Name:	ess_RealEstateNumberOfFloorsToBeDeveloped
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- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

+ 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 210.5-02.29)

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 30

-Article 5

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

The cash outflow from the acquisition of a piece of land, anything permanently fixed to it, including buildings, structures on it and so forth; includes real estate intended to generate income for the owner; excludes real estate acquired for use by the owner.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow from the additional capital contribution to the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

+ References

No definition available.

+ Details

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- Definition

Revenue from the sale of commercial, industrial, or residential property during the period. This element is more likely than not relevant to an entity for which real estate operations are a principal activity. If real estate operations are not a principal activity, the reporting entity would likely use a gain (loss) on sale of property, plant, or equipment type element.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(e))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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Balance Type:	credit
Period Type:	duration

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Subsequent Events (Details) (USD $)	12 Months Ended			1 Months Ended		2 Months Ended
Subsequent Events (Details) (USD $)	Dec. 31, 2014 unit	Dec. 31, 2013 unit	Dec. 31, 2012 unit	Jan. 31, 2015 unit	Feb. 27, 2015 unit sqft	Feb. 24, 2015
Subsequent Event [Line Items]
Number of units sold	594ess_NumberOfUnitsSold	363ess_NumberOfUnitsSold	264ess_NumberOfUnitsSold
Sale of apartment community	$ 120,400,000us-gaap_SalesOfRealEstate	$ 57,500,000us-gaap_SalesOfRealEstate	$ 28,300,000us-gaap_SalesOfRealEstate
Sale of shares of common stock	63,682,646us-gaap_CommonStockSharesIssued	37,421,219us-gaap_CommonStockSharesIssued
Net proceeds from issuance of common stock	532,770,000	138,366,000	357,720,000
Purchase of parcel of land	387,547,000us-gaap_PaymentsToAcquireRealEstate	348,774,000us-gaap_PaymentsToAcquireRealEstate	393,771,000us-gaap_PaymentsToAcquireRealEstate
Number Of Units Acquired	1,480ess_NumberOfUnitsAcquired	1,079ess_NumberOfUnitsAcquired
Subsequent Event [Member] \| Pinnacle South Mountain [Member]
Subsequent Event [Line Items]
Number of units sold				552
Sale of apartment community				63,800,000
Subsequent Event [Member] \| Eighth And Hope [Member]
Subsequent Event [Line Items]
Purchase of parcel of land					200,000,000
Square feet of ground floor retail space					4,000
Number Of Units Acquired					290
Subsequent Event [Member] \| Common Stock [Member]
Subsequent Event [Line Items]
Sale of shares of common stock						636,021
Net proceeds from issuance of common stock						142,000,000
Average price of stock sold (in dollars per share)						$ 224.76
San Francisco, CA [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Purchase of parcel of land					$ 43,600,000
Number of floors of apartment community to be developed					42
Number of units of apartment community to be developed					545
Square feet of ground floor retail space					5,900