10.00%
Investment balance			$ 7,780	7,977
Storage Portfolio III JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			5
Equity Ownership %			10.00%
Excess Profit %			30.00%
Investment balance			$ 5,726	3,995
ESS Bristol Investments LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			8
Equity Ownership %			10.00%
Excess Profit %			30.00%
Investment balance			$ 2,810	3,046
Extra Space Northern Properties Six LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			10
Equity Ownership %			10.00%
Excess Profit %			35.00%
Investment balance			$ (2,541)	(2,091)
Storage Portfolio II JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			36
Equity Ownership %			10.00%
Excess Profit %			30.00%
Investment balance			$ (5,441)	(4,827)
Storage Portfolio I LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			24
Equity Ownership %			34.00%
Excess Profit %			49.00%
Investment balance			$ (39,144)	(38,345)
Other minority owned stores
Schedule of Equity Method Investments [Line Items]
Number of Stores | property			21
Investment balance			$ 28,395	24,832
Other minority owned stores | Minimum
Schedule of Equity Method Investments [Line Items]
Equity Ownership %			10.00%
Excess Profit %			19.00%
Other minority owned stores | Maximum
Schedule of Equity Method Investments [Line Items]
Equity Ownership %			50.00%
Excess Profit %			50.00%
SmartStop Self Storage REIT, Inc. Preferred Stock
Schedule of Equity Method Investments [Line Items]
Investment balance			$ 200,000	$ 150,000
Amount invested	$ 50,000	$ 150
Investment commitment		$ 50
Investment commitment, period		12 months
Investment, preferred dividend rate		6.25%
Period after which preferred stock dividend is subject to increase		5 years
Investment redemption restriction period		5 years

Investments in Unconsolidated_4

Investments in Unconsolidated Real Estate Entities - New Unconsolidated Joint Ventures (Details) $ in Thousands	Dec. 31, 2019USD ($)store	Dec. 31, 2018USD ($)store
Schedule of Equity Method Investments [Line Items]
Number of Stores | store	16	28
Total initial investment | $	$ 19,663	$ 63,723
Minimum
Schedule of Equity Method Investments [Line Items]
Equity ownership %	10.00%	10.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Equity ownership %	50.00%	25.00%

Investments in Unconsolidated_5

Investments in Unconsolidated Real Estate Entities - Schedule of Equity in Earnings of Unconsolidated Real Estate Ventures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	$ 22,361	$ 11,274	$ 14,452
SmartStop Self Storage REIT, Inc. Preferred Stock
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	9,968	1,636	0
PRISA Self Storage LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	2,229	2,327	2,338
Storage Portfolio II JV LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	559	291	79
Storage Portfolio I LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	1,636	1,809	1,886
VRS Self Storage, LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	3,509	3,583	3,640
ESS-NYFL JV LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	(331)	(96)	0
WICNN JV LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	1,878	1,373	622
Extra Space Northern Properties Six LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	1,088	1,091	1,014
Alan Jathoo JV LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	57	(47)	(12)
ESS Bristol Investments LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	(67)	(262)	(152)
GFN JV, LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	788	450	22
PR EXR Self Storage, LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	(211)	(443)	(75)
WCOT Self Storage LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	0	0	359
Extra Space West Two LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	0	0	1,042
Extra Space West One LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	0	0	2,526
Other minority owned stores
Schedule of Equity Method Investments [Line Items]
Equity in earnings and dividend income from unconsolidated real estate entities	$ 1,258	$ (438)	$ 1,163

Investments in Unconsolidated_6

Investments in Unconsolidated Real Estate Entities - Additional Information (Details) $ in Thousands	Apr. 30, 2018USD ($)store	Jan. 31, 2019USD ($)store	Dec. 31, 2020USD ($)store	Dec. 31, 2019USD ($)store	Dec. 31, 2018USD ($)
Schedule of Equity Method Investments [Line Items]
Contributions joint ventures			$ 14,792
Number of operating stores acquired | store			1
Number of stores acquired at certificate of occupancy | store			5
Number of stores acquired | store			23	21
Cash paid to acquire properties			$ 254,111	$ 279,313
Loans assumed			0	17,157	$ 87,500
Amortization amount of excess purchase price included in equity earnings			$ 25,251
Amortization period of excess purchase price included in equity earnings			40 years
Management fee revenues			$ 15,657	$ 14,624	$ 12,650
East Space West One LLC and East Space West Two LLC
Schedule of Equity Method Investments [Line Items]
Number of stores acquired | store		12
Cash paid to acquire properties		$ 172,505
Ownership interest held by entity (as a percent)		100.00%
WCOT Self Storage LLC
Schedule of Equity Method Investments [Line Items]
Number of stores acquired | store	14
Cash paid to acquire properties	$ 115,797
Loans assumed	$ 87,500

Investments in Debt Securitie_3

Investments in Debt Securities and Notes Receivable - Schedule (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]
Dividends Receivable	$ 4,889	$ 0
Investments in debt securities and notes receivable	593,810	43,586
Notes Receivable-Bridge Loans
Schedule of Held-to-maturity Securities [Line Items]
Notes receivable	187,368	43,586
Notes Receivable-Senior Mezzanine Loan
Schedule of Held-to-maturity Securities [Line Items]
Notes receivable	101,553	0
JCAP Series A Preferred Stock
Schedule of Held-to-maturity Securities [Line Items]
Debt securities	200,000	0
JCAP Series B Preferred Stock
Schedule of Held-to-maturity Securities [Line Items]
Debt securities	$ 100,000	$ 0

Investments in Debt Securitie_4

Investments in Debt Securities and Notes Receivable - Additional Information (Details) $ in Thousands	1 Months Ended		2 Months Ended	12 Months Ended
	Nov. 30, 2020USD ($)shares	Jul. 31, 2020USD ($)	Feb. 26, 2021USD ($)	Dec. 31, 2020USD ($)extension_option	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Investment in debt securities	$ 300,000			$ 300,000	$ 0	$ 0
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
Bridge loans, extension option | extension_option				2
Bridge loans, extension term				1 year
Proceeds from sale of notes receivable				$ 62,764	0	0
Payments to purchase notes receivable				$ 313,355	$ 185,993	$ 13,850
Notes Receivable-Bridge Loans
Schedule of Held-to-maturity Securities [Line Items]
Bridge loans, original maturities				3 years
Principal amount of notes sold				$ 63,088
Proceeds from sale of notes receivable				$ 62,764
Notes Receivable-Bridge Loans | Subsequent Event
Schedule of Held-to-maturity Securities [Line Items]
Principal amount of notes sold			$ 76,241
Proceeds from sale of notes receivable			$ 75,707
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%
Payments to purchase notes receivable		$ 101,142
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 and Revolving L_3

Notes Payable and Revolving Lines of Credit - Schedule of Components of Notes Payable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total	$ 4,797,303	$ 4,318,973
Notes Payable
Debt Instrument [Line Items]
Total	4,818,771	4,343,502
Unamortized debt issuance costs	(21,468)	(24,529)
Total	4,797,303	4,318,973
Notes Payable | Secured notes payable
Debt Instrument [Line Items]
Fixed rate notes payable	1,112,220	1,365,408
Variable rate notes payable	$ 1,081,551	878,093
Notes Payable | Secured notes payable | Minimum
Debt Instrument [Line Items]
Fixed Rate	2.53%
Variable Rate	1.39%
Notes Payable | Secured notes payable | Maximum
Debt Instrument [Line Items]
Fixed Rate	5.85%
Variable Rate	2.20%
Notes Payable | Secured notes payable | LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	1.30%
Notes Payable | Secured notes payable | LIBOR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
Notes Payable | Unsecured notes payable
Debt Instrument [Line Items]
Fixed rate notes payable	$ 2,525,000	2,052,521
Variable rate notes payable	$ 100,000	$ 47,480
Notes Payable | Unsecured notes payable | Minimum
Debt Instrument [Line Items]
Fixed Rate	2.80%
Variable Rate	1.04%
Notes Payable | Unsecured notes payable | Maximum
Debt Instrument [Line Items]
Fixed Rate	4.39%
Notes Payable | Unsecured notes payable | LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	0.90%

Notes Payable and Revolving L_4

Notes Payable and Revolving Lines of Credit - Schedule of Lines of Credit (Details)	Dec. 31, 2020USD ($)
Line of Credit Facility [Line Items]
Debt Capacity	$ 1,190,000,000
Line of Credit
Line of Credit Facility [Line Items]
Debt Capacity	1,850,000,000
Revolving Credit Facility | Line of Credit
Line of Credit Facility [Line Items]
Debt Capacity	650,000,000
Tranche 1 Term Loan Facility | Line of Credit
Line of Credit Facility [Line Items]
Debt Capacity	480,000,000
Tranche 2 Term Loan Facility | Line of Credit
Line of Credit Facility [Line Items]
Debt Capacity	220,000,000
Tranche 3 Term Loan Facility | Line of Credit
Line of Credit Facility [Line Items]
Debt Capacity	245,000,000
Tranche 4 Term Loan Facility | Line of Credit
Line of Credit Facility [Line Items]
Debt Capacity	$ 255,000,000

Notes Payable and Revolving L_5

Notes Payable and Revolving Lines of Credit - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)extension_option	Dec. 31, 2019USD ($)
Line of Credit
Debt Instrument [Line Items]
Number of extension options | extension_option	2
Extension term	6 months
Line of Credit | Base rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.00%
Line of Credit | Base rate | Investment grade election | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	0.00%
Line of Credit | Base rate | Investment grade election | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	1.25%
Line of Credit | Federal funds rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Line of Credit | Eurodollar
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Line of Credit | Eurodollar | Investment grade election | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	0.75%
Line of Credit | Eurodollar | Investment grade election | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	2.25%
Notes Payable
Debt Instrument [Line Items]
Notes payable	$ 4,818,771	$ 4,343,502
Notes payable subject to recourse	$ 1,969,323

Notes Payable and Revolving L_6

Notes Payable and Revolving Lines of Credit - Schedule of Maturities of Notes Payable (Details) - Notes Payable - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
2021	$ 459,557
2022	584,865
2023	762,925
2024	705,153
2025	524,827
Thereafter	1,781,444
Total	$ 4,818,771	$ 4,343,502

Notes Payable and Revolving L_7

Notes Payable and Revolving Lines of Credit - Schedule of Information on Lines of Credit (Details)	12 Months Ended
	Dec. 31, 2020USD ($)extension_option	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Amount Drawn	$ 949,000,000	$ 158,000,000
Debt Capacity	1,190,000,000
Credit Line 1
Debt Instrument [Line Items]
Amount Drawn	102,000,000
Debt Capacity	$ 140,000,000
Interest Rate	1.60%
Number of extensions available | extension_option	1
Extension term	2 years
Credit Line 2
Debt Instrument [Line Items]
Amount Drawn	$ 487,000,000
Debt Capacity	$ 650,000,000
Interest Rate	1.00%
Number of extensions available | extension_option	2
Extension term	6 months
Credit Line 3
Debt Instrument [Line Items]
Amount Drawn	$ 360,000,000
Debt Capacity	$ 400,000,000
Interest Rate	1.50%
Number of extensions available | extension_option	1
Extension term	12 months
LIBOR | Credit Line 1
Debt Instrument [Line Items]
Basis spread on variable rate	1.45%
LIBOR | Credit Line 2
Debt Instrument [Line Items]
Basis spread on variable rate	0.90%
LIBOR | Credit Line 3
Debt Instrument [Line Items]
Basis spread on variable rate	1.20%

Derivatives - Additional Inform

Derivatives - Additional Information (Details) $ in Thousands	Dec. 31, 2020USD ($)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	$ 35,080
Number of derivative financial instruments | derivative	22
Combined notional amount	$ 2,091,270
Derivatives with contingent features, net liability position	101,662
Derivatives with contingent features, contingent cash settlement value	$ 101,662

Derivatives - Schedule Summariz

Derivatives - Schedule Summarizing Terms of Entity's Derivative Financial Instruments (Details) $ in Thousands	Dec. 31, 2020USD ($)
Derivative [Line Items]
Notional amounts	$ 2,091,270
Cash flow hedging | Swap Agreements | Minimum
Derivative [Line Items]
Notional amounts	$ 33,681
Strike rate	1.07%
Cash flow hedging | Swap Agreements | Maximum
Derivative [Line Items]
Notional amounts	$ 238,139
Strike rate	3.87%

Derivatives - Schedule of Balan

Derivatives - Schedule of Balance Sheet Classification and Fair Value of Entity's Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other assets
Derivative [Line Items]
Asset derivatives	$ 0	$ 6,214
Other liabilities
Derivative [Line Items]
Liability derivatives	$ 98,325	$ 31,400

Derivatives - Schedule of Infor

Derivatives - Schedule of Information Relating to Gain (Loss) Recognized on Swap Agreements (Details) - Swap Agreements - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (loss) recognized in OCI	$ (100,352)	$ (54,680)
Gain (loss) reclassified from OCI	$ (26,794)	$ 12,322	$ 8,258

Notes Payable to Trusts (Detail

Notes Payable to Trusts (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2019USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2005subsidiary
Variable Interest Entity [Line Items]
Variable interest entity interest in trust number | subsidiary					3
Principal payments on notes payable to trusts		$ 0	$ 30,928	$ 88,662
Notes payable to Trusts | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Principal payments on notes payable to trusts	$ 30,928			88,662
Notes payable to Trusts				$ 30,928

Exchangeable Senior Notes - Add

Exchangeable Senior Notes - Additional Information (Details)	Nov. 02, 2020USD ($)shares	Oct. 01, 2020USD ($)shares	Dec. 31, 2019	Jun. 21, 2013USD ($)	Sep. 30, 2015	Dec. 31, 2020USD ($)day	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2016USD ($)
Debt Instrument [Line Items]
Cash paid for repurchase of debt						$ 2,014,730,000	$ 1,977,805,000	$ 1,109,854,000
2015 Notes
Debt Instrument [Line Items]
Principal amount of notes issued									$ 575,000,000
Fixed interest rate						3.125%			3.125%
Related debt issuance costs									$ 11,992,000
Underwriting fee percentage					2.00%
Amortization period					5 years
Conversion ratio			0.01100
Redemption price as percentage of principal amount of notes plus accrued and unpaid interest					100.00%
Redemption price as percentage of principal amount of notes at request of debt holders and upon occurrence of designated event					100.00%
Notes exchange, threshold percentage						130.00%
Notes exchange, threshold trading days | day						20
Notes exchange, threshold consecutive trading days | day						30
Effective interest rate						4.00%
2015 Notes | 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) | shares		124,819
Repurchase of exchangeable senior notes with common stock		$ 13,495,000
2015 Notes | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Repurchase of exchangeable senior notes	$ 503,432,000
Repurchase of exchangeable senior notes with common stock (in shares) | shares	1,198,962
Repurchase of exchangeable senior notes with common stock	$ 138,900,000
2015 Notes | Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Repurchase of exchangeable senior notes	$ 55,000
2015 Notes | Minimum
Debt Instrument [Line Items]
Number of days of written notice to holders of notes required for redemption					30 days
2015 Notes | Maximum
Debt Instrument [Line Items]
Number of days of written notice to holders of notes required for redemption					60 days
2013 Notes
Debt Instrument [Line Items]
Principal amount of notes issued				$ 250,000,000
Fixed interest rate				2.375%
Related debt issuance costs				$ 1,672,000
Debt, measurement input				1.50%
Unamortized cash discount				$ 3,750,000
Amortization period				5 years

Exchangeable Senior Notes - Equ

Exchangeable Senior Notes - Equity and Liability Components (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2016
Debt Instrument [Line Items]
Principal amount of liability component	$ 0	$ 569,513
2015 Notes
Debt Instrument [Line Items]
Principal amount of liability component	575,000
Unamortized debt issuance costs			$ (11,992)
Senior Notes | 2015 Notes
Debt Instrument [Line Items]
Carrying amount of equity component	0	22,597
Principal amount of liability component	0	575,000
Unamortized discount - equity component	0	(3,675)
Unamortized debt issuance costs	0	(1,812)
Net carrying amount of liability component	$ 0	$ 569,513

Exchangeable Senior Notes - Int

Exchangeable Senior Notes - Interest Cost Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Contractual interest	$ 13,476	$ 17,968	$ 18,106
Amortization of discount	3,675	4,742	4,687
Total interest expense recognized	$ 17,151	$ 22,710	$ 22,793

Exchangeable Senior Notes - Rep

Exchangeable Senior Notes - Repurchase of Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total consideration paid for repurchase	$ 2,014,730	$ 1,977,805	$ 1,109,854
Exchangeable Senior Notes
Debt Instrument [Line Items]
Principal amount repurchased	575,000	0	49,259
Extinguishment of liability component	575,000	0	49,019
Reacquisition of equity component	0	0	31,251
Total consideration paid for repurchase	575,000	0	80,270
Extinguishment of liability component	(575,000)	0	(49,019)
Discount on exchangeable senior notes	0	0	(230)
Related debt issuance costs	0	0	(10)
Gain/(loss) on repurchase	$ 0	$ 0	$ 0

Stockholders' Equity (Details)

Stockholders' Equity (Details)	May 15, 2019USD ($)	Nov. 30, 2017USD ($)	Feb. 26, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)item$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)shares	Oct. 15, 2020USD ($)	Dec. 31, 2017shares
Changes In Equity And Comprehensive Income Line Items [Line Items]
Common stock, authorized (in shares)				500,000,000	500,000,000
Common stock, par value (dollars per share) | $ / shares				$ 0.01	$ 0.01
Preferred stock, authorized (in shares)				50,000,000	50,000,000
Preferred stock, par value (in dollars per share) | $ / shares				$ 0.01	$ 0.01
Common stock, issued (in shares)				131,357,961	129,534,407
Common stock, outstanding (in shares)				131,357,961	129,534,407
Preferred stock, issued (in shares)				0	0
Preferred stock, outstanding (in shares)				0	0
Number of votes, common stockholder rights | item				1
Average share price (in dollars per share) | $ / shares				$ 103.62
Share repurchase program, period		3 years
Share repurchase program, aggregate value | $		$ 400,000,000					$ 400,000,000
Shares repurchased, average price (in dollars per share) | $ / shares				$ 82.09
Shares repurchased, amount paid | $				$ 67,873,000	$ 0	$ 0
Share repurchase program, remaining authorization value | $				$ 400,000,000
Common Stock
Changes In Equity And Comprehensive Income Line Items [Line Items]
Common stock, issued (in shares)				131,357,961	129,534,407	127,103,750		126,007,091
Shares repurchased (in shares)				826,797
“At the market” equity program
Changes In Equity And Comprehensive Income Line Items [Line Items]
Aggregate offering price | $	$ 500,000,000
Common stock sold (in shares)				899,048	1,779,200
Average share price (in dollars per share) | $ / shares				$ 116.42	$ 113.19
Net proceeds from sale of stock | $				$ 103,468,000	$ 198,827,000
Available for issuance | $				$ 193,951,000
“At the market” equity program | Subsequent Event
Changes In Equity And Comprehensive Income Line Items [Line Items]
Common stock sold (in shares)			585,685
Average share price (in dollars per share) | $ / shares			$ 115.90
Net proceeds from sale of stock | $			$ 67,204,000

Noncontrolling Interest Repre_2

Noncontrolling Interest Represented By Preferred Operating Partnership Units (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 25, 2019	Apr. 17, 2019	Dec. 01, 2018	Apr. 18, 2017	Jun. 25, 2007	Dec. 31, 2014	Oct. 31, 2014	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2007
Noncontrolling Interest [Line Items]
Loan to holders of preferred OP units								$ 100,000	$ 100,000
Redemption of noncontrolling interests								$ 0	0	$ 0
Redemption of units for cash
Noncontrolling Interest [Line Items]
Redemption of noncontrolling interests										2,558
Series B Units | Redemption of units for cash
Noncontrolling Interest [Line Items]
Redemption of noncontrolling interests (in shares)								40,000
Redemption of noncontrolling interests								$ 1,000
Operating Partnership
Noncontrolling Interest [Line Items]
Conversion of units, units issued upon conversion (in shares)	270,709		373,113
Reduction of noncontrolling interest for note receivable								2,311	$ 18,524	11,091
Operating Partnership | Redemption of units for cash
Noncontrolling Interest [Line Items]
Redemption of noncontrolling interests										1,126
Series A Units
Noncontrolling Interest [Line Items]
Fixed priority return on preferred OP units, amount							$ 101,700	$ 101,700
Fixed priority return on preferred OP units, stated return rate		5.00%		2.30%				2.30%
Fixed priority return on preferred OP units, liquidation value											$ 115,000
Preferred units outstanding (in shares)							875,480
Series A Units | Holders Of Series A Preferred Operating Partnership Units
Noncontrolling Interest [Line Items]
Loan to holders of preferred OP units					$ 100,000
Maximum number of preferred OP units converted prior to the maturity date of the loan (in shares)							114,500
Note receivable interest rate					4.90%			2.10%
Additional units redeemed (in shares)					0
Series B Units
Noncontrolling Interest [Line Items]
Preferred units outstanding (in shares)								1,636,087
Liquidation value (in dollars per share)								$ 25
Fixed liquidation value								$ 40,902
Annual rate of return percent								6.00%
Series C Units
Noncontrolling Interest [Line Items]
Loan to holders of preferred OP units										19,735
Note receivable interest rate						5.00%
Liquidation value (in dollars per share)								$ 42.10
Quarterly distribution per preferred OP unit payable above quarterly distribution for common OP Unit (in dollars per share)								$ 0.18
Period from date of issuance after which preferred OP units will become redeemable at the option of the holder								1 year
Period from date of issuance after which preferred OP units will become convertible into common OP units at the option of the holder								1 year
Preferred OP units conversion ratio (in units)								0.9145
Notes receivable						$ 20,230
Conversion of units, units converted (in shares)	296,020		407,996
Reduction of noncontrolling interest for note receivable										$ 8,644
Series D Units
Noncontrolling Interest [Line Items]
Preferred units outstanding (in shares)								4,694,485
Liquidation value (in dollars per share)								$ 25
Fixed liquidation value								$ 117,362
Number of units issued (in shares)									1,120,924
Value of units issued									$ 28,022
Series D Units | Minimum
Noncontrolling Interest [Line Items]
Annual rate of return percent								3.00%
Series D Units | Maximum
Noncontrolling Interest [Line Items]
Annual rate of return percent								5.00%

Noncontrolling Interests In O_3

Noncontrolling Interests In Operating Partnership and Other Noncontrolling Interests - Additional Information (Details) $ / shares in Units, $ in Thousands	Apr. 25, 2019shares	Dec. 01, 2018shares	Dec. 31, 2020USD ($)joint_venturestore$ / sharesshares	Dec. 31, 2019USD ($)store	Dec. 31, 2018USD ($)store
Noncontrolling Interest [Line Items]
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			$ 114.15
OP units outstanding (in units) | shares			5,800,785
Consideration to be paid on redemption of common OP units | $			$ 662,160
Number of owned stores				16	28
Joint venture one | Texas
Noncontrolling Interest [Line Items]
Number of owned stores			2
Joint venture one | Colorado
Noncontrolling Interest [Line Items]
Number of owned stores			2
Joint venture two | Pennsylvania
Noncontrolling Interest [Line Items]
Number of owned stores			1
Joint venture two | New Jersey
Noncontrolling Interest [Line Items]
Number of owned stores			1
Operating Partnership
Noncontrolling Interest [Line Items]
Ownership interest held by entity (as a percent)			94.20%
Voting interests of third-party owners			5.80%
Series C Units
Noncontrolling Interest [Line Items]
Conversion of units, units converted (in shares) | shares	296,020	407,996
Reduction of noncontrolling interest for note receivable | $					$ 8,644
Operating Partnership
Noncontrolling Interest [Line Items]
Conversion of units, units issued upon conversion (in shares) | shares	270,709	373,113
Reduction of noncontrolling interest for note receivable | $			$ 2,311	$ 18,524	$ 11,091
Common Stock
Noncontrolling Interest [Line Items]
Unit conversion ratio			1
Other
Noncontrolling Interest [Line Items]
Number of consolidated joint ventures | joint_venture			2
Other | Joint venture one | Minimum
Noncontrolling Interest [Line Items]
Voting interests of third-party owners			5.00%
Other | Joint venture one | Maximum
Noncontrolling Interest [Line Items]
Voting interests of third-party owners			20.00%

Noncontrolling Interests In O_4

Noncontrolling Interests In Operating Partnership and Other Noncontrolling Interests - Schedule of OP Unit Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Noncontrolling Interest [Abstract]
OP Units redeemed for common stock (in shares)	123,993	340,182	35,000
OP Units redeemed for cash (in shares)	0	0	30,000
Cash paid for OP Units redeemed	$ 0	$ 0	$ 2,558
OP Units issued in conjunction with acquisitions (in shares)	0	0	21,768
Value of OP Units issued in conjunction with acquisitions	$ 0	$ 0	$ 1,877
OP Units issued upon redemption of Series C Units (in shares)	0	270,709	373,113

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	1 Months Ended		12 Months Ended
	Aug. 31, 2019USD ($)store	Jun. 30, 2019USD ($)store	Dec. 31, 2020USD ($)storeleaseextension_option	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Jan. 01, 2019USD ($)
Lessee, Lease, Description [Line Items]
Operating lease liabilities			$ 263,485	$ 274,783
Operating lease right-of-use assets			$ 252,172	$ 264,643
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]			us-gaap:RealEstateInvestmentPropertyNet	us-gaap:RealEstateInvestmentPropertyNet
Finance Lease, Liability, Statement of Financial Position [Extensible List]			us-gaap:OtherLiabilities	us-gaap:OtherLiabilities
Noncash acquisition, finance lease liability			$ 41,491	$ 0
Number of acquired stores with land leases | store			3
Noncash acquisition, finance lease liability, completion of construction			$ 8,605
Number of stores added under operating lease | store	5	22
Operating lease, term			25 years
Operating lease, termination option, term			10 years
increase in right-of-use assets under new operating leases	$ 52,224	$ 127,532
Lease expense related to operating leases					$ 8,229
Store Lease
Lessee, Lease, Description [Line Items]
Number of leases | lease			53
Store Lease | Minimum
Lessee, Lease, Description [Line Items]
Operating and finance lease, original lease term			10 years
Operating and finance lease, extension term			5 years
Store Lease | Maximum
Lessee, Lease, Description [Line Items]
Operating and finance lease, original lease term			99 years
Operating and finance lease, extension term			35 years
Corporate Office And Call Center Lease | Minimum
Lessee, Lease, Description [Line Items]
Operating lease, original lease term			5 years 3 months 18 days
Corporate Office And Call Center Lease | Maximum
Lessee, Lease, Description [Line Items]
Operating lease, original lease term			12 years 1 month 6 days
Regional Office Lease
Lessee, Lease, Description [Line Items]
Number of leases | lease			13
Operating lease, renewal term			3 years
Regional Office Lease | Minimum
Lessee, Lease, Description [Line Items]
Operating lease, original lease term			3 years
Regional Office Lease | Maximum
Lessee, Lease, Description [Line Items]
Operating lease, original lease term			5 years
District Office Lease
Lessee, Lease, Description [Line Items]
Operating lease, original lease term			12 months
California Store Lease
Lessee, Lease, Description [Line Items]
Lease not yet commenced, term			15 years
California Store Lease | Lease Option One
Lessee, Lease, Description [Line Items]
Lease not yet commenced, number of extension options | extension_option			3
Lease not yet commenced, term of extension options			10 years
California Store Lease | Lease Option Two
Lessee, Lease, Description [Line Items]
Lease not yet commenced, number of extension options | extension_option			1
Lease not yet commenced, term of extension options			5 years
ASU 2016-02
Lessee, Lease, Description [Line Items]
Operating lease liabilities						$ 95,506
Operating lease right-of-use assets						$ 104,863

Leases - Lease Costs (Details)

Leases - Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finance lease cost:
Amortization of finance lease right-of-use assets	$ 400	$ 168
Interest expense related to finance lease liabilities	712	290
Operating lease cost	28,709	20,268
Variable lease cost	9,056	5,068
Short-term lease cost	80	164
Total lease cost	38,957	25,958
Cash paid for amounts included in the measurement of lease liabilities
Operating cash outflows for finance lease payments	712	231
Operating cash outflows for operating lease payments	25,037	19,226
Total cash flows for lease liability measurement	25,749	19,457
Right-of-use assets obtained in exchange for new operating lease liabilities	8,014	277,557
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 50,096	$ 8,050
Weighted average remaining lease term - finance leases (years)	78 years 5 months 23 days	46 years 10 months 9 days
Weighted average remaining lease term - operating leases (years)	13 years 11 months 26 days	14 years 8 months 4 days
Weighted average discount rate - finance leases	3.47%	6.07%
Weighted average discount rate - operating leases	3.66%	3.65%

Leases - Undiscounted Cash Flow

Leases - Undiscounted Cash Flows on an Annual Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating
2021	$ 29,565
2022	29,591
2023	29,642
2024	30,008
2025	30,485
Thereafter	199,168
Total	348,459
Present value adjustments	(84,974)
Lease liabilities	263,485	$ 274,783
Finance
2021	1,284
2022	1,485
2023	1,496
2024	1,508
2025	1,537
Thereafter	222,529
Total	229,839
Present value adjustments	(174,836)
Lease liabilities	55,003
Total
2021	30,849
2022	31,076
2023	31,138
2024	31,516
2025	32,022
Thereafter	421,697
Total	578,298
Present value adjustments	(259,810)
Lease liabilities	$ 318,488

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance under plans (in shares)	1,239,557
Intrinsic value of options exercised	$ 10,016	$ 18,089	$ 3,693
Options granted (in shares)	0	0	0
Weighted average forfeiture rate	7.40%
Net proceeds from exercise of stock options	$ 4,759	$ 3,063	$ 1,169
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years
Compensation cost	$ 27	364	570
Net proceeds from exercise of stock options	4,759	3,063	1,169
Unrecognized compensation cost	$ 0
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Weighted average forfeiture rate	10.00%
Compensation cost	$ 9,244	9,173	8,733
Unrecognized compensation cost	$ 11,638
Unrecognized compensation cost, period of recognition	2 years 14 days
Performance-Based Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Compensation cost	$ 7,048	3,514	1,873
Unrecognized compensation cost	$ 6,406	$ 4,315	$ 2,739
Unrecognized compensation cost, period of recognition	3 years	3 years	3 years
Performance component weight percentage	50.00%
Minimum shares issued for each PSU (in shares)	0
Maximum shares issued for each PSU (in shares)	2
Dividend yield	0.00%	0.00%	0.00%

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock option activity
Balance at the beginning of the period (in shares)	206,524	417,581	472,156
Exercised (in shares)	(134,930)	(211,057)	(54,575)
Balance at the end of the period (in shares)	71,594	206,524	417,581
Vested and Expected to Vest (in shares)	71,594
Exercisable at the end of the period (in shares)	71,594
Weighted average exercise price
Balance at the beginning of the period (in dollars per share)	$ 48.88	$ 31.58	$ 30.41
Exercised (in dollars per share)	35.26	14.65	21.45
Balance at the end of the period (in dollars per share)	74.54	$ 48.88	$ 31.58
Vested and Expected to Vest (in dollars per share)	74.54
Exercisable at the end of the period (in dollars per share)	$ 74.54
Weighted average remaining contractual life
Outstanding at the beginning of period	4 years 7 months 9 days
Vested and Expected to Vest	4 years 7 months 9 days
Exercisable at the end of period	4 years 7 months 9 days
Aggregate intrinsic value
Outstanding at the end of the period	$ 1,823
Vested and Expected to Vest	1,823
Exercisable at the end of the period	$ 1,823

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary Stock Options Outstanding and Exercisable (Details)	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options outstanding (in shares) | shares	71,594
Options outstanding, weighted average remaining contractual life	4 years 7 months 9 days
Weighted average exercise price (in dollars per share)	$ 74.54
Options exercisable (in shares) | shares	71,594
Options exercisable, weighted average exercise price (in dollars per share)	$ 74.54
$47.50 - $47.50
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	47.50
Exercise price range, upper limit (in dollars per share)	$ 47.50
Options outstanding (in shares) | shares	2,700
Options outstanding, weighted average remaining contractual life	3 years 1 month 17 days
Weighted average exercise price (in dollars per share)	$ 47.50
Options exercisable (in shares) | shares	2,700
Options exercisable, weighted average exercise price (in dollars per share)	$ 47.50
$65.36 - $65.36
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	65.36
Exercise price range, upper limit (in dollars per share)	$ 65.36
Options outstanding (in shares) | shares	1,582
Options outstanding, weighted average remaining contractual life	4 years 1 month 24 days
Weighted average exercise price (in dollars per share)	$ 65.36
Options exercisable (in shares) | shares	1,582
Options exercisable, weighted average exercise price (in dollars per share)	$ 65.36
$65.45 - $65.45
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	65.45
Exercise price range, upper limit (in dollars per share)	$ 65.45
Options outstanding (in shares) | shares	2,900
Options outstanding, weighted average remaining contractual life	4 years 1 month 17 days
Weighted average exercise price (in dollars per share)	$ 65.45
Options exercisable (in shares) | shares	2,900
Options exercisable, weighted average exercise price (in dollars per share)	$ 65.45
$73.52 - $73.52
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	73.52
Exercise price range, upper limit (in dollars per share)	$ 73.52
Options outstanding (in shares) | shares	50,000
Options outstanding, weighted average remaining contractual life	4 years 6 months 29 days
Weighted average exercise price (in dollars per share)	$ 73.52
Options exercisable (in shares) | shares	50,000
Options exercisable, weighted average exercise price (in dollars per share)	$ 73.52
$85.99 - $85.99
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	85.99
Exercise price range, upper limit (in dollars per share)	$ 85.99
Options outstanding (in shares) | shares	14,412
Options outstanding, weighted average remaining contractual life	5 years 1 month 24 days
Weighted average exercise price (in dollars per share)	$ 85.99
Options exercisable (in shares) | shares	14,412
Options exercisable, weighted average exercise price (in dollars per share)	$ 85.99

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Employee and Director Share Grant Activity (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restricted Stock Grants
Balance at the beginning of the period (in shares)	212,608	223,114	266,475
Granted (in shares)	95,671	109,081	85,066
Released (in shares)	(94,164)	(110,724)	(116,656)
Cancelled (in shares)	(5,083)	(8,863)	(11,771)
Balance at the end of the period (in shares)	209,032	212,608	223,114
Weighted-Average Grant-Date Fair Value
Balance at the beginning of the period (in dollars per share)	$ 91.62	$ 80.02	$ 74.76
Granted (in dollars per share)	98.81	101.52	86.14
Released (in dollars per share)	89.43	79.58	72.38
Cancelled (in dollars per share)	93.16	90.11	80.96
Balance at the end of the period (in dollars per share)	$ 95.86	$ 91.62	$ 80.02

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of PSU Activity (Details) - Performance-Based Stock Units - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Units
Balance at the beginning of the period (in shares)	108,140	58,806	30,071
Granted (in shares)	45,242	49,334	28,735
Released (in shares)	(47,516)
Balance at the end of the period (in shares)	105,866	108,140	58,806
Weighted-Average Grant-Date Fair Value
Balance at the beginning of the period (in dollars per share)	$ 95.94	$ 89.87	$ 83.84
Granted (in dollars per share)	129.38	103.18	96.19
Released (in dollars per share)	112.16
Balance at the end of the period (in dollars per share)	$ 102.95	$ 95.94	$ 89.87

Stock-Based Compensation - Assu

Stock-Based Compensation - Assumptions Used to Calculate Fair Value of Awards (Details) - Performance-Based Stock Units - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value	$ 12,266	$ 6,211	$ 5,321
Risk-free rate	1.42%	2.53%	2.37%
Volatility	18.40%	20.70%	22.60%
Expected term	2 years 10 months 24 days	2 years 9 months 18 days	2 years 10 months 24 days
Dividend yield	0.00%	0.00%	0.00%
Unrecognized compensation cost	$ 6,406	$ 4,315	$ 2,739
Term over which compensation cost recognized (in years)	3 years	3 years	3 years

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Employee contribution to retirement saving plan as a percentage of annual salary, maximum	60.00%
Matching contributions made by the entity during the period	$ 3,980	$ 3,355	$ 2,833
Percentage of company's matching contributions of first 3 percent of employee's compensation	100.00%
Percentage of employee's compensation that qualifies for 100 percent matching contribution by the company	3.00%
Maximum percentage of the company's matching contributions of next 2 percent of employee's compensation	50.00%
Percentage of employee's compensation that qualifies for 50 percent matching contribution by the company	2.00%

Income Taxes - Income Tax Provi

Income Taxes - Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Federal
Current expense, federal	$ 15,553	$ 10,164	$ 9,136
Tax credits/true-up, federal	(5,610)	(3,633)	(5,841)
Change in deferred expense/(benefit), federal	594	1,787	3,730
Income tax expense, federal	10,537	8,318	7,025
State
Current expense, state	3,347	2,936	2,426
Tax credits/true-up, state	(135)	(30)	(175)
Change in deferred expense/(benefit), state	61	84	(32)
Income tax expense, state	3,273	2,990	2,219
Current expense, total	18,900	13,100	11,562
Tax credits/true-up, total	(5,745)	(3,663)	(6,016)
Change in deferred expense/(benefit), total	655	1,871	3,698
Total provision	$ 13,810	$ 11,308	$ 9,244

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Statutory Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Expected tax at statutory rate	$ 111,760	$ 97,110	$ 95,828
Non-taxable REIT income	(94,270)	(82,717)	(83,022)
State and local tax expense - net of federal benefit	3,075	2,837	2,385
Change in valuation allowance	(363)	(207)	(1,052)
Tax credits/true-up	(5,745)	(3,663)	(6,016)
Miscellaneous	(647)	(2,052)	1,121
Total provision	$ 13,810	$ 11,308	$ 9,244
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Expected tax at statutory rate	21.00%	21.00%	21.00%
Non-taxable REIT income	(17.70%)	(17.90%)	(18.20%)
State and local tax expense - net of federal benefit	0.60%	0.60%	0.50%
Change in valuation allowance	(0.10%)	0.00%	(0.20%)
Tax credits/true-up	(1.10%)	(0.80%)	(1.30%)
Miscellaneous	(0.10%)	(0.40%)	0.20%
Total provision	2.60%	2.50%	2.00%

Income Taxes - Sources of Tempo

Income Taxes - Sources of Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax liabilities:
Fixed assets	$ (27,374)	$ (23,805)
Operating lease right-of-use assets	(2,223)	(2,475)
Other	(72)	(84)
State deferred taxes	(3,210)	(3,405)
Total deferred tax liabilities	(32,879)	(29,769)
Deferred tax assets:
Captive insurance subsidiary	378	312
Accrued liabilities	2,325	2,006
Stock compensation	2,635	2,118
Operating lease liabilities	2,232	2,478
SmartStop TRS	219	219
Other	1,554	50
State deferred taxes	6,725	7,250
Total deferred tax assets	16,068	14,433
Valuation allowance	(3,302)	(3,665)
Net deferred income tax liabilities	$ (20,113)	$ (19,001)

Segment Information - Additiona

Segment Information - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020segment
Segment Reporting [Abstract]
Number of reportable segments	2

Segment Information - Schedule

Segment Information - Schedule of Financial Information of Business Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 1,356,212	$ 1,308,454	$ 1,196,604
Operating expenses	708,147	674,701	607,708
Net operating income	666,140	634,958	619,703
Property management fees and other income	52,129	49,890	41,757
General and administrative expense	(96,594)	(89,418)	(81,256)
Depreciation and amortization expense	(224,444)	(219,857)	(209,050)
Gain on real estate transactions	18,075	1,205	30,807
Interest expense	(168,626)	(186,526)	(178,436)
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	(3,675)	(4,742)	(4,687)
Interest income	15,192	7,467	5,292
Equity in earnings and dividend income from unconsolidated real estate entities	22,361	11,274	14,452
Income tax expense	(13,810)	(11,308)	(9,244)
Net income	517,582	451,123	447,080
Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,304,083	1,258,564	1,154,847
Operating expenses	387,109	365,426	317,402
Net operating income	916,974	893,138	837,445
Operating Segments | Self-Storage Operations
Segment Reporting Information [Line Items]
Revenues	1,157,522	1,130,177	1,039,340
Operating expenses	360,615	336,050	291,695
Net operating income	796,907	794,127	747,645
Operating Segments | Tenant Reinsurance
Segment Reporting Information [Line Items]
Revenues	146,561	128,387	115,507
Operating expenses	26,494	29,376	25,707
Net operating income	$ 120,067	$ 99,011	$ 89,800

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Thousands	Dec. 31, 2020USD ($)store
Commitment to acquire stores
Other Commitments [Line Items]
Number of properties to be acquired	10
Other commitment | $	$ 165,500
Commitment to acquire stores, 2021
Other Commitments [Line Items]
Number of store acquisitions expected to close	10
Commitment to acquire stores with joint venture partners
Other Commitments [Line Items]
Number of properties to be acquired	1
Other commitment | $	$ 1,600

Schedule III - Real Estate an_2

Schedule III - Real Estate and Accumulated Depreciation - Property Summary (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)store
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	950
Debt	$ 2,205,072
Land Initial Cost	1,961,349
Building and Improvements Initial Cost	6,662,685
Adjustments and Costs to Land and Building Subsequent to Acquisition	951,197
Gross carrying amount - Land	1,955,469
Gross carrying amount - Building and improvements	7,619,762
Gross carrying amount - Total	9,575,231
Accumulated Depreciation	$ 1,681,429
Self storage facilities | AL
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	9
Debt	$ 30,450
Land Initial Cost	8,766
Building and Improvements Initial Cost	53,158
Adjustments and Costs to Land and Building Subsequent to Acquisition	4,026
Gross carrying amount - Land	8,767
Gross carrying amount - Building and improvements	57,183
Gross carrying amount - Total	65,950
Accumulated Depreciation	$ 9,689
Self storage facilities | AZ
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	23
Debt	$ 21,885
Land Initial Cost	27,535
Building and Improvements Initial Cost	117,304
Adjustments and Costs to Land and Building Subsequent to Acquisition	10,218
Gross carrying amount - Land	27,533
Gross carrying amount - Building and improvements	127,524
Gross carrying amount - Total	155,057
Accumulated Depreciation	$ 28,011
Self storage facilities | CA
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	168
Debt	$ 514,047
Land Initial Cost	539,355
Building and Improvements Initial Cost	1,191,333
Adjustments and Costs to Land and Building Subsequent to Acquisition	124,766
Gross carrying amount - Land	540,043
Gross carrying amount - Building and improvements	1,315,411
Gross carrying amount - Total	1,855,454
Accumulated Depreciation	$ 302,214
Self storage facilities | CO
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	17
Debt	$ 29,605
Land Initial Cost	17,224
Building and Improvements Initial Cost	81,144
Adjustments and Costs to Land and Building Subsequent to Acquisition	16,619
Gross carrying amount - Land	17,942
Gross carrying amount - Building and improvements	97,045
Gross carrying amount - Total	114,987
Accumulated Depreciation	$ 22,571
Self storage facilities | CT
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	7
Debt	$ 23,583
Land Initial Cost	9,875
Building and Improvements Initial Cost	50,966
Adjustments and Costs to Land and Building Subsequent to Acquisition	5,402
Gross carrying amount - Land	9,874
Gross carrying amount - Building and improvements	56,369
Gross carrying amount - Total	66,243
Accumulated Depreciation	$ 11,638
Self storage facilities | FL
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	92
Debt	$ 270,055
Land Initial Cost	161,339
Building and Improvements Initial Cost	624,568
Adjustments and Costs to Land and Building Subsequent to Acquisition	57,728
Gross carrying amount - Land	161,465
Gross carrying amount - Building and improvements	682,170
Gross carrying amount - Total	843,635
Accumulated Depreciation	$ 145,939
Self storage facilities | GA
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	66
Debt	$ 86,912
Land Initial Cost	87,450
Building and Improvements Initial Cost	436,339
Adjustments and Costs to Land and Building Subsequent to Acquisition	34,164
Gross carrying amount - Land	87,434
Gross carrying amount - Building and improvements	470,519
Gross carrying amount - Total	557,953
Accumulated Depreciation	$ 73,133
Self storage facilities | HI
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	13
Debt	$ 30,484
Land Initial Cost	17,663
Building and Improvements Initial Cost	133,870
Adjustments and Costs to Land and Building Subsequent to Acquisition	6,664
Gross carrying amount - Land	17,663
Gross carrying amount - Building and improvements	140,534
Gross carrying amount - Total	158,197
Accumulated Depreciation	$ 29,660
Self storage facilities | IL
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	39
Debt	$ 44,694
Land Initial Cost	48,723
Building and Improvements Initial Cost	248,347
Adjustments and Costs to Land and Building Subsequent to Acquisition	30,362
Gross carrying amount - Land	48,176
Gross carrying amount - Building and improvements	279,256
Gross carrying amount - Total	327,432
Accumulated Depreciation	$ 51,032
Self storage facilities | IN
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	15
Debt	$ 10,825
Land Initial Cost	12,447
Building and Improvements Initial Cost	58,247
Adjustments and Costs to Land and Building Subsequent to Acquisition	6,521
Gross carrying amount - Land	12,447
Gross carrying amount - Building and improvements	64,768
Gross carrying amount - Total	77,215
Accumulated Depreciation	$ 13,688
Self storage facilities | KS
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	1
Debt	$ 0
Land Initial Cost	366
Building and Improvements Initial Cost	1,897
Adjustments and Costs to Land and Building Subsequent to Acquisition	1,080
Gross carrying amount - Land	366
Gross carrying amount - Building and improvements	2,977
Gross carrying amount - Total	3,343
Accumulated Depreciation	$ 1,206
Self storage facilities | KY
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	11
Debt	$ 34,289
Land Initial Cost	8,640
Building and Improvements Initial Cost	68,679
Adjustments and Costs to Land and Building Subsequent to Acquisition	18,858
Gross carrying amount - Land	9,412
Gross carrying amount - Building and improvements	86,765
Gross carrying amount - Total	96,177
Accumulated Depreciation	$ 14,883
Self storage facilities | LA
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	2
Debt	$ 0
Land Initial Cost	6,114
Building and Improvements Initial Cost	8,541
Adjustments and Costs to Land and Building Subsequent to Acquisition	4,787
Gross carrying amount - Land	6,115
Gross carrying amount - Building and improvements	13,327
Gross carrying amount - Total	19,442
Accumulated Depreciation	$ 4,541
Self storage facilities | MA
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	46
Debt	$ 103,569
Land Initial Cost	73,544
Building and Improvements Initial Cost	270,243
Adjustments and Costs to Land and Building Subsequent to Acquisition	55,023
Gross carrying amount - Land	73,725
Gross carrying amount - Building and improvements	325,085
Gross carrying amount - Total	398,810
Accumulated Depreciation	$ 90,473
Self storage facilities | MD
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	31
Debt	$ 107,272
Land Initial Cost	97,772
Building and Improvements Initial Cost	275,357
Adjustments and Costs to Land and Building Subsequent to Acquisition	28,895
Gross carrying amount - Land	97,180
Gross carrying amount - Building and improvements	304,844
Gross carrying amount - Total	402,024
Accumulated Depreciation	$ 79,171
Self storage facilities | MI
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	7
Debt	$ 5,690
Land Initial Cost	9,583
Building and Improvements Initial Cost	51,359
Adjustments and Costs to Land and Building Subsequent to Acquisition	3,984
Gross carrying amount - Land	9,583
Gross carrying amount - Building and improvements	55,343
Gross carrying amount - Total	64,926
Accumulated Depreciation	$ 7,338
Self storage facilities | MN
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	6
Debt	$ 0
Land Initial Cost	8,666
Building and Improvements Initial Cost	59,483
Adjustments and Costs to Land and Building Subsequent to Acquisition	589
Gross carrying amount - Land	8,666
Gross carrying amount - Building and improvements	60,072
Gross carrying amount - Total	68,738
Accumulated Depreciation	$ 3,978
Self storage facilities | MO
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	5
Debt	$ 0
Land Initial Cost	4,129
Building and Improvements Initial Cost	15,444
Adjustments and Costs to Land and Building Subsequent to Acquisition	4,407
Gross carrying amount - Land	4,086
Gross carrying amount - Building and improvements	19,894
Gross carrying amount - Total	23,980
Accumulated Depreciation	$ 8,055
Self storage facilities | MS
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	3
Debt	$ 0
Land Initial Cost	2,420
Building and Improvements Initial Cost	20,849
Adjustments and Costs to Land and Building Subsequent to Acquisition	1,575
Gross carrying amount - Land	2,420
Gross carrying amount - Building and improvements	22,424
Gross carrying amount - Total	24,844
Accumulated Depreciation	$ 3,294
Self storage facilities | NC
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	19
Debt	$ 27,881
Land Initial Cost	31,969
Building and Improvements Initial Cost	104,104
Adjustments and Costs to Land and Building Subsequent to Acquisition	8,479
Gross carrying amount - Land	31,967
Gross carrying amount - Building and improvements	112,585
Gross carrying amount - Total	144,552
Accumulated Depreciation	$ 14,470
Self storage facilities | NH
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	2
Debt	$ 5,853
Land Initial Cost	754
Building and Improvements Initial Cost	4,054
Adjustments and Costs to Land and Building Subsequent to Acquisition	1,300
Gross carrying amount - Land	817
Gross carrying amount - Building and improvements	5,291
Gross carrying amount - Total	6,108
Accumulated Depreciation	$ 2,552
Self storage facilities | NJ
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	60
Debt	$ 159,385
Land Initial Cost	142,291
Building and Improvements Initial Cost	560,512
Adjustments and Costs to Land and Building Subsequent to Acquisition	46,254
Gross carrying amount - Land	137,258
Gross carrying amount - Building and improvements	611,799
Gross carrying amount - Total	749,057
Accumulated Depreciation	$ 147,109
Self storage facilities | NM
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	11
Debt	$ 17,387
Land Initial Cost	32,252
Building and Improvements Initial Cost	71,142
Adjustments and Costs to Land and Building Subsequent to Acquisition	5,916
Gross carrying amount - Land	32,252
Gross carrying amount - Building and improvements	77,058
Gross carrying amount - Total	109,310
Accumulated Depreciation	$ 11,655
Self storage facilities | NV
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	14
Debt	$ 37,829
Land Initial Cost	15,252
Building and Improvements Initial Cost	74,376
Adjustments and Costs to Land and Building Subsequent to Acquisition	5,202
Gross carrying amount - Land	15,252
Gross carrying amount - Building and improvements	79,578
Gross carrying amount - Total	94,830
Accumulated Depreciation	$ 12,733
Self storage facilities | NY
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	28
Debt	$ 43,510
Land Initial Cost	121,945
Building and Improvements Initial Cost	237,795
Adjustments and Costs to Land and Building Subsequent to Acquisition	38,200
Gross carrying amount - Land	122,679
Gross carrying amount - Building and improvements	275,261
Gross carrying amount - Total	397,940
Accumulated Depreciation	$ 67,681
Self storage facilities | OH
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	17
Debt	$ 33,744
Land Initial Cost	17,788
Building and Improvements Initial Cost	50,493
Adjustments and Costs to Land and Building Subsequent to Acquisition	8,043
Gross carrying amount - Land	17,787
Gross carrying amount - Building and improvements	58,537
Gross carrying amount - Total	76,324
Accumulated Depreciation	$ 15,166
Self storage facilities | OR
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	6
Debt	$ 29,642
Land Initial Cost	7,906
Building and Improvements Initial Cost	39,576
Adjustments and Costs to Land and Building Subsequent to Acquisition	2,094
Gross carrying amount - Land	7,906
Gross carrying amount - Building and improvements	41,670
Gross carrying amount - Total	49,576
Accumulated Depreciation	$ 8,729
Self storage facilities | PA
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	19
Debt	$ 34,051
Land Initial Cost	25,518
Building and Improvements Initial Cost	155,095
Adjustments and Costs to Land and Building Subsequent to Acquisition	13,573
Gross carrying amount - Land	24,810
Gross carrying amount - Building and improvements	169,376
Gross carrying amount - Total	194,186
Accumulated Depreciation	$ 29,247
Self storage facilities | RI
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	2
Debt	$ 11,621
Land Initial Cost	3,191
Building and Improvements Initial Cost	6,926
Adjustments and Costs to Land and Building Subsequent to Acquisition	1,333
Gross carrying amount - Land	3,191
Gross carrying amount - Building and improvements	8,259
Gross carrying amount - Total	11,450
Accumulated Depreciation	$ 3,210
Self storage facilities | SC
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	24
Debt	$ 34,036
Land Initial Cost	38,684
Building and Improvements Initial Cost	143,826
Adjustments and Costs to Land and Building Subsequent to Acquisition	11,228
Gross carrying amount - Land	38,685
Gross carrying amount - Building and improvements	155,053
Gross carrying amount - Total	193,738
Accumulated Depreciation	$ 27,087
Self storage facilities | TN
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	20
Debt	$ 46,809
Land Initial Cost	29,806
Building and Improvements Initial Cost	125,653
Adjustments and Costs to Land and Building Subsequent to Acquisition	9,950
Gross carrying amount - Land	29,806
Gross carrying amount - Building and improvements	135,603
Gross carrying amount - Total	165,409
Accumulated Depreciation	$ 21,279
Self storage facilities | TX
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	102
Debt	$ 195,522
Land Initial Cost	171,687
Building and Improvements Initial Cost	666,970
Adjustments and Costs to Land and Building Subsequent to Acquisition	65,514
Gross carrying amount - Land	171,539
Gross carrying amount - Building and improvements	732,632
Gross carrying amount - Total	904,171
Accumulated Depreciation	$ 133,990
Self storage facilities | UT
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	10
Debt	$ 23,225
Land Initial Cost	9,008
Building and Improvements Initial Cost	39,295
Adjustments and Costs to Land and Building Subsequent to Acquisition	2,634
Gross carrying amount - Land	9,008
Gross carrying amount - Building and improvements	41,929
Gross carrying amount - Total	50,937
Accumulated Depreciation	$ 11,201
Self storage facilities | VA
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	46
Debt	$ 162,806
Land Initial Cost	139,318
Building and Improvements Initial Cost	414,335
Adjustments and Costs to Land and Building Subsequent to Acquisition	22,410
Gross carrying amount - Land	139,319
Gross carrying amount - Building and improvements	436,744
Gross carrying amount - Total	576,063
Accumulated Depreciation	$ 81,436
Self storage facilities | DC
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	8
Debt	$ 19,936
Land Initial Cost	12,528
Building and Improvements Initial Cost	47,645
Adjustments and Costs to Land and Building Subsequent to Acquisition	3,403
Gross carrying amount - Land	12,530
Gross carrying amount - Building and improvements	51,046
Gross carrying amount - Total	63,576
Accumulated Depreciation	$ 12,843
Self storage facilities | DC
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Store Count | store	1
Debt	$ 8,475
Land Initial Cost	14,394
Building and Improvements Initial Cost	18,172
Adjustments and Costs to Land and Building Subsequent to Acquisition	462
Gross carrying amount - Land	14,394
Gross carrying amount - Building and improvements	18,634
Gross carrying amount - Total	33,028
Accumulated Depreciation	2,344
Other corporate assets
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Debt	0
Land Initial Cost	0
Building and Improvements Initial Cost	656
Adjustments and Costs to Land and Building Subsequent to Acquisition	163,815
Gross carrying amount - Land	0
Gross carrying amount - Building and improvements	164,471
Gross carrying amount - Total	164,471
Accumulated Depreciation	48,232
Intangible tenant relationships and lease rights
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Debt	0
Land Initial Cost	0
Building and Improvements Initial Cost	134,932
Adjustments and Costs to Land and Building Subsequent to Acquisition	2,206
Gross carrying amount - Land	0
Gross carrying amount - Building and improvements	137,138
Gross carrying amount - Total	137,138
Accumulated Depreciation	129,385
Construction in Progress/Undeveloped Land
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Debt	0
Land Initial Cost	5,447
Building and Improvements Initial Cost	0
Adjustments and Costs to Land and Building Subsequent to Acquisition	65,368
Gross carrying amount - Land	3,372
Gross carrying amount - Building and improvements	67,443
Gross carrying amount - Total	70,815
Accumulated Depreciation	0
Right of use asset - finance lease
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Debt	0
Land Initial Cost	0
Building and Improvements Initial Cost	0
Adjustments and Costs to Land and Building Subsequent to Acquisition	58,145
Gross carrying amount - Land	0
Gross carrying amount - Building and improvements	58,145
Gross carrying amount - Total	58,145
Accumulated Depreciation	$ 566

Schedule III - Real Estate an_3

Schedule III - Real Estate and Accumulated Depreciation - Activity in Real Estate Facilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Real estate, gross:
Balance at end of year	$ 9,575,231
Accumulated depreciation:
Balance at end of year	1,681,429
Net real estate assets:
Net non-lease real estate assets	7,893,802	$ 7,696,864	$ 7,491,831
Aggregate cost of real estate for U.S. federal income tax purposes	7,817,038
Operating facilities
Real estate, gross:
Balance at beginning of year	9,129,558	8,709,315	8,158,741
Acquisitions	255,235	303,588	459,223
Improvements	66,693	68,459	64,336
Transfers from construction in progress (to operating facilities)	40,988	59,614	49,449
Dispositions and other	15,314	(11,418)	(22,434)
Balance at end of year	9,507,788	9,129,558	8,709,315
Accumulated depreciation:
Balance at beginning of year	1,473,851	1,262,438	1,060,060
Depreciation expense	217,364	212,202	203,030
Dispositions and other	(9,786)	(789)	(652)
Balance at end of year	1,681,429	1,473,851	1,262,438
Real estate under development/redevelopment
Real estate, gross:
Balance at beginning of year	41,157	44,954	33,750
Current development	67,274	55,817	60,677
Transfers from construction in progress (to operating facilities)	(40,988)	(59,614)	(49,449)
Dispositions and other	0	0	(24)
Balance at end of year	67,443	$ 41,157	$ 44,954
Right of use asset - finance lease
Real estate, gross:
Balance at end of year	58,145
Accumulated depreciation:
Balance at end of year	$ 566