Extra Space Storage (EXR) 10-Q 5 Nov 19 2019 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2019	Oct. 30, 2019
Cover page.
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-32269
Entity Registrant Name	EXTRA SPACE STORAGE INC.
Entity Central Index Key	0001289490
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	20-1076777
Entity Address, Address Line One	2795 East Cottonwood Parkway, Suite 300
Entity Address, City or Town	Salt Lake City
Entity Address, State or Province	UT
Entity Address, Postal Zip Code	84121
City Area Code	801
Local Phone Number	365-4600
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	EXR
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		129,510,514

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets:
Real estate assets, net	$ 7,665,567	$ 7,491,831
Real estate assets - operating lease right-of-use assets	269,318
Investments in unconsolidated real estate ventures	175,442	125,326
Cash and cash equivalents	62,277	57,496
Restricted cash	4,438	15,194
Other assets, net	141,388	158,131
Total assets	8,318,430	7,847,978
Liabilities, Noncontrolling Interests and Equity:
Notes payable, net	4,085,295	4,137,213
Exchangeable senior notes, net	567,705	562,374
Notes payable to trusts	0	30,928
Revolving lines of credit	159,000	81,000
Operating lease liabilities	279,049
Cash distributions in unconsolidated real estate ventures	45,143	45,197
Accounts payable and accrued expenses	122,658	101,461
Other liabilities	151,591	104,383
Total liabilities	5,410,441	5,062,556
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, 129,410,093 and 127,103,750 shares issued and outstanding at September 30, 2019 and December 31, 2018, respectively	1,294	1,271
Additional paid-in capital	2,861,611	2,640,705
Accumulated other comprehensive income (loss)	(43,439)	34,650
Accumulated deficit	(296,752)	(262,902)
Total Extra Space Storage Inc. stockholders' equity	2,522,714	2,413,724
Noncontrolling interest represented by Preferred Operating Partnership units, net	175,918	153,096
Noncontrolling interests in Operating Partnership, net and other noncontrolling interests	209,357	218,602
Total noncontrolling interests and equity	2,907,989	2,785,422
Total liabilities, noncontrolling interests and equity	$ 8,318,430	$ 7,847,978

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in 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 (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	500,000,000	500,000,000
Common stock, issued (in shares)	129,410,093	127,103,750
Common stock, outstanding (in shares)	129,410,093	127,103,750

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Property rental	$ 290,917	$ 266,728	$ 841,504	$ 772,742
Tenant reinsurance	33,588	30,105	95,086	85,660
Management fees and other income	13,000	10,120	36,063	30,849
Total revenues	337,505	306,953	972,653	889,251
Expenses:
Property operations	88,653	73,652	248,288	219,488
Tenant reinsurance	7,644	7,720	21,593	18,798
General and administrative	22,519	19,707	68,548	62,822
Depreciation and amortization	56,051	52,283	165,116	155,924
Total expenses	174,867	153,362	503,545	457,032
Gain on real estate transactions	0	30,807	1,205	30,807
Income from operations	162,638	184,398	470,313	463,026
Interest expense	(46,908)	(45,926)	(141,716)	(130,239)
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	(1,186)	(1,140)	(3,533)	(3,525)
Interest income	2,799	1,371	5,905	3,997
Income before equity in earnings of unconsolidated real estate ventures and income tax expense	117,343	138,703	330,969	333,259
Equity in earnings of unconsolidated real estate ventures	2,704	3,622	8,455	10,648
Income tax expense	(4,052)	(2,638)	(8,580)	(6,077)
Net income	115,995	139,687	330,844	337,830
Net income allocated to Preferred Operating Partnership noncontrolling interests	(3,088)	(3,723)	(9,379)	(10,605)
Net income allocated to Operating Partnership and other noncontrolling interests	(4,820)	(5,546)	(13,780)	(13,398)
Net income attributable to common stockholders	$ 108,087	$ 130,418	$ 307,685	$ 313,827
Earnings per common share
Basic (in dollars per share)	$ 0.84	$ 1.03	$ 2.40	$ 2.49
Diluted (in dollars per share)	$ 0.83	$ 1.02	$ 2.37	$ 2.48
Weighted average number of shares
Basic (in shares)	128,776,549	126,466,837	127,830,272	125,959,926
Diluted (in shares)	137,318,475	134,240,290	136,164,299	133,015,690
Cash dividends paid per common share (in dollars per share)	$ 0.90	$ 0.86	$ 2.66	$ 2.50

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 115,995	$ 139,687	$ 330,844	$ 337,830
Other comprehensive income (loss):
Change in fair value of interest rate swaps	(16,762)	5,716	(82,057)	36,812
Total comprehensive income	99,233	145,403	248,787	374,642
Less: comprehensive income attributable to noncontrolling interests	7,109	9,553	19,191	25,743
Comprehensive income attributable to common stockholders	$ 92,124	$ 135,850	$ 229,596	$ 348,899

Condensed Consolidated Statem_3

Condensed Consolidated Statement of Noncontrolling Interests and Equity - USD ($) $ in Thousands	Total	Redemption of Operating Partnership units for cash	Preferred Operating Partnership	Operating Partnership	Operating PartnershipRedemption of Operating Partnership units for cash	Operating PartnershipRedemption of Operating Partnership units for stock	Other	Common Stock	Common StockRedemption of Operating Partnership units for stock	Additional Paid-in Capital	Additional Paid-in CapitalRedemption of Operating Partnership units for cash	Additional Paid-in CapitalRedemption of Operating Partnership units for stock	Accumulated Other Comprehensive Income	Accumulated Deficit
Balance, beginning of period (in shares) at Dec. 31, 2017								126,007,091
Balance, beginning of period at Dec. 31, 2017	$ 2,723,807		$ 159,636	$ 213,301			$ 119	$ 1,260		$ 2,569,485			$ 33,290	$ (253,284)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)								31,525
Issuance of common stock upon the exercise of options	799									799
Restricted stock grants issued (in shares)								31,136
Restricted stock grants canceled (in shares)								(770)
Compensation expense related to stock-based awards	2,726									2,726
Repayment of receivable for preferred operating units pledged as collateral on loan	495		495
Redemption of Operating Partnership units		$ (2,558)			$ (1,126)						$ (1,432)
Repurchase of equity portion of exchangeable senior notes	(21,000)									(21,000)
Noncontrolling interest in consolidated joint venture	122						122
Net income	95,430		3,390	3,784										88,256
Other comprehensive income (loss)	23,063		144	938									21,981
Distributions to Operating Partnership units held by noncontrolling interests	(7,909)		(3,488)	(4,421)
Dividends paid on common stock	(98,327)													(98,327)
Balance, end of period (in shares) at Mar. 31, 2018								126,068,982
Balance, end of period at Mar. 31, 2018	2,716,648		160,177	212,476			241	$ 1,260		2,550,578			55,271	(263,355)
Balance, beginning of period (in shares) at Dec. 31, 2017								126,007,091
Balance, beginning of period at Dec. 31, 2017	2,723,807		159,636	213,301			119	$ 1,260		2,569,485			33,290	(253,284)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	337,830
Balance, end of period (in shares) at Sep. 30, 2018								126,504,802
Balance, end of period at Sep. 30, 2018	2,770,094		160,250	213,885			240	$ 1,264		2,581,158			68,362	(255,065)
Balance, beginning of period (in shares) at Mar. 31, 2018								126,068,982
Balance, beginning of period at Mar. 31, 2018	2,716,648		160,177	212,476			241	$ 1,260		2,550,578			55,271	(263,355)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)								23,050
Issuance of common stock upon the exercise of options	371							$ 1		370
Restricted stock grants issued (in shares)								50,334
Restricted stock grants canceled (in shares)								(6,311)
Compensation expense related to stock-based awards	3,116									3,116
Redemption of Operating Partnership units (in shares)									10,000
Redemption of Operating Partnership units						$ (383)						$ 383
Issuance of Operating Partnership units in conjunction with acquisitions	1,877			1,877
Net income	102,713		3,492	4,068										95,153
Other comprehensive income (loss)	8,033		50	324									7,659
Distributions to Operating Partnership units held by noncontrolling interests	(8,468)		(3,615)	(4,853)
Dividends paid on common stock	(108,486)													(108,486)
Balance, end of period (in shares) at Jun. 30, 2018								126,146,055
Balance, end of period at Jun. 30, 2018	2,715,804		160,104	213,509			241	$ 1,261		2,554,447			62,930	(276,688)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock grants issued (in shares)								2,794
Restricted stock grants canceled (in shares)								(2,298)
Issuance of common stock, net of offering costs (in shares)								343,251
Issuance of common stock, net of offering costs	33,780							$ 3		33,777
Compensation expense related to stock-based awards	2,613									2,613
Redemption of Operating Partnership units (in shares)									15,000
Redemption of Operating Partnership units						(572)						572
Repurchase of equity portion of exchangeable senior notes	10,251									10,251
Net income	139,687		3,723	5,547			(1)							130,418
Other comprehensive income (loss)	5,716		39	245									5,432
Distributions to Operating Partnership units held by noncontrolling interests	(8,460)		(3,616)	(4,844)
Dividends paid on common stock	(108,795)													(108,795)
Balance, end of period (in shares) at Sep. 30, 2018								126,504,802
Balance, end of period at Sep. 30, 2018	$ 2,770,094		160,250	213,885			240	$ 1,264		2,581,158			68,362	(255,065)
Balance, beginning of period (in shares) at Dec. 31, 2018	127,103,750							127,103,750
Balance, beginning of period at Dec. 31, 2018	$ 2,785,422		153,096	218,362			240	$ 1,271		2,640,705			34,650	(262,902)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)								169,021
Issuance of common stock upon the exercise of options	1,757							$ 3		1,754
Restricted stock grants issued (in shares)								35,022
Restricted stock grants canceled (in shares)								(1,244)
Compensation expense related to stock-based awards	2,954									2,954
Redemption of Operating Partnership units (in shares)									85,501
Redemption of Operating Partnership units						(3,310)						3,310
Issuance of Operating Partnership units in conjunction with acquisitions	23,447		23,447
Net income	102,160		3,164	4,235			(9)							94,770
Other comprehensive income (loss)	(23,993)		(147)	(1,003)									(22,843)
Distributions to Operating Partnership units held by noncontrolling interests	(8,412)		(3,296)	(5,116)
Dividends paid on common stock	(109,523)													(109,523)
Balance, end of period (in shares) at Mar. 31, 2019								127,392,050
Balance, end of period at Mar. 31, 2019	$ 2,773,812		176,264	213,168			231	$ 1,274		2,648,723			11,807	(277,655)
Balance, beginning of period (in shares) at Dec. 31, 2018	127,103,750							127,103,750
Balance, beginning of period at Dec. 31, 2018	$ 2,785,422		153,096	218,362			240	$ 1,271		2,640,705			34,650	(262,902)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 330,844
Balance, end of period (in shares) at Sep. 30, 2019	129,410,093							129,410,093
Balance, end of period at Sep. 30, 2019	$ 2,907,989		175,918	209,011			346	$ 1,294		2,861,611			(43,439)	(296,752)
Balance, beginning of period (in shares) at Mar. 31, 2019								127,392,050
Balance, beginning of period at Mar. 31, 2019	2,773,812		176,264	213,168			231	$ 1,274		2,648,723			11,807	(277,655)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)								17,042
Issuance of common stock upon the exercise of options	468									468
Restricted stock grants issued (in shares)								53,789
Restricted stock grants issued	2							$ 2
Restricted stock grants canceled (in shares)								(4,786)
Issuance of common stock, net of offering costs (in shares)								930,000
Issuance of common stock, net of offering costs	98,796							$ 9		98,787
Compensation expense related to stock-based awards	3,998									3,998
Redemption of Operating Partnership units (in shares)									125,000
Redemption of Operating Partnership units						(4,823)						4,823
Issuance of Operating Partnership units in conjunction with acquisitions	4,575		4,575
Noncontrolling interest in consolidated joint venture	50						50
Conversion of Preferred C Units in the Operating Partnership for Common Operating Partnership Units			(4,374)	4,374
Net income	112,689		3,129	4,754			(22)							104,828
Other comprehensive income (loss)	(41,302)		(254)	(1,765)									(39,283)
Distributions to Operating Partnership units held by noncontrolling interests	(8,705)		(3,232)	(5,473)
Dividends paid on common stock	(115,572)													(115,572)
Balance, end of period (in shares) at Jun. 30, 2019								128,513,095
Balance, end of period at Jun. 30, 2019	2,828,811		176,108	210,235			259	$ 1,285		2,756,799			(27,476)	(288,399)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)								14,850
Issuance of common stock upon the exercise of options	605									605
Restricted stock grants issued (in shares)								5,099
Restricted stock grants issued	0							$ 0
Restricted stock grants canceled (in shares)								(1,269)
Issuance of common stock, net of offering costs (in shares)								849,200
Issuance of common stock, net of offering costs	100,056							$ 9		100,047
Compensation expense related to stock-based awards	3,035									3,035
Repayment of receivable for preferred operating units pledged as collateral on loan	1,211			1,211
Redemption of Operating Partnership units (in shares)									29,118
Redemption of Operating Partnership units						$ (1,125)						$ 1,125
Noncontrolling interest in consolidated joint venture	96						96
Net income	115,995		3,089	4,828			(9)							108,087
Other comprehensive income (loss)	(16,762)		(101)	(698)									(15,963)
Distributions to Operating Partnership units held by noncontrolling interests	(8,618)		(3,178)	(5,440)
Dividends paid on common stock	$ (116,440)													(116,440)
Balance, end of period (in shares) at Sep. 30, 2019	129,410,093							129,410,093
Balance, end of period at Sep. 30, 2019	$ 2,907,989		$ 175,918	$ 209,011			$ 346	$ 1,294		$ 2,861,611			$ (43,439)	$ (296,752)

Condensed Consolidated Statem_4

Condensed Consolidated Statement of Noncontrolling Interests and Equity (Parenthetical) - $ / shares	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Stockholders' Equity [Abstract]
Dividends paid on common stock (in dollars per share)	$ 0.90	$ 0.90	$ 0.86	$ 0.86	$ 0.86	$ 0.78	$ 2.66	$ 2.50

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 115,995	$ 102,160	$ 139,687	$ 95,430	$ 330,844	$ 337,830
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	56,051		52,283		165,116	155,924
Amortization of deferred financing costs					8,912	9,230
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes					3,533	3,525
Compensation expense related to stock-based awards					9,987	8,455
Gain on real estate transactions					(1,205)	(30,807)
Distributions from unconsolidated real estate ventures in excess of earnings					4,752	5,235
Changes in operating assets and liabilities:
Other assets					(11,153)	(639)
Accounts payable and accrued expenses					29,310	27,677
Other liabilities					4,370	12,597
Net cash provided by operating activities					544,466	529,027
Cash flows from investing activities:
Acquisition of real estate assets					(287,114)	(327,011)
Development and redevelopment of real estate assets					(34,413)	(45,376)
Proceeds from sale of real estate assets, investments in real estate ventures and other assets					11,254	51,889
Investment in unconsolidated real estate ventures					(33,661)	(52,806)
Return of investment in unconsolidated real estate ventures					3,982	47,964
Issuance of notes receivable					(162,677)	(13,889)
Principal payments received from notes receivable					151,211	25,226
Purchase of equipment and fixtures					(4,959)	(3,026)
Net cash used in investing activities					(356,377)	(317,029)
Cash flows from financing activities:
Proceeds from the sale of common stock, net of offering costs					198,852	33,780
Proceeds from notes payable and revolving lines of credit					1,508,000	973,386
Principal payments on notes payable and revolving lines of credit					(1,503,686)	(787,939)
Principal payments on notes payable to trusts					(30,928)	(21,650)
Deferred financing costs					(2,008)	(7,055)
Repurchase of exchangeable senior notes					0	(80,270)
Net proceeds from exercise of stock options					2,830	1,170
Redemption of Operating Partnership units held by noncontrolling interests					0	(2,558)
Contributions from noncontrolling interests					146	122
Dividends paid on common stock					(341,535)	(315,608)
Distributions to noncontrolling interests					(25,735)	(24,837)
Net cash used in financing activities					(194,064)	(231,459)
Net decrease in cash, cash equivalents, and restricted cash					(5,975)	(19,461)
Cash, cash equivalents, and restricted cash, beginning of the period		72,690		86,044	72,690	86,044	$ 86,044
Cash, cash equivalents, and restricted cash, end of the period	66,715		66,583		66,715	66,583	$ 72,690
Supplemental schedule of cash flow information
Interest paid					136,563	117,627
Income taxes paid					6,197	803
Redemption of Operating Partnership units held by noncontrolling interests for common stock
Common stock and paid-in capital					9,258	955
Establishment of operating lease right of use assets and lease liabilities
Real estate assets - operating lease right-of-use assets	52,413				277,430
Operating lease liabilities					(286,787)
Accounts payable and accrued expenses					9,357
Acquisitions of real estate assets
Real estate assets, net	16,937	223,740	74,694	70,787	249,101	382,765
Notes payable assumed	0	(17,157)	0	0	(17,157)	(87,500)
Investment in unconsolidated real estate ventures	$ 0	$ 2,780	$ 0	$ 489	2,780	(535)
Accrued construction costs and capital expenditures
Acquisition of real estate assets					1,292	275
Accounts payable and accrued expenses					(1,292)	(275)
Conversion of Preferred OP Units to common OP Units
Preferred OP Units					4,374	0
Common OP Units					(4,374)	0
Redemption of Operating Partnership units held by noncontrolling interests for common stock
Redemption of Operating Partnership units held by noncontrolling interests for common stock
Noncontrolling interests in Operating Partnership					(9,258)	(955)
Acquisitions of real estate assets
Acquisitions of real estate assets
Real estate assets, net					19,937	88,842
Value of Operating Partnership units issued					0	(1,877)
Notes payable assumed					(17,157)	(87,500)
Investment in unconsolidated real estate ventures					(2,780)	535
Contribution of Preferred OP Units to unconsolidated real estate venture
Contribution of Preferred OP Units to unconsolidated real estate venture
Investments in unconsolidated real estate ventures					(28,022)	0
Value of Preferred Operating Partnership units issued					$ 28,022	$ 0

Organization

Organization	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	ORGANIZATION Extra Space Storage Inc. (the “Company”) is a fully integrated, self-administered and self-managed real estate investment trust (“REIT”), formed as a Maryland corporation on April 30, 2004, to own, operate, manage, acquire, develop and redevelop professionally managed self-storage properties ("stores") located throughout the United States. The Company 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 September 30, 2019 , the Company had direct and indirect equity interests in 1,167 stores. In addition, the Company managed 630 stores for third parties, bringing the total number of stores which it owns and/or manages to 1,797 . 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.

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	BASIS OF PRESENTATION The accompanying unaudited condensed consolidated financial statements of the Company are presented on the accrual basis of accounting in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information, and in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they may not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (including normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three and nine months ended September 30, 2019 are not necessarily indicative of results that may be expected for the year ending December 31, 2019 . The condensed consolidated balance sheet as of December 31, 2018 has been derived from the Company’s audited financial statements as of that date, but does not include all of the information and footnotes required by GAAP for complete financial statements. For further information refer to the consolidated financial statements and footnotes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 , as filed with the Securities and Exchange Commission. Recently Issued Accounting Standards In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("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. Lease obligations are measured at their present value and accounted for using the effective interest method. The accounting for the leased asset differs slightly depending on whether the agreement is deemed to be a financing or operating lease. For financing leases, the leased asset is depreciated on a straight-line basis and is recorded separately from the interest expense in the statements of operations, resulting in higher expense in the earlier part of the lease term. For operating leases, the depreciation and interest expense components are combined, recognized evenly over the term of the lease, and presented as a reduction to operating income. ASU 2016-02 requires that assets and liabilities be presented or disclosed separately, and requires additional disclosure of certain qualitative and quantitative information related to these lease agreements. ASU 2016-02 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 the standard that removed the requirement to separate lease and nonlease components. The Company did not record a significant cumulative catch-up adjustment to retained earnings upon adoption of ASU 2016-02. The primary impact was related to the Company's 21 operating ground leases and two corporate facility leases under which it served as lessee at the time of adoption. The Company recognized lease liabilities of $104,863 and right-of-use assets related to operating leases totaling $95,506 as of the adoption date. Refer to footnote 13 for further discussion of the Company's leases. In August 2018, the FASB issued ASU 2018-15, "Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract." ASU 2018-15 amends the accounting for implementation costs incurred in a hosting arrangement that is a service contract, and aligns them with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. ASU 2018-15 also requires that entities amortize the capitalized implementation costs over the term of the hosting arrangement. ASU 2018-15 is effective for annual periods beginning after December 15, 2020, with early adoption permitted, including early adoption in any interim period. The Company adopted this standard on a prospective basis as of October 1, 2018. The adoption of this standard did not have a material impact on the Company's financial statements. 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 will be effective for the Company on January 1, 2020. The Company is evaluating the impact this new standard will have and does not expect this new standard to have a material impact on the Company's consolidated financial statements.

Fair Value Disclosures

Fair Value Disclosures	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Disclosures	FAIR VALUE DISCLOSURES Derivative Financial Instruments Currently, the Company uses interest rate swaps to manage its interest rate risk. The valuation of these instruments is determined using widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves. The fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash payments and the discounted expected variable cash receipts. The variable cash receipts are based on an expectation of future interest rates (forward curves) derived from observable market interest rate forward curves. The Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts and guarantees. In conjunction with the FASB’s fair value measurement guidance, the Company made an accounting policy election to measure the credit risk of its derivative financial instruments that are subject to master netting agreements on a net basis by counterparty portfolio. Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by the Company and its counterparties. However, as of September 30, 2019 , the Company assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and determined that the credit valuation adjustments were not significant to the overall valuation of its derivatives. As a result, the Company has determined that its derivative valuations in their entirety were classified in Level 2 of the fair value hierarchy. The table below presents the Company’s assets and liabilities measured at fair value on a recurring basis as of September 30, 2019 , aggregated by the level in the fair value hierarchy within which those measurements fall. Fair Value Measurements at Reporting Date Using Description Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other assets - Cash flow hedge swap agreements $ — $ 3,141 $ — Other liabilities - Cash flow hedge swap agreements $ — $ 43,880 $ — The Company did not have any significant assets or liabilities that are re-measured on a recurring basis using significant unobservable inputs as of September 30, 2019 or December 31, 2018 . Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Long-lived assets held for use are evaluated for impairment when events or circumstances indicate there may be impairment. The Company reviews each store at least annually to determine if any such events or circumstances have occurred or exist. The Company focuses on stores where occupancy and/or rental income have decreased by a significant amount. For these stores, the Company determines whether the decrease is temporary or permanent, and whether the store will likely recover the lost occupancy and/or revenue in the short term. In addition, the Company reviews stores in the lease-up stage and compares actual operating results to original projections. When the Company determines that an event that may indicate impairment has occurred, the Company compares the carrying value of the related long-lived assets to the undiscounted future net operating cash flows attributable to the assets. An impairment loss is recorded if the net carrying value of the assets exceeds the undiscounted future net operating cash flows attributable to the assets. The impairment loss recognized equals the excess of net carrying value over the related fair value of the assets. When real estate assets are identified by management as held for sale, the Company discontinues depreciating the assets and estimates the fair value of the assets, net of selling costs. If the estimated fair value, net of selling costs, of the assets that have been identified as held for sale is less than the net carrying value of the assets, the Company would recognize an impairment loss on the assets held for sale. The operations of assets held for sale or sold during the period are presented as part of normal operations for all periods presented. As of September 30, 2019 , the Company had one parcel of land classified as held for sale which is included in real estate assets, net. The estimated fair value less selling costs for this asset is greater than the carrying value of the asset, and therefore no loss has been recorded. The Company assesses annually whether there are any indicators that the value of the Company’s investments in unconsolidated real estate ventures may be impaired annually and when events or circumstances indicate that there may be impairment. An investment is impaired if management’s estimate of the fair value of the investment is less than its carrying value. To the extent impairment has occurred, and is considered to be other than temporary, the loss is measured as the excess of the carrying amount of the investment over the fair value of the investment. In connection with the Company’s acquisition of stores, the purchase price is allocated to the tangible and intangible assets and liabilities acquired based on their relative fair values, which are estimated using significant unobservable inputs. The value of the tangible assets, consisting of land and buildings, is determined as if vacant. Intangible assets, which represent the value of existing tenant relationships, are recorded at their fair values based on the avoided cost to replace the current leases. The Company measures the value of tenant relationships based on the rent lost due to the amount of time required to replace existing customers, which is based on the Company’s historical experience with turnover in its stores. Any debt assumed as part of an acquisition is recorded at fair value based on current interest rates compared to contractual rates. Acquisition-related transaction costs are capitalized as part of the purchase price. Fair Value of Financial Instruments The carrying values of cash and cash equivalents, restricted cash, receivables, other financial instruments included in other assets, accounts payable and accrued expenses, variable-rate notes payable, lines of credit and other liabilities reflected in the condensed consolidated balance sheets at September 30, 2019 and December 31, 2018 approximate fair value. 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, insurance and capital expenditures. The fair values of the Company’s notes receivable from Preferred and Common Operating Partnership unit holders, were based on the discounted estimated future cash flows of the notes (categorized within Level 3 of the fair value hierarchy); the discount rate used approximated the current market rate for loans with similar maturities and credit quality. The fair values of the Company’s fixed-rate notes payable and notes payable to trusts were estimated using the discounted estimated future cash payments to be made on such debt (categorized within Level 3 of the fair value hierarchy); the discount rates used approximated current market rates for loans, or groups of loans, with similar maturities and credit quality. The fair value of the Company’s exchangeable senior notes was estimated using an average market price for similar securities obtained from a third party. The fair values of the Company’s fixed-rate assets and liabilities were as follows for the periods indicated: September 30, 2019 December 31, 2018 Fair Carrying Fair Carrying Notes receivable from Preferred and Common Operating Partnership unit holders $ 118,756 $ 118,524 $ 115,467 $ 119,735 Fixed rate notes payable and notes payable to trusts $ 3,296,231 $ 3,166,208 $ 2,985,731 $ 3,022,414 Exchangeable senior notes $ 724,500 $ 575,000 $ 620,149 $ 575,000

Earnings Per Common Share

Earnings Per Common Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings Per Common Share	EARNINGS PER COMMON SHARE Basic earnings per common share is computed using the two-class method by dividing net income attributable to common stockholders by the weighted average number of common shares outstanding during the period. All outstanding unvested restricted stock awards contain rights to non-forfeitable dividends and participate in undistributed earnings with common stockholders; accordingly, they are considered participating securities that are included in the two-class method. Diluted earnings per common share measures the performance of the Company over the reporting period while giving effect to all potential common shares that were dilutive and outstanding during the period. The denominator includes the weighted average number of basic shares and the number of additional common shares that would have been outstanding if the potential common shares that were dilutive had been issued, and is calculated using either the two-class, treasury stock or as if-converted method, whichever is most dilutive. Potential common shares are securities (such as options, convertible debt, Series A Participating Redeemable Preferred Units (“Series A Units”), Series B Redeemable Preferred Units (“Series B Units”), Series C Convertible Redeemable Preferred Units (“Series C Units”), Series D Redeemable Preferred Units (“Series D Units” and, 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 (i.e. those that reduce earnings per common share) are included. For the three and nine months ended September 30, 2019 , and for the three months ended September 30, 2018 , there were no anti-dilutive options. For the nine months ended September 30, 2018 , options to purchase an aggregate of approximately 36,404 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 Operating Partnership units for common shares upon redemption, where the Company has the option to redeem in cash or shares and where the Company has stated the intent and ability to settle the redemption in shares, the Company divided the total value of the Preferred Operating Partnership units by the average share price for the period presented. The average share price for the three months ended September 30, 2019 and 2018 was $115.63 and $92.83 , respectively. The average share price for the nine months ended September 30, 2019 and 2018 was $105.74 and $90.09 , respectively. The following table presents the number of Preferred Operating Partnership units, and the potential common shares, that were excluded from the computation of earnings per share as their effect would have been anti-dilutive. For the Three Months Ended September 30, For the Nine Months Ended September 30, 2019 2018 2019 2018 Equivalent Shares (if converted) Equivalent Shares (if converted) Equivalent Shares (if converted) Equivalent Shares (if converted) Series B Units 362,382 451,386 396,276 465,115 Series C Units (1) — 319,283 — 328,994 Series D Units 1,038,538 — 1,074,417 1,021,901 1,400,920 770,669 1,470,693 1,816,010 (1) The remainder of the Series C Units were converted to OP Units on April 25, 2019. In July 2018, the Operating Partnership redeemed the remaining balance of its 2.375% Exchangeable Senior Notes due 2033 (the “2013 Notes”). Prior to their redemption, the 2013 Notes could potentially have had a dilutive impact on the Company’s earnings per share calculations. The 2013 Notes were exchangeable by holders into shares of the Company’s common stock under certain circumstances per the terms of the indenture governing the 2013 Notes. The Company had irrevocably agreed to pay only cash for the accreted principal amount of the 2013 Notes relative to its exchange obligations, but retained the right to satisfy the exchange obligation in excess of the accreted principal amount in cash and/or common stock. The Operating Partnership had $575,000 of its 3.125% Exchangeable Senior Notes due 2035 (the “2015 Notes”) issued and outstanding as of September 30, 2019 . The 2015 Notes could potentially have a dilutive impact on the Company’s earnings per share calculations. The 2015 Notes are exchangeable by holders into shares of the Company’s common stock under certain circumstances per the terms of the indenture governing the 2015 Notes. The exchange price of the 2015 Notes was $92.04 per share as of September 30, 2019 , and could change over time as described in the indenture. The Company has irrevocably agreed to pay only cash for the accreted principal amount of the 2015 Notes relative to its exchange obligations, but retained the right to satisfy the exchange obligation in excess of the accreted principal amount in cash and/or common stock. Although the Company has retained the right to satisfy the exchange obligation in excess of the accreted principal amount of the 2013 Notes and 2015 Notes in cash and/or common stock, Accounting Standards Codification (“ASC”) 260, “Earnings per Share,” requires an assumption that shares would be used to pay the exchange obligation in excess of the accreted principal amount, and requires that those shares be included in the Company’s calculation of weighted average common shares outstanding for the diluted earnings per share computation. For the three and nine months ended September 30, 2019 and 2018 , zero shares related to the 2013 Notes were included in the computation for diluted earnings per share, as the Company had repaid all outstanding 2013 Notes in July 2018. For the three and nine months ended September 30, 2019 and 2018 , 1,274,675 and zero shares, respectively, related to the 2015 Notes were included in the computation for diluted earnings per share. For the purposes of computing the diluted impact on earnings per share of the potential exchange of Series A Units for common shares upon redemption, where the Company has the option to redeem in cash or shares and where the Company has stated the positive intent and ability to settle at least $101,700 of the instrument in cash (or net settle a portion of the Series A Units against the related outstanding note receivable), only the amount of the instrument in excess of $101,700 is considered in the calculation of shares contingently issuable for the purposes of computing diluted earnings per share as allowed by ASC 260-10-45-46. Accordingly, the number of shares included in the computation for diluted earnings per share related to the Series A Units is equal to the number of Series A Units outstanding, with no additional shares included related to the fixed $101,700 amount. The computation of earnings per common share is as follows for the periods presented: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2019 2018 2019 2018 Net income attributable to common stockholders $ 108,087 $ 130,418 $ 307,685 $ 313,827 Earnings and dividends allocated to participating securities (165 ) (219 ) (508 ) (550 ) Earnings for basic computations 107,922 130,199 307,177 313,277 Earnings and dividends allocated to participating securities 165 — — 550 Income allocated to noncontrolling interest - Preferred Operating Partnership Units and Operating Partnership Units 6,100 7,336 17,539 17,191 Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units) (572 ) (572 ) (1,716 ) (1,716 ) Net income for diluted computations $ 113,615 $ 136,963 $ 323,000 $ 329,302 Weighted average common shares outstanding: Average number of common shares outstanding - basic 128,776,549 126,466,837 127,830,272 125,959,926 OP Units 6,050,028 5,636,845 6,032,656 5,650,599 Series A Units 875,480 875,480 875,480 875,480 Series D Units — 991,738 — — Unvested restricted stock awards included for treasury stock method 209,963 — — 250,630 Shares related to exchangeable senior notes and dilutive stock options 1,406,455 269,390 1,425,891 279,055 Average number of common shares outstanding - diluted 137,318,475 134,240,290 136,164,299 133,015,690 Earnings per common share Basic $ 0.84 $ 1.03 $ 2.40 $ 2.49 Diluted $ 0.83 $ 1.02 $ 2.37 $ 2.48

Store Acquisitions and Disposit

Store Acquisitions and Dispositions	9 Months Ended
	Sep. 30, 2019
Real Estate [Abstract]
Store Acquisitions and Dispositions	STORE ACQUISITIONS AND DISPOSITIONS Store Acquisitions The following table shows the Company’s acquisitions of stores for the three and nine months ended September 30, 2019 and 2018 . The table excludes purchases of raw land and improvements made to existing assets. All acquisitions are considered asset acquisitions under ASU 2017-01, " Business Combinations (Topic 805): Clarifying the Definition of a Business ." Consideration Paid Total Quarter Number of Stores Total Cash Paid Loan Assumed Investments in Real Estate Ventures Net Liabilities/ (Assets) Assumed Value of OP Units Issued Number of OP Units Issued Real estate assets Q3 2019 1 $ 16,937 $ 16,941 $ — $ — $ (4 ) $ — — $ 16,937 Q2 2019 1 8,424 8,424 — — — — — 8,424 Q1 2019 14 (1) 223,740 202,890 17,157 2,780 913 — — 223,740 16 $ 249,101 $ 228,255 $ 17,157 $ 2,780 $ 909 $ — — $ 249,101 Q3 2018 6 $ 74,694 $ 71,989 $ — $ — $ 2,705 $ — — $ 74,694 Q2 2018 17 (2) 237,284 148,650 87,500 (1,024 ) 281 1,877 21,768 237,284 Q1 2018 5 (2) 70,787 70,171 — 489 127 — — 70,787 28 $ 382,765 $ 290,810 $ 87,500 $ (535 ) $ 3,113 $ 1,877 21,768 $ 382,765 (1) Store acquisitions during the three months ended March 31, 2019 include the purchase 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. (2) Store acquisitions during the six months ended June 30, 2018 include the acquisition of 15 stores that had been owned by a joint venture in which the Company held a noncontrolling interest. No gain or loss was recognized as a result of these acquisitions. Store Dispositions On April 11, 2019, the Company closed on the sale of 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 closed on the sale of 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 Ventures	9 Months Ended
	Sep. 30, 2019
Equity Method Investments and Joint Ventures [Abstract]
Investments in Unconsolidated Real Estate Ventures	INVESTMENTS IN UNCONSOLIDATED REAL ESTATE VENTURES Investments in unconsolidated real estate ventures represent the Company's noncontrolling interests in properties. The Company accounts for these investments using the equity method of accounting. The Company initially records these investments at cost and subsequently adjusts for cash contributions, distributions and net equity in income or loss, which is allocated in accordance with the provisions of the applicable partnership or joint venture agreement. In these joint ventures, the Company and the joint venture partner generally receive a preferred return on their invested capital. To the extent that cash or profits in excess of these preferred returns are generated through operations or capital transactions, the Company would receive a higher percentage of the excess cash or profits than its equity interest. The Company separately reports investments with net equity less than zero in cash distributions in unconsolidated real estate ventures in the condensed consolidated balance sheets. The net equity of certain joint ventures is less than zero because distributions have exceeded the Company's investment in and share of income from these joint ventures. This is generally the result of financing distributions, capital events or operating distributions that are usually greater than net income, as net income includes non‑cash charges for depreciation and amortization while distributions do not. During May 2019, the Company entered into a new joint venture, ESS-NYFL JV LP with two joint venture partners. The Company contributed a total of $13,936 to this joint venture for the purchase of 11 operating stores and four annex sites and received a 16.0% interest in the joint venture. During the nine months ended September 30, 2019 , the Company contributed a total of $56,799 to its joint ventures for the purchase of 19 operating stores and six stores acquired at the issuance of certificate of occupancy. Net investments in unconsolidated real estate ventures and cash distributions in unconsolidated real estate ventures consist of the following: Number of Stores Equity Ownership % Excess Profit % (1) September 30, December 31, 2019 2018 PRISA Self Storage LLC 85 4% 4% $ 9,182 $ 9,334 Storage Portfolio II JV LLC 36 10% 30% (4,754 ) (4,233 ) Storage Portfolio I LLC 24 34% 49% (38,406 ) (38,129 ) VRS Self Storage, LLC 16 45% 54% 17,560 18,281 ESS-NYFL JV LP 15 16% 24% 13,931 — Extra Space Northern Properties Six LLC 10 10% 35% (1,969 ) (1,700 ) WICNN JV LLC 9 10% 25% 32,428 26,885 Alan Jathoo JV LLC 9 10% 10% 8,021 8,180 ESS Bristol Investments LLC 8 10% 28% 3,065 2,331 GFN JV, LLC 5 10% 25% 12,238 10,586 Extra Space West Two LLC (2) — 5% 40% — 3,818 Extra Space West One LLC (2) — 5% 40% — (1,038 ) Other minority owned stores 25 10-50% 19-50% 79,003 45,814 Net Investments in and Cash distributions in unconsolidated real estate ventures 242 $ 130,299 $ 80,129 (1) Includes pro-rata equity ownership share and promoted interest. (2) In January 2019, the Company purchased its joint venture partners' 95% 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% of the joint ventures and the related stores.

Variable Interests

Variable Interests	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interests	VARIABLE INTERESTS The Operating Partnership had three wholly-owned unconsolidated subsidiaries (“Trust,” “Trust II” and “Trust III,” together, the “Trusts”) that had issued trust preferred securities to third parties and common securities to the Operating Partnership. The proceeds from the sale of the preferred and common securities were loaned in the form of notes to the Operating Partnership. The Trusts were variable interest entities ("VIEs") because the holders of the equity investment at risk (the trust preferred securities) did not have the power to direct the activities of the entities that most significantly affect the entities’ economic performance because of their lack of voting or similar rights. Because the Operating Partnership’s investment in the Trusts’ common securities was financed directly by the Trusts as a result of its loan of the proceeds to the Operating Partnership, that investment 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 cannot be 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 condensed consolidated balance sheets. During the year ended December 31, 2018, the Company repaid a total principal amount of $88,662 , 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 they 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. The Company had no consolidated VIEs during the three and nine months ended September 30, 2019 .

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	DERIVATIVES The Company is exposed to certain risks arising from both its business operations and economic conditions. The Company principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company manages economic risks, including interest rate, liquidity and credit risk, primarily by managing the amount, sources and duration of its debt funding and by using derivative financial instruments. Specifically, the Company enters into derivative financial instruments to manage exposure that arises from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. The Company’s derivative financial instruments are used to manage differences in the amount, timing and duration of the Company’s known or expected cash receipts and its known or expected cash payments principally related to the Company’s investments and borrowings. Cash Flow Hedges of Interest Rate Risk The Company’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish these objectives, the Company primarily uses interest rate swaps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in accumulated other comprehensive income (“OCI”) and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. A portion of these changes is excluded from accumulated other comprehensive income as it is allocated to noncontrolling interests. During the three and nine months ended September 30, 2019 and 2018 , such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt. In the coming 12 months, the Company estimates that $3,296 will be reclassified and increase interest expense. The Company held 25 derivative financial instruments which had a total combined notional amount of $2,402,883 as of September 30, 2019 . Fair Values of Derivative Instruments The table below presents the fair value of the Company’s derivative financial instruments as well as their classification on the condensed consolidated balance sheets: Asset / Liability Derivatives September 30, 2019 December 31, 2018 Derivatives designated as hedging instruments: Fair Value Other assets $ 3,141 $ 42,324 Other liabilities $ 43,880 $ 2,131 Effect of Derivative Instruments The table below presents the effect of the Company’s derivative financial instruments on the condensed consolidated statements of operations for the periods presented. No tax effect has been presented as the derivative instruments are held by the Company: Gain (loss) recognized in OCI For the Three Months Ended September 30, Location of amounts reclassified from OCI into income Gain (loss) reclassified from OCI For the Three Months Ended September 30, Type 2019 2018 2019 2018 Swap Agreements $ (14,517 ) $ 8,325 Interest expense $ 2,992 $ 2,561 Gain (loss) recognized in OCI For the Nine Months Ended September 30, Location of amounts reclassified from OCI into income Gain reclassified from OCI For the Nine Months Ended September 30, Type 2019 2018 2019 2018 Swap Agreements $ (70,387 ) $ 41,610 Interest expense $ 11,792 $ 4,684 Credit-risk-related Contingent Features The Company has agreements with some of its derivative counterparties that contain provisions pursuant to which the Company could be declared in default of its derivative obligations if the Company defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender. The Company also has an agreement with some of its derivative counterparties that incorporates the loan covenant provisions of the Company’s indebtedness with a lender affiliate of the derivative counterparty. Failure to comply with the loan covenant provisions would result in the Company being in default on any derivative instrument obligations covered by the agreement. As of September 30, 2019 , the fair value of derivatives in a net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, related to these agreements was $44,985 . As of September 30, 2019 , the Company had not posted any collateral related to these agreements. If the Company had breached any of these provisions as of September 30, 2019 , it could have been required to cash settle its obligations under the agreements at their termination value of $45,120 , including accrued interest.

Exchangeable Senior Notes

Exchangeable Senior Notes	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Exchangeable Senior Notes	EXCHANGEABLE SENIOR NOTES In September 2015, the Operating Partnership issued $575,000 of its 3.125% Exchangeable Senior Notes due 2035. Costs incurred to issue the 2015 Notes were approximately $11,992 , consisting primarily of a 2.0% underwriting fee. These costs are being amortized as an adjustment to interest expense over five years , which represents the estimated term based on the first available redemption date, and are included in exchangeable senior notes, net, in the condensed consolidated balance sheets. The 2015 Notes are general unsecured senior obligations of the Operating Partnership and are fully guaranteed by the Company. Interest is payable on April 1 and October 1 of each year beginning April 1, 2016, until the maturity date of October 1, 2035. The 2015 Notes bear interest at 3.125% per annum and contain an exchange settlement feature, which provides that the 2015 Notes may, under certain circumstances, be exchangeable for cash (for the principal amount of the 2015 Notes) and, with respect to any excess exchange value, for cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock, at the Company’s option. The exchange rate of the 2015 Notes as of September 30, 2019 was approximately 10.87 shares of the Company’s common stock per $1,000 principal amount of the 2015 Notes. The Operating Partnership may redeem the 2015 Notes at any time to preserve the Company’s status as a REIT. In addition, on or after October 5, 2020, the Operating Partnership may redeem the 2015 Notes for cash, in whole or in part, at 100% of the principal amount plus accrued and unpaid interest, upon at least 30 days but not more than 60 days prior written notice to the holders of the 2015 Notes. The holders of the 2015 Notes have the right to require the Operating Partnership to repurchase the 2015 Notes for cash, in whole or in part, on October 1 of the years 2020, 2025 and 2030 (unless the Operating Partnership has called the 2015 Notes for redemption), and upon the occurrence of certain designated events, in each case for a repurchase price equal to 100% of the principal amount of the 2015 Notes plus accrued and unpaid interest. Certain events are considered “Events of Default,” as defined in the indenture governing the 2015 Notes, which may result in the accelerated maturity of the 2015 Notes. Additionally, the 2015 Notes can be exchanged during any calendar quarter, if the last reported sale price of the common stock of the Company is greater than or equal to 130% of the exchange price for at least 20 trading days during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter. The price of the Company’s common stock did not exceed 130% of the exchange price for the required time period for the 2015 Notes during the quarter ended September 30, 2019 . On June 21, 2013, the Operating Partnership issued $250,000 of its 2.375% Exchangeable Senior Notes due 2033 at a 1.5% discount, or $3,750 , and 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. During the three months ended March 31, 2018, the Company repurchased a total principal amount of $37,709 of the 2013 Notes. The Company paid cash of $58,469 for the total of the principal amount and the exchange value in excess of the principal amount. 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 accounts for the liability and equity components of the 2013 Notes and 2015 Notes separately. The equity components are included in paid-in capital in stockholders’ equity in the condensed consolidated balance sheets, and the value of the equity components are treated as original issue discount for purposes of accounting for the debt components. The discounts are amortized as interest expense over the remaining period of the debt through its first redemption date: July 1, 2018 for the 2013 Notes, and October 1, 2020 for the 2015 Notes. The effective interest rate on the liability components of the 2013 Notes and the 2015 Notes is 4.0% , which approximated the market rate of interest of similar debt without exchange features (i.e. nonconvertible debt) at the time of issuance. Information about the Company’s 2015 Notes, including the total carrying amount of the equity component, the principal amount of the liability component, the unamortized discount and the net carrying amount was as follows for the periods indicated: September 30, 2019 December 31, 2018 Carrying amount of equity component $ 22,597 $ 22,597 Principal amount of liability component $ 575,000 $ 575,000 Unamortized discount - equity component (4,884 ) (8,417 ) Unamortized debt issuance costs (2,411 ) (4,209 ) Net carrying amount of liability components $ 567,705 $ 562,374 The amount of interest cost recognized relating to the contractual interest rate and the amortization of the discount on the liability component of the Notes were as follows for the periods indicated: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2019 2018 2019 2018 Contractual interest $ 4,492 $ 4,492 $ 13,476 $ 13,614 Amortization of discount 1,186 1,140 3,533 3,525 Total interest expense recognized $ 5,678 $ 5,632 $ 17,009 $ 17,139

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2019
Stockholders' Equity Note [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY On May 15, 2019, the Company filed its $500,000 "at the market" equity program with the Securities and Exchange Commission using a shelf registration statement on Form S-3, and entered into separate equity distribution agreements with nine sales agents. During the three months ended September 30, 2019 , the Company sold 849,200 shares of common stock under its "at the market" equity program at an average sales price of $119.30 per share, resulting in net proceeds of $100,056 . As of September 30, 2019 , the Company had $298,621 available for issuance under the equity distribution agreements.

Noncontrolling Interest Represe

Noncontrolling Interest Represented by Preferred Operating Partnership Units	9 Months Ended
	Sep. 30, 2019
Noncontrolling Interest [Abstract]
Noncontrolling Interest Represented by Preferred Operating Partnership Units	NONCONTROLLING INTEREST REPRESENTED BY PREFERRED OPERATING PARTNERSHIP UNITS Classification of Noncontrolling Interests GAAP requires a company to present ownership interests in subsidiaries held by parties other than the company in the consolidated financial statements within the equity section, but separate from the company’s equity. It also requires the amount of consolidated net income attributable to the parent and to the noncontrolling interest to be clearly identified and presented on the face of the consolidated statement of operations and requires changes in ownership interest to be accounted for similarly as equity transactions. If noncontrolling interests are determined to be redeemable, they are to be carried at their redemption value as of the balance sheet date and reported as temporary equity. The Company has evaluated the terms of the Operating Partnership’s preferred units and classifies the noncontrolling interest represented by such preferred units as stockholders’ equity in the accompanying condensed consolidated balance sheets. The Company will periodically evaluate individual noncontrolling interests for the ability to continue to recognize the noncontrolling interest as permanent equity in the condensed consolidated balance sheets. Any noncontrolling interests that fail to qualify as permanent equity will be reclassified as temporary equity and adjusted to the greater of (1) the carrying amount and (2) the redemption value as of the end of the period in which the determination is made. At September 30, 2019 and December 31, 2018 , the noncontrolling interests represented by the Preferred OP Units qualified for classification as permanent equity on the Company's condensed consolidated balance sheets. The partnership agreement of the Operating Partnership (as amended, the "Partnership Agreement") provides for the designation and issuance of the OP Units. As of September 30, 2019 and December 31, 2018 , noncontrolling interests in Preferred OP Units were presented net of notes receivable from Preferred OP Unit holders of $100,000 and $108,644 , respectfully, as more fully described below. Series A Participating Redeemable Preferred Units The Partnership Agreement provides for the designation and issuance of the Series A Units. The Series A Units have priority over all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series A Units were issued in June 2007. Series A Units in the amount of $101,700 bear a fixed priority return of 2.3% and originally had a fixed liquidation value of $115,000 . The remaining balance participates in distributions with, and has a liquidation value equal to that of the OP Units. The Series A Units are redeemable at the option of the holder, which redemption obligation may be satisfied, at the Company’s option, in cash or shares of its common stock. As a result of the redemption of 114,500 Series A Units in October 2014, the remaining fixed liquidation value was reduced to $101,700 , which represents 875,480 Series A Units. On 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. On June 25, 2007, the Operating Partnership loaned the holder of the Series A Units $100,000 . 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 receivable is also the holder of the Series A Units. Series B Redeemable Preferred Units The Partnership Agreement provides for the designation and issuance of the Series B Units. The Series B Units rank junior to the Series A Units, on parity with the Series C Units and Series D Units, and senior to all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series B Units were issued in 2013 and 2014 and have a liquidation value of $25.00 per unit for a fixed liquidation value of $41,902 , which represents 1,676,087 Series B Units. Holders of the Series B Units receive distributions at an annual rate of 6.0% . These distributions are cumulative. The Series B Units became redeemable at the option of the holder on the first anniversary of the date of issuance, which redemption obligation may be satisfied at the Company’s option in cash or shares of its common stock. Series C Convertible Redeemable Preferred Units The Partnership Agreement provides for the designation and issuance of the Series C Units. The Series C Units ranked junior to the Series A Units, on parity with the Series B Units and Series D Units, and senior to all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series C Units were issued in 2013 and 2014 and had a liquidation value of $42.10 per unit. The Series C Units became redeemable at the option of the holder one year from the date of issuance, which redemption obligation could be satisfied at the Company’s option in cash or shares of its common stock. The Series C Units were convertible into OP Units at the option of the holder at a rate of 0.9145 OP Units per Series C Unit converted. This conversion option expired upon the fifth anniversary of the date of issuance. In December 2014, the Operating Partnership loaned certain holders of the Series C Units $20,230 . The loan receivable, which was collateralized by the Series C Units, bears interest at 5.0% per annum and matures on December 15, 2024 . The Series C Units were shown on the balance sheet net of the loan balance because the borrower under the loan receivable was also the holder of the Series C Units. On December 1, 2018, certain holders of the Series C Units converted their Series C Units into OP Units, with a total of 407,996 Series C Units being converted into a total of 373,113 OP Units. As part of this conversion, the holders of the Series C Units agreed to pledge the 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 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 $18,524 is shown as a reduction of the noncontrolling interests related to the OP Units as of September 30, 2019. See footnote 12 for further discussion of noncontrolling interests. Series D Redeemable Preferred Units The Partnership Agreement provides for the designation and issuance of the Series D Units. The Series D Units rank junior to the Series A Units, on parity with the Series B Units and Series C Units, and senior to all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series D Units have been issued at various times from 2014 to 2019. In addition, during the nine months ended September 30, 2019 , the Operating Partnership issued 1,120,924 Series D Units valued at $28,022 in conjunction with joint venture acquisitions. The Series D Units have a liquidation value of $25.00 per unit, for a fixed liquidation value of $120,086 , which represents 4,803,445 Series D Units. Holders of the Series D Units receive distributions at an annual rate between 3.0% and 5.0% . These distributions are cumulative. The Series D Units become redeemable at the option of the holder on the first anniversary of the date of issuance, which redemption obligation may be satisfied at the Company’s option in cash or shares of its common stock. In addition, certain of the Series D Units are exchangeable for OP Units at the option of the holder until the tenth anniversary of the date of issuance, with the number of OP Units to be issued equal to $25.00 per Series D Unit, divided by the value of a share of common stock as of the exchange date. NONCONTROLLING INTEREST IN OPERATING PARTNERSHIP AND OTHER NONCONTROLLING INTERESTS 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 90.6% ownership interest in the Operating Partnership as of September 30, 2019 . The remaining ownership interests in the Operating Partnership (including Preferred OP Units) of 9.4% are held by certain former owners of assets acquired by the Operating Partnership. As of September 30, 2019 , and December 31, 2018 the noncontrolling interests in the Operating Partnership are shown on the balance sheet net of notes receivable of $18,524 and $11,091 , respectively, because the borrowers under the loan receivable are also holders of OP Units. This loan receivable bears interest at 5.0% per annum and matures on December 15, 2024 . The noncontrolling interest in the Operating Partnership represents OP Units that are not owned by the Company. OP Units are redeemable at the option of the holder, which redemption may be satisfied at the Company's option in cash, based upon the fair market value of an equivalent number of shares of the Company’s common stock (based on the ten-day average trading price) at the time of the redemption, or shares of the Company's common stock on a one-for-one basis , subject to anti-dilution adjustments provided in the Partnership Agreement. As of September 30, 2019 , the ten-day average closing price of the Company's common stock was $116.80 and there were 6,025,341 OP Units outstanding. Assuming that all of the OP Unit holders exercised their right to redeem all of their OP Units on September 30, 2019 and the Company elected to pay the OP Unit holders cash, the Company would have paid $703,760 in cash consideration to redeem the units. OP Unit activity is summarized as follows for the periods presented: For the Nine Months Ended September 30, 2019 2018 OP Units redeemed for common stock 239,619 25,000 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 — GAAP requires a company to present ownership interests in subsidiaries held by parties other than the company in the consolidated financial statements within the equity section, but separate from the company’s equity. It also requires the amount of consolidated net income attributable to the parent and to the noncontrolling interest to be clearly identified and presented on the face of the consolidated statement of operations, and requires changes in ownership interest to be accounted for similarly as equity transactions. If noncontrolling interests are determined to be redeemable, they are to be carried at their redemption value as of the balance sheet date and reported as temporary equity. The Company has evaluated the terms of the OP Units and classifies the noncontrolling interest represented by the OP Units as stockholders’ equity in the accompanying condensed consolidated balance sheets. The Company will periodically evaluate individual noncontrolling interests for the ability to continue to recognize the noncontrolling amount as permanent equity in the condensed consolidated balance sheets. Any noncontrolling interests that fail to qualify as permanent equity will be reclassified as temporary equity and adjusted to the greater of (1) the carrying amount and (2) the redemption value as of the end of the period in which the determination is made. Other Noncontrolling Interests Other noncontrolling interests represent the ownership interests of third parties in two consolidated joint ventures as of September 30, 2019 . One joint venture owns two operating stores in Texas and two operating stores in Colorado, and the other joint venture owns one operating store in Pennsylvania and one development property in New Jersey. The voting interests of the third-party owners are between 5.0% and 20.0% .

Noncontrolling Interest in Oper

Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests	9 Months Ended
	Sep. 30, 2019
Noncontrolling Interest [Abstract]
Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests	NONCONTROLLING INTEREST REPRESENTED BY PREFERRED OPERATING PARTNERSHIP UNITS Classification of Noncontrolling Interests GAAP requires a company to present ownership interests in subsidiaries held by parties other than the company in the consolidated financial statements within the equity section, but separate from the company’s equity. It also requires the amount of consolidated net income attributable to the parent and to the noncontrolling interest to be clearly identified and presented on the face of the consolidated statement of operations and requires changes in ownership interest to be accounted for similarly as equity transactions. If noncontrolling interests are determined to be redeemable, they are to be carried at their redemption value as of the balance sheet date and reported as temporary equity. The Company has evaluated the terms of the Operating Partnership’s preferred units and classifies the noncontrolling interest represented by such preferred units as stockholders’ equity in the accompanying condensed consolidated balance sheets. The Company will periodically evaluate individual noncontrolling interests for the ability to continue to recognize the noncontrolling interest as permanent equity in the condensed consolidated balance sheets. Any noncontrolling interests that fail to qualify as permanent equity will be reclassified as temporary equity and adjusted to the greater of (1) the carrying amount and (2) the redemption value as of the end of the period in which the determination is made. At September 30, 2019 and December 31, 2018 , the noncontrolling interests represented by the Preferred OP Units qualified for classification as permanent equity on the Company's condensed consolidated balance sheets. The partnership agreement of the Operating Partnership (as amended, the "Partnership Agreement") provides for the designation and issuance of the OP Units. As of September 30, 2019 and December 31, 2018 , noncontrolling interests in Preferred OP Units were presented net of notes receivable from Preferred OP Unit holders of $100,000 and $108,644 , respectfully, as more fully described below. Series A Participating Redeemable Preferred Units The Partnership Agreement provides for the designation and issuance of the Series A Units. The Series A Units have priority over all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series A Units were issued in June 2007. Series A Units in the amount of $101,700 bear a fixed priority return of 2.3% and originally had a fixed liquidation value of $115,000 . The remaining balance participates in distributions with, and has a liquidation value equal to that of the OP Units. The Series A Units are redeemable at the option of the holder, which redemption obligation may be satisfied, at the Company’s option, in cash or shares of its common stock. As a result of the redemption of 114,500 Series A Units in October 2014, the remaining fixed liquidation value was reduced to $101,700 , which represents 875,480 Series A Units. On 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. On June 25, 2007, the Operating Partnership loaned the holder of the Series A Units $100,000 . 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 receivable is also the holder of the Series A Units. Series B Redeemable Preferred Units The Partnership Agreement provides for the designation and issuance of the Series B Units. The Series B Units rank junior to the Series A Units, on parity with the Series C Units and Series D Units, and senior to all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series B Units were issued in 2013 and 2014 and have a liquidation value of $25.00 per unit for a fixed liquidation value of $41,902 , which represents 1,676,087 Series B Units. Holders of the Series B Units receive distributions at an annual rate of 6.0% . These distributions are cumulative. The Series B Units became redeemable at the option of the holder on the first anniversary of the date of issuance, which redemption obligation may be satisfied at the Company’s option in cash or shares of its common stock. Series C Convertible Redeemable Preferred Units The Partnership Agreement provides for the designation and issuance of the Series C Units. The Series C Units ranked junior to the Series A Units, on parity with the Series B Units and Series D Units, and senior to all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series C Units were issued in 2013 and 2014 and had a liquidation value of $42.10 per unit. The Series C Units became redeemable at the option of the holder one year from the date of issuance, which redemption obligation could be satisfied at the Company’s option in cash or shares of its common stock. The Series C Units were convertible into OP Units at the option of the holder at a rate of 0.9145 OP Units per Series C Unit converted. This conversion option expired upon the fifth anniversary of the date of issuance. In December 2014, the Operating Partnership loaned certain holders of the Series C Units $20,230 . The loan receivable, which was collateralized by the Series C Units, bears interest at 5.0% per annum and matures on December 15, 2024 . The Series C Units were shown on the balance sheet net of the loan balance because the borrower under the loan receivable was also the holder of the Series C Units. On December 1, 2018, certain holders of the Series C Units converted their Series C Units into OP Units, with a total of 407,996 Series C Units being converted into a total of 373,113 OP Units. As part of this conversion, the holders of the Series C Units agreed to pledge the 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 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 $18,524 is shown as a reduction of the noncontrolling interests related to the OP Units as of September 30, 2019. See footnote 12 for further discussion of noncontrolling interests. Series D Redeemable Preferred Units The Partnership Agreement provides for the designation and issuance of the Series D Units. The Series D Units rank junior to the Series A Units, on parity with the Series B Units and Series C Units, and senior to all other partnership interests of the Operating Partnership with respect to distributions and liquidation. The Series D Units have been issued at various times from 2014 to 2019. In addition, during the nine months ended September 30, 2019 , the Operating Partnership issued 1,120,924 Series D Units valued at $28,022 in conjunction with joint venture acquisitions. The Series D Units have a liquidation value of $25.00 per unit, for a fixed liquidation value of $120,086 , which represents 4,803,445 Series D Units. Holders of the Series D Units receive distributions at an annual rate between 3.0% and 5.0% . These distributions are cumulative. The Series D Units become redeemable at the option of the holder on the first anniversary of the date of issuance, which redemption obligation may be satisfied at the Company’s option in cash or shares of its common stock. In addition, certain of the Series D Units are exchangeable for OP Units at the option of the holder until the tenth anniversary of the date of issuance, with the number of OP Units to be issued equal to $25.00 per Series D Unit, divided by the value of a share of common stock as of the exchange date. NONCONTROLLING INTEREST IN OPERATING PARTNERSHIP AND OTHER NONCONTROLLING INTERESTS 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 90.6% ownership interest in the Operating Partnership as of September 30, 2019 . The remaining ownership interests in the Operating Partnership (including Preferred OP Units) of 9.4% are held by certain former owners of assets acquired by the Operating Partnership. As of September 30, 2019 , and December 31, 2018 the noncontrolling interests in the Operating Partnership are shown on the balance sheet net of notes receivable of $18,524 and $11,091 , respectively, because the borrowers under the loan receivable are also holders of OP Units. This loan receivable bears interest at 5.0% per annum and matures on December 15, 2024 . The noncontrolling interest in the Operating Partnership represents OP Units that are not owned by the Company. OP Units are redeemable at the option of the holder, which redemption may be satisfied at the Company's option in cash, based upon the fair market value of an equivalent number of shares of the Company’s common stock (based on the ten-day average trading price) at the time of the redemption, or shares of the Company's common stock on a one-for-one basis , subject to anti-dilution adjustments provided in the Partnership Agreement. As of September 30, 2019 , the ten-day average closing price of the Company's common stock was $116.80 and there were 6,025,341 OP Units outstanding. Assuming that all of the OP Unit holders exercised their right to redeem all of their OP Units on September 30, 2019 and the Company elected to pay the OP Unit holders cash, the Company would have paid $703,760 in cash consideration to redeem the units. OP Unit activity is summarized as follows for the periods presented: For the Nine Months Ended September 30, 2019 2018 OP Units redeemed for common stock 239,619 25,000 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 — GAAP requires a company to present ownership interests in subsidiaries held by parties other than the company in the consolidated financial statements within the equity section, but separate from the company’s equity. It also requires the amount of consolidated net income attributable to the parent and to the noncontrolling interest to be clearly identified and presented on the face of the consolidated statement of operations, and requires changes in ownership interest to be accounted for similarly as equity transactions. If noncontrolling interests are determined to be redeemable, they are to be carried at their redemption value as of the balance sheet date and reported as temporary equity. The Company has evaluated the terms of the OP Units and classifies the noncontrolling interest represented by the OP Units as stockholders’ equity in the accompanying condensed consolidated balance sheets. The Company will periodically evaluate individual noncontrolling interests for the ability to continue to recognize the noncontrolling amount as permanent equity in the condensed consolidated balance sheets. Any noncontrolling interests that fail to qualify as permanent equity will be reclassified as temporary equity and adjusted to the greater of (1) the carrying amount and (2) the redemption value as of the end of the period in which the determination is made. Other Noncontrolling Interests Other noncontrolling interests represent the ownership interests of third parties in two consolidated joint ventures as of September 30, 2019 . One joint venture owns two operating stores in Texas and two operating stores in Colorado, and the other joint venture owns one operating store in Pennsylvania and one development property in New Jersey. The voting interests of the third-party owners are between 5.0% and 20.0% .

Leases

Leases	9 Months Ended
	Sep. 30, 2019
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 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. 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 49 stores classified as wholly-owned. These leases generally have original lease terms between 10 - 67 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. • Leases of 13 regional offices. These leases have original lease terms between three and five years . The Company has the option on five of these leases to extend the lease term for three additional years. • 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, and the Company will recognize lease payments as expense on a straight-line basis over the related lease terms. 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, etc. 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 signed a lease agreement for a store in New Jersey. The store is currently 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 early 2020. The lease term is 75 years from the lease commencement date, with three 10 -year extension options. The Company has also signed a 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-2020. 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 assets or lease liabilities related to these leases as of September 30, 2019 as the lease term has not yet commenced for either lease. 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 leases 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(s) indicated: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2019 2019 Finance lease cost: Amortization of finance lease right-of-use assets $ 42 $ 126 Interest expense related to finance lease liabilities 73 216 Operating lease cost 7,060 12,737 Variable lease cost 1,624 3,426 Short-term lease cost 28 138 Total lease cost $ 8,827 $ 16,643 Cash paid for amounts included in the measurement of lease liabilities Operating cash outflows for finance lease payments $ 58 $ 173 Operating cash outflows for operating lease payments 6,573 12,122 Total cash flows for lease liability measurement $ 6,631 $ 12,295 Right-of-use assets obtained in exchange for new operating lease liabilities $ 52,413 $ 277,430 Right-of-use assets obtained in exchange for new finance lease liabilities $ — $ 8,050 Weighted average remaining lease term - finance leases (years) 47.1 Weighted average remaining lease term - operating leases (years) 14.9 Weighted average discount rate - finance leases 6.07 % Weighted average discount rate - operating leases 3.65 % Following is 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 2019 $ 6,982 $ 57 $ 7,039 2020 28,331 232 28,563 2021 28,586 237 28,823 2022 28,611 255 28,866 2023 28,698 255 28,953 Thereafter 252,832 16,777 269,609 Total $ 374,040 $ 17,813 $ 391,853 Present value adjustments (94,991 ) (12,990 ) (107,981 ) Lease liabilities $ 279,049 $ 4,823 $ 283,872 Lessor Accounting
Leases	LEASES The Company adopted ASC 842, "Leases," effective January 1, 2019 on a modified retrospective basis as allowed under the standard and 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. 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 49 stores classified as wholly-owned. These leases generally have original lease terms between 10 - 67 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. • Leases of 13 regional offices. These leases have original lease terms between three and five years . The Company has the option on five of these leases to extend the lease term for three additional years. • 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, and the Company will recognize lease payments as expense on a straight-line basis over the related lease terms. 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, etc. 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 signed a lease agreement for a store in New Jersey. The store is currently 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 early 2020. The lease term is 75 years from the lease commencement date, with three 10 -year extension options. The Company has also signed a 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-2020. 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 assets or lease liabilities related to these leases as of September 30, 2019 as the lease term has not yet commenced for either lease. 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 leases 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(s) indicated: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2019 2019 Finance lease cost: Amortization of finance lease right-of-use assets $ 42 $ 126 Interest expense related to finance lease liabilities 73 216 Operating lease cost 7,060 12,737 Variable lease cost 1,624 3,426 Short-term lease cost 28 138 Total lease cost $ 8,827 $ 16,643 Cash paid for amounts included in the measurement of lease liabilities Operating cash outflows for finance lease payments $ 58 $ 173 Operating cash outflows for operating lease payments 6,573 12,122 Total cash flows for lease liability measurement $ 6,631 $ 12,295 Right-of-use assets obtained in exchange for new operating lease liabilities $ 52,413 $ 277,430 Right-of-use assets obtained in exchange for new finance lease liabilities $ — $ 8,050 Weighted average remaining lease term - finance leases (years) 47.1 Weighted average remaining lease term - operating leases (years) 14.9 Weighted average discount rate - finance leases 6.07 % Weighted average discount rate - operating leases 3.65 % Following is 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 2019 $ 6,982 $ 57 $ 7,039 2020 28,331 232 28,563 2021 28,586 237 28,823 2022 28,611 255 28,866 2023 28,698 255 28,953 Thereafter 252,832 16,777 269,609 Total $ 374,040 $ 17,813 $ 391,853 Present value adjustments (94,991 ) (12,990 ) (107,981 ) Lease liabilities $ 279,049 $ 4,823 $ 283,872 Lessor Accounting
Leases	LEASES The Company adopted ASC 842, "Leases," effective January 1, 2019 on a modified retrospective basis as allowed under the standard and 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. 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 49 stores classified as wholly-owned. These leases generally have original lease terms between 10 - 67 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. • Leases of 13 regional offices. These leases have original lease terms between three and five years . The Company has the option on five of these leases to extend the lease term for three additional years. • 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, and the Company will recognize lease payments as expense on a straight-line basis over the related lease terms. 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, etc. 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 signed a lease agreement for a store in New Jersey. The store is currently 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 early 2020. The lease term is 75 years from the lease commencement date, with three 10 -year extension options. The Company has also signed a 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-2020. 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 assets or lease liabilities related to these leases as of September 30, 2019 as the lease term has not yet commenced for either lease. 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 leases 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(s) indicated: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2019 2019 Finance lease cost: Amortization of finance lease right-of-use assets $ 42 $ 126 Interest expense related to finance lease liabilities 73 216 Operating lease cost 7,060 12,737 Variable lease cost 1,624 3,426 Short-term lease cost 28 138 Total lease cost $ 8,827 $ 16,643 Cash paid for amounts included in the measurement of lease liabilities Operating cash outflows for finance lease payments $ 58 $ 173 Operating cash outflows for operating lease payments 6,573 12,122 Total cash flows for lease liability measurement $ 6,631 $ 12,295 Right-of-use assets obtained in exchange for new operating lease liabilities $ 52,413 $ 277,430 Right-of-use assets obtained in exchange for new finance lease liabilities $ — $ 8,050 Weighted average remaining lease term - finance leases (years) 47.1 Weighted average remaining lease term - operating leases (years) 14.9 Weighted average discount rate - finance leases 6.07 % Weighted average discount rate - operating leases 3.65 % Following is 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 2019 $ 6,982 $ 57 $ 7,039 2020 28,331 232 28,563 2021 28,586 237 28,823 2022 28,611 255 28,866 2023 28,698 255 28,953 Thereafter 252,832 16,777 269,609 Total $ 374,040 $ 17,813 $ 391,853 Present value adjustments (94,991 ) (12,990 ) (107,981 ) Lease liabilities $ 279,049 $ 4,823 $ 283,872 Lessor Accounting

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION The Company’s segment disclosures present the measure used by the chief operating decision makers ("CODMs") for purposes of assessing each segment’s performance. The Company’s CODMs are comprised of several members of its executive management team who use net operating income ("NOI") to assess the performance of the business for the Company’s reportable operating segments. NOI for the Company's self-storage operations represents total property revenue less direct property operating expenses. NOI for the Company's tenant reinsurance segment represents tenant reinsurance revenues less tenant reinsurance expense. The Company has two reportable segments: (1) self-storage operations and (2) tenant reinsurance. The self-storage operations activities include rental operations of wholly-owned stores. The Company's consolidated revenues equal total segment revenues plus property management fees and other income. Tenant reinsurance activities include the reinsurance of risks relating to the loss of goods stored by tenants in the stores operated by the Company. Excluded from segment revenues and net operating income is property management fees and other income. For all periods presented, substantially all of the Company's real estate assets, intangible assets, other assets, and accrued and other liabilities are associated with the self-storage operations segment. Financial information for the Company’s business segments is set forth below: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2019 2018 2019 2018 Revenues: Self-Storage Operations $ 290,917 $ 266,728 $ 841,504 $ 772,742 Tenant Reinsurance 33,588 30,105 95,086 85,660 Total segment revenues $ 324,505 $ 296,833 $ 936,590 $ 858,402 Operating expenses: Self-Storage Operations $ 88,653 $ 73,652 $ 248,288 $ 219,488 Tenant Reinsurance 7,644 7,720 21,593 18,798 Total segment operating expenses $ 96,297 $ 81,372 $ 269,881 $ 238,286 Net operating income: Self-Storage Operations $ 202,264 $ 193,076 $ 593,216 $ 553,254 Tenant Reinsurance 25,944 22,385 73,493 66,862 Total segment net operating income: $ 228,208 $ 215,461 $ 666,709 $ 620,116 Other components of net income (loss): Property management fees and other income $ 13,000 $ 10,120 $ 36,063 $ 30,849 General and administrative expense (22,519 ) (19,707 ) (68,548 ) (62,822 ) Depreciation and amortization expense (56,051 ) (52,283 ) (165,116 ) (155,924 ) Gain on real estate transactions — 30,807 1,205 30,807 Interest expense (46,908 ) (45,926 ) (141,716 ) (130,239 ) Non-cash interest expense related to the amortization of discount on equity component of exchangeable senior notes (1,186 ) (1,140 ) (3,533 ) (3,525 ) Interest income 2,799 1,371 5,905 3,997 Equity in earnings of unconsolidated real estate ventures 2,704 3,622 8,455 10,648 Income tax expense (4,052 ) (2,638 ) (8,580 ) (6,077 ) Net income $ 115,995 $ 139,687 $ 330,844 $ 337,830

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES As of September 30, 2019 , the Company was involved in various legal proceedings and was subject to various claims and complaints arising in the ordinary course of business. Because litigation is inherently unpredictable, the outcome of these matters cannot presently be determined with any degree of certainty. In accordance with applicable accounting guidance, management establishes an accrued liability for litigation when those matters present loss contingencies that are both probable and reasonably estimable. In such cases, there may be an exposure to loss in excess of any amounts accrued. The estimated loss, if any, is based upon currently available information and is subject to significant judgment, a variety of assumptions, and known and unknown uncertainties. The Company could in the future incur judgments or enter into settlements of claims that could have a material adverse effect on its results of operations in any particular period, notwithstanding the fact that the Company is currently vigorously defending any legal proceedings against it. As of September 30, 2019 , the Company was under agreement to acquire four stores at a total purchase price of $41,828 . These stores are scheduled to close in 2020. Additionally, the Company is under agreement to acquire five stores with joint venture partners, for a total investment of $31,384 . Three of these stores are scheduled to close in 2019 and the remaining stores are expected to close in 2020. Although there can be no assurance, the Company is not aware of any material environmental liability, for which it believes it will be ultimately responsible, that could have a material adverse effect on its financial condition or results of operations. However, changes in applicable environmental laws and regulations, the uses and conditions of properties in the vicinity of the Company’s stores, the activities of its tenants and other environmental conditions of which the Company is unaware with respect to its stores could result in future material environmental liabilities.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS On October 29, 2019, the Company invested $150.0 million in shares of newly issued convertible preferred stock of SmartStop Self Storage REIT, Inc. ("SmartStop"), with an additional commitment to purchase up to $50.0 million of the preferred shares over the next 12 months . 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.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	The accompanying unaudited condensed consolidated financial statements of the Company are presented on the accrual basis of accounting in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information, and in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they may not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (including normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three and nine months ended September 30, 2019 are not necessarily indicative of results that may be expected for the year ending December 31, 2019 . The condensed consolidated balance sheet as of December 31, 2018 has been derived from the Company’s audited financial statements as of that date, but does not include all of the information and footnotes required by GAAP for complete financial statements. For further information refer to the consolidated financial statements and footnotes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 , as filed with the Securities and Exchange Commission.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("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. Lease obligations are measured at their present value and accounted for using the effective interest method. The accounting for the leased asset differs slightly depending on whether the agreement is deemed to be a financing or operating lease. For financing leases, the leased asset is depreciated on a straight-line basis and is recorded separately from the interest expense in the statements of operations, resulting in higher expense in the earlier part of the lease term. For operating leases, the depreciation and interest expense components are combined, recognized evenly over the term of the lease, and presented as a reduction to operating income. ASU 2016-02 requires that assets and liabilities be presented or disclosed separately, and requires additional disclosure of certain qualitative and quantitative information related to these lease agreements. ASU 2016-02 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 the standard that removed the requirement to separate lease and nonlease components. The Company did not record a significant cumulative catch-up adjustment to retained earnings upon adoption of ASU 2016-02. The primary impact was related to the Company's 21 operating ground leases and two corporate facility leases under which it served as lessee at the time of adoption. The Company recognized lease liabilities of $104,863 and right-of-use assets related to operating leases totaling $95,506 as of the adoption date. Refer to footnote 13 for further discussion of the Company's leases. In August 2018, the FASB issued ASU 2018-15, "Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract." ASU 2018-15 amends the accounting for implementation costs incurred in a hosting arrangement that is a service contract, and aligns them with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. ASU 2018-15 also requires that entities amortize the capitalized implementation costs over the term of the hosting arrangement. ASU 2018-15 is effective for annual periods beginning after December 15, 2020, with early adoption permitted, including early adoption in any interim period. The Company adopted this standard on a prospective basis as of October 1, 2018. The adoption of this standard did not have a material impact on the Company's financial statements. 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,"
Fair Value Disclosures	Derivative Financial Instruments Currently, the Company uses interest rate swaps to manage its interest rate risk. The valuation of these instruments is determined using widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves. The fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash payments and the discounted expected variable cash receipts. The variable cash receipts are based on an expectation of future interest rates (forward curves) derived from observable market interest rate forward curves. The Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts and guarantees. In conjunction with the FASB’s fair value measurement guidance, the Company made an accounting policy election to measure the credit risk of its derivative financial instruments that are subject to master netting agreements on a net basis by counterparty portfolio. Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by the Company and its counterparties. However, as of September 30, 2019 , the Company assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and determined that the credit valuation adjustments were not significant to the overall valuation of its derivatives. As a result, the Company has determined that its derivative valuations in their entirety were classified in Level 2 of the fair value hierarchy. Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Long-lived assets held for use are evaluated for impairment when events or circumstances indicate there may be impairment. The Company reviews each store at least annually to determine if any such events or circumstances have occurred or exist. The Company focuses on stores where occupancy and/or rental income have decreased by a significant amount. For these stores, the Company determines whether the decrease is temporary or permanent, and whether the store will likely recover the lost occupancy and/or revenue in the short term. In addition, the Company reviews stores in the lease-up stage and compares actual operating results to original projections. When the Company determines that an event that may indicate impairment has occurred, the Company compares the carrying value of the related long-lived assets to the undiscounted future net operating cash flows attributable to the assets. An impairment loss is recorded if the net carrying value of the assets exceeds the undiscounted future net operating cash flows attributable to the assets. The impairment loss recognized equals the excess of net carrying value over the related fair value of the assets. When real estate assets are identified by management as held for sale, the Company discontinues depreciating the assets and estimates the fair value of the assets, net of selling costs. If the estimated fair value, net of selling costs, of the assets that have been identified as held for sale is less than the net carrying value of the assets, the Company would recognize an impairment loss on the assets held for sale. The operations of assets held for sale or sold during the period are presented as part of normal operations for all periods presented. As of September 30, 2019 , the Company had one parcel of land classified as held for sale which is included in real estate assets, net. The estimated fair value less selling costs for this asset is greater than the carrying value of the asset, and therefore no loss has been recorded. The Company assesses annually whether there are any indicators that the value of the Company’s investments in unconsolidated real estate ventures may be impaired annually and when events or circumstances indicate that there may be impairment. An investment is impaired if management’s estimate of the fair value of the investment is less than its carrying value. To the extent impairment has occurred, and is considered to be other than temporary, the loss is measured as the excess of the carrying amount of the investment over the fair value of the investment. In connection with the Company’s acquisition of stores, the purchase price is allocated to the tangible and intangible assets and liabilities acquired based on their relative fair values, which are estimated using significant unobservable inputs. The value of the tangible assets, consisting of land and buildings, is determined as if vacant. Intangible assets, which represent the value of existing tenant relationships, are recorded at their fair values based on the avoided cost to replace the current leases. The Company measures the value of tenant relationships based on the rent lost due to the amount of time required to replace existing customers, which is based on the Company’s historical experience with turnover in its stores. Any debt assumed as part of an acquisition is recorded at fair value based on current interest rates compared to contractual rates. Acquisition-related transaction costs are capitalized as part of the purchase price. Fair Value of Financial Instruments The carrying values of cash and cash equivalents, restricted cash, receivables, other financial instruments included in other assets, accounts payable and accrued expenses, variable-rate notes payable, lines of credit and other liabilities reflected in the condensed consolidated balance sheets at September 30, 2019 and December 31, 2018 approximate fair value. 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, insurance and capital expenditures.
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.
Derivatives	The Company’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish these objectives, the Company primarily uses interest rate swaps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. The Company is exposed to certain risks arising from both its business operations and economic conditions. The Company principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company manages economic risks, including interest rate, liquidity and credit risk, primarily by managing the amount, sources and duration of its debt funding and by using derivative financial instruments. Specifically, the Company enters into derivative financial instruments to manage exposure that arises from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. The Company’s derivative financial instruments are used to manage differences in the amount, timing and duration of the Company’s known or expected cash receipts and its known or expected cash payments principally related to the Company’s investments and borrowings.
Convertible Debt	GAAP requires entities with convertible debt instruments that may be settled entirely or partially in cash upon conversion to separately account for the liability and equity components of the instrument in a manner that reflects the issuer’s economic interest cost. The Company therefore accounts for the liability and equity components of the 2013 Notes and 2015 Notes separately. The equity components are included in paid-in capital in stockholders’ equity in the condensed consolidated balance sheets, and the value of the equity components are treated as original issue discount for purposes of accounting for the debt components. The discounts are amortized as interest expense over the remaining period of the debt through its first redemption date: July 1, 2018 for the 2013 Notes, and October 1, 2020 for the 2015 Notes.

Fair Value Disclosures (Tables)

Fair Value Disclosures (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The table below presents the Company’s assets and liabilities measured at fair value on a recurring basis as of September 30, 2019 , aggregated by the level in the fair value hierarchy within which those measurements fall. Fair Value Measurements at Reporting Date Using Description Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Other assets - Cash flow hedge swap agreements $ — $ 3,141 $ — Other liabilities - Cash flow hedge swap agreements $ — $ 43,880 $ —
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: September 30, 2019 December 31, 2018 Fair Carrying Fair Carrying Notes receivable from Preferred and Common Operating Partnership unit holders $ 118,756 $ 118,524 $ 115,467 $ 119,735 Fixed rate notes payable and notes payable to trusts $ 3,296,231 $ 3,166,208 $ 2,985,731 $ 3,022,414 Exchangeable senior notes $ 724,500 $ 575,000 $ 620,149 $ 575,000

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Schedule of Antidilutive Shares Excluded from Computation of Earnings Per Share	The following table presents the number of Preferred Operating Partnership units, and the potential common shares, that were excluded from the computation of earnings per share as their effect would have been anti-dilutive. For the Three Months Ended September 30, For the Nine Months Ended September 30, 2019 2018 2019 2018 Equivalent Shares (if converted) Equivalent Shares (if converted) Equivalent Shares (if converted) Equivalent Shares (if converted) Series B Units 362,382 451,386 396,276 465,115 Series C Units (1) — 319,283 — 328,994 Series D Units 1,038,538 — 1,074,417 1,021,901 1,400,920 770,669 1,470,693 1,816,010 (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 common share is as follows for the periods presented: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2019 2018 2019 2018 Net income attributable to common stockholders $ 108,087 $ 130,418 $ 307,685 $ 313,827 Earnings and dividends allocated to participating securities (165 ) (219 ) (508 ) (550 ) Earnings for basic computations 107,922 130,199 307,177 313,277 Earnings and dividends allocated to participating securities 165 — — 550 Income allocated to noncontrolling interest - Preferred Operating Partnership Units and Operating Partnership Units 6,100 7,336 17,539 17,191 Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units) (572 ) (572 ) (1,716 ) (1,716 ) Net income for diluted computations $ 113,615 $ 136,963 $ 323,000 $ 329,302 Weighted average common shares outstanding: Average number of common shares outstanding - basic 128,776,549 126,466,837 127,830,272 125,959,926 OP Units 6,050,028 5,636,845 6,032,656 5,650,599 Series A Units 875,480 875,480 875,480 875,480 Series D Units — 991,738 — — Unvested restricted stock awards included for treasury stock method 209,963 — — 250,630 Shares related to exchangeable senior notes and dilutive stock options 1,406,455 269,390 1,425,891 279,055 Average number of common shares outstanding - diluted 137,318,475 134,240,290 136,164,299 133,015,690 Earnings per common share Basic $ 0.84 $ 1.03 $ 2.40 $ 2.49 Diluted $ 0.83 $ 1.02 $ 2.37 $ 2.48

Store Acquisitions and Dispos_2

Store Acquisitions and Dispositions (Tables)	9 Months Ended
	Sep. 30, 2019
Real Estate [Abstract]
Schedule of Operating Properties Acquired	The following table shows the Company’s acquisitions of stores for the three and nine months ended September 30, 2019 and 2018 . The table excludes purchases of raw land and improvements made to existing assets. All acquisitions are considered asset acquisitions under ASU 2017-01, " Business Combinations (Topic 805): Clarifying the Definition of a Business ." Consideration Paid Total Quarter Number of Stores Total Cash Paid Loan Assumed Investments in Real Estate Ventures Net Liabilities/ (Assets) Assumed Value of OP Units Issued Number of OP Units Issued Real estate assets Q3 2019 1 $ 16,937 $ 16,941 $ — $ — $ (4 ) $ — — $ 16,937 Q2 2019 1 8,424 8,424 — — — — — 8,424 Q1 2019 14 (1) 223,740 202,890 17,157 2,780 913 — — 223,740 16 $ 249,101 $ 228,255 $ 17,157 $ 2,780 $ 909 $ — — $ 249,101 Q3 2018 6 $ 74,694 $ 71,989 $ — $ — $ 2,705 $ — — $ 74,694 Q2 2018 17 (2) 237,284 148,650 87,500 (1,024 ) 281 1,877 21,768 237,284 Q1 2018 5 (2) 70,787 70,171 — 489 127 — — 70,787 28 $ 382,765 $ 290,810 $ 87,500 $ (535 ) $ 3,113 $ 1,877 21,768 $ 382,765 (1) Store acquisitions during the three months ended March 31, 2019 include the purchase 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. (2) Store acquisitions during the six months ended June 30, 2018 include the acquisition of 15 stores that had been owned by a joint venture in which the Company held a noncontrolling interest. No gain or loss was recognized as a result of these acquisitions.

Investments in Unconsolidated_2

Investments in Unconsolidated Real Estate Ventures - (Tables)	9 Months Ended
	Sep. 30, 2019
Equity Method Investments and Joint Ventures [Abstract]
Schedule of investments in unconsolidated real estate ventures	Net investments in unconsolidated real estate ventures and cash distributions in unconsolidated real estate ventures consist of the following: Number of Stores Equity Ownership % Excess Profit % (1) September 30, December 31, 2019 2018 PRISA Self Storage LLC 85 4% 4% $ 9,182 $ 9,334 Storage Portfolio II JV LLC 36 10% 30% (4,754 ) (4,233 ) Storage Portfolio I LLC 24 34% 49% (38,406 ) (38,129 ) VRS Self Storage, LLC 16 45% 54% 17,560 18,281 ESS-NYFL JV LP 15 16% 24% 13,931 — Extra Space Northern Properties Six LLC 10 10% 35% (1,969 ) (1,700 ) WICNN JV LLC 9 10% 25% 32,428 26,885 Alan Jathoo JV LLC 9 10% 10% 8,021 8,180 ESS Bristol Investments LLC 8 10% 28% 3,065 2,331 GFN JV, LLC 5 10% 25% 12,238 10,586 Extra Space West Two LLC (2) — 5% 40% — 3,818 Extra Space West One LLC (2) — 5% 40% — (1,038 ) Other minority owned stores 25 10-50% 19-50% 79,003 45,814 Net Investments in and Cash distributions in unconsolidated real estate ventures 242 $ 130,299 $ 80,129 (1) Includes pro-rata equity ownership share and promoted interest. (2) In January 2019, the Company purchased its joint venture partners' 95% 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% of the joint ventures and the related stores.

Derivatives (Tables)

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of balance sheet classification and fair value of entity's derivative financial instruments	The table below presents the fair value of the Company’s derivative financial instruments as well as their classification on the condensed consolidated balance sheets: Asset / Liability Derivatives September 30, 2019 December 31, 2018 Derivatives designated as hedging instruments: Fair Value Other assets $ 3,141 $ 42,324 Other liabilities $ 43,880 $ 2,131
Schedule of information relating to gain (loss) recognized on swap agreements	The table below presents the effect of the Company’s derivative financial instruments on the condensed consolidated statements of operations for the periods presented. No tax effect has been presented as the derivative instruments are held by the Company: Gain (loss) recognized in OCI For the Three Months Ended September 30, Location of amounts reclassified from OCI into income Gain (loss) reclassified from OCI For the Three Months Ended September 30, Type 2019 2018 2019 2018 Swap Agreements $ (14,517 ) $ 8,325 Interest expense $ 2,992 $ 2,561 Gain (loss) recognized in OCI For the Nine Months Ended September 30, Location of amounts reclassified from OCI into income Gain reclassified from OCI For the Nine Months Ended September 30, Type 2019 2018 2019 2018 Swap Agreements $ (70,387 ) $ 41,610 Interest expense $ 11,792 $ 4,684

Exchangeable Senior Notes (Tabl

Exchangeable Senior Notes (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Schedule of information about total carrying amounts of equity components, principal amounts of liability components, unamortized discounts and net carrying amounts for notes	Information about the Company’s 2015 Notes, including the total carrying amount of the equity component, the principal amount of the liability component, the unamortized discount and the net carrying amount was as follows for the periods indicated: September 30, 2019 December 31, 2018 Carrying amount of equity component $ 22,597 $ 22,597 Principal amount of liability component $ 575,000 $ 575,000 Unamortized discount - equity component (4,884 ) (8,417 ) Unamortized debt issuance costs (2,411 ) (4,209 ) Net carrying amount of liability components $ 567,705 $ 562,374
Summary of amount of interest cost recognized relating to contractual interest rates and amortization of discounts on liability components of notes	The amount of interest cost recognized relating to the contractual interest rate and the amortization of the discount on the liability component of the Notes were as follows for the periods indicated: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2019 2018 2019 2018 Contractual interest $ 4,492 $ 4,492 $ 13,476 $ 13,614 Amortization of discount 1,186 1,140 3,533 3,525 Total interest expense recognized $ 5,678 $ 5,632 $ 17,009 $ 17,139

Noncontrolling Interest in Op_2

Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests (Tables)	9 Months Ended
	Sep. 30, 2019
Noncontrolling Interest [Abstract]
Redeemable Noncontrolling Interest	OP Unit activity is summarized as follows for the periods presented: For the Nine Months Ended September 30, 2019 2018 OP Units redeemed for common stock 239,619 25,000 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 —

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Lease costs	Following is information on our total lease costs as of the period(s) indicated: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2019 2019 Finance lease cost: Amortization of finance lease right-of-use assets $ 42 $ 126 Interest expense related to finance lease liabilities 73 216 Operating lease cost 7,060 12,737 Variable lease cost 1,624 3,426 Short-term lease cost 28 138 Total lease cost $ 8,827 $ 16,643 Cash paid for amounts included in the measurement of lease liabilities Operating cash outflows for finance lease payments $ 58 $ 173 Operating cash outflows for operating lease payments 6,573 12,122 Total cash flows for lease liability measurement $ 6,631 $ 12,295 Right-of-use assets obtained in exchange for new operating lease liabilities $ 52,413 $ 277,430 Right-of-use assets obtained in exchange for new finance lease liabilities $ — $ 8,050 Weighted average remaining lease term - finance leases (years) 47.1 Weighted average remaining lease term - operating leases (years) 14.9 Weighted average discount rate - finance leases 6.07 % Weighted average discount rate - operating leases 3.65 %
Undiscounted cash flows on an annual basis, operating leases	Following is 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 2019 $ 6,982 $ 57 $ 7,039 2020 28,331 232 28,563 2021 28,586 237 28,823 2022 28,611 255 28,866 2023 28,698 255 28,953 Thereafter 252,832 16,777 269,609 Total $ 374,040 $ 17,813 $ 391,853 Present value adjustments (94,991 ) (12,990 ) (107,981 ) Lease liabilities $ 279,049 $ 4,823 $ 283,872
Undiscounted cash flows on an annual basis, finance leases	Following is 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 2019 $ 6,982 $ 57 $ 7,039 2020 28,331 232 28,563 2021 28,586 237 28,823 2022 28,611 255 28,866 2023 28,698 255 28,953 Thereafter 252,832 16,777 269,609 Total $ 374,040 $ 17,813 $ 391,853 Present value adjustments (94,991 ) (12,990 ) (107,981 ) Lease liabilities $ 279,049 $ 4,823 $ 283,872

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Schedule of Financial Information of Business Segments	Financial information for the Company’s business segments is set forth below: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2019 2018 2019 2018 Revenues: Self-Storage Operations $ 290,917 $ 266,728 $ 841,504 $ 772,742 Tenant Reinsurance 33,588 30,105 95,086 85,660 Total segment revenues $ 324,505 $ 296,833 $ 936,590 $ 858,402 Operating expenses: Self-Storage Operations $ 88,653 $ 73,652 $ 248,288 $ 219,488 Tenant Reinsurance 7,644 7,720 21,593 18,798 Total segment operating expenses $ 96,297 $ 81,372 $ 269,881 $ 238,286 Net operating income: Self-Storage Operations $ 202,264 $ 193,076 $ 593,216 $ 553,254 Tenant Reinsurance 25,944 22,385 73,493 66,862 Total segment net operating income: $ 228,208 $ 215,461 $ 666,709 $ 620,116 Other components of net income (loss): Property management fees and other income $ 13,000 $ 10,120 $ 36,063 $ 30,849 General and administrative expense (22,519 ) (19,707 ) (68,548 ) (62,822 ) Depreciation and amortization expense (56,051 ) (52,283 ) (165,116 ) (155,924 ) Gain on real estate transactions — 30,807 1,205 30,807 Interest expense (46,908 ) (45,926 ) (141,716 ) (130,239 ) Non-cash interest expense related to the amortization of discount on equity component of exchangeable senior notes (1,186 ) (1,140 ) (3,533 ) (3,525 ) Interest income 2,799 1,371 5,905 3,997 Equity in earnings of unconsolidated real estate ventures 2,704 3,622 8,455 10,648 Income tax expense (4,052 ) (2,638 ) (8,580 ) (6,077 ) Net income $ 115,995 $ 139,687 $ 330,844 $ 337,830

Organization (Detail)

Organization (Detail)	Sep. 30, 2019storestate
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating storage facilities in which the entity has equity interests (in stores)	1,167
Number of stores owned by franchisees and third parties	630
Number of operating stores owned and/or managed	1,797
Number of states in which operating storage facilities are located | state	40

Basis of Presentation (Details)

Basis of Presentation (Details) $ in Thousands	Sep. 30, 2019USD ($)	Jan. 01, 2019USD ($)	Dec. 31, 2018lease
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities	$ 279,049
Operating lease right-of-use assets	$ 269,318
Operating ground leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of leases | lease			21
Corporate facility leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of leases | lease			2
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities		$ 104,863
Operating lease right-of-use assets		$ 95,506

Fair Value Disclosures - Assets

Fair Value Disclosures - Assets and Liabilities on a Recurring Basis (Detail) - Recurring Basis $ in Thousands	Sep. 30, 2019USD ($)
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	3,141
Other liabilities - Cash flow hedge swap agreements	43,880
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets - Cash flow hedge swap agreements	0
Other liabilities - Cash flow hedge swap agreements	$ 0

Fair Value Disclosures - Additi

Fair Value Disclosures - Additional Information (Detail)	Sep. 30, 2019land_parcel
Fair Value Disclosures [Abstract]
Number of parcels of land held-for-sale	1

Fair Value Disclosures - Schedu

Fair Value Disclosures - Schedule of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value
Fair Value of Financial Instruments [Line Items]
Notes receivable from Preferred and Common Operating Partnership unit holders	$ 118,756	$ 115,467
Fixed rate notes payable and notes payable to trusts	3,296,231	2,985,731
Exchangeable senior notes	724,500	620,149
Carrying Value
Fair Value of Financial Instruments [Line Items]
Notes receivable from Preferred and Common Operating Partnership unit holders	118,524	119,735
Fixed rate notes payable and notes payable to trusts	3,166,208	3,022,414
Exchangeable senior notes	$ 575,000	$ 575,000

Earnings Per Common Share - Add

Earnings Per Common Share - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Sep. 30, 2015	Jun. 21, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Average share price (in dollars per share)	$ 115.63	$ 92.83	$ 105.74	$ 90.09
Principal amount of notes outstanding	$ 567,705,000		$ 567,705,000		$ 562,374,000
Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Debt stated interest rate	2.375%		2.375%				2.375%
Shares related to the Notes included in the computation for diluted earnings per share (in shares)	0	0	0	0
Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Principal amount of notes outstanding	$ 575,000,000		$ 575,000,000
Debt stated interest rate	3.125%		3.125%			3.125%
Exchange price (in dollars per share)	$ 92.04		$ 92.04
Shares related to the Notes included in the computation for diluted earnings per share (in shares)	1,274,675	0	1,274,675	0
Series A Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Exchangeable preferred operating partnership units settled in cash, minimum	$ 101,700,000		$ 101,700,000
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per common share (in shares)	0	0	0	36,404

Earnings Per Common Share - Ant

Earnings Per Common Share - Antidilutive Shares (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent Shares (if converted)	1,400,920	770,669	1,470,693	1,816,010
Series B Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent Shares (if converted)	362,382	451,386	396,276	465,115
Series C Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent Shares (if converted)	0	319,283	0	328,994
Series D Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equivalent Shares (if converted)	1,038,538	0	1,074,417	1,021,901

Earnings Per Common Share - Sch

Earnings Per Common Share - Schedule of Computation (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Class of Stock [Line Items]
Net income attributable to common stockholders	$ 108,087	$ 130,418	$ 307,685	$ 313,827
Earnings and dividends allocated to participating securities	(165)	(219)	(508)	(550)
Earnings for basic computations	107,922	130,199	307,177	313,277
Earnings and dividends allocated to participating securities	165	0	0	550
Income allocated to noncontrolling interest - Preferred Operating Partnership Units and Operating Partnership Units	6,100	7,336	17,539	17,191
Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units)	(572)	(572)	(1,716)	(1,716)
Net income for diluted computations	$ 113,615	$ 136,963	$ 323,000	$ 329,302
Weighted average common shares outstanding:
Average number of common shares outstanding - basic (in shares)	128,776,549	126,466,837	127,830,272	125,959,926
OP Units (in shares)	6,050,028	5,636,845	6,032,656	5,650,599
Unvested restricted stock awards included for treasury stock method (in shares)	209,963	0	0	250,630
Shares related to exchangeable senior notes and dilutive stock options (in shares)	1,406,455	269,390	1,425,891	279,055
Average number of common shares outstanding - diluted (in shares)	137,318,475	134,240,290	136,164,299	133,015,690
Earnings per common share
Basic (in dollars per share)	$ 0.84	$ 1.03	$ 2.40	$ 2.49
Diluted (in dollars per share)	$ 0.83	$ 1.02	$ 2.37	$ 2.48
Series A Units
Weighted average common shares outstanding:
Preferred series units (in shares)	875,480	875,480	875,480	875,480
Series D Units
Weighted average common shares outstanding:
Preferred series units (in shares)	0	991,738	0	0

Store Acquisitions and Dispos_3

Store Acquisitions and Dispositions (Detail) $ in Thousands	Apr. 11, 2019USD ($)	Aug. 16, 2018USD ($)	Sep. 30, 2019USD ($)storeshares	Jun. 30, 2019USD ($)storeshares	Mar. 31, 2019USD ($)storeshares	Sep. 30, 2018USD ($)storeshares	Jun. 30, 2018USD ($)storeshares	Mar. 31, 2018USD ($)storeshares	Jun. 30, 2018store	Sep. 30, 2019USD ($)storeshares	Sep. 30, 2018USD ($)storeshares
Real Estate [Abstract]
Number of Stores | store			1	1	14	6	17	5		16	28
Total Consideration Paid			$ 16,937	$ 8,424	$ 223,740	$ 74,694	$ 237,284	$ 70,787		$ 249,101	$ 382,765
Cash Paid			16,941	8,424	202,890	71,989	148,650	70,171		228,255	290,810
Loan Assumed			0	0	17,157	0	87,500	0		17,157	87,500
Investments in Real Estate Ventures			0	0	2,780	0	(1,024)	489		2,780	(535)
Net Liabilities/ (Assets) Assumed			(4)	0	913	2,705	281	127		909	3,113
Value of OP Units Issued			$ 0	$ 0	$ 0	$ 0	$ 1,877	$ 0		$ 0	$ 1,877
Number of OP Units Issued | shares			0	0	0	0	21,768	0		0	21,768
Real estate assets			$ 16,937	$ 8,424	$ 223,740	$ 74,694	$ 237,284	$ 70,787		$ 249,101	$ 382,765
Number of stores acquired, previously held noncontrolling interest | store					12				15
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of real estate assets										$ 11,254	$ 51,889
New York store | Disposed of by sale, not discontinued operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of real estate assets	$ 11,272
Gain on sale of real estate assets	$ 1,205
California store | Disposed of by sale, not discontinued operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of real estate assets		$ 40,235
Gain on sale of real estate assets		$ 30,671

Investments in Unconsolidated_3

Investments in Unconsolidated Real Estate Ventures - Schedule of Investments (Details) $ in Thousands	1 Months Ended	3 Months Ended						9 Months Ended
	Jan. 31, 2019USD ($)store	Sep. 30, 2019USD ($)storeproperty	Jun. 30, 2019USD ($)store	Mar. 31, 2019USD ($)store	Sep. 30, 2018USD ($)store	Jun. 30, 2018USD ($)store	Mar. 31, 2018USD ($)store	Sep. 30, 2019USD ($)storeproperty	Sep. 30, 2018USD ($)store	May 31, 2019	Dec. 31, 2018USD ($)
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		242						242
Investment balance		$ 130,299						$ 130,299			$ 80,129
Number of stores acquired | store		1	1	14	6	17	5	16	28
Cash paid		$ 16,941	$ 8,424	$ 202,890	$ 71,989	$ 148,650	$ 70,171	$ 228,255	$ 290,810
PRISA Self Storage LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		85						85
Equity Ownership %		4.00%						4.00%
Excess Profit %		4.00%						4.00%
Investment balance		$ 9,182						$ 9,182			9,334
Storage Portfolio II JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		36						36
Equity Ownership %		10.00%						10.00%
Excess Profit %		30.00%						30.00%
Investment balance		$ (4,754)						$ (4,754)			(4,233)
Storage Portfolio I LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		24						24
Equity Ownership %		34.00%						34.00%
Excess Profit %		49.00%						49.00%
Investment balance		$ (38,406)						$ (38,406)			(38,129)
VRS Self Storage, LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		16						16
Equity Ownership %		45.00%						45.00%
Excess Profit %		54.00%						54.00%
Investment balance		$ 17,560						$ 17,560			18,281
ESS-NYFL JV LP
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		15						15
Equity Ownership %		16.00%						16.00%		16.00%
Excess Profit %		24.00%						24.00%
Investment balance		$ 13,931						$ 13,931			0
Extra Space Northern Properties Six LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		10						10
Equity Ownership %		10.00%						10.00%
Excess Profit %		35.00%						35.00%
Investment balance		$ (1,969)						$ (1,969)			(1,700)
WICNN JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		9						9
Equity Ownership %		10.00%						10.00%
Excess Profit %		25.00%						25.00%
Investment balance		$ 32,428						$ 32,428			26,885
Alan Jathoo JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		9						9
Equity Ownership %		10.00%						10.00%
Excess Profit %		10.00%						10.00%
Investment balance		$ 8,021						$ 8,021			8,180
ESS Bristol Investments LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		8						8
Equity Ownership %		10.00%						10.00%
Excess Profit %		28.00%						28.00%
Investment balance		$ 3,065						$ 3,065			2,331
GFN JV, LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		5						5
Equity Ownership %		10.00%						10.00%
Excess Profit %		25.00%						25.00%
Investment balance		$ 12,238						$ 12,238			10,586
Extra Space West Two LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		0						0
Equity Ownership %		5.00%						5.00%
Excess Profit %		40.00%						40.00%
Investment balance		$ 0						$ 0			3,818
Extra Space West One LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		0						0
Equity Ownership %		5.00%						5.00%
Excess Profit %		40.00%						40.00%
Investment balance		$ 0						$ 0			(1,038)
Other minority owned stores
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		25						25
Investment balance		$ 79,003						$ 79,003			$ 45,814
Other minority owned stores | Minimum
Schedule of Equity Method Investments [Line Items]
Equity Ownership %		10.00%						10.00%
Excess Profit %		19.00%						19.00%
Other minority owned stores | Maximum
Schedule of Equity Method Investments [Line Items]
Equity Ownership %		50.00%						50.00%
Excess Profit %		50.00%						50.00%
Extra Space West One and Two LLC
Schedule of Equity Method Investments [Line Items]
Equity Ownership %	100.00%
Percentage interest purchased	95.00%
Number of stores acquired | store	12
Cash paid	$ 172,505

Investments in Unconsolidated_4

Investments in Unconsolidated Real Estate Ventures - Narrative (Details) $ in Thousands	1 Months Ended	9 Months Ended
	May 31, 2019USD ($)annex_sitestorejoint_venture_partner	Sep. 30, 2019USD ($)store
Schedule of Equity Method Investments [Line Items]
Contributions to joint ventures | $		$ 56,799
Number of operating stores acquired		19
Number of stores acquired at certificate of occupancy		6
ESS-NYFL JV LP
Schedule of Equity Method Investments [Line Items]
Number of joint venture partners | joint_venture_partner	2
Contributions to joint ventures | $	$ 13,936
Number of operating stores acquired	11
Number of annex sites acquired | annex_site	4
Equity method ownership percentage	16.00%	16.00%

Variable Interests (Detail)

Variable Interests (Detail) $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended		12 Months Ended
	Jan. 31, 2019USD ($)	Sep. 30, 2019joint_venturesubsidiary	Sep. 30, 2019USD ($)joint_venturesubsidiary	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Variable Interest Entity [Line Items]
Number of wholly-owned unconsolidated subsidiaries | subsidiary		3	3
Repayments of debt			$ 30,928	$ 21,650
Number of interests in consolidated VIE joint ventures | joint_venture		0	0
Notes payable to Trusts | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Repayments of debt	$ 30,928				$ 88,662
Notes payable to Trusts					$ 30,928

Derivatives - Additional Inform

Derivatives - Additional Information (Detail) $ in Thousands	Sep. 30, 2019USD ($)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	$ 3,296
Number of derivative financial instruments | derivative	25
Combined notional amount	$ 2,402,883
Fair value, net liability position	44,985
Contingent cash settlement value	$ 45,120

Derivatives - Schedule of Balan

Derivatives - Schedule of Balance Sheet Classification and Fair Value of Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Other assets
Derivative [Line Items]
Other assets	$ 3,141	$ 42,324
Other liabilities
Derivative [Line Items]
Other liabilities	$ 43,880	$ 2,131

Derivatives - Gain (Loss) Recog

Derivatives - Gain (Loss) Recognized on Swap Agreements (Detail) - Swap Agreements - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative [Line Items]
Gain (loss) recognized in OCI	$ (14,517)	$ 8,325	$ (70,387)	$ 41,610
Gain reclassified from OCI	$ 2,992	$ 2,561	$ 11,792	$ 4,684

Exchangeable Senior Notes - Add

Exchangeable Senior Notes - Additional Information (Detail)	Jun. 21, 2013USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2019day	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)
Debt Instrument [Line Items]
Total consideration paid for repurchase					$ 1,503,686,000	$ 787,939,000
Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes)
Debt Instrument [Line Items]
Principal amount of notes issued		$ 575,000,000
Debt stated interest rate		3.125%	3.125%		3.125%
Related debt issuance costs		$ 11,992,000
Underwriting fee percentage		2.00%
Amortization period		5 years
Conversion ratio					0.01084
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 on the liability component			4.00%		4.00%
Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes) | Minimum
Debt Instrument [Line Items]
Number of days of written notice to holders of notes required for redemption		30 days
Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes) | Maximum
Debt Instrument [Line Items]
Number of days of written notice to holders of notes required for redemption		60 days
Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes)
Debt Instrument [Line Items]
Principal amount of notes issued	$ 250,000,000
Debt stated interest rate	2.375%		2.375%		2.375%
Related debt issuance costs	$ 1,672,000
Discount rate	1.50%
Unamortized cash discount	$ 3,750,000
Amortization period	5 years
Principal amount repurchased				$ 37,709,000		$ 37,709,000
Total consideration paid for repurchase				$ 58,469,000
Effective interest rate on the liability component			4.00%		4.00%

Exchangeable Senior Notes - Sch

Exchangeable Senior Notes - Schedule of Information about Total Carrying Amounts of Equity Components, Principal Amounts of Liability Components, Unamortized Discounts and Net Carrying Amounts for Notes (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2015
Debt Instrument [Line Items]
Principal amount of liability component	$ 567,705	$ 562,374
Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes)
Debt Instrument [Line Items]
Principal amount of liability component	575,000
Unamortized debt issuance costs			$ (11,992)
Senior Notes | Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes)
Debt Instrument [Line Items]
Carrying amount of equity component	22,597	22,597
Principal amount of liability component	575,000	575,000
Unamortized discount - equity component	(4,884)	(8,417)
Unamortized debt issuance costs	(2,411)	(4,209)
Net carrying amount of liability components	$ 567,705	$ 562,374

Exchangeable Senior Notes - Sum

Exchangeable Senior Notes - Summary of Amount of Interest Cost Recognized Relating to Contractual Interest Rates and Amortization of Discounts on Liability Components of Notes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Debt Disclosure [Abstract]
Contractual interest	$ 4,492	$ 4,492	$ 13,476	$ 13,614
Amortization of discount	1,186	1,140	3,533	3,525
Total interest expense recognized	$ 5,678	$ 5,632	$ 17,009	$ 17,139

Stockholders' Equity (Detail)

Stockholders' Equity (Detail)	May 15, 2019USD ($)sales_agent	Sep. 30, 2019USD ($)$ / sharesshares
Class of Stock [Line Items]
Number of sales agents | sales_agent	9
At the Market Equity Distribution Agreement
Class of Stock [Line Items]
Aggregate offering price of common shares	$ 500,000,000
Shares issued (in shares) | shares		849,200
Average sales price (in dollars per share) | $ / shares		$ 119.30
Net proceeds		$ 100,056,000
Value of stock available for issuance under ATM		$ 298,621,000

Noncontrolling Interest Repre_2

Noncontrolling Interest Represented by Preferred Operating Partnership Units (Details) - USD ($)	Apr. 25, 2019	Apr. 17, 2019	Dec. 01, 2018	Apr. 18, 2017	Jun. 25, 2007	Dec. 31, 2014	Oct. 31, 2014	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Jun. 30, 2007
Noncontrolling Interest [Line Items]
Loans and notes to affiliates								$ 100,000,000						$ 100,000,000		$ 108,644,000
Number of OP Units Issued								0	0	0	0	21,768	0	0	21,768
Value of OP Units Issued								$ 0	$ 0	$ 0	$ 0	$ 1,877,000	$ 0	$ 0	$ 1,877,000
Series A Units
Noncontrolling Interest [Line Items]
Fixed priority return on preferred OP units, amount								$ 101,700,000						$ 101,700,000
Fixed priority return on preferred OP units, stated return rate		5.00%		2.30%
Fixed priority return on preferred OP units, liquidation value							$ 101,700,000										$ 115,000,000
Preferred units outstanding (in units)							875,480
Series B Units
Noncontrolling Interest [Line Items]
Preferred units outstanding (in units)								1,676,087						1,676,087
Liquidation value (in dollars per share)								$ 25						$ 25
Fixed liquidation value								$ 41,902,000						$ 41,902,000
Annual rate of return percentage														6.00%
Series C Units
Noncontrolling Interest [Line Items]
Loans and notes to affiliates																19,735,000
Note receivable interest rate						5.00%
Liquidation value (in dollars per share)								$ 42.10						$ 42.10
Period from date of issuance after which preferred OP units will become redeemable at the option of the holder														1 year
Preferred OP units conversion ratio (in shares)														0.9145
Loan to affiliates						$ 20,230,000
Units converted (in units)	296,020		407,996
Note receivable, reduction of noncontrolling interests																8,644,000
Series D Units
Noncontrolling Interest [Line Items]
Preferred units outstanding (in units)								4,803,445						4,803,445
Liquidation value (in dollars per share)								$ 25						$ 25
Fixed liquidation value								$ 120,086,000						$ 120,086,000
Number of OP Units Issued														1,120,924
Value of OP Units Issued														$ 28,022,000
Series D Units | Minimum
Noncontrolling Interest [Line Items]
Annual rate of return percentage														3.00%
Series D Units | Maximum
Noncontrolling Interest [Line Items]
Annual rate of return percentage														5.00%
Operating Partnership Holders of A Units | Series A Units
Noncontrolling Interest [Line Items]
Loans and notes to affiliates					$ 100,000,000			100,000,000						$ 100,000,000
Maximum number of preferred OP units converted prior to the maturity date of the loan (in units)							114,500
Note receivable interest rate				2.10%	4.90%
Operating Partnership
Noncontrolling Interest [Line Items]
Issuance of units upon conversion (in units)	270,709		373,113
Note receivable, reduction of noncontrolling interests								$ 18,524,000						$ 18,524,000		$ 11,091,000

Noncontrolling Interest in Op_3

Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests - Additional Information (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Dec. 31, 2014	Sep. 30, 2019USD ($)storepropertyjoint_venture$ / sharesshares	Dec. 31, 2018USD ($)
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		$ 116.80
OP units outstanding (in units) | shares		6,025,341
Consideration to be paid on redemption of common OP units		$ 703,760
Operating Partnership
Noncontrolling Interest [Line Items]
Note receivable, reduction of noncontrolling interests		$ 18,524	$ 11,091
Common Stock
Noncontrolling Interest [Line Items]
OP units conversion ratio		1
Other noncontrolling interests
Noncontrolling Interest [Line Items]
Number of consolidated joint ventures | joint_venture		2
Operating Partnership
Noncontrolling Interest [Line Items]
Ownership interest held by entity		90.60%
Ownership percentage in joint venture by joint venture partner		9.40%
Minimum | Other noncontrolling interests
Noncontrolling Interest [Line Items]
Ownership percentage in joint venture by joint venture partner		5.00%
Maximum | Other noncontrolling interests
Noncontrolling Interest [Line Items]
Ownership percentage in joint venture by joint venture partner		20.00%
Texas | Joint Venture 1
Noncontrolling Interest [Line Items]
Number of operating stores owned | store		2
Colorado | Joint Venture 1
Noncontrolling Interest [Line Items]
Number of operating stores owned | store		2
Pennsylvania | Joint Venture 2
Noncontrolling Interest [Line Items]
Number of operating stores owned | property		1
New Jersey | Joint Venture 2
Noncontrolling Interest [Line Items]
Number of development stores owned | property		1
Series C Units
Noncontrolling Interest [Line Items]
Note receivable, reduction of noncontrolling interests			$ 8,644
Note receivable interest rate	5.00%

Noncontrolling Interest in Op_4

Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests - Schedule of OP Unit Activity (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Noncontrolling Interest [Abstract]
OP Units redeemed for common stock (in units)	239,619	25,000
OP Units redeemed for cash (in units)	0	30,000
Cash paid for OP Units redeemed	$ 0	$ 2,558
OP Units issued in conjunction with acquisitions (in units)	0	21,768
Value of OP Units issued in conjunction with acquisitions	$ 0	$ 1,877
OP Units issued upon redemption of Series C Units (in units)	270,709	0

Leases - Lease Costs (Details)

Leases - Lease Costs (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)
Finance lease cost:
Amortization of finance lease right-of-use assets	$ 42	$ 126
Interest expense related to finance lease liabilities	73	216
Operating lease cost	7,060	12,737
Variable lease cost	1,624	3,426
Short-term lease cost	28	138
Total lease cost	8,827	16,643
Cash paid for amounts included in the measurement of lease liabilities
Operating cash outflows for finance lease payments	58	173
Operating cash outflows for operating lease payments	6,573	12,122
Total cash flows for lease liability measurement	6,631	12,295
Right-of-use assets obtained in exchange for new operating lease liabilities	52,413	277,430
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 0	$ 8,050
Weighted average remaining lease term - finance leases	47 years 1 month 6 days	47 years 1 month 6 days
Weighted average remaining lease term - operating leases	14 years 10 months 24 days	14 years 10 months 24 days
Weighted average discount rate - operating leases	6.07%	6.07%
Weighted average discount rate - finance leases	3.65%	3.65%

Leases - Undiscounted Cash Flow

Leases - Undiscounted Cash Flows on an Annual Basis (Details) $ in Thousands	Sep. 30, 2019USD ($)
Operating
2019	$ 6,982
2020	28,331
2021	28,586
2022	28,611
2023	28,698
Thereafter	252,832
Total	374,040
Present value adjustments	(94,991)
Lease liabilities	279,049
Finance
2019	57
2020	232
2021	237
2022	255
2023	255
Thereafter	16,777
Total	17,813
Present value adjustments	(12,990)
Lease liabilities	4,823
Total
2019	7,039
2020	28,563
2021	28,823
2022	28,866
2023	28,953
Thereafter	269,609
Total	391,853
Present value adjustments	(107,981)
Lease liabilities	$ 283,872

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Thousands	1 Months Ended		9 Months Ended
	Aug. 31, 2019USD ($)store	Jun. 30, 2019USD ($)store	Sep. 30, 2019USD ($)leaseextension	Jan. 01, 2019USD ($)
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets			$ 269,318
Operating lease liabilities			$ 279,049
Number of stores added under new operating leases | 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
Increase in operating lease liabilities under new operating leases		$ 127,532
Store leases
Lessee, Lease, Description [Line Items]
Number of leases | lease			49
Store leases | Minimum
Lessee, Lease, Description [Line Items]
Operating and finance lease, original lease term			10 years
Operating and finance lease, extension term			5 years
Store leases | Maximum
Lessee, Lease, Description [Line Items]
Operating and finance lease, original lease term			67 years
Operating and finance lease, extension term			35 years
Corporate offices and call center leases | Minimum
Lessee, Lease, Description [Line Items]
Operating lease, original lease term			5 years 3 months 18 days
Corporate offices and call center leases | Maximum
Lessee, Lease, Description [Line Items]
Operating lease, original lease term			12 years 1 month 6 days
Regional office leases
Lessee, Lease, Description [Line Items]
Number of leases | lease			13
Operating lease, number of options to extend | extension			5,000
Operating lease, extension term			3 years
Regional office leases | Maximum
Lessee, Lease, Description [Line Items]
Operating lease, original lease term			5 years
District office leases
Lessee, Lease, Description [Line Items]
Operating lease, original lease term			12 months
New Jersey store lease
Lessee, Lease, Description [Line Items]
Lease not yet commenced, lease term			75 years
Lease not yet commenced, number of extension options | extension			3
Lease not yet commenced, term of extension options			10 years
California store lease
Lessee, Lease, Description [Line Items]
Lease not yet commenced, lease term			15 years
California store lease | Lease option one
Lessee, Lease, Description [Line Items]
Lease not yet commenced, number of extension options | extension			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			1
Lease not yet commenced, term of extension options			5 years
ASU 2016-02
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets				$ 95,506
Operating lease liabilities				$ 104,863

Segment Information - Additiona

Segment Information - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2019segment
Segment Reporting [Abstract]
Number of reportable segments	2

Segment Information - Schedule

Segment Information - Schedule of Financial Information (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Revenues:	$ 337,505			$ 306,953			$ 972,653	$ 889,251
Operating expenses:	174,867			153,362			503,545	457,032
Income from operations	162,638			184,398			470,313	463,026
Management fees and other income	13,000			10,120			36,063	30,849
General and administrative expense	(22,519)			(19,707)			(68,548)	(62,822)
Depreciation and amortization expense	(56,051)			(52,283)			(165,116)	(155,924)
Gain on real estate transactions	0			30,807			1,205	30,807
Interest expense	(46,908)			(45,926)			(141,716)	(130,239)
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	(1,186)			(1,140)			(3,533)	(3,525)
Interest income	2,799			1,371			5,905	3,997
Equity in earnings of unconsolidated real estate ventures	2,704			3,622			8,455	10,648
Income tax expense	(4,052)			(2,638)			(8,580)	(6,077)
Net income	115,995	$ 112,689	$ 102,160	139,687	$ 102,713	$ 95,430	330,844	337,830
Operating Segments
Segment Reporting Information [Line Items]
Revenues:	324,505			296,833			936,590	858,402
Operating expenses:	96,297			81,372			269,881	238,286
Income from operations	228,208			215,461			666,709	620,116
Operating Segments | Self-Storage Operations
Segment Reporting Information [Line Items]
Revenues:	290,917			266,728			841,504	772,742
Operating expenses:	88,653			73,652			248,288	219,488
Income from operations	202,264			193,076			593,216	553,254
Operating Segments | Tenant Reinsurance
Segment Reporting Information [Line Items]
Revenues:	33,588			30,105			95,086	85,660
Operating expenses:	7,644			7,720			21,593	18,798
Income from operations	$ 25,944			$ 22,385			$ 73,493	$ 66,862

Commitments and Contingencies (

Commitments and Contingencies (Detail) $ in Thousands	Sep. 30, 2019USD ($)store
Commitment To Acquire Retail Space
Other Commitments [Line Items]
Number of real estate properties to be acquired	4
Purchase price | $	$ 41,828
Commitment To Acquire Retail Space With Joint Venture Partners
Other Commitments [Line Items]
Number of real estate properties to be acquired	5
Purchase price | $	$ 31,384
Commitment To Acquire Retail Space With Joint Venture Partners, Scheduled To Close in 2019
Other Commitments [Line Items]
Number of stores scheduled to be closed	3

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ in Thousands	Oct. 29, 2019	Sep. 30, 2019	Sep. 30, 2018
Subsequent Event [Line Items]
Amount invested		$ 33,661	$ 52,806
SmartStop Self Storage REIT | Subsequent Event
Subsequent Event [Line Items]
Amount invested	$ 150,000
Investment commitment	$ 50,000
Investment commitment, period	12 months
Investment, preferred dividend rate	6.25%
Period after which preferred stock dividend is subject to increase	5 years
Period after which preferred stock is redeemable	5 years