Unconsolidated Joint Ventures Excess Profit Participation Percentage Forfeited

No definition available.

Name:	exr_UnconsolidatedJointVenturesExcessProfitParticipationPercentageForfeited
Namespace Prefix:	exr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

+ 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 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_EquityMethodInvestmentAggregateCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of stores.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfStores
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
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

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

- Details

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- Details

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Namespace Prefix:
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- Details

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- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=exr_EssPrisaTwoLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=exr_PREXRSelfStorageLLCMember
Namespace Prefix:
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- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=exr_BaychesterInvestmentsLLCMember
Namespace Prefix:
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Investments in Unconsolidated Real Estate Ventures - Additional Information (Detail) $ in Thousands	May 20, 2016 USD ($) store	Apr. 08, 2016 USD ($) store	Apr. 01, 2016	Mar. 31, 2016 USD ($) store	Mar. 31, 2015
BH [Member]
Schedule of Equity Method Investments [Line Items]
Number of stores \| store	1
Amount paid for interest \| $	$ 1,034
Equity method ownership percentage	20.00%
ESS PRISA LLC and ESS PRISA TWO LLC [Member]
Schedule of Equity Method Investments [Line Items]
Excess profit participation percentage forfeited in amendments			17.00%
ESS PRISA LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage			4.00%		2.00%
ESS PRISA II LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage			4.40%		2.00%
PREXR [Member]
Schedule of Equity Method Investments [Line Items]
Number of stores \| store		1
Amount paid for interest \| $		$ 12,114
Equity method ownership percentage		25.00%
Baychester [Member]
Schedule of Equity Method Investments [Line Items]
Number of stores \| store				1
Amount paid for interest \| $				$ 4,794
Equity method ownership percentage				44.40%