Conversion Ratio, Incentive Units

No definition available.

Name:	ess_ConversionRatioIncentiveUnits
Namespace Prefix:	ess_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

The conversion ratio of incentive units to common units of the operating partnership.

+ References

No definition available.

+ Details

Name:	ess_IncentiveUnitsConversionRatio
Namespace Prefix:	ess_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangement By Share Based Payment Award, Liquidity Measurement Period

+ References

No definition available.

+ Details

Name:	ess_ShareBasedCompensationArrangementByShareBasedPaymentAwardLiquidityMeasurementPeriod
Namespace Prefix:	ess_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Percent Of Awards Earned

+ References

No definition available.

+ Details

Name:	ess_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsPercentOfAwardsEarned
Namespace Prefix:	ess_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Units Issued Subject To Performance Measurement

+ References

No definition available.

+ Details

Name:	ess_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsUnitsIssuedSubjectToPerformanceMeasurement
Namespace Prefix:	ess_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Cap On Appreciation of The Market Price Over The Exercise Price, Option 1

+ References

No definition available.

+ Details

Name:	ess_SharebasedCompensationArrangementbySharebasedPaymentAwardCapOnAppreciationofTheMarketPriceOverTheExercisePriceOption1
Namespace Prefix:	ess_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Cap On Appreciation of The Market Price Over The Exercise Price, Option 2

+ References

No definition available.

+ Details

Name:	ess_SharebasedCompensationArrangementbySharebasedPaymentAwardCapOnAppreciationofTheMarketPriceOverTheExercisePriceOption2
Namespace Prefix:	ess_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Measurement Period

+ References

No definition available.

+ Details

Name:	ess_SharebasedCompensationArrangementbySharebasedPaymentAwardFairValueAssumptionsMeasurementPeriod
Namespace Prefix:	ess_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

This line item represents the vesting percentage for 2011 Z 1 Units to be convertible.

+ References

No definition available.

+ Details

Name:	ess_VestingPercentageFor2011Z1UnitsToBeConvertible
Namespace Prefix:	ess_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This line item represents the vesting percentage of units per year.

+ References

No definition available.

+ Details

Name:	ess_VestingPercentageOfUnitsPerYear
Namespace Prefix:	ess_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_AllocatedShareBasedCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the compensation cost capitalized during the period arising from equity-based compensation arrangements (for example, shares of stock, units, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

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

- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Additional share-based compensation cost recognized as a result of an occurrence of an event that accelerates its recognition.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

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

- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

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

- Definition

Intrinsic value of equity-based compensation awards outstanding. Excludes stock and unit options.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=ess_A2015LTIPUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=ess_SeriesZIncentiveUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=ess_LongTermIncentivePlan2014UnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=ess_LongTermIncentivePlanZUnitsandLTIPUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Equity Based Compensation Plans (Details)		1 Months Ended	12 Months Ended				24 Months Ended
Equity Based Compensation Plans (Details)	Dec. 09, 2014 shares	Dec. 31, 2013 shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 09, 2015	Dec. 31, 2011 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized \| shares			2,000,000
Accelerated share-based compensation cost			$ 3,500,000
Intrinsic value of the options outstanding and fully vested			$ 12,500,000	$ 11,300,000
Average fair value of stock options granted (in dollars per share) \| $ / shares			$ 26.13	$ 22.41	$ 21.65
Cap on the appreciation of the market price over the exercise price, option 1			$ 100	$ 100	$ 100
Cap on the appreciation of the market price over the exercise price, option 2			125	125	125
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense			12,100,000	9,800,000	8,500,000
Stock-based compensation capitalized			2,000,000	1,500,000	500,000
Intrinsic value of options exercised			3,100,000	$ 16,700,000	$ 11,900,000
Unrecognized compensation cost			$ 6,000,000
Unrecognized compensation cost, period for recognition			2 years 1 month 15 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost			$ 11,400,000
Unrecognized compensation cost, period for recognition			2 years 8 months 1 day
Granted (in shares) \| shares			51,945	62,706	49,183
2015 LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, period for recognition			6 years 6 months
Granted (in shares) \| shares	44,750
Units issued subject only to performance measurement \| shares	24,000
Vesting percentage of units per year	20.00%
Option grants to officers and employees vesting period	5 years
Percent of awards earned						95.75%
Conversion ratio, incentive units			1
Liquidity measurement period			10 years
Measurement period			10 years
Series Z Incentive Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares) \| shares		50,500					154,500
Option grants to officers and employees vesting period		4 years
Conversion ratio, incentive units							1
Incentive units conversion ratio							one-for-one
Series Z Incentive Units [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage of units per year							0.00%
Option grants to officers and employees vesting period			8 years
Series Z Incentive Units [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage of units per year							14.00%
Option grants to officers and employees vesting period			15 years
Long Term Incentive Plan 2014 Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, period for recognition			1 year
Vesting percentage of units per year		25.00%
Conversion ratio, incentive units			1
Liquidity measurement period			10 years
Measurement period			10 years
Vesting percentage for 2011 Z 1 Units to be convertible							100.00%
Long Term Incentive Plans - Z Units and 2014 LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense			$ 800,000	$ 1,500,000	$ 2,400,000
Stock-based compensation capitalized			200,000	$ 500,000	$ 600,000
Unrecognized compensation cost			$ 900,000
Granted (in shares) \| shares			0	0	0
Intrinsic value of vested and unvested LTIP units			$ 58,000,000