Statement of Financial Position [Abstract] Assets: Assets [Abstract] Real estate assets, net Real Estate Investment Property, Net Real estate assets - operating lease right-of-use assets Operating Lease, Right-of-Use Asset Investments in unconsolidated real estate ventures Real Estate Investments, Unconsolidated Real Estate and Other Joint Ventures Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash and Cash Equivalents Other assets, net Other Assets Total assets Assets Liabilities, Noncontrolling Interests and Equity: Liabilities and Equity [Abstract] Notes payable, net Notes Payable Exchangeable senior notes, net Convertible Debt Notes payable to trusts Notes Payable To Trusts Aggregate carrying amount of all notes payable to trusts as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer. Revolving lines of credit Long-term Line of Credit Operating lease liabilities Operating Lease, Liability Cash distributions in unconsolidated real estate ventures Cash Distributions In Unconsolidated Real Estate Ventures Cash Distributions In Unconsolidated Real Estate Ventures Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities Other liabilities Other Liabilities Total liabilities Liabilities Commitments and contingencies Commitments and Contingencies Noncontrolling Interests and Equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Extra Space Storage Inc. stockholders' equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, $0.01 par value, 50,000,000 shares authorized, no shares issued or outstanding Preferred Stock, Value, Issued Common stock, $0.01 par value, 500,000,000 shares authorized, 129,410,093 and 127,103,750 shares issued and outstanding at September 30, 2019 and December 31, 2018, respectively Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated deficit Retained Earnings (Accumulated Deficit) Total Extra Space Storage Inc. stockholders' equity Stockholders' Equity Attributable to Parent Noncontrolling interest represented by Preferred Operating Partnership units, net Noncontrolling Interest in Preferred Unit Holders Noncontrolling interests in Operating Partnership, net and other noncontrolling interests Noncontrolling Interest in Operating Partnerships Total noncontrolling interests and equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities, noncontrolling interests and equity Liabilities and Equity Income Statement [Abstract] Revenues: Revenues [Abstract] Property rental Lease Income Tenant reinsurance Direct Premiums Earned Management fees and other income Revenue from Contract with Customer, Excluding Assessed Tax Total revenues Revenues Expenses: Costs and Expenses [Abstract] Property operations Cost of Revenue Tenant reinsurance Tenant Reinsurance Expense The expense in the period incurred with respect to the entity's tenant reinsurance program. General and administrative General and Administrative Expense Depreciation and amortization Depreciation, Depletion and Amortization Total expenses Costs and Expenses Gain on real estate transactions Gains (Losses) On Real Estate Transactions and Earn Out From Prior Acquisition and Sale of Other Assets Gains losses on real estate transactions and earn out from prior acquisition and sales of other assets Income from operations Operating Income (Loss) Interest expense Interest Expense Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes Amortization of Debt Discount (Premium) Interest income Investment Income, Interest Income before equity in earnings of unconsolidated real estate ventures and income tax expense Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Equity in earnings of unconsolidated real estate ventures Income (Loss) from Equity Method Investments Income tax expense Income Tax Expense (Benefit) Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income allocated to Preferred Operating Partnership noncontrolling interests Noncontrolling Interest in Net Income (Loss) Preferred Unit Holders, Redeemable 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. Net income attributable to common stockholders Net Income (Loss) Attributable to Parent Earnings per common share Earnings Per Share, Basic and Diluted [Abstract] Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Weighted average number of shares Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Cash dividends paid per common share (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid Real Estate [Abstract] Number of Stores Number Of Real Estate Properties Acquired Represents the number of real estate properties acquired. Total Consideration Paid Real Estate Property Asset Acquisition, Consideration Transferred Real Estate Property Asset Acquisition, Consideration Transferred Cash Paid Payments To Acquire Assets, Gross Payments To Acquire Assets, Gross Loan Assumed Noncash or Part Noncash Acquisition, Debt Assumed 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 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. Value of OP 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 Number of OP Units Issued Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued Real estate assets 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. 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 Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] New York store New York Store [Member] New York Store [Member] California store California Store [Member] California Store [Member] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Disposed of by sale, not discontinued operations Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Proceeds from sale of real estate assets Proceeds from Sale of Other Real Estate Gain on sale of real estate assets Gain (Loss) on Disposition of Assets Commitments and Contingencies Disclosure [Abstract] Other Commitments [Table] Other Commitments [Table] Other Commitments [Axis] Other Commitments [Axis] Other Commitments [Domain] Other Commitments [Domain] Commitment To Acquire Retail Space Commitment To Acquire Retail Space [Member] Commitment To Acquire Retail Space [Member] Commitment To Acquire Retail Space With Joint Venture Partners Commitment To Acquire Retail Space With Joint Venture Partners [Member] Commitment To Acquire Retail Space With Joint Venture Partners [Member] Commitment To Acquire Retail Space With Joint Venture Partners, Scheduled To Close in 2019 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] Other Commitments [Line Items] Other Commitments [Line Items] Number of real estate properties to be acquired Number Of Real Estate Properties To Be Acquired Number Of Real Estate Properties To Be Acquired Purchase price Other Commitment 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. Noncontrolling Interest [Abstract] Noncontrolling Interest Represented by Preferred Operating Partnership Units Noncontrolling Interest Disclosure [Text Block] Segment Reporting [Abstract] Schedule of Financial Information of Business Segments Schedule of Segment Reporting Information, by Segment [Table Text Block] Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] ESS-NYFL JV LP ESS-NYFL JV LP [Member] ESS-NYFL JV LP [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Number of joint venture partners Number Of Joint Venture Partners Number Of Joint Venture Partners Contributions to joint ventures Contributions To Equity Method Investments, Including Noncash Amounts Contributions To Equity Method Investments, Including Noncash Amounts Number of operating stores acquired Number Of Real Estate Properties Acquired By Joint Ventures Number Of Real Estate Properties Acquired By Joint Ventures Number of annex sites acquired Number Of Annex Sites Acquired By Joint Venture Number Of Annex Sites Acquired By Joint Venture Equity method ownership percentage Equity Method Investment, Ownership Percentage 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 Investments in Unconsolidated Real Estate Ventures Equity Method Investments and Joint Ventures Disclosure [Text Block] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Self-Storage Operations Self Storage Operations [Member] Self Storage Operations [Member] Tenant Reinsurance Tenant Reinsurance [Member] Tenant Reinsurance [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Revenues: Operating expenses: General and administrative expense Depreciation and amortization expense Income tax expense Schedule of Operating Properties Acquired Schedule of Asset Acquisitions [Table Text Block] Schedule of Asset Acquisitions [Table Text Block] Redeemable Noncontrolling Interest Redeemable Noncontrolling Interest [Table Text Block] Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Senior Notes Senior Notes [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 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] Debt Instrument [Line Items] Debt Instrument [Line Items] Carrying amount of equity component Debt Instrument, Convertible, Carrying Amount of Equity Component Principal amount of liability component 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. Unamortized debt issuance costs Debt Issuance Costs, Net Net carrying amount of liability components Long-term Debt Earnings Per Share [Abstract] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Award Type [Axis] Award Type [Axis] Award Type [Domain] Award Type [Domain] Stock Options Share-based Payment Arrangement, Option [Member] Preferred Units by Name [Axis] Preferred Units by Name [Axis] Preferred Units, Class [Domain] Preferred Units, Class [Domain] Series A Units Series A Units [Member] Series A Units [Member] Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes) Exchangeable Senior Notes Two Point Three Seven Five Percent Due Two Thousand Thirty Three [Member] Exchangeable Senior Notes Two Point Three Seven Five Percent Due Two Thousand Thirty Three [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Anti-dilutive securities excluded from computation of earnings per common share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Average share price (in dollars per share) Average Share Price Per Share Average Share Price Per Share Principal amount of notes outstanding Debt stated interest rate Debt Instrument, Interest Rate, Stated Percentage Exchange price (in dollars per share) Debt Instrument, Convertible, Conversion Price 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 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. Statement of Stockholders' Equity [Abstract] Dividends paid on common stock (in dollars per share) Fair Value Disclosures [Abstract] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Carrying Value Reported Value Measurement [Member] Fair Value of Financial Instruments [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] 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). Fixed rate notes payable and notes payable to trusts Notes Payable, Fair Value Disclosure Exchangeable senior notes Convertible Debt, Fair Value Disclosures Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Measurement Frequency [Domain] Measurement Frequency [Domain] Recurring Basis Fair Value, Recurring [Member] 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] Other assets - Cash flow hedge swap agreements Interest Rate Cash Flow Hedge Asset at Fair Value Other liabilities - Cash flow hedge swap agreements Interest Rate Cash Flow Hedge Liability at Fair Value Accounting Policies [Abstract] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Recently Issued Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Fair Value Disclosures Fair Value of Financial Instruments, Policy [Policy Text Block] Earnings Per Common Share Earnings Per Share, Policy [Policy Text Block] Derivatives Derivatives, Policy [Policy Text Block] Convertible Debt Convertible Debt Policy [Policy Text Block] Convertible Debt Policy [Policy Text Block] 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] Schedule of Fair Value of Financial Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Variable Interests Variable Interest Entity Disclosure [Text Block] 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] 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. Derivative Instruments and Hedging Activities Disclosure [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 Number of derivative financial instruments Derivative, Number of Instruments Held Combined notional amount Derivative, Notional Amount Fair value, net liability position Derivative, Fair Value, Net Contingent cash settlement value Derivative Instruments With Contingent Features, Contingent Cash Settlement Value Derivative Instruments With Contingent Features, Contingent Cash Settlement Value Store Acquisitions and Dispositions Mergers, Acquisitions and Dispositions Disclosures [Text Block] Statement [Table] Statement [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Preferred Operating Partnership Preferred Operating Partnership [Member] Preferred Operating Partnership [Member] Operating Partnership Common Operating Partnership [Member] Common Operating Partnership [Member] Other Non Controlling Interest Other [Member] Non Controlling Interest Other [Member] Common Stock Common Stock [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Accumulated Other Comprehensive Income AOCI Attributable to Parent [Member] Accumulated Deficit Retained Earnings [Member] Sale of Stock [Axis] Sale of Stock [Axis] Sale of Stock [Domain] Sale of Stock [Domain] Redemption of Operating Partnership units for cash Redemption Of Units For Cash [Member] Redemption Of Units For Cash [Member] Redemption of Operating Partnership units for stock Redemption Of Units For Common Stock [Member] Redemption Of Units For Common Stock [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance, beginning of period (in shares) Common Stock, Shares, Issued Balance, beginning of period Issuance of common stock upon the exercise of options (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Issuance of common stock upon the exercise of options Stock Issued During Period, Value, Stock Options Exercised Restricted stock grants issued (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross Restricted stock grants issued Stock Issued During Period, Value, Restricted Stock Award, Gross Restricted stock grants canceled (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Forfeited Issuance of common stock, net of offering costs (in shares) Stock Issued During Period, Shares, New Issues Issuance of common stock, net of offering costs Stock Issued During Period, Value, New Issues Compensation expense related to stock-based awards APIC, Share-based Payment Arrangement, Increase for Cost Recognition Repayment of receivable for preferred operating units pledged as collateral on loan Noncontrolling Interest, Repayment Of Receivable For Preferred Operating Units Pledged As Collateral On Loan Noncontrolling Interest, Repayment Of Receivable For Preferred Operating Units Pledged As Collateral On Loan 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. Redemption of Operating Partnership units Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Repurchase of equity portion of exchangeable senior notes Debt Instrument, Repurchase of Equity Component Debt instrument, repurchase of equity component. Issuance of Operating Partnership units in conjunction with acquisitions Partners' Capital Account, Acquisitions Noncontrolling interest in consolidated joint venture Noncontrolling Interest, Increase From Transactions With Other Noncontrolling Interests, Net Noncontrolling Interest, Increase From Transactions With Other Noncontrolling Interests, Net Conversion of Preferred C Units in the Operating Partnership for Common Operating Partnership Units Noncontrolling Interest, Conversion Of Preferred Equity To Common Equity Noncontrolling Interest, Conversion Of Preferred Equity To Common Equity Net income Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Distributions to Operating Partnership units held by noncontrolling interests Partners' Capital Account, Distributions Dividends paid on common stock Dividends, Common Stock Balance, end of period (in shares) Balance, end of period Basis of Presentation Basis of Presentation and Significant Accounting Policies [Text Block] Derivative [Table] Derivative [Table] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other assets Other Assets [Member] Other liabilities Other Liabilities [Member] Derivative [Line Items] Derivative [Line Items] Other assets Other liabilities Statement of Cash Flows [Abstract] Noncash or Part Noncash Acquisitions by Unique Description [Axis] Noncash or Part Noncash Acquisitions by Unique Description [Axis] Noncash or Part Noncash Acquisition, Name [Domain] Noncash or Part Noncash Acquisition, Name [Domain] Redemption of Operating Partnership units held by noncontrolling interests for common stock Redemption Of Operating Partnership Units [Member] Redemption Of Operating Partnership Units [Member] Acquisitions of real estate assets Acquisitions Of Real Estate [Member] Acquisitions Of Real Estate [Member] 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] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] 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] Amortization of deferred financing costs Amortization of Debt Issuance Costs 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 Compensation expense related to stock-based awards Share-based Payment Arrangement, Noncash Expense Gain on real estate transactions Gains (Losses) on Sales of Investment Real Estate Distributions from unconsolidated real estate ventures in excess of earnings Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Other assets Increase (Decrease) in Other Operating Assets Accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Other liabilities Increase (Decrease) in Other Operating Liabilities Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Acquisition of real estate assets Payments to Acquire Real Estate Development and redevelopment of real estate assets Payments to Develop Real Estate Assets Proceeds from sale of real estate assets, investments in real estate ventures and other assets Investment in unconsolidated real estate ventures Payments to Acquire Equity Method Investments Return of investment in unconsolidated real estate ventures Return Of Investment Real Estate Ventures Distributions that represent a return of original investment from real estate ventures. Issuance of notes receivable Payments to Acquire Notes Receivable Principal payments received from notes receivable Proceeds from Collection of Notes Receivable Purchase of equipment and fixtures Payments to Acquire Furniture and Fixtures Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Proceeds from the sale of common stock, net of offering costs Proceeds from Issuance of Common Stock Proceeds from notes payable and revolving lines of credit Proceeds from Issuance of Secured Debt Principal payments on notes payable and revolving lines of credit Repayments of Debt Principal payments on notes payable to trusts Repayments of Notes Payable Deferred financing costs Payments of Financing Costs Repurchase of exchangeable senior notes Repayments of Debt Instruments The cash outflow to repay fair value of debt instruments. Net proceeds from exercise of stock options Proceeds from Stock Options Exercised Redemption of Operating Partnership units held by noncontrolling interests Cash Portion Of Redemption Of Preferred Operating Partnership Units The amount of cash paid upon the redemption of Preferred Operating Partnership Units. Contributions from noncontrolling interests Proceeds from Noncontrolling Interests Dividends paid on common stock Payments of Ordinary Dividends, Common Stock Distributions to noncontrolling interests Payments of Ordinary Dividends, Noncontrolling Interest Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Net decrease in cash, cash equivalents, and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash, cash equivalents, and restricted cash, beginning of the period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents, and restricted cash, end of the period Supplemental schedule of cash flow information Supplemental Cash Flow Information [Abstract] Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activities Income taxes paid Income Taxes Paid, Net Supplemental schedule of noncash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] 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] Noncontrolling interests in Operating Partnership Conversion of Stock, Amount Converted 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. 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] Real estate assets - operating lease right-of-use assets Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Operating lease liabilities Establishment Of Operating Lease Liability Establishment Of Operating Lease Liability 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 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] Real estate assets, net Value of Operating Partnership units issued Partnership Units Issued Partnership Units Issued Notes payable assumed Investment in unconsolidated real estate ventures Accrued construction costs and capital expenditures Accrued Construction Costs And Capital Expenditures [Abstract] Accrued Construction Costs And Capital Expenditures [Abstract] Acquisition of real estate assets Real Estate Additions, Portion Not Yet Paid Real Estate Additions, Portion Not Yet Paid Accounts payable and accrued expenses Construction In Progress And Capital Expenditures Incurred But Not Paid Construction In Progress And Capital Expenditures Incurred But Not Paid 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] Investments in unconsolidated real estate ventures Non-Cash Decrease In Investments In Unconsolidated Entities Non-Cash Decrease In Investments In Unconsolidated Entities Value of Preferred Operating Partnership units issued Stock Issued Conversion of Preferred OP Units to common OP Units Conversion Of Preferred Operating Units To Common Units [Abstract] Conversion Of Preferred Operating Units To Common Units [Abstract] Preferred OP Units Conversion Of Preferred Operating Units To Common Units Conversion Of Preferred Operating Units To Common Units Common OP Units Issuance Of Common Units For Conversion Of Preferred Units Issuance Of Common Units For Conversion Of Preferred Units 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] Schedule of Computation of Earnings Per Common Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Stockholders' Equity Note [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] At the Market Equity Distribution Agreement At The Market Equity Distribution Agreement [Member] At The Market Equity Distribution Agreement [Member] Class of Stock [Line Items] Class of Stock [Line Items] Aggregate offering price of common shares Aggregate Offering Price Of Common Share Aggregate offering price of common share. Number of sales agents Number Of Sales Agents Number Of Sales Agents Shares issued (in shares) Sale of Stock, Number of Shares Issued in Transaction Average sales price (in dollars per share) Sale of Stock, Price Per Share Net proceeds Sale of Stock, Consideration Received on Transaction 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 Derivatives Derivative Instruments and Hedging Activities Disclosure [Text Block] Segment Information Segment Reporting Disclosure [Text Block] Leases [Abstract] Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] ASU 2016-02 Accounting Standards Update 2016-02 [Member] Lease Arrangement [Axis] Lease Arrangement [Axis] Lease Arrangement [Axis] Lease Arrangement [Domain] Lease Arrangement [Domain] [Domain] for Lease Arrangement [Axis] Store leases Store Lease [Member] Store Lease [Member] Corporate offices and call center leases Corporate Office And Call Center Lease [Member] Corporate Office And Call Center Lease [Member] Regional office leases Regional Office Lease [Member] Regional Office Lease [Member] District office leases District Office Lease [Member] District Office Lease [Member] New Jersey store lease New Jersey Store Lease [Member] New Jersey Store Lease [Member] California store lease California Store Lease [Member] California Store Lease [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Lease Option [Axis] Lease Option [Axis] Lease Option [Axis] Lease Option [Domain] Lease Option [Domain] [Domain] for Lease Option [Axis] Lease option one Lease Option One [Member] Lease Option One [Member] Lease option two Lease Option Two [Member] Lease Option Two [Member] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Operating lease right-of-use assets Number of stores added under new operating leases Number Of Stores Added Under Operating Lease Number Of Stores Added Under Operating Lease Operating lease, term Lessor, Operating Lease, Term of Contract Operating lease, termination option, term Lease Contract, Term After Which Can Be Terminated Lease Contract, Term After Which Can Be Terminated Increase in right-of-use assets under new operating leases Increase In Operating Lease, Right-Of-Use Assets Increase In Operating Lease, Right-Of-Use Assets Increase in operating lease liabilities under new operating leases Increase In Operating Lease Liability Increase In Operating Lease Liability Number of leases Lessee, Lease, Number Of Leases Lessee, Lease, Number Of Leases Operating and finance lease, original lease term Lessee, Lease, Term Of Contract Lessee, Lease, Term Of Contract Operating and finance lease, extension term Lessee, Lease, Renewal Term Lessee, Lease, Renewal Term Operating lease, original lease term Lessee, Operating Lease, Term of Contract Operating lease, number of options to extend Lessee, Operating Lease, Number Of Options To Extend Lessee, Operating Lease, Number Of Options To Extend Operating lease, extension term Lessee, Operating Lease, Renewal Term Lease not yet commenced, lease term Lessee, Lease Not Yet Commenced, Term Of Contract Lessee, Lease Not Yet Commenced, Term Of Contract Lease not yet commenced, number of extension options Lessee, Lease Not Yet Commenced, Number Of Options To Extend Lessee, Lease Not Yet Commenced, Number Of Options To Extend Lease not yet commenced, term of extension options Lessee, Lease Not Yet Commenced, Renewal Term Lessee, Lease Not Yet Commenced, Renewal Term Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Swap Agreements Interest Rate Swap [Member] Gain (loss) recognized in OCI Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax Gain reclassified from OCI Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax Fair Value Disclosures Fair Value Disclosures [Text Block] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Notes payable to Trusts Trust Preferred Securities Subject to Mandatory Redemption [Member] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Not Primary Beneficiary Variable Interest Entity, Not Primary Beneficiary [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Number of wholly-owned unconsolidated subsidiaries Variable Interest Entity Interest In Trust Number Represents the number of wholly-owned unconsolidated subsidiaries. Repayments of debt Notes payable to Trusts Long-term Debt, Gross 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. Noncontrolling Interest [Table] Noncontrolling Interest [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Operating Partnership Holders of A Units Holders Of Series A Preferred Operating Partnership Units [Member] Holders Of Series A Preferred Operating Partnership Units [Member] Series B Units Series B Units [Member] Series B Units [Member] Series C Units Series C Units [Member] Series C Units [Member] Series D Units Series D Units [Member] Series D Units [Member] Noncontrolling Interest [Line Items] Noncontrolling Interest [Line Items] Loans and notes to affiliates Due from Related Parties, Noncurrent 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. 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. 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. Maximum number of preferred OP units converted prior to the maturity date of the loan (in units) 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. Preferred units outstanding (in units) Preferred Units, Outstanding Note receivable interest rate Notes Receivable Stated Interest Rate Represents the stated interest rate of notes receivable. 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. Fixed liquidation value Noncontrolling Interest In Preferred Operating Partnership Units Fixed Liquidation Value Represents the fixed liquidation value of preferred operating partnership units. 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. 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. Preferred OP units conversion ratio (in shares) Noncontrolling Interest In Preferred Operating Partnership Units Conversion Ratio Represents the ratio for conversion of preferred operating partnership units into common OP units. Loan to affiliates Origination of Notes Receivable from Related Parties Units converted (in units) Conversion of Stock, Shares Converted Issuance of units upon conversion (in units) 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 Note receivable, reduction of noncontrolling interests Note Receivable, Reduction Of Noncontrolling Interests Note Receivable, Reduction Of Noncontrolling Interests 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. Cover page. Document Type Document Type Amendment Flag Amendment Flag Document Quarterly Report Document Quarterly Report Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Organization Nature of Operations [Text Block] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Operating ground leases Operating Ground Lease [Member] Operating Ground Lease [Member] Corporate facility leases Corporate Facility Lease [Member] Corporate Facility Lease [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Number of leases Lessee, Operating Lease, Number Of Leases Lessee, Operating Lease, Number Of Leases Number of operating storage facilities in which the entity has equity interests (in stores) Number of Real Estate Properties 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. 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. Number of states in which operating storage facilities are located Number of States in which Entity Operates Number of parcels of land held-for-sale Number Of Parcels Of Land Held-For-Sale Number Of Parcels Of Land Held-For-Sale Operating Lessee, Operating Lease, Liability, Payment, Due [Abstract] 2019 Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year 2020 Lessee, Operating Lease, Liability, Payments, Due Year Two 2021 Lessee, Operating Lease, Liability, Payments, Due Year Three 2022 Lessee, Operating Lease, Liability, Payments, Due Year Four 2023 Lessee, Operating Lease, Liability, Payments, Due Year Five Thereafter Lessee, Operating Lease, Liability, Payments, Due after Year Five Total Lessee, Operating Lease, Liability, Payments, Due Present value adjustments Lessee, Operating Lease, Liability, Undiscounted Excess Amount Lease liabilities Finance Finance Lease, Liability, Payment, Due [Abstract] 2019 Finance Lease, Liability, Payments, Remainder of Fiscal Year 2020 Finance Lease, Liability, Payments, Due Year Two 2021 Finance Lease, Liability, Payments, Due Year Three 2022 Finance Lease, Liability, Payments, Due Year Four 2023 Finance Lease, Liability, Payments, Due Year Five Thereafter Finance Lease, Liability, Payments, Due after Year Five Total Finance Lease, Liability, Payment, Due Present value adjustments Finance Lease, Liability, Undiscounted Excess Amount Lease liabilities Finance Lease, Liability Total Lessee, Operating And Finance Lease, Liability, Payments, Due [Abstract] Lessee, Operating And Finance Lease, Liability, Payments, Due [Abstract] 2019 Lessee, Operating And Finance Lease, Liability, Payments, Remainder of Fiscal Year Lessee, Operating And Finance Lease, Liability, Payments, Remainder of Fiscal Year 2020 Lessee, Operating And Finance Lease, Liability, Payments, Due Year Two Lessee, Operating And Finance Lease, Liability, Payments, Due Year Two 2021 Lessee, Operating And Finance Lease, Liability, Payments, Due Year Three Lessee, Operating And Finance Lease, Liability, Payments, Due Year Three 2022 Lessee, Operating And Finance Lease, Liability, Payments, Due Year Four Lessee, Operating And Finance Lease, Liability, Payments, Due Year Four 2023 Lessee, Operating And Finance Lease, Liability, Payments, Due Year Five Lessee, Operating And Finance Lease, Liability, Payments, Due Year Five Thereafter Lessee, Operating And Finance Lease, Liability, Payments, Due After Year Five Lessee, Operating And Finance Lease, Liability, Payments, Due After Year Five Total Lessee, Operating And Finance Lease, Liability, Payments, Due Lessee, Operating And Finance Lease, Liability, Payments, Due Present value adjustments Lessee, Operating And Finance Lease, Liability, Undiscounted Excess Amount Lessee, Operating And Finance Lease, Liability, Undiscounted Excess Amount Lease liabilities Lessee, Operating And Finance Lease, Liability Lessee, Operating And Finance Lease, Liability Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] Principal amount of notes issued Debt Instrument, Face Amount Related debt issuance costs Underwriting fee percentage Percentage of Underwriting Fee Percentage of Underwriting Fee Amortization period Debt Issuance Cost Amortization Period Debt Issuance Cost Amortization Period Conversion ratio Debt Instrument, Convertible, Conversion Ratio Redemption price as percentage of principal amount of notes plus accrued and unpaid interest Debt Instrument, Redemption Price, Percentage 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. 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. Notes exchange, threshold percentage Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger Notes exchange, threshold trading days Debt Instrument, Convertible, Threshold Trading Days Notes exchange, threshold consecutive trading days Debt Instrument, Convertible, Threshold Consecutive Trading Days Discount rate Debt Instrument Discount Rate Represents the percentage of debt discount that was originally recognized at the issuance of the instrument. Unamortized cash discount Debt Instrument, Unamortized Discount Amortization period Debt Instrument, Term Principal amount repurchased Debt Instrument, Repurchased Face Amount Total consideration paid for repurchase Effective interest rate on the liability component Debt Instrument, Interest Rate, Effective Percentage Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Texas TEXAS Colorado COLORADO Pennsylvania PENNSYLVANIA New Jersey NEW JERSEY Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Joint Venture 1 Joint Venture One [Member] Joint Venture One [Member] Joint Venture 2 Joint Venture Two [Member] Joint Venture Two [Member] Ownership [Axis] Ownership [Axis] Ownership [Domain] Ownership [Domain] Other noncontrolling interests Ownership interest held by entity Noncontrolling Interest, Ownership Percentage by Parent Ownership percentage in joint venture by joint venture partner Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners 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. OP units conversion ratio Shareholders' Equity, Units Conversion Ratio Shareholders' Equity, Units Conversion Ratio 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. OP units outstanding (in units) Units of Partnership Interest, Amount 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. Number of consolidated joint ventures Real Estate Consolidated Joint Ventures Number Represents the number of consolidated joint ventures as of the balance sheet date. Number of operating stores owned Number Of Operating Stores Owned Number Of Operating Stores Owned Number of development stores owned Number Of Development Stores Owned Number Of Development Stores Owned Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, authorized (in shares) Preferred Stock, Shares Authorized Preferred stock, issued (in shares) Preferred Stock, Shares Issued Preferred stock, outstanding (in shares) Preferred Stock, Shares Outstanding Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, authorized (in shares) Common Stock, Shares Authorized Common stock, issued (in shares) Common stock, outstanding (in shares) Common Stock, Shares, Outstanding 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] Schedule of information relating to gain (loss) recognized on swap agreements Derivative Instruments, Gain (Loss) [Table Text Block] Leases Lessee, Operating Leases [Text Block] Leases Lessee, Finance Leases [Text Block] Leases Lessor, Operating Leases [Text Block] Lease cost Lease, Cost [Abstract] Finance lease cost: Finance Lease, Cost1 [Abstract] Finance Lease, Cost1 [Abstract] Amortization of finance lease right-of-use assets Finance Lease, Right-of-Use Asset, Amortization Interest expense related to finance lease liabilities Finance Lease, Interest Expense Operating lease cost Operating Lease, Cost Variable lease cost Variable Lease, Cost Short-term lease cost Short-term Lease, Cost Total lease cost Lease, Cost Cash paid for amounts included in the measurement of lease liabilities Cash Flow, Operating Activities, Lessee [Abstract] Operating cash outflows for finance lease payments Finance Lease, Interest Payment on Liability Operating cash outflows for operating lease payments Operating Lease, Payments Total cash flows for lease liability measurement Cash Paid For Operating Activities, Lessee Cash Paid For Operating Activities, Lessee Right-of-use assets obtained in exchange for new operating lease liabilities Right-of-use assets obtained in exchange for new finance lease liabilities Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Weighted average remaining lease term - finance leases Finance Lease, Weighted Average Remaining Lease Term Weighted average remaining lease term - operating leases Operating Lease, Weighted Average Remaining Lease Term Weighted average discount rate - operating leases Finance Lease, Weighted Average Discount Rate, Percent Weighted average discount rate - finance leases Operating Lease, Weighted Average Discount Rate, Percent PRISA Self Storage LLC Prisa Self Storage LLC [Member] Prisa Self Storage LLC [Member] Storage Portfolio II JV LLC Storage Portfolio II JV LLC [Member] Storage Portfolio II JV LLC [Member] Storage Portfolio I LLC Storage PortfolioI LLC [Member] Storage PortfolioI LLC [Member] VRS Self Storage, LLC Vrs Self Storage LLC [Member] Vrs Self Storage LLC [Member] Extra Space Northern Properties Six LLC Extra Space Northern Properties Six LLC [Member] Extra Space Northern Properties Six LLC [Member] WICNN JV LLC WICNN JV LLC [Member] WICNN JV LLC [Member] Alan Jathoo JV LLC Alan Jathoo JV LLC [Member] Alan Jathoo JV LLC [Member] ESS Bristol Investments LLC ESS Bristol Investments, LLC [Member] ESS Bristol Investments, LLC [Member] GFN JV, LLC GFN JV, LLC [Member] GFN JV, LLC [Member] Extra Space West Two LLC Extra Space West Two LLC [Member] Extra Space West Two LLC [Member] Extra Space West One LLC Extra Space West One LLC [Member] Extra Space West One LLC [Member] Other minority owned stores Other Minority Owned Properties [Member] Other Minority Owned Properties [Member] Extra Space West One and Two LLC Extra Space West One And Two LLC [Member] Extra Space West One And Two LLC [Member] Number of Stores Equity Method Investment, Number Of Properties Equity Method Investment, Number Of Properties Equity Ownership % Excess Profit % Unconsolidated Joint Ventures Excess Profit Participation Percentage The percentage of excess profit participation in unconsolidated joint ventures. Investment balance Real Estate Investments, Unconsolidated Real Estate and Other Joint Ventures, Net Of Distributions Real Estate Investments, Unconsolidated Real Estate and Other Joint Ventures, Net Of Distributions Percentage interest purchased Asset Acquisition, Percentage Of Voting Interests Acquired Asset Acquisition, Percentage Of Voting Interests Acquired Number of stores acquired Cash paid Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Earnings Per Common Share Earnings Per Share [Text Block] Lease costs Lease, Cost [Table Text Block] Undiscounted cash flows on an annual basis, operating leases Lessee, Operating Lease, Liability, Maturity [Table Text Block] Undiscounted cash flows on an annual basis, finance leases Finance Lease, Liability, Maturity [Table Text Block] 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. Statement of Comprehensive Income [Abstract] Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] Change in fair value of interest rate swaps Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Total comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income attributable to common stockholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Contractual interest Interest Expense, Debt, Excluding Amortization Amortization of discount Total interest expense recognized Interest Expense, Debt 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 OP Units redeemed for cash (in units) Noncontrolling Interest, Operating Partnership Units Redeemed For Cash Noncontrolling Interest, Operating Partnership Units Redeemed For Cash Cash paid for OP Units redeemed Noncontrolling Interest, Operating Partnership Units Redeemed, Cash Paid Noncontrolling Interest, Operating Partnership Units Redeemed, Cash Paid OP Units issued in conjunction with acquisitions (in units) Noncontrolling Interest, Operating Partnership Units Issued With Acquisition Noncontrolling Interest, Operating Partnership Units Issued With Acquisition Value of OP Units issued in conjunction with acquisitions Noncontrolling Interest, Operating Partnership Units Issued With Acquisition, Value Noncontrolling Interest, Operating Partnership Units Issued With Acquisition, Value OP Units issued upon redemption of Series C Units (in units) Increase In Noncontrolling Interest Units, Conversion Of Preferred Units Increase In Noncontrolling Interest Units, Conversion Of Preferred Units Net income attributable to common stockholders Earnings and dividends allocated to participating securities Undistributed Earnings (Loss) Allocated to Participating Securities, Basic Earnings for basic computations Net Income (Loss) Available to Common Stockholders, Basic Earnings and dividends allocated to participating securities Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted 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 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. Net income for diluted computations Net Income (Loss) Available to Common Stockholders, Diluted Weighted average common shares outstanding: Average number of common shares outstanding - basic (in shares) 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. Preferred series 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. Unvested restricted stock awards included for treasury stock method (in shares) Incremental Common Shares Attributable To Share Based Payment Arrangements Restricted Stock Awards Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements related to restricted stock awards. 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. Average number of common shares outstanding - diluted (in shares) 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. Subsequent Event [Table] Subsequent Event [Table] SmartStop Self Storage REIT SmartStop Self Storage REIT Inc Series A Convertible Preferred Stock [Member] SmartStop Self Storage REIT Inc Series A Convertible Preferred Stock [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Amount invested Investment commitment Equity Method Investment, Investment Commitment Equity Method Investment, Investment Commitment Investment commitment, period Equity Method Investment, Investment Commitment, Period Equity Method Investment, Investment Commitment, Period Investment, preferred dividend rate Equity Method Investment, Preferred Stock, Dividend Rate Equity Method Investment, Preferred Stock, Dividend Rate Period after which preferred stock dividend is subject to increase Equity Method Investment, Preferred Stock, Period After Which Dividend Rate Is Subject To Increase Equity Method Investment, Preferred Stock, Period After Which Dividend Rate Is Subject To Increase Period after which preferred stock is redeemable Equity Method Investment, Preferred Stock, Period After Which Redeemable Equity Method Investment, Preferred Stock, Period After Which Redeemable Number of reportable segments Number of Reportable Segments Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block]