Debt Instrument, Basis Spread on Variable Rate, Alternative Rating

No definition available.

Name:	exr_DebtInstrumentBasisSpreadonVariableRateAlternativeRating
Namespace Prefix:	exr_
Data Type:	xbrli:pureItemType
Balance Type:	na
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- Definition

Debt Instrument, Number of Extension Periods

+ References

No definition available.

+ Details

Name:	exr_DebtInstrumentNumberofExtensionPeriods
Namespace Prefix:	exr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of Credit Facility, Accordion Feature, Increase Limit

+ References

No definition available.

+ Details

Name:	exr_LineofCreditFacilityAccordionFeatureIncreaseLimit
Namespace Prefix:	exr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of Credit Rating Agencies

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the principal amount of recourse debt due to guarantees at the balance sheet date.

+ References

No definition available.

+ Details

Name:	exr_RecourseDebtPrincipalAmount
Namespace Prefix:	exr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_NotesPayableToBanksMember
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=exr_CreditAgreementMember
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_FederalFundsEffectiveSwapRateMember
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_VariableRateAxis=us-gaap_EurodollarMember
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- Details

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- Details

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- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
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Data Type:	na
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- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=exr_FourYearRevolvingCreditFacilityMember
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Data Type:	na
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- Details

Name:	us-gaap_DebtInstrumentAxis=exr_FiveYearTermLoanMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=exr_SevenYearTermLoanMember
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Notes Payable and Revolving Lines of Credit - Additional Information (Details)	Oct. 14, 2016 USD ($) extension agency	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 600,000,000
Notes payable to trusts		3,763,474,000
Notes Payable
Debt Instrument [Line Items]
Notes payable to trusts		3,763,474,000	$ 3,240,938,000
Notes payable subject to recourse		$ 2,545,278,000
Credit Agreement
Debt Instrument [Line Items]
Debt instrument, term \| extension	2
Credit Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate	0.00%
Number of credit rating agencies \| agency	2
Credit Agreement \| Revolving Credit Facility \| Federal Funds Effective Swap Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Credit Agreement \| Revolving Credit Facility \| Eurodollar
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Credit Agreement \| Revolving Credit Facility \| Eurodollar \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	1.35%
Basis spread on variable rate, alternative rating	0.0085
Credit Agreement \| Revolving Credit Facility \| Eurodollar \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	2.50%
Basis spread on variable rate, alternative rating	0.0245
Credit Agreement \| Revolving Credit Facility \| Base Rate \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	0.35%
Basis spread on variable rate, alternative rating	0
Credit Agreement \| Revolving Credit Facility \| Base Rate \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	1.50%
Basis spread on variable rate, alternative rating	0.0145
Credit Agreement \| Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 1,150,000,000.00
Increase limit	1,500,000,000.0
Four Year Revolving Credit Facility \| Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	500,000,000
Five Year Term Loan \| Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	430,000,000
Seven Year Term Loan \| Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 220,000,000