National Storage Affiliates Trust (NSA) 10-Q 3 May 19 2019 Q1 Quarterly report Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION - shares	3 Months Ended
	Mar. 31, 2019	May 02, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	National Storage Affiliates Trust
Entity Central Index Key	0001618563
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		56,882,863

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Real estate
Self storage properties	$ 2,832,745	$ 2,637,723
Less accumulated depreciation	(267,796)	(246,261)
Self storage properties, net	2,564,949	2,391,462
Cash and cash equivalents	15,878	13,181
Restricted cash	3,545	3,182
Debt issuance costs, net	1,017	1,260
Investment in unconsolidated real estate ventures	238,606	245,125
Other assets, net	48,926	75,053
Operating lease right-of-use assets	23,110	0
Total assets	2,896,031	2,729,263
Liabilities
Debt financing	1,414,926	1,278,102
Accounts payable and accrued liabilities	37,682	33,130
Operating lease liabilities	24,166	0
Deferred revenue	16,069	15,732
Total liabilities	1,492,843	1,326,964
Commitments and contingencies (Note 11)
Equity
Preferred shares of beneficial interest, par value $0.01 per share. 50,000,000 authorized, 6,900,000 issued and outstanding at March 31, 2019 and December 31, 2018, at liquidation preference	172,500	172,500
Common shares of beneficial interest, par value $0.01 per share. 250,000,000 shares authorized, 56,698,686 and 56,654,009 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	567	567
Additional paid-in capital	839,162	844,276
Distributions in excess of earnings	(126,309)	(114,122)
Accumulated other comprehensive income	7,526	13,618
Total shareholders' equity	893,446	916,839
Noncontrolling interests	509,742	485,460
Total equity	1,403,188	1,402,299
Total liabilities and equity	$ 2,896,031	$ 2,729,263

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Series A Preferred shares of beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Series A Preferred shares of beneficial interest, authorized (in shares)	50,000,000	50,000,000
Series A Preferred shares of beneficial interest, issued (in shares)	6,900,000	6,900,000
Series A Preferred shares of beneficial interest, outstanding (in shares)	6,900,000	6,900,000
Common shares of beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares of beneficial interest, authorized (in shares)	250,000,000	250,000,000
Common shares of beneficial interest, issued (in shares)	56,698,686	56,654,009
Common shares of beneficial interest, outstanding (in shares)	56,698,686	56,654,009

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
REVENUE
Rental revenue	$ 82,855
Rental revenue		$ 72,011
Total revenue	90,572	76,493
OPERATING EXPENSES
Property operating expenses	26,457	25,226
General and administrative expenses	10,766	8,306
Depreciation and amortization	24,349	21,368
Total operating expenses	61,572	54,900
OTHER (EXPENSE) INCOME
Interest expense	(13,211)	(9,635)
Equity in losses of unconsolidated real estate ventures	(2,102)	(52)
Acquisition costs	(157)	(180)
Non-operating expense	(98)	(84)
Gain on sale of self storage properties	0	474
Other expense	(15,568)	(9,477)
Income before income taxes	13,432	12,116
Income tax expense	(492)	(143)
Net income	12,940	11,973
Net income attributable to noncontrolling interests	(5,529)	(1,513)
Net income attributable to National Storage Affiliates Trust	7,411	10,460
Distributions to preferred shareholders	(2,588)	(2,588)
Net income attributable to common shareholders	$ 4,823	$ 7,872
Earnings (loss) per common share - basic and diluted
Earnings (loss) per share - basic	$ 0.08	$ 0.16
Earnings (loss) per share - diluted	$ 0.08	$ 0.09
Weighted average shares outstanding - basic	56,655	50,299
Weighted average shares outstanding - diluted	56,655	99,935
Dividends declared per common share	$ 0.3	$ 0.28
Other property-related revenue
REVENUE
Revenue	$ 2,824	$ 2,321
Management fees and other revenue
REVENUE
Revenue	$ 4,893	$ 2,161

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 12,940	$ 11,973
Other comprehensive (loss) income
Unrealized (loss) gain on derivative contracts	(8,039)	8,990
Reclassification of other comprehensive (income) loss to interest expense	(1,276)	49
Other comprehensive (loss) income	(9,315)	9,039
Comprehensive income	3,625	21,012
Comprehensive income attributable to noncontrolling interests	(2,131)	(5,004)
Comprehensive income attributable to National Storage Affiliates Trust	$ 1,494	$ 16,008

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Series A-1 preferred units, OP units, and subordinated performance units	OP units	Preferred Shares	Common Shares	Additional Paid-in Capital	Distributions In Excess Of Earnings	Accumulated Other Comprehensive Income	Noncontrolling Interests	Noncontrolling InterestsSeries A-1 preferred units, OP units, and subordinated performance units	Noncontrolling InterestsOP units
Balances (in shares) at Dec. 31, 2017				6,900,000
Balances (in shares) at Dec. 31, 2017					50,284,934
Balances at Dec. 31, 2017	$ 1,271,487			$ 172,500	$ 503	$ 711,467	$ (55,729)	$ 12,282	$ 430,464
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of equity units		$ 22,403	$ 5							$ 22,403	$ 5
Redemptions of OP units (in shares)					145,334
Redemptions of OP units	0				$ 1	1,921		51	(1,973)
Effect of changes in ownership for consolidated entities	0					(12,621)		(396)	13,017
Equity-based compensation expense	867					70			797
Issuance of restricted common shares (in shares)					12,311
Issuance of restricted common shares	0
Vesting and forfeitures of restricted common shares, net (in shares)					(3,848)
Vesting and forfeitures of restricted common shares, net	(75)					(75)
Reduction in receivables from partners of the operating partnership	191								191
Preferred share dividends	(2,588)						(2,588)
Common share dividends	(14,099)						(14,099)
Distributions to noncontrolling interests	(14,515)								(14,515)
Other comprehensive income	9,039							5,548	3,491
Net income	11,973						10,460		1,513
Balances (in shares) at Mar. 31, 2018				6,900,000
Balances (in shares) at Mar. 31, 2018					50,438,731
Balances at Mar. 31, 2018	$ 1,284,688			$ 172,500	$ 504	700,762	(61,956)	17,485	455,393
Balances (in shares) at Dec. 31, 2018	6,900,000			6,900,000
Balances (in shares) at Dec. 31, 2018	56,654,009				56,654,009
Balances at Dec. 31, 2018	$ 1,402,299			$ 172,500	$ 567	844,276	(114,122)	13,618	485,460
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of equity units		$ 32,856								$ 32,856
Redemptions of OP units (in shares)					29,910
Redemptions of OP units	0				$ 0	250		7	(257)
Effect of changes in ownership for consolidated entities	0					(5,385)		(182)	5,567
Equity-based compensation expense	1,112					90			1,022
Issuance of LTIP units for acquisition expenses	5								5
Issuance of restricted common shares (in shares)					18,218
Issuance of restricted common shares	0
Vesting and forfeitures of restricted common shares, net (in shares)					(3,451)
Vesting and forfeitures of restricted common shares, net	(69)					(69)
Reduction in receivables from partners of the operating partnership	139								139
Preferred share dividends	(2,588)						(2,588)
Common share dividends	(17,010)						(17,010)
Distributions to noncontrolling interests	(17,181)								(17,181)
Other comprehensive income	(9,315)							(5,917)	(3,398)
Net income	$ 12,940						7,411		5,529
Balances (in shares) at Mar. 31, 2019	6,900,000			6,900,000
Balances (in shares) at Mar. 31, 2019	56,698,686				56,698,686
Balances at Mar. 31, 2019	$ 1,403,188			$ 172,500	$ 567	$ 839,162	$ (126,309)	$ 7,526	$ 509,742

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 12,940	$ 11,973
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	24,349	21,368
Amortization of debt issuance costs	693	590
Amortization of debt discount and premium, net	(352)	(373)
Gain on sale of self storage properties	0	(474)
Equity-based compensation expense	1,112	867
Equity in losses of unconsolidated real estate ventures	2,102	52
Distributions from unconsolidated real estate ventures	3,400	1,339
Change in assets and liabilities, net of effects of self storage property acquisitions:
Other assets	2,008	(854)
Accounts payable and accrued liabilities	607	(808)
Deferred revenue	(461)	179
Net Cash Provided by Operating Activities	46,398	33,859
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisition of self storage properties	(139,579)	(100,450)
Capital expenditures	(4,208)	(3,901)
Investments in and advances to unconsolidated real estate ventures	0	(2,390)
Distributions from unconsolidated real estate ventures	1,017	0
Deposits and advances for self storage property and other acquisitions	811	342
Expenditures for corporate furniture, equipment and other	(125)	(51)
Proceeds from sale of self storage properties	0	2,029
Net Cash Used In Investing Activities	(143,706)	(105,105)
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings under debt financings	188,500	250,000
Receipts for OP unit subscriptions	318	312
Principal payments under debt financings	(51,778)	(145,212)
Payment of dividends to common shareholders	(17,010)	(14,099)
Distributions to preferred shareholders	(2,588)	(2,588)
Distributions to noncontrolling interests	(17,002)	(14,369)
Debt issuance costs	(22)	(796)
Equity offering costs	(50)	(218)
Net Cash Provided By Financing Activities	100,368	73,030
Increase in Cash, Cash Equivalents and Restricted Cash	3,060	1,784
CASH, CASH EQUIVALENTS AND RESTRICTED CASH
Beginning of period	16,363	16,407
End of period	19,423	18,191
Supplemental Cash Flow Information
Cash paid for interest	12,142	$ 8,939
Operating lease right-of-use assets added upon implementation of leases standard	23,110
Operating lease liabilities added upon implementation of leases standard	$ 24,166

ORGANIZATION AND NATURE OF OPER

ORGANIZATION AND NATURE OF OPERATIONS	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION AND NATURE OF OPERATIONS	ORGANIZATION AND NATURE OF OPERATIONS National Storage Affiliates Trust was organized in the state of Maryland on May 16, 2013 and is a fully integrated, self-administered and self-managed real estate investment trust focused on the self storage sector. As used herein, "NSA," the "Company," "we," "our," and "us" refers to National Storage Affiliates Trust and its consolidated subsidiaries, except where the context indicates otherwise. The Company has elected and believes that it has qualified to be taxed as a real estate investment trust for U.S. federal income tax purposes ("REIT") commencing with its taxable year ended December 31, 2015. Through its controlling interest as the sole general partner of NSA OP, LP (its "operating partnership"), a Delaware limited partnership formed on February 13, 2013, the Company is focused on the ownership, operation, and acquisition of self storage properties located within the top 100 metropolitan statistical areas throughout the United States. Pursuant to the Agreement of Limited Partnership (as amended, the "LP Agreement") of its operating partnership, the Company's operating partnership is authorized to issue preferred units, Class A Units ("OP units"), different series of Class B Units ("subordinated performance units"), and Long-Term Incentive Plan Units ("LTIP units"). The Company also owns certain of its self storage properties through other consolidated limited partnership subsidiaries of its operating partnership, which the Company refers to as "DownREIT partnerships." The DownREIT partnerships issue equity ownership interests that are intended to be economically equivalent to the Company's OP units ("DownREIT OP units") and subordinated performance units ("DownREIT subordinated performance units"). The Company owned 531 consolidated self storage properties in 28 states and Puerto Rico with approximately 32.1 million rentable square feet in approximately 257,000 storage units as of March 31, 2019 . These properties are managed with local operational focus and expertise by the Company and its participating regional operators ("PROs"). These PROs are SecurCare Self Storage, Inc. and its controlled affiliates ("SecurCare"), Kevin Howard Real Estate Inc., d/b/a Northwest Self Storage and its controlled affiliates ("Northwest"), Optivest Properties LLC and its controlled affiliates ("Optivest"), Guardian Storage Centers LLC and its controlled affiliates ("Guardian"), Move It Self Storage and its controlled affiliates ("Move It"), Arizona Mini Storage Management Company d/b/a Storage Solutions and its controlled affiliates ("Storage Solutions"), Hide-Away Storage Services, Inc. and its controlled affiliates ("Hide-Away"), an affiliate of Shader Brothers Corporation d/b/a Personal Mini Storage ("Personal Mini"), Southern Self Storage, LLC d/b/a Southern Self Storage ("Southern") and affiliates of Investment Real Estate Management, LLC d/b/a Moove In Self Storage of York, Pennsylvania ("Moove In"). As of March 31, 2019 , the Company also managed through its property management platform an additional portfolio of 175 properties owned by the Company's unconsolidated real estate ventures. These properties contain approximately 12.6 million rentable square feet, configured in approximately 104,000 storage units and located across 21 states. The Company owns a 25% equity interest in each of its unconsolidated real estate ventures. As of March 31, 2019 , in total, the Company operated and held ownership interests in 706 self storage properties located across 34 states and Puerto Rico with approximately 44.7 million rentable square feet in approximately 361,000 storage units.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying condensed consolidated financial statements are presented on the accrual basis of accounting in accordance with U.S. generally accepted accounting principles ("GAAP") and have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (the "SEC") regarding interim financial reporting. Accordingly, certain information and footnote disclosures required by GAAP for complete financial statements have been condensed or omitted in accordance with such rules and regulations. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation of the condensed consolidated financial statements have been included. The Company's results of operations for the quarterly period ended March 31, 2019 are not necessarily indicative of the results to be expected for the full year or any other future period. Principles of Consolidation The Company's financial statements include the accounts of its operating partnership and its controlled subsidiaries. All significant intercompany balances and transactions have been eliminated in the consolidation of entities. When the Company obtains an economic interest in an entity, the Company evaluates the entity to determine if the entity is deemed a variable interest entity ("VIE"), and if the Company is deemed to be the primary beneficiary, in accordance with authoritative guidance issued on the consolidation of VIEs. When an entity is not deemed to be a VIE, the Company considers the provisions of additional guidance to determine whether the general partner controls a limited partnership or similar entity when the limited partners have certain rights. The Company consolidates all entities that are VIEs and of which the Company is deemed to be the primary beneficiary. The Company has determined that its operating partnership is a VIE. The sole significant asset of National Storage Affiliates Trust is its investment in its operating partnership, and consequently, substantially all of the Company’s assets and liabilities represent those assets and liabilities of its operating partnership. As of March 31, 2019 and December 31, 2018 , the Company's operating partnership was the primary beneficiary of, and therefore consolidated, 21 DownREIT partnerships that are considered VIEs, which owned 34 self storage properties. The net book value of the real estate owned by these VIEs was $238.7 million and $240.4 million as of March 31, 2019 and December 31, 2018 , respectively. For certain DownREIT partnerships which are subject to fixed rate mortgages payable, the carrying value of such fixed rate mortgages payable held by these VIEs was $137.9 million and $138.4 million as of March 31, 2019 and December 31, 2018 , respectively. The creditors of the consolidated VIEs do not have recourse to the Company's general credit. Revenue Recognition Rental revenue Rental revenue consists of space rentals and related fees. Management has determined that all of the Company's leases are operating leases. Substantially all leases may be terminated on a month-to-month basis and rental income is recognized ratably over the lease term using the straight-line method. Rents received in advance are deferred and recognized on a straight-line basis over the related lease term associated with the prepayment. Promotional discounts and other incentives are recognized as a reduction to rental income over the applicable lease term. Other property-related revenue Other property-related revenue primarily consists of ancillary revenues such as tenant insurance and/or tenant warranty protection-related access fees and sales of storage supplies which are recognized in the period earned. The Company and certain of the Company’s PROs have tenant insurance- and/or tenant warranty protection plan-related arrangements with insurance companies and the Company’s tenants. During the three months ended March 31, 2019 and 2018 , the Company recognized $2.1 million and $1.7 million , respectively, of tenant insurance and tenant warranty protection plan revenues. The Company sells boxes, packing supplies, locks and other retail merchandise at its properties. During the three months ended March 31, 2019 and 2018 , the Company recognized retail sales of $0.4 million and $0.4 million , respectively. Management fees and other revenue Management fees and other revenue consist of property management fees, platform fees, call center fees, acquisition fees, and a portion of tenant warranty protection or tenant insurance proceeds that the Company earns for managing and operating its unconsolidated real estate ventures. With respect to both the 2018 Joint Venture and the 2016 Joint Venture (as each are defined in Note 5), the Company provides supervisory and administrative property management services, centralized call center services, and technology platform and revenue management services to the properties in the unconsolidated real estate ventures. The property management fees are equal to 6% of monthly gross revenues and net sales revenues from the assets of the unconsolidated real estate ventures, and the platform fees are equal to $1,250 per month per unconsolidated real estate venture property. With respect to the 2016 Joint Venture only, the call center fees are equal to 1% of each of monthly gross revenues and net sales revenues from the 2016 Joint Venture properties. During the three months ended March 31, 2019 and 2018 , the Company recognized property management fees, call center fees and platform fees of $3.2 million and $1.3 million , respectively. For acquisition fees, the Company provides sourcing, underwriting and administration services to the unconsolidated real estate ventures. The 2016 Joint Venture paid the Company a $4.1 million acquisition fee equal to 0.65% of the gross capitalization (including debt and equity) of the original 66 -property 2016 Joint Venture portfolio (the "Initial 2016 JV Portfolio") in 2016, at the time of the Initial 2016 JV Portfolio acquisition. The 2018 Joint Venture paid the Company a $4.0 million acquisition fee related to the initial acquisition of properties by the 2018 Joint Venture (the "Initial 2018 JV Portfolio") in 2018, at the time of the Initial 2018 JV Portfolio acquisition. These fees are refundable to the unconsolidated real estate ventures, on a prorated basis, if the Company is removed as the managing member during the initial four year life of the unconsolidated real estate ventures and as such, the Company's performance obligation for these acquisition fees are satisfied over a four year period. As of March 31, 2019 and December 31, 2018 , the Company had deferred revenue related to the acquisition fees of $4.1 million and $4.6 million , respectively. The Company also earns acquisition fees for properties acquired by the unconsolidated real estate ventures subsequent to the Initial 2016 JV Portfolio and the Initial 2018 JV Portfolio. These fees are based on a percentage of the gross capitalization of the acquired assets determined by the members of the 2016 Joint Venture and the 2018 Joint Venture, and are generally earned when the unconsolidated real estate ventures obtain title and control of an acquired property. During the three months ended March 31, 2019 and 2018 , the Company recognized acquisition fees of $0.5 million and $0.3 million , respectively. An affiliate of the Company facilitates tenant warranty protection or tenant insurance programs for tenants of the properties in the unconsolidated real estate ventures in exchange for 50% of all proceeds from such programs at each unconsolidated real estate venture property. During the three months ended March 31, 2019 and 2018 , the Company recognized $1.2 million and $0.5 million , respectively, of revenue related to these activities. Gain on sale of self storage properties The Company recognizes gains from disposition of facilities only upon closing in accordance with the guidance on sales of nonfinancial assets. Profit on real estate sold is recognized upon closing when all, or substantially all, of the promised consideration has been received and is nonrefundable and the Company has transferred control of the facilities to the purchaser. Investments in Unconsolidated Real Estate Ventures The Company’s investments in its unconsolidated real estate ventures are recorded under the equity method of accounting in the accompanying condensed consolidated financial statements. Under the equity method, the Company’s investments in unconsolidated real estate ventures are stated at cost and adjusted for the Company’s share of net earnings or losses and reduced by distributions. Equity in earnings (losses) is recognized based on the Company’s ownership interest in the earnings (losses) of the unconsolidated real estate ventures. The Company follows the "nature of the distribution approach" for classification of distributions from its unconsolidated real estate ventures in its condensed consolidated statements of cash flows. Under this approach, distributions are reported on the basis of the nature of the activity or activities that generated the distributions as either a return on investment, which are classified as operating cash flows, or a return of investment (e.g., proceeds from the unconsolidated real estate ventures' sale of assets) which are reported as investing cash flows. Noncontrolling Interests All of the limited partner equity interests ("OP equity") in the operating partnership not held by the Company are reflected as noncontrolling interests. Noncontrolling interests also include ownership interests in DownREIT partnerships held by entities other than the operating partnership or its subsidiaries. In the condensed consolidated statements of operations, the Company allocates net income (loss) attributable to noncontrolling interests to arrive at net income (loss) attributable to National Storage Affiliates Trust. For transactions that result in changes to the Company's ownership interest in its operating partnership, the carrying amount of noncontrolling interests is adjusted to reflect such changes. The difference between the fair value of the consideration received or paid and the amount by which the noncontrolling interest is adjusted is reflected as an adjustment to additional paid-in capital on the condensed consolidated balance sheets. Allocation of Net Income (Loss) The distribution rights and priorities set forth in the operating partnership's LP Agreement differ from what is reflected by the underlying percentage ownership interests of the unitholders. Accordingly, the Company allocates GAAP income (loss) utilizing the hypothetical liquidation at book value ("HLBV") method, in which the Company allocates income or loss based on the change in each unitholders’ claim on the net assets of its operating partnership at period end after adjusting for any distributions or contributions made during such period. The HLBV method is commonly applied to equity investments where cash distribution percentages vary at different points in time and are not directly linked to an equity holder’s ownership percentage. The HLBV method is a balance sheet-focused approach to income (loss) allocation. A calculation is prepared at each balance sheet date to determine the amount that unitholders would receive if the operating partnership were to liquidate all of its assets (at GAAP net book value) and distribute the resulting proceeds to its creditors and unitholders based on the contractually defined liquidation priorities. The difference between the calculated liquidation distribution amounts at the beginning and the end of the reporting period, after adjusting for capital contributions and distributions, is used to derive each unitholder's share of the income (loss) for the period. Due to the stated liquidation priorities and because the HLBV method incorporates non-cash items such as depreciation expense, in any given period, income or loss may be allocated disproportionately to unitholders as compared to their respective ownership percentage in the operating partnership, and net income (loss) attributable to National Storage Affiliates Trust could be more or less net income than actual cash distributions received and more or less income or loss than what may be received in the event of an actual liquidation. Additionally, the HLBV method could result in net income (or net loss) attributable to National Storage Affiliates Trust during a period when the Company reports consolidated net loss (or net income), or net income (or net loss) attributable to National Storage Affiliates Trust in excess of the Company's consolidated net income (or net loss). The computations of basic and diluted earnings (loss) per share may be materially affected by these disproportionate income (loss) allocations, resulting in volatile fluctuations of basic and diluted earnings (loss) per share. Other Comprehensive Income (Loss) The Company has cash flow hedge derivative instruments that are measured at fair value with unrealized gains or losses recognized in other comprehensive income (loss) with a corresponding adjustment to accumulated other comprehensive income (loss) within equity, as discussed further in Note 12. Under the HLBV method of allocating income (loss) discussed above, a calculation is prepared at each balance sheet date by applying the HLBV method including, and excluding, the assets and liabilities resulting from the Company's cash flow hedge derivative instruments to determine comprehensive income (loss) attributable to National Storage Affiliates Trust. As a result of the distribution rights and priorities set forth in the operating partnership's LP Agreement, in any given period, other comprehensive income (loss) may be allocated disproportionately to unitholders as compared to their respective ownership percentage in the operating partnership and as compared to their respective allocation of net income (loss). Restricted Cash The Company's restricted cash consists of escrowed funds deposited with financial institutions for real estate taxes, insurance and other reserves for capital improvements in accordance with the Company's loan agreements. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board ("FASB") issued ASU 2016-02, Leases, which amends the existing guidance for accounting for leases, including requiring lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases and lessees to recognize most leases on-balance sheet as lease liabilities with corresponding right-of-use assets. In July 2018, the FASB issued ASU 2018-11, Leases - Targeted Improvements, which allows entities the option to apply the new standard at adoption date with a cumulative-effect adjustment in the period of adoption. The Company adopted ASU 2016-02 and ASU 2018-11 effective January 1, 2019 and applied it to leases that were in place on the effective date. The Company elected the practical expedients which permit the Company to combine lease and nonlease components and to not reassess (i) whether any expired or existing contracts are or contain leases, (ii) the lease classification for any expired or existing leases, and (iii) any initial direct costs for any existing leases as of the effective date. Results for reporting periods beginning January 1, 2019 are presented under ASU 2016-02 and ASU 2018-11. As a result, beginning on January 1, 2019, activity related to uncollectible accounts are recognized as a current-period adjustment within revenue. For periods prior to January 1, 2019, such amounts were previously included in operating expenses. The adoption of the lease standard did not result in a cumulative catch-up adjustment to opening equity. See Note 13 for additional detail about the Company's non-cancelable leasehold interest agreements where the Company is a lessee.

NONCONTROLLING INTERESTS

NONCONTROLLING INTERESTS	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
SHAREHOLDERS' AND NONCONTROLLING INTERESTS	NONCONTROLLING INTERESTS Noncontrolling Interests All of the OP equity in the Company's operating partnership not held by the Company are reflected as noncontrolling interests. Noncontrolling interests also include ownership interests in DownREIT partnerships held by entities other than the Company's operating partnership. NSA is the general partner of its operating partnership and is authorized to cause its operating partnership to issue additional partner interests, including OP units and subordinated performance units, at such prices and on such other terms as it determines in its sole discretion. As of March 31, 2019 and December 31, 2018 , units reflecting noncontrolling interests consisted of the following: March 31, 2019 December 31, 2018 Series A-1 preferred units 501,918 343,719 OP units 30,229,228 28,874,103 Subordinated performance units 10,739,868 10,749,475 LTIP units 762,720 931,671 DownREIT units DownREIT OP units 1,848,261 1,834,786 DownREIT subordinated performance units 4,371,622 4,386,999 Total 48,453,617 47,120,753 Series A-1 Preferred Units The 6.000% Series A-1 Cumulative Redeemable Preferred Units ("Series A-1 preferred units") rank senior to OP units and subordinated performance units in the Company's operating partnership with respect to distributions and liquidation. The Series A-1 preferred units have a stated value of $25.00 per unit and receive distributions at an annual rate of 6.000% . These distributions are cumulative. The Series A-1 preferred units are redeemable at the option of the holder after the first anniversary of the date of issuance, which redemption obligations may be satisfied at the Company’s option in cash in an amount equal to the market value of an equivalent number of the Company's 6.000% Series A cumulative redeemable preferred shares of beneficial interest ("Series A preferred shares") or the issuance of Series A preferred shares on a one -for-one basis, subject to adjustments. The increase in Series A-1 preferred units outstanding from December 31, 2018 to March 31, 2019 was due to the issuance of Series A-1 preferred units in connection with the acquisition of self storage properties. OP Units and DownREIT OP units OP units in the Company's operating partnership are redeemable for cash or, at the Company's option, exchangeable for the Company's common shares of beneficial interest, $0.01 par value per share ("common shares") on a one -for-one basis, and DownREIT OP units are redeemable for cash or, at the Company's option, exchangeable for OP units in its operating partnership on a one -for-one basis, subject to certain adjustments in each case. The OP holders of OP units are generally not entitled to elect redemption until one year after the issuance of the OP units. The holders of DownREIT OP units are generally not entitled to elect redemption until five years after the date of the contributor's initial contribution. The increase in OP Units outstanding from December 31, 2018 to March 31, 2019 was due to the issuance of 863,148 OP units related to the voluntary conversions of 913,680 subordinated performance units (as discussed further below), the issuance of 184,040 OP units in connection with the acquisition of self storage properties and 337,847 LTIP units which were converted into OP units, partially offset by the redemption of 29,910 OP units for common shares. The increase in DownREIT OP units outstanding from December 31, 2018 to March 31, 2019 was due to the issuance of 13,475 DownREIT OP units related to the conversion of 15,377 DownREIT subordinated performance units (as discussed further below). Subordinated Performance Units and DownREIT Subordinated Performance Units Subordinated performance units may also, under certain circumstances, be convertible into OP units which are exchangeable for common shares as described above, and DownREIT subordinated performance units may, under certain circumstances, be exchangeable for subordinated performance units on a one -for-one basis. Subordinated performance units are only convertible into OP units after a two year lock-out period and then generally (i) at the holder’s election only upon the achievement of certain performance thresholds relating to the properties to which such subordinated performance units relate or (ii) at the Company's election upon a retirement event of a PRO that holds such subordinated performance units or upon certain qualifying terminations. The holders of DownREIT subordinated performance units are generally not entitled to elect redemption until at least five years after the date of the contributor's initial contribution. Following such lock-out period, a holder of subordinated performance units in the Company's operating partnership may elect a voluntary conversion one time each year prior to December 1st to convert a pre-determined portion of such subordinated performance units into OP units in the Company's operating partnership, with such conversion effective January 1st of the following year, with each subordinated performance unit being converted into the number of OP units determined by dividing the average cash available for distribution, or CAD, per unit on the series of specific subordinated performance units over the one-year period prior to conversion by 110% of the CAD per unit on the OP units determined over the same period. CAD per unit on the series of specific subordinated performance units and OP units is determined by the Company based generally upon the application of the provisions of the LP Agreement applicable to the distributions of operating cash flow and capital transactions proceeds. The decrease in subordinated performance units outstanding from December 31, 2018 to March 31, 2019 was due to the voluntary conversion of 913,680 subordinated performance units into 863,148 OP units partially offset by the issuance of 904,073 subordinated performance units for co-investment by certain of the Company's PROs in connection with the acquisition of self storage properties. The decrease in DownREIT subordinated performance units outstanding from December 31, 2018 to March 31, 2019 was due to the conversion of 15,377 DownREIT subordinated performance units into 13,475 DownREIT OP units. LTIP Units LTIP units are a special class of partnership interest in the Company's operating partnership that allow the holder to participate in the ordinary and liquidating distributions received by holders of the OP units (subject to the achievement of specified levels of profitability by the Company's operating partnership or the achievement of certain events). LTIP units may also, under certain circumstances, be convertible into OP units on a one -for-one basis, which are then exchangeable for common shares as described above. The decrease in LTIP units outstanding from December 31, 2018 to March 31, 2019 was due to the conversion of 337,847 LTIP units into OP units partially offset by the issuance of 168,896 compensatory LTIP units to employees and consultants.

SELF STORAGE PROPERTIES

SELF STORAGE PROPERTIES	3 Months Ended
	Mar. 31, 2019
Real Estate [Abstract]
SELF STORAGE PROPERTIES	SELF STORAGE PROPERTIES Self storage properties are summarized as follows (dollars in thousands): March 31, 2019 December 31, 2018 Land $ 612,273 $ 583,455 Buildings and improvements 2,214,345 2,048,281 Furniture and equipment 6,127 5,987 Total self storage properties 2,832,745 2,637,723 Less accumulated depreciation (267,796 ) (246,261 ) Self storage properties, net $ 2,564,949 $ 2,391,462 Depreciation expense related to self storage properties amounted to $21.5 million and $18.0 million during the three months ended March 31, 2019 and 2018 , respectively.

INVESTMENT IN UNCONSOLIDATED RE

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES	3 Months Ended
	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES	INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES 2018 Joint Venture As of March 31, 2019 , the Company's unconsolidated real estate venture, formed in September 2018 with an affiliate of Heitman America Real Estate REIT LLC (the "2018 Joint Venture"), owned and operated a portfolio of 103 self storage properties containing approximately 7.7 million rentable square feet, configured in over 63,000 storage units and located across 17 states. 2016 Joint Venture As of March 31, 2019 , the Company's unconsolidated real estate venture, formed in September 2016 with a state pension fund advised by Heitman Capital Management LLC (the "2016 Joint Venture"), owned and operated a portfolio of 72 properties containing approximately 4.9 million rentable square feet, configured in approximately 40,000 storage units and located across 13 states. During the three months ended March 31, 2019 , the 2016 Joint Venture sold to the Company one self storage property for a gross sales price of $4.1 million . See Note 10 for additional details about the Company's acquisition of the self storage property from the 2016 Joint Venture. The following table presents the combined condensed financial position of the Company's unconsolidated real estate ventures as of March 31, 2019 and December 31, 2018 (in thousands): March 31, 2019 December 31, 2018 ASSETS Self storage properties, net $ 1,876,504 $ 1,894,412 Other assets 34,334 50,915 Total assets $ 1,910,838 $ 1,945,327 LIABILITIES AND EQUITY Debt financing $ 947,391 $ 956,357 Other liabilities 17,122 16,516 Equity 946,325 972,454 Total liabilities and equity $ 1,910,838 $ 1,945,327 The following table presents the combined condensed operating information of the Company's unconsolidated real estate ventures for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 2018 Total revenue $ 39,795 $ 14,806 Property operating expenses 12,544 5,293 Net operating income 27,251 9,513 Supervisory, administrative and other expenses (2,653 ) (1,057 ) Depreciation and amortization (21,826 ) (5,507 ) Interest expense (10,020 ) (2,899 ) Loss on sale of self storage properties (806 ) — Acquisition and other expenses (408 ) (262 ) Net loss $ (8,462 ) $ (212 ) The combined condensed operating information in the table above only includes information for the 2018 Joint Venture following the acquisition of the Initial 2018 JV Portfolio in September 2018.

SELF STORAGE PROPERTY ACQUISITI

SELF STORAGE PROPERTY ACQUISITIONS AND DISPOSITIONS	3 Months Ended
	Mar. 31, 2019
Business Combinations [Abstract]
SELF STORAGE PROPERTY ACQUISITIONS AND DISPOSITIONS	SELF STORAGE PROPERTY ACQUISITIONS AND DISPOSITIONS Acquisitions The Company acquired 32 self storage properties with an estimated fair value of $194.6 million during the three months ended March 31, 2019 . Of these acquisitions, 13 self storage properties with an estimated fair value of $85.5 million were acquired by the Company from its PROs and one self storage property with an estimated fair value of $4.1 million was acquired by the Company from the 2016 Joint Venture. The 32 self storage property acquisitions were accounted for as asset acquisitions and accordingly, $1.3 million of transaction costs related to the acquisitions were capitalized as part of the basis of the acquired properties. The Company recognized the estimated fair value of the acquired assets and assumed liabilities on the respective dates of such acquisitions. The Company allocated the total purchase price to the estimated fair value of tangible and intangible assets acquired, and liabilities assumed. The Company allocated a portion of the purchase price to identifiable intangible assets consisting of customer in-place leases which were recorded at estimated fair value of $4.6 million , resulting in a total fair value of $190.0 million allocated to real estate. The following table summarizes the investment in self storage property acquisitions completed by the Company during the three months ended March 31, 2019 (dollars in thousands): Acquisitions Closed During the Three Months Ended: Number of Properties Summary of Investment Cash and Acquisition Costs Value of OP Equity (1) Other Liabilities Total March 31, 2019 32 $ 160,531 $ 33,356 $ 674 $ 194,561 (1) Value of OP equity represents the fair value of Series A-1 preferred units, OP units and subordinated performance units.

OTHER ASSETS

OTHER ASSETS	3 Months Ended
	Mar. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
OTHER ASSETS	OTHER ASSETS Other assets consist of the following (dollars in thousands): March 31, 2019 December 31, 2018 Customer in-place leases, net of accumulated amortization of $4,193 and $5,090, respectively $ 6,217 $ 4,063 Receivables: Trade, net 3,208 3,402 PROs and other affiliates 737 2,027 Receivable from unconsolidated real estate venture 2,818 4,573 Property acquisition and other deposits 911 20,977 Interest rate swaps 9,993 16,164 Prepaid expenses and other 5,628 4,266 Corporate furniture, equipment and other, net 1,584 1,574 Trade name 3,200 3,200 Management contract, net of accumulated amortization of $1,741 and $1,564, respectively 8,880 9,057 Goodwill 5,750 5,750 Total $ 48,926 $ 75,053 Amortization expense related to customer in-place leases amounted to $2.5 million and $3.0 million for the three months ended March 31, 2019 and 2018 , respectively. Amortization expense related to the management contract amounted to $0.2 million and $0.2 million for the three months ended March 31, 2019 and 2018 , respectively.

DEBT FINANCING

DEBT FINANCING	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
DEBT FINANCING	DEBT FINANCING The Company's outstanding debt as of March 31, 2019 and December 31, 2018 is summarized as follows (dollars in thousands): Interest Rate (1) March 31, 2019 December 31, 2018 Credit Facility: Revolving line of credit 3.89% $ 277,500 $ 139,500 Term loan A 2.91% 235,000 235,000 Term loan B 2.94% 155,000 155,000 Term loan C 3.71% 105,000 105,000 Term loan D 3.79% 125,000 125,000 2023 Term loan facility 3.13% 175,000 175,000 2028 Term loan facility 4.62% 75,000 75,000 Fixed rate mortgages payable 4.18% 266,860 268,138 Total principal 1,414,360 1,277,638 Unamortized debt issuance costs and debt premium, net 566 464 Total debt $ 1,414,926 $ 1,278,102 (1) Represents the effective interest rate as of March 31, 2019 . Effective interest rate incorporates the stated rate plus the impact of interest rate cash flow hedges and discount and premium amortization, if applicable. For the revolving line of credit, the effective interest rate excludes fees for unused borrowings. As of March 31, 2019 , the Company's unsecured credit facility provided for total borrowings of $1.0 billion consisting of the following components: (i) a $400.0 million revolving line of credit (the "Revolver"), (ii) a tranche A term loan facility (the "Term Loan A"), which provides for a total borrowing commitment of up to $235.0 million , (iii) a tranche B term loan facility (the "Term Loan B"), which provides for a total borrowing commitment of up to $155.0 million , (iv) a tranche C term loan facility (the "Term Loan C"), which provides for a total borrowing commitment of up to $105.0 million and (v) a tranche D term loan facility, (the "Term Loan D" and together with the Revolver, the Term Loan A, Term Loan B and Term Loan C, the "credit facility"), which provides for a total borrowing commitment of up to $125.0 million . The Company has an expansion option under the credit facility, which, if exercised in full, would provide for a total borrowing capacity under the credit facility of $1.3 billion . As of March 31, 2019 , the Company had outstanding letters of credit totaling $5.7 million and would have had the capacity to borrow remaining Revolver commitments of $116.8 million while remaining in compliance with the credit facility's financial covenants. At March 31, 2019 , the Company was in compliance with all such covenants. For a summary of the Company's financial covenants and additional detail regarding the Company's credit facility, 2023 Term Loan Facility, 2028 Term Loan Facility and fixed rate mortgages payable, please see Note 8 to the Company's most recent Annual Report on Form 10-K for the year ended December 31, 2018 filed with the SEC. As discussed Note 14, in April 2019, the Company entered into a credit agreement with BMO Harris Bank N.A. to make available a term loan facility that matures in April 2029 in an aggregate amount of $100.0 million . Future Debt Obligations Based on existing debt agreements in effect as of March 31, 2019 , the scheduled principal and maturity payments for the Company's outstanding borrowings are presented in the table below (in thousands): Year Ending December 31, Scheduled Principal and Maturity Payments Amortization of Premium and Unamortized Debt Issuance Costs Total 2019 $ 3,850 $ (262 ) $ 3,588 2020 316,897 (699 ) 316,198 2021 242,603 (779 ) 241,824 2022 159,205 (441 ) 158,764 2023 377,049 (42 ) 377,007 2024 126,964 270 127,234 Thereafter 187,792 2,519 190,311 $ 1,414,360 $ 566 $ 1,414,926

EARNINGS PER SHARE

EARNINGS PER SHARE	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE The following table sets forth the computation of basic and diluted earnings (loss) per common share for the three months ended March 31, 2019 and 2018 , (in thousands, except per share amounts): Three Months Ended 2019 2018 Earnings (loss) per common share - basic and diluted Numerator Net income $ 12,940 $ 11,973 Net income attributable to noncontrolling interests (5,529 ) (1,513 ) Net income attributable to National Storage Affiliates Trust 7,411 10,460 Distributions to preferred shareholders (2,588 ) (2,588 ) Distributed and undistributed earnings allocated to participating securities (9 ) (7 ) Net income attributable to common shareholders - basic and diluted $ 4,814 $ 7,865 Effect of assumed conversion of dilutive securities — 1,370 Net income attributable to common shareholders - diluted $ 4,814 $ 9,235 Three Months Ended 2019 2018 Denominator Weighted average shares outstanding - basic 56,655 50,299 Effect of dilutive securities: Weighted average OP units outstanding — 29,135 Weighted average DownREIT OP unit equivalents outstanding — 1,835 Weighted average LTIP units outstanding — 321 Weighted average subordinated performance units and DownREIT subordinated performance unit equivalents — 18,345 Weighted average shares outstanding - diluted 56,655 99,935 Earnings (loss) per share - basic $ 0.08 $ 0.16 Earnings (loss) per share - diluted $ 0.08 $ 0.09 As discussed in Note 2 , the Company allocates GAAP income (loss) utilizing the HLBV method, in which the Company allocates income or loss based on the change in each unitholders' claim on the net assets of its operating partnership at period end after adjusting for any distributions or contributions made during such period. Due to the stated liquidation priorities and because the HLBV method incorporates non-cash items such as depreciation expense, in any given period, income or loss may be allocated disproportionately to National Storage Affiliates Trust and noncontrolling interests, resulting in volatile fluctuations of basic and diluted earnings (loss) per share. Outstanding equity interests of the Company's operating partnership and DownREIT partnerships are considered potential common shares for purposes of calculating diluted earnings (loss) per share as the unitholders may, through the exercise of redemption rights, obtain common shares, subject to various restrictions. Basic earnings per share is calculated based on the weighted average number of common shares outstanding during the period. Diluted earnings per share is calculated by further adjusting for the dilutive impact using the treasury stock method for unvested LTIP units subject to a service condition outstanding during the period and the if-converted method for any convertible securities outstanding during the period. Generally, following certain lock-out periods, OP units in the Company's operating partnership are redeemable for cash or, at the Company's option, exchangeable for common shares on a one -for-one basis, subject to certain adjustments and DownREIT OP units are redeemable for cash or, at the Company's option, exchangeable for OP units in its operating partnership on a one -for-one basis, subject to certain adjustments in each case. LTIP units may also, under certain circumstances, be convertible into OP units on a one-for-one basis, which are then exchangeable for common shares as described above. Certain LTIP units vested prior to or upon the completion of the Company's initial public offering and certain LTIP units have vested upon the satisfaction of a service condition or will vest upon the satisfaction of future service and market conditions. Vested LTIP units and unvested LTIP units that vest based on a service or market condition are allocated income or loss in a similar manner as OP units. Unvested LTIP units subject to a service or market condition are evaluated for dilution using the treasury stock method. For the three months ended March 31, 2019 , 450,722 unvested LTIP units that vest based on a service or market condition are excluded from the calculation of diluted earnings (loss) per share as they are not dilutive to earnings (loss) per share. In addition, certain LTIP units vest upon the future acquisition of properties sourced by PROs. For the three months ended March 31, 2019 , 224,000 unvested LTIP units that vest upon the future acquisition of properties are excluded from the calculation of diluted earnings (loss) per share because the contingency for the units to vest has not been attained as of the end of the reported periods. Subordinated performance units may also, under certain circumstances, be convertible into OP units which are exchangeable for common shares as described above, and DownREIT subordinated performance units may, under certain circumstances, be exchangeable for subordinated performance units on a one -for-one basis. Subordinated performance units are only convertible into OP units, after a two year lock-out period and then generally (i) at the holder’s election only upon the achievement of certain performance thresholds relating to the properties to which such subordinated performance units relate or (ii) at the Company's election upon a retirement event of a PRO that holds such subordinated performance units or upon certain qualifying terminations. Although subordinated performance units may only be convertible after a two year lock-out period, the Company assumes a hypothetical conversion of each subordinated performance unit (including each DownREIT subordinated performance unit) into OP units (with subsequently assumed redemption into common shares) for the purposes of calculating diluted weighted average common shares. This hypothetical conversion is calculated using historical financial information, and as a result, is not necessarily indicative of the results of operations, cash flows or financial position of the Company upon expiration of the two -year lock out period on conversions. For the three months ended March 31, 2019 , potential common shares totaling 54.6 million related to OP units, DownREIT OP units, subordinated performance units and DownREIT subordinated performance units have been excluded from the calculation of diluted earnings (loss) per share as they are not dilutive to earnings (loss) per share. Participating securities, which consist of unvested restricted common shares, receive dividends equal to those received by common shares. The effect of participating securities for the periods presented above is calculated using the two-class method of allocating distributed and undistributed earnings.

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	3 Months Ended
	Mar. 31, 2019
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS Supervisory and Administrative Fees For the self storage properties that are managed by the PROs, the Company has entered into asset management agreements with the PROs to provide leasing, operating, supervisory and administrative services. The asset management agreements generally provide for fees ranging from 5% to 6% of gross revenue for the managed self storage properties. During the three months ended March 31, 2019 and 2018 , the Company incurred $4.7 million and $4.1 million , respectively, for supervisory and administrative fees to the PROs. Such fees are included in general and administrative expenses in the accompanying condensed consolidated statements of operations. Payroll Services For the self storage properties that are managed by the PROs, the employees responsible for operations are employees of the PROs who charge the Company for the costs associated with the respective employees. For the three months ended March 31, 2019 and 2018 , the Company incurred $7.8 million and $7.3 million , respectively, for payroll and related costs reimbursable to these PROs. Such costs are included in property operating expenses in the accompanying condensed consolidated statements of operations. Due Diligence Costs During the three months ended March 31, 2019 and 2018 , the Company incurred less than $0.3 million and $0.2 million , respectively, of expenses payable to certain PROs related to self storage property acquisitions sourced by the PROs. These expenses, which are based on the volume of transactions sourced by the PROs, are intended to reimburse the PROs for due diligence costs incurred in the sourcing and underwriting process. These due diligence costs are capitalized as part of the basis of the acquired self storage properties. Self Storage Property Acquisitions During the three months ended March 31, 2019 , the Company acquired one self storage property from the 2016 Joint Venture for $4.1 million .

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Legal Proceedings The Company is subject to litigation, claims, and assessments that may arise in the ordinary course of its business activities. Such matters include contractual matters, employment related issues, and regulatory proceedings. Although occasional adverse decisions or settlements may occur, the Company believes that the final disposition of such matters will not have a material adverse effect on the Company's financial position, results of operations, or liquidity.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS Recurring Fair Value Measurements The Company sometimes limits its exposure to interest rate fluctuations by entering into interest rate swap agreements. The interest rate swap agreements moderate the Company's exposure to interest rate risk by effectively converting the interest on variable rate debt to a fixed rate. The Company measures its interest rate swap derivatives at fair value on a recurring basis. The changes in the fair value of derivatives designated and that qualify as cash flow hedges are recorded in accumulated other comprehensive income (loss) and are subsequently reclassified into earnings in the period that the hedged transaction affects earnings. Information regarding the Company's interest rate swaps measured at fair value, which are classified within Level 2 of the GAAP fair value hierarchy, is presented below (dollars in thousands): Fair value at December 31, 2017 $ 12,414 Losses on interest rate swaps reclassified into interest expense from accumulated other comprehensive income 49 Unrealized gains on interest rate swaps included in accumulated other comprehensive income 8,990 Fair value at March 31, 2018 $ 21,453 Fair value at December 31, 2018 $ 14,195 Gains on interest rate swaps reclassified into interest expense from accumulated other comprehensive income (1,276 ) Unrealized losses on interest rate swaps included in accumulated other comprehensive income (8,039 ) Fair value at March 31, 2019 $ 4,880 As of March 31, 2019 and December 31, 2018 , the Company had outstanding interest rate swaps with aggregate notional amounts of $795.0 million and $795.0 million , respectively, designated as cash flow hedges. As of March 31, 2019 , the Company's swaps had a weighted average remaining term of approximately 4.2 years . The fair value of these swaps are presented within accounts payable and accrued liabilities and other assets in the Company's balance sheets, and the Company recognizes any changes in the fair value as an adjustment of accumulated other comprehensive income (loss) within equity. If the forward rates at March 31, 2019 remain constant, the Company estimates that during the next 12 months , the Company would reclassify into earnings approximately $4.2 million of the unrealized gains included in accumulated other comprehensive income (loss). If market interest rates increase above the 1.87% weighted average fixed rate under these interest rate swaps, the Company will benefit from net cash payments due from its counterparties to the interest rate swaps. There were no transfers between levels of the three-tier fair value measurement hierarchy during the three months ended March 31, 2019 and 2018 . For financial assets and liabilities that utilize Level 2 inputs, the Company utilizes both direct and indirect observable price quotes, including LIBOR yield curves. The Company uses valuation techniques for Level 2 financial assets and liabilities which include LIBOR yield curves at the reporting date as well as assessing counterparty credit risk. Counterparties to these contracts are highly rated financial institutions. 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 the Company's derivatives utilize Level 3 inputs, such as estimates of current credit spreads, to evaluate the likelihood of default by the Company and the counterparties. As of March 31, 2019 , the Company determined that the effect of credit valuation adjustments on the overall valuation of its derivative positions are not significant to the overall valuation of its derivatives. Therefore, the Company has determined that its derivative valuations are appropriately classified in Level 2 of the fair value hierarchy. Fair Value Disclosures The carrying values of cash and cash equivalents, restricted cash, trade receivables, and accounts payable and accrued liabilities reflected in the balance sheets at March 31, 2019 and December 31, 2018 , approximate fair value due to the short term nature of these financial assets and liabilities. The carrying value of variable rate debt financing reflected in the balance sheets at March 31, 2019 and December 31, 2018 approximates fair value as the changes in their associated interest rates reflect the current market and credit risk is similar to when the loans were originally obtained. The combined principal balance of the Company's fixed rate mortgages payable was approximately $266.9 million as of March 31, 2019 with a fair value of approximately $279.0 million (categorized within Level 2 of the fair value hierarchy). In determining the fair value, the Company estimated a weighted average market interest rate of approximately 3.88% , compared to the weighted average contractual interest rate of 4.84% . The combined principal balance of the Company's fixed rate mortgages was approximately $268.1 million as of December 31, 2018 with a fair value of approximately $276.5 million . In determining the fair value as of December 31, 2018 , the Company estimated a weighted average market interest rate of approximately 4.17% , compared to the weighted average contractual interest rate of 4.85% .

LEASES

LEASES	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
LEASES	LEASES The Company determines if a contractual arrangement is a lease at inception. As a lessee, the Company has non-cancelable lease agreements for real estate and its corporate office space that are classified as operating leases. The Company's operating leases are included in operating lease right-of-use ("ROU") assets and operating lease liabilities in its condensed consolidated balance sheets. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As the Company's operating leases do not provide an implicit rate, the Company used its incremental borrowing rate based on the information available at commencement date in determining the discount rate for the present value of the lease payments. To the extent that the lease agreements provide for fixed increases throughout the term of the lease, the Company recognizes lease expense on a straight-line basis over the expected lease terms. Real Estate Leasehold Interests The Company has seven properties that are subject to non-cancelable leasehold interest agreements with remaining lease terms ranging from 15 to 73 years, inclusive of extension options that the Company anticipates exercising. Rent expense under these leasehold interest agreements is included in property operating expenses in the accompanying condensed consolidated statements of operations and amounted to $0.4 million and $0.4 million for the three months ended March 31, 2019 and 2018 , respectively. Office Leases The Company has entered into non-cancelable lease agreements for its corporate office space with remaining lease terms ranging from four to eight years. Rent expense related to these office leases is included in general and administrative expenses in the accompanying condensed consolidated statements of operations and amounted to $0.1 million and less than $0.1 million for the three months ended March 31, 2019 and 2018 , respectively. The weighted-average remaining lease term and the weighted-average discount rate for the Company's operating leases as of March 31, 2019 are as follows: March 31, 2019 Weighted-average remaining lease term Real estate leasehold interests 29 years Office leases 7 years Weighted-average remaining discount rate Real estate leasehold interests 4.9 % Office leases 4.1 % As of March 31, 2019 , the future minimum lease payments under the Company's operating leases, for which the Company is a lessee, are as follows (in thousands): Year Ending December 31, Real Estate Leasehold Interests Office Leases Total 2019 $ 1,005 $ 144 $ 1,149 2020 1,385 286 1,671 2021 1,410 387 1,797 2022 1,425 381 1,806 2023 1,431 346 1,777 2024 through 2092 36,419 1,043 37,462 Total lease payments $ 43,075 $ 2,587 $ 45,662 Less imputed interest (21,108 ) (388 ) (21,496 ) Total $ 21,967 $ 2,199 $ 24,166 As of December 31, 2018, the future minimum lease payments under the Company's operating leases, for which the Company is a lessee, are as follows (in thousands): Year Ending December 31, Real Estate Leasehold Interests Office Leases Total 2019 $ 1,334 $ 345 $ 1,679 2020 1,379 398 1,777 2021 1,404 387 1,791 2022 1,419 381 1,800 2023 1,424 346 1,770 2024 through 2092 36,074 1,073 37,147 Total lease payments $ 43,034 $ 2,930 $ 45,964

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On April 24, 2019, the Company entered into a credit agreement with BMO Harris Bank N.A. to make available a term loan facility that matures in April 2029 (the "2029 Term Loan Facility") in an aggregate amount of $100.0 million . The entire outstanding principal amount of, and all accrued but unpaid interest, is due on the maturity date. Interest rates applicable to loans under the 2029 Term Loan Facility are payable during such periods as such loans are LIBOR loans, at the applicable LIBOR based on a 1, 2, 3 or 6 month LIBOR period (as elected by the Company at the beginning of any applicable interest period) plus an applicable margin, and during the period that such loans are base rate loans, at the base rate under the 2029 Term Loan Facility in effect from time to time plus an applicable margin. The base rate under the 2029 Term Loan Facility is equal to the greatest of the BMO Harris Bank prime rate, the federal funds rate plus 0.50% or one month LIBOR plus 1.00% . The applicable margin for the 2029 Term Loan Facility is leverage-based and ranges from 1.85% to 2.30% for LIBOR loans and 0.85% to 1.30% for base rate loans; provided that after such time as the Company achieves an investment grade rating from at least two rating agencies, the Company may elect (but is not required to elect) that the 2029 Term Loan Facility be subject to rating-based margins ranging from 1.40% to 2.25% for LIBOR Loans and 0.40% to 1.25% for base rate loans. On April 24, 2019, the Company also entered into an interest rate swap agreement with a notional amount of $100.0 million that matures in April 2029 fixing the interest rate of the 2029 Term Loan Facility at an effective interest rate of 4.27% . The Company is required to comply with the same financial covenants under the 2029 Term Loan Facility as it is with the credit facility, 2023 Term Loan Facility and the 2028 Term Loan Facility. In addition, the terms of the 2029 Term Loan Facility contain customary affirmative and negative covenants that are consistent with those contained in the 2023 Term Loan Facility and 2028 Term Loan Facility, and, among other things, limit the Company's ability to make distributions, make certain investments, incur debt, incur liens and enter into certain transactions.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements are presented on the accrual basis of accounting in accordance with U.S. generally accepted accounting principles ("GAAP") and have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (the "SEC") regarding interim financial reporting. Accordingly, certain information and footnote disclosures required by GAAP for complete financial statements have been condensed or omitted in accordance with such rules and regulations. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation of the condensed consolidated financial statements have been included. The Company's results of operations for the quarterly period ended March 31, 2019 are not necessarily indicative of the results to be expected for the full year or any other future period.
Principles of Consolidation	Principles of Consolidation The Company's financial statements include the accounts of its operating partnership and its controlled subsidiaries. All significant intercompany balances and transactions have been eliminated in the consolidation of entities.
Variable Interest Entities	When the Company obtains an economic interest in an entity, the Company evaluates the entity to determine if the entity is deemed a variable interest entity ("VIE"), and if the Company is deemed to be the primary beneficiary, in accordance with authoritative guidance issued on the consolidation of VIEs. When an entity is not deemed to be a VIE, the Company considers the provisions of additional guidance to determine whether the general partner controls a limited partnership or similar entity when the limited partners have certain rights. The Company consolidates all entities that are VIEs and of which the Company is deemed to be the primary beneficiary. The Company has determined that its operating partnership is a VIE. The sole significant asset of National Storage Affiliates Trust is its investment in its operating partnership, and consequently, substantially all of the Company’s assets and liabilities represent those assets and liabilities of its operating partnership.
Revenue Recognition - Rental revenue	Rental revenue Rental revenue consists of space rentals and related fees. Management has determined that all of the Company's leases are operating leases. Substantially all leases may be terminated on a month-to-month basis and rental income is recognized ratably over the lease term using the straight-line method. Rents received in advance are deferred and recognized on a straight-line basis over the related lease term associated with the prepayment. Promotional discounts and other incentives are recognized as a reduction to rental income over the applicable lease term.
Revenue Recognition - Other property-related revenue, management fees and other revenue	Other property-related revenue Other property-related revenue primarily consists of ancillary revenues such as tenant insurance and/or tenant warranty protection-related access fees and sales of storage supplies which are recognized in the period earned. The Company and certain of the Company’s PROs have tenant insurance- and/or tenant warranty protection plan-related arrangements with insurance companies and the Company’s tenants. During the three months ended March 31, 2019 and 2018 , the Company recognized $2.1 million and $1.7 million , respectively, of tenant insurance and tenant warranty protection plan revenues. The Company sells boxes, packing supplies, locks and other retail merchandise at its properties. During the three months ended March 31, 2019 and 2018 , the Company recognized retail sales of $0.4 million and $0.4 million , respectively. Management fees and other revenue Management fees and other revenue consist of property management fees, platform fees, call center fees, acquisition fees, and a portion of tenant warranty protection or tenant insurance proceeds that the Company earns for managing and operating its unconsolidated real estate ventures. With respect to both the 2018 Joint Venture and the 2016 Joint Venture (as each are defined in Note 5), the Company provides supervisory and administrative property management services, centralized call center services, and technology platform and revenue management services to the properties in the unconsolidated real estate ventures. The property management fees are equal to 6% of monthly gross revenues and net sales revenues from the assets of the unconsolidated real estate ventures, and the platform fees are equal to $1,250 per month per unconsolidated real estate venture property. With respect to the 2016 Joint Venture only, the call center fees are equal to 1% of each of monthly gross revenues and net sales revenues from the 2016 Joint Venture properties. During the three months ended March 31, 2019 and 2018 , the Company recognized property management fees, call center fees and platform fees of $3.2 million and $1.3 million , respectively. For acquisition fees, the Company provides sourcing, underwriting and administration services to the unconsolidated real estate ventures. The 2016 Joint Venture paid the Company a $4.1 million acquisition fee equal to 0.65% of the gross capitalization (including debt and equity) of the original 66 -property 2016 Joint Venture portfolio (the "Initial 2016 JV Portfolio") in 2016, at the time of the Initial 2016 JV Portfolio acquisition. The 2018 Joint Venture paid the Company a $4.0 million acquisition fee related to the initial acquisition of properties by the 2018 Joint Venture (the "Initial 2018 JV Portfolio") in 2018, at the time of the Initial 2018 JV Portfolio acquisition. These fees are refundable to the unconsolidated real estate ventures, on a prorated basis, if the Company is removed as the managing member during the initial four year life of the unconsolidated real estate ventures and as such, the Company's performance obligation for these acquisition fees are satisfied over a four year period. As of March 31, 2019 and December 31, 2018 , the Company had deferred revenue related to the acquisition fees of $4.1 million and $4.6 million , respectively. The Company also earns acquisition fees for properties acquired by the unconsolidated real estate ventures subsequent to the Initial 2016 JV Portfolio and the Initial 2018 JV Portfolio. These fees are based on a percentage of the gross capitalization of the acquired assets determined by the members of the 2016 Joint Venture and the 2018 Joint Venture, and are generally earned when the unconsolidated real estate ventures obtain title and control of an acquired property. During the three months ended March 31, 2019 and 2018 , the Company recognized acquisition fees of $0.5 million and $0.3 million , respectively. An affiliate of the Company facilitates tenant warranty protection or tenant insurance programs for tenants of the properties in the unconsolidated real estate ventures in exchange for 50% of all proceeds from such programs at each unconsolidated real estate venture property. During the three months ended March 31, 2019 and 2018 , the Company recognized $1.2 million and $0.5 million , respectively, of revenue related to these activities
Gain on sale of self storage properties	Gain on sale of self storage properties The Company recognizes gains from disposition of facilities only upon closing in accordance with the guidance on sales of nonfinancial assets. Profit on real estate sold is recognized upon closing when all, or substantially all, of the promised consideration has been received and is nonrefundable and the Company has transferred control of the facilities to the purchaser.
Investments in Unconsolidated Real Estate Ventures	Investments in Unconsolidated Real Estate Ventures The Company’s investments in its unconsolidated real estate ventures are recorded under the equity method of accounting in the accompanying condensed consolidated financial statements. Under the equity method, the Company’s investments in unconsolidated real estate ventures are stated at cost and adjusted for the Company’s share of net earnings or losses and reduced by distributions. Equity in earnings (losses) is recognized based on the Company’s ownership interest in the earnings (losses) of the unconsolidated real estate ventures. The Company follows the "nature of the distribution approach" for classification of distributions from its unconsolidated real estate ventures in its condensed consolidated statements of cash flows. Under this approach, distributions are reported on the basis of the nature of the activity or activities that generated the distributions as either a return on investment, which are classified as operating cash flows, or a return of investment (e.g., proceeds from the unconsolidated real estate ventures' sale of assets) which are reported as investing cash flows.
Noncontrolling Interests	Noncontrolling Interests All of the limited partner equity interests ("OP equity") in the operating partnership not held by the Company are reflected as noncontrolling interests. Noncontrolling interests also include ownership interests in DownREIT partnerships held by entities other than the operating partnership or its subsidiaries. In the condensed consolidated statements of operations, the Company allocates net income (loss) attributable to noncontrolling interests to arrive at net income (loss) attributable to National Storage Affiliates Trust. For transactions that result in changes to the Company's ownership interest in its operating partnership, the carrying amount of noncontrolling interests is adjusted to reflect such changes. The difference between the fair value of the consideration received or paid and the amount by which the noncontrolling interest is adjusted is reflected as an adjustment to additional paid-in capital on the condensed consolidated balance sheets.
Allocation of Net Income (Loss)	Allocation of Net Income (Loss) The distribution rights and priorities set forth in the operating partnership's LP Agreement differ from what is reflected by the underlying percentage ownership interests of the unitholders. Accordingly, the Company allocates GAAP income (loss) utilizing the hypothetical liquidation at book value ("HLBV") method, in which the Company allocates income or loss based on the change in each unitholders’ claim on the net assets of its operating partnership at period end after adjusting for any distributions or contributions made during such period. The HLBV method is commonly applied to equity investments where cash distribution percentages vary at different points in time and are not directly linked to an equity holder’s ownership percentage. The HLBV method is a balance sheet-focused approach to income (loss) allocation. A calculation is prepared at each balance sheet date to determine the amount that unitholders would receive if the operating partnership were to liquidate all of its assets (at GAAP net book value) and distribute the resulting proceeds to its creditors and unitholders based on the contractually defined liquidation priorities. The difference between the calculated liquidation distribution amounts at the beginning and the end of the reporting period, after adjusting for capital contributions and distributions, is used to derive each unitholder's share of the income (loss) for the period. Due to the stated liquidation priorities and because the HLBV method incorporates non-cash items such as depreciation expense, in any given period, income or loss may be allocated disproportionately to unitholders as compared to their respective ownership percentage in the operating partnership, and net income (loss) attributable to National Storage Affiliates Trust could be more or less net income than actual cash distributions received and more or less income or loss than what may be received in the event of an actual liquidation. Additionally, the HLBV method could result in net income (or net loss) attributable to National Storage Affiliates Trust during a period when the Company reports consolidated net loss (or net income), or net income (or net loss) attributable to National Storage Affiliates Trust in excess of the Company's consolidated net income (or net loss). The computations of basic and diluted earnings (loss) per share may be materially affected by these disproportionate income (loss) allocations, resulting in volatile fluctuations of basic and diluted earnings (loss) per share.
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) The Company has cash flow hedge derivative instruments that are measured at fair value with unrealized gains or losses recognized in other comprehensive income (loss) with a corresponding adjustment to accumulated other comprehensive income (loss) within equity, as discussed further in Note 12. Under the HLBV method of allocating income (loss) discussed above, a calculation is prepared at each balance sheet date by applying the HLBV method including, and excluding, the assets and liabilities resulting from the Company's cash flow hedge derivative instruments to determine comprehensive income (loss) attributable to National Storage Affiliates Trust. As a result of the distribution rights and priorities set forth in the operating partnership's LP Agreement, in any given period, other comprehensive income (loss) may be allocated disproportionately to unitholders as compared to their respective ownership percentage in the operating partnership and as compared to their respective allocation of net income (loss).
Restricted Cash	Restricted Cash The Company's restricted cash consists of escrowed funds deposited with financial institutions for real estate taxes, insurance and other reserves for capital improvements in accordance with the Company's loan agreements
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board ("FASB") issued ASU 2016-02, Leases, which amends the existing guidance for accounting for leases, including requiring lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases and lessees to recognize most leases on-balance sheet as lease liabilities with corresponding right-of-use assets. In July 2018, the FASB issued ASU 2018-11, Leases - Targeted Improvements, which allows entities the option to apply the new standard at adoption date with a cumulative-effect adjustment in the period of adoption. The Company adopted ASU 2016-02 and ASU 2018-11 effective January 1, 2019 and applied it to leases that were in place on the effective date. The Company elected the practical expedients which permit the Company to combine lease and nonlease components and to not reassess (i) whether any expired or existing contracts are or contain leases, (ii) the lease classification for any expired or existing leases, and (iii) any initial direct costs for any existing leases as of the effective date. Results for reporting periods beginning January 1, 2019 are presented under ASU 2016-02 and ASU 2018-11. As a result, beginning on January 1, 2019, activity related to uncollectible accounts are recognized as a current-period adjustment within revenue. For periods prior to January 1, 2019, such amounts were previously included in operating expenses. The adoption of the lease standard did not result in a cumulative catch-up adjustment to opening equity. See Note 13 for additional detail about the Company's non-cancelable leasehold interest agreements where the Company is a lessee.

NONCONTROLLING INTERESTS (Table

NONCONTROLLING INTERESTS (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Schedule of outstanding equity interests	As of March 31, 2019 and December 31, 2018 , units reflecting noncontrolling interests consisted of the following: March 31, 2019 December 31, 2018 Series A-1 preferred units 501,918 343,719 OP units 30,229,228 28,874,103 Subordinated performance units 10,739,868 10,749,475 LTIP units 762,720 931,671 DownREIT units DownREIT OP units 1,848,261 1,834,786 DownREIT subordinated performance units 4,371,622 4,386,999 Total 48,453,617 47,120,753

SELF STORAGE PROPERTIES (Tables

SELF STORAGE PROPERTIES (Tables)	3 Months Ended
	Mar. 31, 2019
Real Estate [Abstract]
Schedule of self storage properties	Self storage properties are summarized as follows (dollars in thousands): March 31, 2019 December 31, 2018 Land $ 612,273 $ 583,455 Buildings and improvements 2,214,345 2,048,281 Furniture and equipment 6,127 5,987 Total self storage properties 2,832,745 2,637,723 Less accumulated depreciation (267,796 ) (246,261 ) Self storage properties, net $ 2,564,949 $ 2,391,462

INVESTMENT IN UNCONSOLIDATED _2

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES (Tables)	3 Months Ended
	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Schedule of condensed financial information of joint ventures	The following table presents the combined condensed financial position of the Company's unconsolidated real estate ventures as of March 31, 2019 and December 31, 2018 (in thousands): March 31, 2019 December 31, 2018 ASSETS Self storage properties, net $ 1,876,504 $ 1,894,412 Other assets 34,334 50,915 Total assets $ 1,910,838 $ 1,945,327 LIABILITIES AND EQUITY Debt financing $ 947,391 $ 956,357 Other liabilities 17,122 16,516 Equity 946,325 972,454 Total liabilities and equity $ 1,910,838 $ 1,945,327 The following table presents the combined condensed operating information of the Company's unconsolidated real estate ventures for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 2018 Total revenue $ 39,795 $ 14,806 Property operating expenses 12,544 5,293 Net operating income 27,251 9,513 Supervisory, administrative and other expenses (2,653 ) (1,057 ) Depreciation and amortization (21,826 ) (5,507 ) Interest expense (10,020 ) (2,899 ) Loss on sale of self storage properties (806 ) — Acquisition and other expenses (408 ) (262 ) Net loss $ (8,462 ) $ (212 ) The combined condensed operating information in the table above only includes information for the 2018 Joint Venture following the acquisition of the Initial 2018 JV Portfolio in September 2018.

SELF STORAGE PROPERTY ACQUISI_2

SELF STORAGE PROPERTY ACQUISITIONS AND DISPOSITIONS (Tables)	3 Months Ended
	Mar. 31, 2019
Business Combinations [Abstract]
Schedule of investments in self storage property acquisitions	The following table summarizes the investment in self storage property acquisitions completed by the Company during the three months ended March 31, 2019 (dollars in thousands): Acquisitions Closed During the Three Months Ended: Number of Properties Summary of Investment Cash and Acquisition Costs Value of OP Equity (1) Other Liabilities Total March 31, 2019 32 $ 160,531 $ 33,356 $ 674 $ 194,561 (1) Value of OP equity represents the fair value of Series A-1 preferred units, OP units and subordinated performance units

OTHER ASSETS (Tables)

OTHER ASSETS (Tables)	3 Months Ended
	Mar. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of other assets	Other assets consist of the following (dollars in thousands): March 31, 2019 December 31, 2018 Customer in-place leases, net of accumulated amortization of $4,193 and $5,090, respectively $ 6,217 $ 4,063 Receivables: Trade, net 3,208 3,402 PROs and other affiliates 737 2,027 Receivable from unconsolidated real estate venture 2,818 4,573 Property acquisition and other deposits 911 20,977 Interest rate swaps 9,993 16,164 Prepaid expenses and other 5,628 4,266 Corporate furniture, equipment and other, net 1,584 1,574 Trade name 3,200 3,200 Management contract, net of accumulated amortization of $1,741 and $1,564, respectively 8,880 9,057 Goodwill 5,750 5,750 Total $ 48,926 $ 75,053

DEBT FINANCING (Tables)

DEBT FINANCING (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Schedule of debt	The Company's outstanding debt as of March 31, 2019 and December 31, 2018 is summarized as follows (dollars in thousands): Interest Rate (1) March 31, 2019 December 31, 2018 Credit Facility: Revolving line of credit 3.89% $ 277,500 $ 139,500 Term loan A 2.91% 235,000 235,000 Term loan B 2.94% 155,000 155,000 Term loan C 3.71% 105,000 105,000 Term loan D 3.79% 125,000 125,000 2023 Term loan facility 3.13% 175,000 175,000 2028 Term loan facility 4.62% 75,000 75,000 Fixed rate mortgages payable 4.18% 266,860 268,138 Total principal 1,414,360 1,277,638 Unamortized debt issuance costs and debt premium, net 566 464 Total debt $ 1,414,926 $ 1,278,102 (1) Represents the effective interest rate as of March 31, 2019 . Effective interest rate incorporates the stated rate plus the impact of interest rate cash flow hedges and discount and premium amortization, if applicable. For the revolving line of credit, the effective interest rate excludes fees for unused borrowings.
Schedule of future debt maturities	Based on existing debt agreements in effect as of March 31, 2019 , the scheduled principal and maturity payments for the Company's outstanding borrowings are presented in the table below (in thousands): Year Ending December 31, Scheduled Principal and Maturity Payments Amortization of Premium and Unamortized Debt Issuance Costs Total 2019 $ 3,850 $ (262 ) $ 3,588 2020 316,897 (699 ) 316,198 2021 242,603 (779 ) 241,824 2022 159,205 (441 ) 158,764 2023 377,049 (42 ) 377,007 2024 126,964 270 127,234 Thereafter 187,792 2,519 190,311 $ 1,414,360 $ 566 $ 1,414,926

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Schedule of the computation of basic and diluted earnings per common share	The following table sets forth the computation of basic and diluted earnings (loss) per common share for the three months ended March 31, 2019 and 2018 , (in thousands, except per share amounts): Three Months Ended 2019 2018 Earnings (loss) per common share - basic and diluted Numerator Net income $ 12,940 $ 11,973 Net income attributable to noncontrolling interests (5,529 ) (1,513 ) Net income attributable to National Storage Affiliates Trust 7,411 10,460 Distributions to preferred shareholders (2,588 ) (2,588 ) Distributed and undistributed earnings allocated to participating securities (9 ) (7 ) Net income attributable to common shareholders - basic and diluted $ 4,814 $ 7,865 Effect of assumed conversion of dilutive securities — 1,370 Net income attributable to common shareholders - diluted $ 4,814 $ 9,235 Three Months Ended 2019 2018 Denominator Weighted average shares outstanding - basic 56,655 50,299 Effect of dilutive securities: Weighted average OP units outstanding — 29,135 Weighted average DownREIT OP unit equivalents outstanding — 1,835 Weighted average LTIP units outstanding — 321 Weighted average subordinated performance units and DownREIT subordinated performance unit equivalents — 18,345 Weighted average shares outstanding - diluted 56,655 99,935 Earnings (loss) per share - basic $ 0.08 $ 0.16 Earnings (loss) per share - diluted $ 0.08 $ 0.09

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of interest rate swap derivatives measured at fair value	Information regarding the Company's interest rate swaps measured at fair value, which are classified within Level 2 of the GAAP fair value hierarchy, is presented below (dollars in thousands): Fair value at December 31, 2017 $ 12,414 Losses on interest rate swaps reclassified into interest expense from accumulated other comprehensive income 49 Unrealized gains on interest rate swaps included in accumulated other comprehensive income 8,990 Fair value at March 31, 2018 $ 21,453 Fair value at December 31, 2018 $ 14,195 Gains on interest rate swaps reclassified into interest expense from accumulated other comprehensive income (1,276 ) Unrealized losses on interest rate swaps included in accumulated other comprehensive income (8,039 ) Fair value at March 31, 2019 $ 4,880

LEASES (Tables)

LEASES (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Schedule of weighted-average remaining lease terms and weighted-average discount rates	The weighted-average remaining lease term and the weighted-average discount rate for the Company's operating leases as of March 31, 2019 are as follows: March 31, 2019 Weighted-average remaining lease term Real estate leasehold interests 29 years Office leases 7 years Weighted-average remaining discount rate Real estate leasehold interests 4.9 % Office leases 4.1 %
Schedule of Future Minimum Lease Payments Under Operating Leases	As of March 31, 2019 , the future minimum lease payments under the Company's operating leases, for which the Company is a lessee, are as follows (in thousands): Year Ending December 31, Real Estate Leasehold Interests Office Leases Total 2019 $ 1,005 $ 144 $ 1,149 2020 1,385 286 1,671 2021 1,410 387 1,797 2022 1,425 381 1,806 2023 1,431 346 1,777 2024 through 2092 36,419 1,043 37,462 Total lease payments $ 43,075 $ 2,587 $ 45,662 Less imputed interest (21,108 ) (388 ) (21,496 ) Total $ 21,967 $ 2,199 $ 24,166
Schedule of Future Minimum Lease Payments Under Operating Leases at Prior Year	As of December 31, 2018, the future minimum lease payments under the Company's operating leases, for which the Company is a lessee, are as follows (in thousands): Year Ending December 31, Real Estate Leasehold Interests Office Leases Total 2019 $ 1,334 $ 345 $ 1,679 2020 1,379 398 1,777 2021 1,404 387 1,791 2022 1,419 381 1,800 2023 1,424 346 1,770 2024 through 2092 36,074 1,073 37,147 Total lease payments $ 43,034 $ 2,930 $ 45,964

ORGANIZATION AND NATURE OF OP_2

ORGANIZATION AND NATURE OF OPERATIONS (Details) ft² in Millions	Mar. 31, 2019ft²storage_unitstateproperty
Schedule of Equity Method Investments [Line Items]
Number of self storage properties owned | property	706
Number of states in which self storage properties are owned | state	34
Total rentable square feet in self storage properties | ft²	44.7
Number of storage units owned and operated | storage_unit	361,000
Consolidated Properties
Schedule of Equity Method Investments [Line Items]
Number of self storage properties owned | property	531
Number of states in which self storage properties are owned | state	28
Total rentable square feet in self storage properties | ft²	32.1
Number of storage units owned and operated | storage_unit	257,000
Unconsolidated Properties | Unconsolidated Real Estate Ventures | Corporate Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of self storage properties owned | property	175
Number of states in which self storage properties are owned | state	21
Total rentable square feet in self storage properties | ft²	12.6
Number of storage units owned and operated | storage_unit	104,000
Company's equity interest in Joint Venture (percent)	25.00%

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Thousands	Mar. 31, 2019USD ($)partnershipproperty	Dec. 31, 2018USD ($)partnershipproperty
Variable Interest Entity [Line Items]
Number of self storage properties | property	706
Net book value of real estate owned	$ 2,564,949	$ 2,391,462
Carrying value of fixed rate mortgages	1,414,360	1,277,638
Mortgages | Fixed rate mortgages payable
Variable Interest Entity [Line Items]
Carrying value of fixed rate mortgages	$ 266,860	$ 268,138
VIE, Primary Beneficiary
Variable Interest Entity [Line Items]
Number of partnerships considered to be VIEs | partnership	21	21
Number of self storage properties | property	34	34
Net book value of real estate owned	$ 238,700	$ 240,400
VIE, Primary Beneficiary | Mortgages | Fixed rate mortgages payable
Variable Interest Entity [Line Items]
Carrying value of fixed rate mortgages	$ 137,900	$ 138,400

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition (Details)	3 Months Ended			4 Months Ended
	Mar. 31, 2019USD ($)property	Mar. 31, 2018USD ($)	Dec. 31, 2016USD ($)property	Dec. 31, 2018USD ($)
Disaggregation of Revenue [Line Items]
Number of self storage properties | property	706
Initial term of Joint Venture agreements	4 years
Performance obligation period of recognition	4 years
Corporate Joint Venture | 2016 Joint Venture
Disaggregation of Revenue [Line Items]
Number of self storage properties | property			66
Tenant Insurance and Tenant Warranty Protection Plan Revenues
Disaggregation of Revenue [Line Items]
Revenue	$ 2,100,000	$ 1,700,000
Retail Products and Supplies
Disaggregation of Revenue [Line Items]
Revenue	400,000	400,000
Property Management, Call Center, and Platform Fees
Disaggregation of Revenue [Line Items]
Revenue	$ 3,200,000	1,300,000
Property management fees as percent of monthly gross revenues and net sales revenue of Joint Venture assets	6.00%
Platform fees per Joint Venture property per month	$ 1,250
Call center fees as percent of monthly gross revenues and net sales revenue of Joint Venture assets	1.00%
Acquisition Fees
Disaggregation of Revenue [Line Items]
Revenue	$ 500,000	300,000
Acquisition fee for the Initial JV Portfolio			$ 4,100,000	$ 4,000,000
Acquisition fees received as a percent of gross capitalization of Initial JV Portfolio			0.65%
Deferred revenue	4,100,000			$ 4,600,000
Tenant Warranty Protection or Tenant Insurance
Disaggregation of Revenue [Line Items]
Revenue	$ 1,200,000	$ 500,000
Percent of total warranty protection plan proceeds received per Joint Venture property (percent)	50.00%

NONCONTROLLING INTERESTS - Narr

NONCONTROLLING INTERESTS - Narrative (Details) - $ / shares	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Series A-1 preferred units stated value (in dollars per share)	$ 0.01	$ 0.01
Common shares of beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Series A-1 Preferred Units
Class of Stock [Line Items]
Series A-1 preferred units dividend rate (percent)	6.00%
Series A-1 preferred units stated value (in dollars per share)	$ 25
Series A-1 Preferred Units | NSA OP, LP
Class of Stock [Line Items]
Unit conversion ratio	1
OP units | NSA OP, LP
Class of Stock [Line Items]
Unit conversion ratio	1
Minimum conversion period (in years)	1 year
Issuance of shares/units (in shares)	863,148
Redemptions/conversions of units (in shares)	29,910
OP units | NSA OP, LP | Self Storage Properties
Class of Stock [Line Items]
Issuance of shares/units (in shares)	184,040
OP units | DownREIT Partnership
Class of Stock [Line Items]
Unit conversion ratio	1
Minimum conversion period (in years)	5 years
Issuance of shares/units (in shares)	13,475
Subordinated performance units
Class of Stock [Line Items]
Percentage of cash available for distribution used in conversion ratio calculation	110.00%
Subordinated performance units | NSA OP, LP
Class of Stock [Line Items]
Redemptions/conversions of units (in shares)	913,680
Unit conversion, lock out period	2 years
Subordinated performance units | NSA OP, LP | Self Storage Properties
Class of Stock [Line Items]
Issuance of shares/units (in shares)	904,073
Subordinated performance units | DownREIT Partnership
Class of Stock [Line Items]
Unit conversion ratio	1
Minimum conversion period (in years)	5 years
Redemptions/conversions of units (in shares)	15,377
LTIP units | NSA OP, LP
Class of Stock [Line Items]
Unit conversion ratio	1
Issuance of shares/units (in shares)	168,896
Conversion of LTIP units into OP units (in shares)	337,847

NONCONTROLLING INTERESTS - Equi

NONCONTROLLING INTERESTS - Equity Interests (Details) - shares	Mar. 31, 2019	Dec. 31, 2018
Partnership Subsidiaries [Member]
Noncontrolling Interest [Line Items]
Outstanding equity interest (in shares)	48,453,617	47,120,753
Series A-1 Preferred Units | NSA OP, LP
Noncontrolling Interest [Line Items]
Outstanding equity interest (in shares)	501,918	343,719
OP units | NSA OP, LP
Noncontrolling Interest [Line Items]
Outstanding equity interest (in shares)	30,229,228	28,874,103
OP units | DownREIT Partnership
Noncontrolling Interest [Line Items]
Outstanding equity interest (in shares)	1,848,261	1,834,786
Subordinated performance units | NSA OP, LP
Noncontrolling Interest [Line Items]
Outstanding equity interest (in shares)	10,739,868	10,749,475
Subordinated performance units | DownREIT Partnership
Noncontrolling Interest [Line Items]
Outstanding equity interest (in shares)	4,371,622	4,386,999
LTIP units | NSA OP, LP
Noncontrolling Interest [Line Items]
Outstanding equity interest (in shares)	762,720	931,671

SELF STORAGE PROPERTIES (Detail

SELF STORAGE PROPERTIES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Real Estate [Abstract]
Land	$ 612,273		$ 583,455
Buildings and improvements	2,214,345		2,048,281
Furniture and equipment	6,127		5,987
Total self storage properties	2,832,745		2,637,723
Less accumulated depreciation	(267,796)		(246,261)
Self storage properties, net	2,564,949		$ 2,391,462
Depreciation expense related to self storage properties	$ 21,500	$ 18,000

INVESTMENT IN UNCONSOLIDATED _3

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Narrative (Details) ft² in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)ft²storage_unitstateproperty	Dec. 31, 2016property
Schedule of Equity Method Investments [Line Items]
Number of self storage properties	706
Rentable square feet in self storage properties | ft²	44.7
Number of storage units owned and operated | storage_unit	361,000
Number of states in which self storage properties are owned | state	34
Corporate Joint Venture | 2016 Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of self storage properties		66
Unconsolidated Properties | Corporate Joint Venture | 2018 Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of self storage properties	103
Rentable square feet in self storage properties | ft²	7.7
Number of storage units owned and operated | storage_unit	63,000
Number of states in which self storage properties are owned | state	17
Unconsolidated Properties | Corporate Joint Venture | 2016 Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of self storage properties	72
Rentable square feet in self storage properties | ft²	4.9
Number of storage units owned and operated | storage_unit	40,000
Number of states in which self storage properties are owned | state	13
Number of self storage properties sold	1
Gross selling price of self storage properties sold | $	$ 4.1

INVESTMENT IN UNCONSOLIDATED _4

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Condensed Financial Position (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
ASSETS
Self storage properties, net	$ 1,876,504	$ 1,894,412
Other assets	34,334	50,915
Total assets	1,910,838	1,945,327
LIABILITIES AND EQUITY
Debt financing	947,391	956,357
Other liabilities	17,122	16,516
Equity	946,325	972,454
Total liabilities and equity	$ 1,910,838	$ 1,945,327

INVESTMENT IN UNCONSOLIDATED _5

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Condensed Operating Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Total revenue	$ 39,795	$ 14,806
Property operating expenses	12,544	5,293
Net operating income	27,251	9,513
Supervisory, administrative and other expenses	(2,653)	(1,057)
Depreciation and amortization	(21,826)	(5,507)
Interest expense	(10,020)	(2,899)
Loss on sale of self storage properties	(806)	0
Acquisition and other expenses	(408)	(262)
Net loss	$ (8,462)	$ (212)

SELF STORAGE PROPERTY ACQUISI_3

SELF STORAGE PROPERTY ACQUISITIONS AND DISPOSITIONS - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)property
Business Acquisition [Line Items]
Acquisition-related costs capitalized	$ 1.3
Recognized fair value allocated to real estate	190
Customer In-Place Leases
Business Acquisition [Line Items]
Recognized fair value allocated to in-place leases	$ 4.6
Affiliated Entity | Participating Regional Operator (PRO)
Business Acquisition [Line Items]
Number of properties acquired | property	13
Estimated fair value of acquired self storage properties	$ 85.5
Corporate Joint Venture | 2016 Joint Venture
Business Acquisition [Line Items]
Number of properties acquired | property	1
Estimated fair value of acquired self storage properties	$ 4.1
2019 Acquisitions
Business Acquisition [Line Items]
Number of properties acquired | property	32
Estimated fair value of acquired self storage properties	$ 194.6

SELF STORAGE PROPERTY ACQUISI_4

SELF STORAGE PROPERTY ACQUISITIONS AND DISPOSITIONS - Acquisitions (Details) - 2019 Acquisitions $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)property
Business Acquisition [Line Items]
Number of Properties | property	32
Cash and Acquisition Costs	$ 160,531
Value of OP Equity(1)	33,356
Other Liabilities	674
Total	$ 194,561

OTHER ASSETS (Details)

OTHER ASSETS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Receivables:
Trade, net	$ 3,208		$ 3,402
PROs and other affiliates	737		2,027
Receivable from unconsolidated real estate venture	2,818		4,573
Property acquisition and other deposits	911		20,977
Interest rate swaps	9,993		16,164
Prepaid expenses and other	5,628		4,266
Corporate furniture, equipment and other, net	1,584		1,574
Goodwill	5,750		5,750
Total	48,926		75,053
Customer In-Place Leases
Finite-Lived Intangible Assets [Line Items]
Amortization expense	2,500	$ 3,000
Accumulated amortization	4,193		5,090
Other Assets [Abstract]
Intangible assets, net of amortization	6,217		4,063
Trade Name
Receivables:
Trade name	3,200		3,200
Management Contract
Finite-Lived Intangible Assets [Line Items]
Amortization expense	200	$ 200
Accumulated amortization	1,741		1,564
Other Assets [Abstract]
Intangible assets, net of amortization	$ 8,880		$ 9,057

DEBT FINANCING - Debt Summary (

DEBT FINANCING - Debt Summary (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt, principal amount	$ 1,414,360	$ 1,277,638
Unamortized debt issuance costs and debt premium, net	566	464
Total debt	$ 1,414,926	1,278,102
Line of Credit | Credit Facility | Revolving line of credit
Debt Instrument [Line Items]
Effective interest rate (percent)	3.89%
Debt, principal amount	$ 277,500	139,500
Unsecured Debt | Credit Facility | Term loan A
Debt Instrument [Line Items]
Effective interest rate (percent)	2.91%
Debt, principal amount	$ 235,000	235,000
Unsecured Debt | Credit Facility | Term loan B
Debt Instrument [Line Items]
Effective interest rate (percent)	2.94%
Debt, principal amount	$ 155,000	155,000
Unsecured Debt | Credit Facility | Term loan C
Debt Instrument [Line Items]
Effective interest rate (percent)	3.71%
Debt, principal amount	$ 105,000	105,000
Unsecured Debt | Credit Facility | Term loan D
Debt Instrument [Line Items]
Effective interest rate (percent)	3.79%
Debt, principal amount	$ 125,000	125,000
Unsecured Debt | 2023 Term loan facility
Debt Instrument [Line Items]
Effective interest rate (percent)	3.13%
Debt, principal amount	$ 175,000	175,000
Unsecured Debt | 2028 Term loan facility
Debt Instrument [Line Items]
Effective interest rate (percent)	4.62%
Debt, principal amount	$ 75,000	75,000
Mortgages | Fixed rate mortgages payable
Debt Instrument [Line Items]
Effective interest rate (percent)	4.18%
Debt, principal amount	$ 266,860	$ 268,138

DEBT FINANCING - Future maturit

DEBT FINANCING - Future maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Scheduled Principal and Maturity Payments
2019	$ 3,850
2020	316,897
2021	242,603
2022	159,205
2023	377,049
2024	126,964
Thereafter	187,792
Total principal	1,414,360	$ 1,277,638
Amortization of Premium and Unamortized Debt Issuance Costs
2019	(262)
2020	(699)
2021	(779)
2022	(441)
2023	(42)
2024	270
Thereafter	2,519
Total premium amortization and unamortized debt issuance costs	566
Total
2019	3,588
2020	316,198
2021	241,824
2022	158,764
2023	377,007
2024	127,234
Thereafter	190,311
Total debt	$ 1,414,926	$ 1,278,102

DEBT FINANCING - Narrative (Det

DEBT FINANCING - Narrative (Details) - USD ($)	Apr. 24, 2019	Mar. 31, 2019
Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity if expansion option is exercised		$ 1,300,000,000
Unsecured Debt | Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		1,000,000,000
Unsecured Debt | Credit Facility | Term loan A
Debt Instrument [Line Items]
Maximum borrowing capacity		235,000,000
Unsecured Debt | Credit Facility | Term loan B
Debt Instrument [Line Items]
Maximum borrowing capacity		155,000,000
Unsecured Debt | Credit Facility | Term loan C
Debt Instrument [Line Items]
Maximum borrowing capacity		105,000,000
Unsecured Debt | Credit Facility | Term loan D
Debt Instrument [Line Items]
Maximum borrowing capacity		125,000,000
Unsecured Debt | 2029 Term Loan Facility | Subsequent Event
Debt Instrument [Line Items]
Debt instrument, face amount	$ 100,000,000
Line of Credit | Credit Facility | Revolving line of credit
Debt Instrument [Line Items]
Maximum borrowing capacity		400,000,000
Revolving line of credit remaining borrowing capacity		116,800,000
Line of Credit | Credit Facility | Letter of credit
Debt Instrument [Line Items]
Letters of credit outstanding		$ 5,700,000

EARNINGS PER SHARE - Basic and

EARNINGS PER SHARE - Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator
Net income	$ 12,940	$ 11,973
Net income attributable to noncontrolling interests	(5,529)	(1,513)
Net income attributable to National Storage Affiliates Trust	7,411	10,460
Distributions to preferred shareholders	(2,588)	(2,588)
Distributed and undistributed earnings allocated to participating securities	(9)	(7)
Net income attributable to common shareholders - basic and diluted	4,814	7,865
Effect of assumed conversion of dilutive securities	0	1,370
Net income attributable to common shareholders - diluted	$ 4,814	$ 9,235
Denominator
Weighted average shares outstanding - basic	56,655	50,299
Effect of dilutive securities:
Weighted average shares outstanding - diluted	56,655	99,935
Earnings (loss) per share - basic	$ 0.08	$ 0.16
Earnings (loss) per share - diluted	$ 0.08	$ 0.09
OP units | NSA OP, LP
Effect of dilutive securities:
Effect of dilutive securities	0	29,135
OP units | DownREIT Partnership
Effect of dilutive securities:
Effect of dilutive securities	0	1,835
LTIP units | NSA OP, LP
Effect of dilutive securities:
Effect of dilutive securities	0	321
Subordinated performance units | NSA OP, LP And DownREIT Partnership
Effect of dilutive securities:
Effect of dilutive securities	0	18,345

EARNINGS PER SHARE - Narrative

EARNINGS PER SHARE - Narrative (Details)	3 Months Ended
	Mar. 31, 2019shares
NSA OP, LP | OP units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Unit conversion ratio	1
Minimum conversion period (in years)	1 year
DownREIT Partnership | OP units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Unit conversion ratio	1
Minimum conversion period (in years)	5 years
DownREIT Partnership | Subordinated performance units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Unit conversion ratio	1
Minimum conversion period (in years)	5 years
NSA OP, LP And DownREIT Partnership | Subordinated performance units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Unit conversion ratio	1
Minimum conversion period (in years)	2 years
Long-Term Incentive Plan Unit based on service or market condition
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average outstanding equity interests excluded from computation of diluted earnings per share (in units)	450,722
Long-Term Incentive Plan Unit based on future acquisitions
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average outstanding equity interests excluded from computation of diluted earnings per share (in units)	224,000
OP units, DownREIT OP units, Subordinated performance units, DownREIT subordinated performance units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average outstanding equity interests excluded from computation of diluted earnings per share (in units)	54,600,000

RELATED PARTY TRANSACTIONS (Det

RELATED PARTY TRANSACTIONS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Related Party Transaction [Line Items]
Payroll and related costs reimbursed to the PROs by the Company	$ 26,457	$ 25,226
Supervisory and Administrative Fee Agreement | Management | Participating Regional Operator (PRO)
Related Party Transaction [Line Items]
Supervisory and administrative fees paid to the PROs	$ 4,700	4,100
Supervisory and Administrative Fee Agreement | Management | Participating Regional Operator (PRO) | Minimum
Related Party Transaction [Line Items]
Supervisory and administrative fee agreement of gross revenue, percent	5.00%
Supervisory and Administrative Fee Agreement | Management | Participating Regional Operator (PRO) | Maximum
Related Party Transaction [Line Items]
Supervisory and administrative fee agreement of gross revenue, percent	6.00%
Payroll Services | Management | Participating Regional Operator (PRO)
Related Party Transaction [Line Items]
Payroll and related costs reimbursed to the PROs by the Company	$ 7,800	7,300
Due Diligence Costs | Management | Participating Regional Operator (PRO)
Related Party Transaction [Line Items]
Due diligence expenses payable to the PROs	$ 300	$ 200
Real Estate Purchases | Corporate Joint Venture
Related Party Transaction [Line Items]
Number of properties acquired	1
Estimated fair value of acquired self storage properties	$ 4,100

FAIR VALUE MEASUREMENTS - Inter

FAIR VALUE MEASUREMENTS - Interest Swap Derivatives (Details) - Interest Rate Swap - Level 2 - Designated as Hedging Instrument - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis [Roll Forward]
Fair value at beginning of period	$ 14,195	$ 12,414
Losses (Gains) on interest rate swaps reclassified into interest expense from accumulated other comprehensive income	(1,276)	49
Unrealized gains (losses) on interest rate swaps included in accumulated other comprehensive income	(8,039)	8,990
Fair value of end of period	$ 4,880	$ 21,453

FAIR VALUE MEASUREMENTS - Narra

FAIR VALUE MEASUREMENTS - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized gains forecasted to be included in earnings transferred from AOCI in the next twelve months	$ (4.2)
Level 2 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed rate mortgages, fair value disclosure	$ 279		$ 276.5
Weighted average market interest rate (percent)	3.88%	4.17%
Weighted average contractual interest rate (percent)	4.84%	4.85%
Designated as Hedging Instrument | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount	$ 795		795
Weighted average remaining term	4 years 2 months
Weighted average fixed rate (percent)	1.87%
Reported Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed rate mortgages, fair value disclosure	$ 266.9		$ 268.1

LEASES - Narrative (Details)

LEASES - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)
Real Estate Leasehold Interest
Lessee, Lease, Description [Line Items]
Number of properties subject to non-cancelable leasehold interest agreements	7
Rent expense	$ 0.4
Rent expense		$ 0.4
Real Estate Leasehold Interest | Minimum
Lessee, Lease, Description [Line Items]
Operating leases, term (in years)	15 years
Real Estate Leasehold Interest | Maximum
Lessee, Lease, Description [Line Items]
Operating leases, term (in years)	73 years
Office Leases
Lessee, Lease, Description [Line Items]
Rent expense	$ 0.1
Rent expense		$ 0.1
Office Leases | Minimum
Lessee, Lease, Description [Line Items]
Operating leases, term (in years)	4 years
Office Leases | Maximum
Lessee, Lease, Description [Line Items]
Operating leases, term (in years)	8 years

LEASES - Weighted-Average Remai

LEASES - Weighted-Average Remaining Term and Weighted-Average Discount Rate (Details)	3 Months Ended
	Mar. 31, 2019
Real Estate Leasehold Interest
Lessee, Lease, Description [Line Items]
Weighted-average remaining lease term	29 years
Weighted-average remaining discount rate	4.90%
Office Leases
Lessee, Lease, Description [Line Items]
Weighted-average remaining lease term	7 years
Weighted-average remaining discount rate	4.10%

LEASES - Future Minimum Lease P

LEASES - Future Minimum Lease Payments Under Operating Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Future Minimum Lease Payments
2019	$ 1,149
2020	1,671
2021	1,797
2022	1,806
2023	1,777
2024 through 2092	37,462
Total lease payments	45,662
Less imputed interest	(21,496)
Operating lease liabilities	24,166	$ 0
Future Minimum Lease Payments, Prior Year End
2019		1,679
2020		1,777
2021		1,791
2022		1,800
2023		1,770
2024 through 2092		37,147
Total lease payments		45,964
Real Estate Leasehold Interest
Future Minimum Lease Payments
2019	1,005
2020	1,385
2021	1,410
2022	1,425
2023	1,431
2024 through 2092	36,419
Total lease payments	43,075
Less imputed interest	(21,108)
Operating lease liabilities	21,967
Future Minimum Lease Payments, Prior Year End
2019		1,334
2020		1,379
2021		1,404
2022		1,419
2023		1,424
2024 through 2092		36,074
Total lease payments		43,034
Office Leases
Future Minimum Lease Payments
2019	144
2020	286
2021	387
2022	381
2023	346
2024 through 2092	1,043
Total lease payments	2,587
Less imputed interest	(388)
Operating lease liabilities	$ 2,199
Future Minimum Lease Payments, Prior Year End
2019		345
2020		398
2021		387
2022		381
2023		346
2024 through 2092		1,073
Total lease payments		$ 2,930

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - Subsequent Event - 2029 Term Loan Facility - Unsecured Debt $ in Millions	Apr. 24, 2019USD ($)
Subsequent Event [Line Items]
Debt instrument, face amount	$ 100
Notional amount	$ 100
Effective interest rate (percent)	4.27%
Federal Funds Rate
Subsequent Event [Line Items]
Borrowing rate spread (percent)	0.50%
LIBOR
Subsequent Event [Line Items]
Borrowing rate spread (percent)	1.00%
Minimum | LIBOR
Subsequent Event [Line Items]
Leverage-based margin threshold (percent)	1.85%
Elective rating-based margin threshold (percent)	1.40%
Minimum | Base Rate
Subsequent Event [Line Items]
Leverage-based margin threshold (percent)	0.85%
Elective rating-based margin threshold (percent)	0.40%
Maximum | LIBOR
Subsequent Event [Line Items]
Leverage-based margin threshold (percent)	2.30%
Elective rating-based margin threshold (percent)	2.25%
Maximum | Base Rate
Subsequent Event [Line Items]
Leverage-based margin threshold (percent)	1.30%
Elective rating-based margin threshold (percent)	1.25%