Restricted stock grants issued Stock Issued During Period, Value, Restricted Stock Award, Gross Total noncontrolling interests and equity Balance, beginning of period Balance, end of period Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Schedule of investments in unconsolidated real estate ventures Schedule Of Real Estate Joint Ventures [Table Text Block] Tabular disclosure of information related to real estate joint ventures. Other assets Other Assets [Member] Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Gain (loss) reclassified from OCI Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax Revolving lines of credit Long-term Line of Credit Acquisition of real estate assets Payments to Acquire Real Estate Number of interests in consolidated VIE joint ventures Variable Interest Entity Interest In Consolidated Joint Ventures Number Represents the number of consolidated joint ventures that were variable interest entities. Compensation expense related to stock-based awards APIC, Share-based Payment Arrangement, Increase for Cost Recognition Note receivable interest rate Notes Receivable Stated Interest Rate Represents the stated interest rate of notes receivable. Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Number of Stores Equity Method Investment, Number Of Properties Equity Method Investment, Number Of Properties Recently Issued Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Commitment To Acquire Retail Space With Joint Venture Partners, Scheduled To Close in 2020 Commitment To Acquire Retail Space With Joint Venture Partners, Expected To Close Next Fiscal Year [Member] Commitment To Acquire Retail Space With Joint Venture Partners, Expected To Close Next Fiscal Year [Member] Current Fiscal Year End Date Current Fiscal Year End Date Total revenues Revenues: Revenues Derivative [Line Items] Derivative [Line Items] Diluted (in shares) Average number of common shares outstanding - diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Entity Address, Postal Zip Code Entity Address, Postal Zip Code Carrying Value Reported Value Measurement [Member] Notes exchange, threshold consecutive trading days Debt Instrument, Convertible, Threshold Consecutive Trading Days Storage Portfolio II JV LLC Storage Portfolio II JV LLC [Member] Storage Portfolio II JV LLC [Member] Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Investment commitment Preferred Stock Investment, Investment Commitment Preferred Stock Investment, Investment Commitment Exchangeable senior notes Convertible Debt, Fair Value Disclosures Noncontrolling Interest - Preferred Operating Partnership Preferred Operating Partnership [Member] Preferred Operating Partnership [Member] Accumulated Other Comprehensive Income AOCI Attributable to Parent [Member] Total assets Assets Entity Shell Company Entity Shell Company Operating lease liabilities Operating Lease, Liability Cover page. Cover [Abstract] Period after which preferred stock is subject to increase Preferred Stock Investment, Period After Which Redeemable Preferred Stock Investment, Period After Which Redeemable Document Type Document Type Interest expense Interest Expense, Excluding Amortization of Debt Discount (Premium) Interest Expense, Excluding Amortization of Debt Discount (Premium) Effective interest rate on the liability component Debt Instrument, Interest Rate, Effective Percentage Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Loans and notes to affiliates Due from Related Parties, Noncurrent Notes exchange, threshold trading days Debt Instrument, Convertible, Threshold Trading Days Real estate assets - operating lease right-of-use assets Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Issuance of Preferred D Units in the Operating Partnership in conjunction with acquisitions Noncontrolling Interest, Increase from Subsidiary Equity Issuance Segment Information Segment Reporting Disclosure [Text Block] Preferred stock, outstanding (in shares) Preferred Stock, Shares Outstanding Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Document Quarterly Report Document Quarterly Report Commitments and contingencies Commitments and Contingencies Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Cash, cash equivalents, and restricted cash, beginning of the period Cash, cash equivalents, and restricted cash, end of the period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Debt Instrument [Line Items] Debt Instrument [Line Items] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Remaining authorized repurchase amount Stock Repurchase Program, Remaining Authorized Repurchase Amount Consolidation Items [Domain] Consolidation Items [Domain] Stockholders' Equity Note [Abstract] Stockholders' Equity Note [Abstract] Net Liabilities/ (Assets) Assumed Real Estate Property Acquisition, Increase Assets Acquired And Liabilities Assumed, Net The net value of assets transferred (liabilities assumed) in connection with the acquisition of real estate operating property. Noncontrolling interests in Operating Partnership, net and other noncontrolling interests Noncontrolling Interest in Operating Partnerships Non-cash lease expense Operating Lease Right Of Use Asset Amortization Expense Operating Lease Right Of Use Asset Amortization Expense At the Market Equity Distribution Agreement At The Market Equity Distribution Agreement [Member] At The Market Equity Distribution Agreement [Member] Restricted stock grants issued (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross Series D Units Series D Units [Member] Series D Units [Member] Other Commitments [Line Items] Other Commitments [Line Items] Entity File Number Entity File Number Aggregate offering price of common shares Aggregate Offering Price Of Common Share Aggregate offering price of common share. Earnings per common share Earnings Per Share, Basic and Diluted [Abstract] Value of stock available for issuance under ATM Value Of Stock Available For Issuance Under ATM The dollar amount of shares available for issuance under the entity's "at the market" (ATM) equity program Segments [Axis] Segments [Axis] Exchangeable senior notes, net Principal amount of liability component Convertible Debt Document Fiscal Period Focus Document Fiscal Period Focus Other liabilities Other Liabilities [Member] SmartStop Self Storage REIT, Inc. Preferred Stock SmartStop Self Storage REIT Inc Series A Convertible Preferred Stock [Member] SmartStop Self Storage REIT Inc Series A Convertible Preferred Stock [Member] Basis of Presentation Basis of Presentation and Significant Accounting Policies [Text Block] Number of derivative financial instruments Derivative, Number of Instruments Held Income from operations Operating Income (Loss) Segments [Domain] Segments [Domain] Measurement Frequency [Domain] Measurement Frequency [Domain] Statement [Line Items] Statement [Line Items] Management fees and other income Property management fees and other income Revenue from Contract with Customer, Excluding Assessed Tax Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Basic (in dollars per share) Earnings Per Share, Basic Noncontrolling interests in Operating Partnership Conversion of Stock, Amount Converted Earnings Per Common Share Earnings Per Share, Policy [Policy Text Block] Distributions to noncontrolling interests Payments of Ordinary Dividends, Noncontrolling Interest Comprehensive income attributable to common stockholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Contractual interest Interest Expense, Debt, Excluding Amortization Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes Amortization of discount Amortization of Debt Discount (Premium) Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Noncontrolling Interest [Line Items] Noncontrolling Interest [Line Items] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Amendment Flag Amendment Flag Other liabilities - Cash flow hedge swap agreements Derivative liability, fair value Interest Rate Cash Flow Hedge Liability at Fair Value Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Income before equity in earnings of unconsolidated real estate entities and income tax expense Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Common stock, outstanding (in shares) Common Stock, Shares, Outstanding Issuance of notes receivable Payments to Acquire Notes Receivable Consolidation Items [Axis] Consolidation Items [Axis] Excess Profit % Unconsolidated Joint Ventures Excess Profit Participation Percentage The percentage of excess profit participation in unconsolidated joint ventures. Preferred Units by Name [Axis] Preferred Units by Name [Axis] Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Interest expense Interest Expense Restricted cash Restricted Cash and Cash Equivalents Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Income allocated to noncontrolling interest - Preferred Operating Partnership Units and Operating Partnership Units Net Income Loss Attributable To Noncontrolling Interest In Operating Partnership Net Income Loss Attributable To Noncontrolling Interest In Operating Partnership Fixed priority return on preferred OP units, stated return rate Noncontrolling Interest In Preferred Operating Partnership Units Fixed Priority Return Stated Rate Of Return Represents the fixed priority return, as a percent, of preferred operating partnership units attributable to noncontrolling preferred unit holders on which the fixed priority return is granted. Equity in earnings and dividend income from unconsolidated real estate entities Income (Loss) from Equity Method Investments Acquisitions of real estate assets Noncash Or Part Noncash Acquisition Net Real Estate Assets Acquired [Abstract] Noncash Or Part Noncash Acquisition Net Real Estate Assets Acquired [Abstract] Local Phone Number Local Phone Number Joint Venture 1 Joint Venture One [Member] Joint Venture One [Member] Amount invested Payments For Investment In Unconsolidated Real Estate Entities Payments For Investment In Unconsolidated Real Estate Entities Equity Method Investments and Joint Ventures [Abstract] Equity Method Investments and Joint Ventures [Abstract] Operating Partnership Holders of A Units Holders Of Series A Preferred Operating Partnership Units [Member] Holders Of Series A Preferred Operating Partnership Units [Member] Other assets, net Other Assets Noncontrolling Interest Represented by Preferred Operating Partnership Units Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests Noncontrolling Interest Disclosure [Text Block] Redemption of Operating Partnership units (in shares) Minority Interest, Decrease From Redemptions, Shares Decrease in noncontrolling interests as a result of the redemption of Operating Partnership units in exchange for common shares. Issuance of common stock upon the exercise of options (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Less: comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest OP Units redeemed for common stock (in units) Noncontrolling Interest, Operating Partnership Units Redeemed For Common Stock Noncontrolling Interest, Operating Partnership Units Redeemed For Common Stock Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Derivatives Derivatives, Policy [Policy Text Block] Entity Current Reporting Status Entity Current Reporting Status Noncontrolling Interest [Abstract] Noncontrolling Interest [Abstract] GFN JV, LLC GFN JV, LLC [Member] GFN JV, LLC [Member] Net increase (decrease) in cash, cash equivalents, and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Distributions from unconsolidated real estate ventures in excess of earnings Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Carrying amount of equity component Debt Instrument, Convertible, Carrying Amount of Equity Component Net income attributable to common stockholders Net income attributable to common stockholders Net Income (Loss) Attributable to Parent Net income allocated to Preferred Operating Partnership noncontrolling interests Noncontrolling Interest in Net Income (Loss) Preferred Unit Holders, Redeemable Net proceeds from exercise of stock options Proceeds from Stock Options Exercised Common Stock Common Stock [Member] Redemption of Operating Partnership units held by noncontrolling interests for common stock Redemption Of Operating Partnership Units Held By Noncontrolling Interests For Common Stock [Abstract] Redemption Of Operating Partnership Units Held By Noncontrolling Interests For Common Stock [Abstract] Debt Instrument [Axis] Debt Instrument [Axis] Other minority owned stores Other Minority Owned Properties [Member] Other Minority Owned Properties [Member] Fair Value of Financial Instruments [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Entity Small Business Entity Small Business Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Real Estate [Abstract] Real Estate [Abstract] Entity Filer Category Entity Filer Category Fixed priority return on preferred OP units, amount Noncontrolling Interest In Preferred Operating Partnership Units Fixed Priority Return Amount Represents the carrying amount of preferred operating partnership units attributable to noncontrolling preferred unit holders on which the fixed priority return is granted. Fair Value Disclosures Fair Value of Financial Instruments, Policy [Policy Text Block] Period used as a denomination to determine the average closing price of common stock Average Closing Market Price Measurement Period Represents the period over which the average market closing price is measured. Earnings and dividends allocated to participating securities Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted Swap Agreements Interest Rate Swap [Member] Total liabilities, noncontrolling interests and equity Liabilities and Equity Entity Address, City or Town Entity Address, City or Town Contribution of Preferred OP Units to unconsolidated real estate venture Contribution Of Preferred Operating Partnership Units to Equity Method Investment [Abstract] Contribution Of Preferred Operating Partnership Units to Equity Method Investment [Abstract] Schedule of information relating to gain (loss) recognized on swap agreements Derivative Instruments, Gain (Loss) [Table Text Block] Notes exchange, threshold percentage Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger Investments in unconsolidated real estate entities Real Estate Investments, Unconsolidated Real Estate and Other Joint Ventures Amortization period Debt Issuance Cost Amortization Period Debt Issuance Cost Amortization Period Variable Interest Entities [Axis] Variable Interest Entities [Axis] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Preferred stock, authorized (in shares) Preferred Stock, Shares Authorized Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Restricted stock grants cancelled (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Forfeited Real estate assets, net Real Estate Investment Property, Net Liquidation value (in dollars per share) Noncontrolling Interest In Preferred Operating Partnership Units Liquidation Value Per Unit Represents the liquidation value per unit of preferred operating partnership units. Extra Space Storage Inc. stockholders' equity: Stockholders' Equity Attributable to Parent [Abstract] Document Fiscal Year Focus Document Fiscal Year Focus Shares issued (in shares) Sale of Stock, Number of Shares Issued in Transaction Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Fair Value of Financial Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Investment in unconsolidated real estate ventures Investments in Real Estate Ventures Investments In Real Estate Joint Ventures, Net Of Distributions Received Investments In Real Estate Joint Ventures, Net Of Distributions Received Subsequent Events Subsequent Events [Text Block] Revenues: Revenues [Abstract] Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities Recurring Basis Fair Value, Recurring [Member] Loan to affiliates Origination of Notes Receivable from Related Parties Noncash or Part Noncash Acquisitions by Unique Description [Axis] Noncash or Part Noncash Acquisitions by Unique Description [Axis] Schedule of Antidilutive Shares Excluded from Computation of Earnings Per Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Award Type [Axis] Award Type [Axis] Property operations Cost of Revenue Preferred units outstanding (in shares) Preferred Units, Outstanding Class of Stock [Line Items] Class of Stock [Line Items] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Subsequent Events [Abstract] Subsequent Events [Abstract] VRS Self Storage, LLC VRS Self Storage LLC [Member] VRS Self Storage LLC [Member] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Expenses: Costs and Expenses [Abstract] Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Investment, preferred dividend rate Preferred Stock Investment, Dividend Rate Preferred Stock Investment, Dividend Rate Buyback of common stock, net of offering costs Stock Repurchased During Period, Value Redemption price as percentage of principal amount of notes at request of debt holders and upon occurrence of designated event Redemption Price Of Debt As Percentage Of Principal Amount At Request Of Debt Holders Represents the percentage of principal amount used in computation of the redemption price to be paid on conversion of convertible notes at the request of the debt holders and upon the occurrence of a designated event. Number of operating storage facilities in which the entity has equity interests (in stores) Number of Real Estate Properties Accumulated Deficit Retained Earnings [Member] Noncontrolling interest represented by Preferred Operating Partnership units, net Noncontrolling Interest in Preferred Unit Holders Amortization of deferred financing costs Amortization of Debt Issuance Costs Series A Units Series A Units [Member] Series A Units [Member] Accounts payable and accrued expenses Capital Expenditures Incurred but Not yet Paid Document Period End Date Document Period End Date Statement [Table] Statement [Table] Weighted average number of shares Weighted average common shares outstanding: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Redeemable Noncontrolling Interest Redeemable Noncontrolling Interest [Table Text Block] Entity Registrant Name Entity Registrant Name Investment, Name [Domain] Investment, Name [Domain] Schedule of information about total carrying amounts of equity components, principal amounts of liability components, unamortized discounts and net carrying amounts for notes Convertible Debt [Table Text Block] Alan Jathoo JV LLC Alan Jathoo JV LLC [Member] Alan Jathoo JV LLC [Member] Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Number of operating stores acquired Number Of Real Estate Properties Acquired By Joint Ventures Number Of Real Estate Properties Acquired By Joint Ventures Maximum Maximum [Member] Earnings for basic computations Net Income (Loss) Available to Common Stockholders, Basic Average share price (in dollars per share) Average Share Price Per Share Average Share Price Per Share Ownership [Axis] Ownership [Axis] Fixed component of income allocated to noncontrolling interest - Preferred Operating Partnership (Series A Units) Income (Loss) Attributable to Noncontrolling Interest Fixed Component Represents the component of income or loss attributable to the noncontrolling interest as a result of fixed distributions paid to Preferred Operating unit holders. Underwriting fee percentage Percentage of Underwriting Fee Percentage of Underwriting Fee Equivalent Shares (if converted) Number Of Preferred Operating Partnership Units Represents the number of Preferred Operating Partnership units outstanding at the balance sheet date that are excluded from the earnings per share computation as their effect would have been anti-dilutive. Exchangeable preferred operating partnership units settled in cash, minimum Preferred Operating Partnership Units Amount to be Settled in Cash Minimum Represents the minimum amount of convertible preferred operating partnership units which will be settled in cash upon conversion. Accumulated deficit Retained Earnings (Accumulated Deficit) Repurchase of common stock Payments for repurchase of common stock Payments for Repurchase of Common Stock Number of development stores owned Number Of Development Stores Owned Number Of Development Stores Owned Entity Tax Identification Number Entity Tax Identification Number Other Commitments [Domain] Other Commitments [Domain] Distributions to Operating Partnership units held by noncontrolling interests Partners' Capital Account, Distributions Principal amount of notes issued Debt Instrument, Face Amount Diluted (in dollars per share) Earnings Per Share, Diluted Noncontrolling Interests and Equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Number of reportable segments Number of Reportable Segments Trading Symbol Trading Symbol Minimum Minimum [Member] Earnings and dividends allocated to participating securities Undistributed Earnings (Loss) Allocated to Participating Securities, Basic Issuance of units upon conversion (in shares) Noncontrolling Interest, Conversion Of Preferred Units to Common Units, Number Of Units Issued Noncontrolling Interest, Conversion Of Preferred Units to Common Units, Number Of Units Issued Legal Entity [Axis] Legal Entity [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Statistical Measurement [Domain] Statistical Measurement [Domain] Tenant reinsurance Tenant Reinsurance Expense The expense in the period incurred with respect to the entity's tenant reinsurance program. Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Number of parcels of land held-for-sale Number Of Parcels Of Land Held-For-Sale Number Of Parcels Of Land Held-For-Sale Accrued construction costs and capital expenditures Accrued Construction Costs And Capital Expenditures [Abstract] Accrued Construction Costs And Capital Expenditures [Abstract] Number of stores owned by franchisees and third parties Number Of Real Estate Properties Franchisees And Others The number of real estate properties owned by franchisees and other third parties as of the balance sheet date. Gain (loss) recognized in OCI Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax Common stock and paid-in capital Redemption Of Operating Partnership Units For Common Stock Including Additional Paid In Capital Represents the value of Operating Partnership units redeemed for common stock including additional paid in capital. Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Entity [Domain] Entity [Domain] Income tax expense Income tax expense Income Tax Expense (Benefit) Repurchase of common stock, average price (in dollars per share) Stock Repurchased During Period, Average Cost Per Share Stock Repurchased During Period, Average Cost Per Share Other Commitments [Table] Other Commitments [Table] City Area Code City Area Code Preferred Units, Class [Domain] Preferred Units, Class [Domain] Other liabilities Other Liabilities Title of 12(b) Security Title of 12(b) Security Number of units issued (in shares) Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued Joint Venture 2 Joint Venture Two [Member] Joint Venture Two [Member] PRISA Self Storage LLC Prisa Self Storage LLC [Member] Prisa Self Storage LLC [Member] Number of sales agents Number Of Sales Agents Number Of Sales Agents Fair Value Estimate of Fair Value Measurement [Member] Earnings Per Share [Abstract] Earnings Per Share [Abstract] Proceeds from notes payable and revolving lines of credit Proceeds from Issuance of Secured Debt Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Notes payable to Trusts Trust Preferred Securities Subject to Mandatory Redemption [Member] Notes payable to Trusts Long-term Debt, Gross Assets: Assets [Abstract] Investment commitment, period Preferred Stock Investment, Investment Commitment, Period Preferred Stock Investment, Investment Commitment, Period Preferred Stock, Par or Stated Value Per Share Preferred Stock, Par or Stated Value Per Share Number of stores acquired at certificate of occupancy Number Of Stores Acquired At Issuance Of Certificate Of Occupancy Number Of Stores Acquired At Issuance Of Certificate Of Occupancy Shares related to the Notes included in the computation for diluted earnings per share (in shares) Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities Fixed rate notes payable Notes Payable, Fair Value Disclosure Organization Nature of Operations [Text Block] PR EXR Self Storage, LLC PR EXR Self Storage, LLC [Member] PR EXR Self Storage, LLC [Member] Derivative asset, fair value Interest Rate Cash Flow Hedge Asset at Fair Value Restricted stock grants cancelled Stock Issued During Period, Value, Restricted Stock Award, Forfeitures Schedule of Financial Information of Business Segments Schedule of Segment Reporting Information, by Segment [Table Text Block] Segment Reporting [Abstract] Segment Reporting [Abstract] Number of days of written notice to holders of notes required for redemption Written Notice Required For Redemption Period Represents the number of days of written notice to be made to the holders of the notes required for redemption. Conversion ratio Debt Instrument, Convertible, Conversion Ratio Measurement Basis [Axis] Measurement Basis [Axis] Supplemental schedule of noncash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Principal payments on notes payable and revolving lines of credit Repayments of Debt Property rental Lease Income Issuance of common stock upon the exercise of options Stock Issued During Period, Value, Stock Options Exercised Fixed priority return on preferred OP units, liquidation value Noncontrolling Interest In Preferred Operating Partnership Units Fixed Priority Return Redemption Value Represents the liquidation value of preferred operating partnership units attributable to noncontrolling preferred unit holders on which the fixed priority return is granted. Purchase of equipment and fixtures Payments to Acquire Furniture and Fixtures Debt Disclosure [Abstract] Debt Disclosure [Abstract] Number of consolidated joint ventures Real Estate Consolidated Joint Ventures Number Represents the number of consolidated joint ventures as of the balance sheet date. Derivative Instrument [Axis] Derivative Instrument [Axis] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Statistical Measurement [Axis] Statistical Measurement [Axis] Acquisition of real estate assets Real Estate Additions, Portion Not Yet Paid Real Estate Additions, Portion Not Yet Paid Supplemental schedule of cash flow information Supplemental Cash Flow Information [Abstract] Commitment To Acquire Stores With Joint Venture Partners Commitment To Acquire Retail Space With Joint Venture Partners [Member] Commitment To Acquire Retail Space With Joint Venture Partners [Member] Contributions to joint ventures Contributions To Equity Method Investments, Including Noncash Amounts Contributions To Equity Method Investments, Including Noncash Amounts Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Commitment To Acquire Stores Commitment To Acquire Retail Space [Member] Commitment To Acquire Retail Space [Member] Annual rate of return percentage Noncontrolling Interest In Preferred Operating Partnership Units Annual Rate Of Return Represents the annual rate of return of preferred operating partnership units. Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Combined notional amount Derivative, Notional Amount Redemption price as percentage of principal amount of notes plus accrued and unpaid interest Debt Instrument, Redemption Price, Percentage Buyback of common stock, net of offering costs (in shares) Repurchase of common stock (in shares) Stock Repurchased During Period, Shares Income taxes paid Income Taxes Paid, Net Noncontrolling Interest [Table] Noncontrolling Interest [Table] Change in fair value of interest rate swaps Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Equity Ownership % Equity Method Investment, Ownership Percentage Investment, Name [Axis] Investment, Name [Axis] Common stock, authorized (in shares) Common Stock, Shares Authorized Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Estimated amount of unrealized gains (losses) expected to be reclassified as interest expense in next fiscal year Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Entity Central Index Key Entity Central Index Key Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes) Exchangeable Senior Notes Three Point One Two Five Percent Due Two Thousand And Thirty Five [Member] Exchangeable Senior Notes Three Point One Two Five Percent Due Two Thousand And Thirty Five [Member] Entity Emerging Growth Company Entity Emerging Growth Company Senior Notes Senior Notes [Member] Sale of Stock [Domain] Sale of Stock [Domain] Value of units issued Real Estate Property Asset Acquisition, Consideration Transferred, Equity Interest Issued Or Issuable Real Estate Property Asset Acquisition, Consideration Transferred, Equity Interest Issued Or Issuable Compensation expense related to stock-based awards Share-based Payment Arrangement, Noncash Expense Schedule of Computation of Earnings Per Common Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Derivatives Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative [Table] Derivative [Table] Consideration to be paid on redemption of common OP units Operating Partnership Units Redemption Amount Represents the amount the entity would have paid in cash to redeem the operating partnership units. Storage Portfolio I LLC Storage Portfolio I LLC [Member] Storage Portfolio I LLC [Member] Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Ownership interest held Noncontrolling Interest, Ownership Percentage by Parent Convertible Debt Convertible Debt Policy [Policy Text Block] Convertible Debt Policy [Policy Text Block] Dividends paid on common stock Dividends, Common Stock Real estate assets, net Noncash Or Part Noncash Acquisition Net Real Estate Assets Acquired Represents the amount of real estate assets that an Entity acquires in a noncash (or part noncash) acquisition. Real estate assets refer to the lands, buildings and intangible assets (including those that are part of operations and those under development) of a real estate entity, net of accumulated depreciation and amortization. Noncash is defined as information about all investing and financing activities of an enterprise during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. Preferred stock, issued (in shares) Preferred Stock, Shares Issued Storage Portfolio III JV LLC Storage Portfolio III JV LLC [Member] Storage Portfolio III JV LLC Liabilities, Noncontrolling Interests and Equity: Liabilities and Equity [Abstract] Other comprehensive income Other Comprehensive Income (Loss), Net of Tax Derivative Contract [Domain] Derivative Contract [Domain] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Net carrying amount of liability component Long-term Debt Number of states in which operating storage facilities are located Number of States in which Entity Operates Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Period from date of issuance after which preferred OP units will become redeemable at the option of the holder Noncontrolling Interest In Preferred Operating Partnership Units Period From Date Of Issuance After Which Units Become Redeemable Represents the period from the date of issuance after which preferred units will become redeemable at the option of the holder. Variable Interest Entity, Not Primary Beneficiary Variable Interest Entity, Not Primary Beneficiary [Member] Period of share repurchase program Stock Repurchase Program, Period in Force Schedule of balance sheet classification and fair value of entity's derivative financial instruments Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Number of wholly-owned unconsolidated subsidiaries Variable Interest Entity Interest In Trust Number Represents the number of wholly-owned unconsolidated subsidiaries. Investments in Unconsolidated Real Estate Ventures Equity Method Investments and Joint Ventures Disclosure [Text Block] Series B Units Series B Units [Member] Series B Units [Member] Sale of Stock [Axis] Sale of Stock [Axis] Accounting Policies [Abstract] Accounting Policies [Abstract] Establishment of operating lease right of use assets and lease liabilities Noncash Right-Of-Use Assets And Lease Liabilities [Abstract] Noncash Right-Of-Use Assets And Lease Liabilities [Abstract] Additional Paid-in Capital Additional Paid-in Capital [Member] Issuance of common stock in connection with share based compensation (in shares) Shares Issued, Shares, Share-based Payment Arrangement, before Forfeiture Noncash or Part Noncash Acquisition, Name [Domain] Noncash or Part Noncash Acquisition, Name [Domain] Interest income Investment Income, Interest Development and redevelopment of real estate assets Payments to Develop Real Estate Assets Maximum number of preferred OP units converted prior to the maturity date of the loan (in shares) Noncontrolling Interest Conversion Of Preferred Operating Partnership Units Before Maturity Of Loan Maximum Represents the maximum number of preferred operating partnership units that can be converted by noncontrolling holders of preferred units before maturity date of the loan. Cash dividends paid per common share (in dollars per share) Dividends paid on common stock (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid Notes payable, net Notes Payable Fair Value Measurement [Domain] Fair Value Measurement [Domain] Contribution of Preferred OP Units to unconsolidated real estate venture Contribution Of Preferred Operating Partnership Units to Equity Method Investment [Member] Contribution Of Preferred Operating Partnership Units to Equity Method Investment [Member] Debt stated interest rate Debt Instrument, Interest Rate, Stated Percentage OP Units (in shares) Incremental Common Shares Attributable To Conversion Of Operating Partnership Units Shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible operating partnership units. Deferred financing costs Payments of Financing Costs Entity Address, Address Line One Entity Address, Address Line One Net income allocated to Operating Partnership and other noncontrolling interests Minority Interest In Net Income Loss Operating Partnerships And Other Amount of net income (loss) for the period allocated to noncontrolling partners of an operating partnership and others included in the entity's consolidated financial statements. Summary of amount of interest cost recognized relating to contractual interest rates and amortization of discounts on liability components of notes Schedule of Interest and Amortization Discount Cost [Table Text Block] Tabular disclosure of interest cost recognized and the amortization of the discount on the liability component of the convertible debt instrument. Shares related to exchangeable senior notes and dilutive stock options (in shares) Incremental Common Shares Attributable To Share Based Payment Arrangements Stock Options Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements related to stock options. Principal payments on notes payable to trusts Repayments of debt Repayments of Notes Payable Entity Address, State or Province Entity Address, State or Province Cash Paid Payments To Acquire Assets, Gross Payments To Acquire Assets, Gross Operating Segments Operating Segments [Member] Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Unvested restricted stock awards included for treasury stock method (in shares) Incremental Common Shares Attributable to Dilutive Effect of Nonvested Shares with Forfeitable Dividends Investments in unconsolidated real estate ventures Non-Cash Decrease In Investments In Unconsolidated Entities Non-Cash Decrease In Investments In Unconsolidated Entities Ten day average closing stock price (in dollars per share) Common Stock Average Closing Market Price The average closing market price of the entity's common stock. Noncontrolling Interest - Other Other noncontrolling interests Non Controlling Interest Other [Member] Non Controlling Interest Other [Member] Number of real estate properties to be acquired Number Of Real Estate Properties To Be Acquired Number Of Real Estate Properties To Be Acquired General and administrative General and administrative expense General and Administrative Expense Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes Amortization Of Debt Discount (Premium), Equity Component Of Senior Notes Amortization Of Debt Discount (Premium), Equity Component Of Senior Notes Entity Interactive Data Current Entity Interactive Data Current Common stock, issued (in shares) Balance, beginning of period (in shares) Balance, end of period (in shares) Common Stock, Shares, Issued Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Total expenses Operating expenses: Costs and Expenses Common Stock, Par or Stated Value Per Share Common Stock, Par or Stated Value Per Share Cash distributions in unconsolidated real estate ventures Cash Distributions In Unconsolidated Real Estate Ventures Cash Distributions In Unconsolidated Real Estate Ventures Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Total interest expense recognized Interest Expense, Debt Self-Storage Operations Self Storage Operations [Member] Self Storage Operations [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] OP units conversion ratio Shareholders' Equity, Units Conversion Ratio Shareholders' Equity, Units Conversion Ratio Units converted (in shares) Conversion of Stock, Shares Converted Earnings Per Common Share Earnings Per Share [Text Block] Exchange price (in dollars per share) Debt Instrument, Convertible, Conversion Price Accounts payable and accrued expenses Establishment Of Operating Lease Right Of Use Assets And Lease Liabilities, Increase (Decrease) In Accounts Payable And Accrued Expenses Establishment Of Operating Lease Right Of Use Assets And Lease Liabilities, Increase (Decrease) In Accounts Payable And Accrued Expenses Award Type [Domain] Award Type [Domain] Other assets Increase (Decrease) in Other Operating Assets Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Exchangeable Senior Notes Exchangeable Senior Notes Disclosure [Text Block] The entire disclosure for information about the entity's exchangeable senior notes, including amounts of borrowings and about the underlying arrangements, including repayment terms, interest rates, collateral provided, and other matters important to the users of the financial statements. Ownership [Domain] Ownership [Domain] Dividends paid on common stock Payments of Ordinary Dividends, Common Stock OP units outstanding (in shares) Units of Partnership Interest, Amount Tenant Reinsurance Tenant Reinsurance [Member] Tenant Reinsurance [Member] Total Consideration Paid Real Estate Property Asset Acquisition, Consideration Transferred Real Estate Property Asset Acquisition, Consideration Transferred Investments [Domain] Investments [Domain] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Total liabilities Liabilities Preferred OP units conversion ratio Noncontrolling Interest In Preferred Operating Partnership Units Conversion Ratio Represents the ratio for conversion of preferred operating partnership units into common OP units. Common Stock, Value, Issued Common Stock, Value, Issued Other Commitments [Axis] Other Commitments [Axis] Redemption of Operating Partnership units for stock Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Store Acquisitions Mergers, Acquisitions and Dispositions Disclosures [Text Block] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] ESS Bristol Investments LLC ESS Bristol Investments, LLC [Member] ESS Bristol Investments, LLC [Member] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Number of operating stores owned and/or managed Number Of Real Estate Properties Owned And Or Managed The number of real estate properties owned and/or managed as of the balance sheet date. ESS-NYFL JV LP ESS-NYFL JV LP [Member] ESS-NYFL JV LP [Member] Fair value - net liability position Derivative With Contingent Features, Fair Value Of Asset (Liability), Net Derivative With Contingent Features, Fair Value Of Asset (Liability), Net Basic (in shares) Average number of common shares outstanding - basic (in shares) Weighted Average Number of Shares Outstanding, Basic Real estate assets - operating lease right-of-use assets Operating Lease, Right-of-Use Asset Equity Components [Axis] Equity Components [Axis] Number of Stores Number Of Real Estate Properties Acquired Represents the number of real estate properties acquired. Investment in unconsolidated real estate entities Payments to Acquire Equity Method Investments Total Extra Space Storage Inc. stockholders' equity Stockholders' Equity Attributable to Parent Note receivable, reduction of noncontrolling interests Note Receivable, Reduction Of Noncontrolling Interests Note Receivable, Reduction Of Noncontrolling Interests Extra Space Northern Properties Six LLC Extra Space Northern Properties Six LLC [Member] Extra Space Northern Properties Six LLC [Member] Other liabilities Increase (Decrease) in Other Operating Liabilities WICNN JV LLC WICNN JV LLC [Member] WICNN JV LLC [Member] Investment balance Investment In Unconsolidated Real Estate Entities, Net Of Distributions Investment In Unconsolidated Real Estate Entities, Net Of Distributions Notes payable assumed Loan Assumed Noncash or Part Noncash Acquisition, Debt Assumed Number of operating stores owned Number Of Operating Stores Owned Number Of Operating Stores Owned Issuance of common stock in connection with share based compensation Shares Issued, Value, Share-based Payment Arrangement, before Forfeiture Number of stores acquired, previously held noncontrolling interest Number Of Real Estate Properties Acquired, Previous Noncontrolling Interest Held Number Of Real Estate Properties Acquired, Previous Noncontrolling Interest Held Fair Value Disclosures Fair Value Disclosures [Text Block] Notes receivable from Preferred and Common Operating Partnership unit holders Due From Related Parties Fair Value Disclosure Fair value of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due after one year (or one business cycle). Depreciation and amortization Depreciation and amortization expense Depreciation, Depletion and Amortization Tenant reinsurance Direct Premiums Earned Investment Type [Axis] Investment Type [Axis] Fixed liquidation value Noncontrolling Interest In Preferred Operating Partnership Units Fixed Liquidation Value Represents the fixed liquidation value of preferred operating partnership units. Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activities Ownership interest held by joint venture partner Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Value of Preferred Operating Partnership units issued Stock Issued Preferred Stock, Value, Issued Preferred Stock, Value, Issued Purchase price Other Commitment Security Exchange Name Security Exchange Name Anti-dilutive securities excluded from computation of earnings per common share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Number of stores scheduled to be closed Number Of Store Acquisitions Expected To Close The number of stores that are under contract as of balance sheet date for which the entity expects the acquisitions to close by the end of the annual reporting period. Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Total comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Additional paid-in capital Additional Paid in Capital, Common Stock Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Period after which preferred stock dividend is subject to increase Preferred Stock Investment, Period After Which Dividend Rate Is Subject To Increase Preferred Stock Investment, Period After Which Dividend Rate Is Subject To Increase Equity Component [Domain] Equity Component [Domain] Unamortized discount - equity component Debt Instrument Unamortized Discount Of Equity Component Represents the amount of debt discount related to equity component that was originally recognized at the issuance of the instrument that has yet to be amortized. Document Transition Report Document Transition Report Contingent cash settlement value Derivative Instruments With Contingent Features, Contingent Cash Settlement Value Derivative Instruments With Contingent Features, Contingent Cash Settlement Value Stock Options Share-based Payment Arrangement, Option [Member] Related debt issuance costs Unamortized debt issuance costs Debt Issuance Costs, Net Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Authorized amount for repurchase Stock Repurchase Program, Authorized Amount Noncontrolling Interest - Operating Partnership Common Operating Partnership [Member] Common Operating Partnership [Member] Net income for diluted computations Net Income (Loss) Available to Common Stockholders, Diluted Preferred Units (in shares) Incremental Common Shares Attributable to Exchangeable Preferred Operating Partnership Units Shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of exchangeable preferred operating partnership units. Schedule of Operating Properties Acquired Schedule of Asset Acquisitions [Table Text Block] Schedule of Asset Acquisitions [Table Text Block] Operating lease liabilities Establishment Of Operating Lease Liability Establishment Of Operating Lease Liability Income Statement [Abstract] Income Statement [Abstract] Series C Units Series C Units [Member] Series C Units [Member] Variable Interests Variable Interest Entity Disclosure [Text Block] Balance Sheet Location [Axis] Balance Sheet Location [Axis]