Unsecured Debt - Unsecured Debt Summary (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Unsecured debt, net	$ 3,088,680	$ 2,603,548
Unsecured Debt And Line Of Credit	3,100,387	2,846,372
Fixed Rate Bond One [Member]
Debt Instrument [Line Items]
Unsecured debt, net	$ 463,891	463,443
Debt instruments, maturity period	3 years 2 months 12 days
Loans Payable [Member]
Debt Instrument [Line Items]
Unsecured debt, net	$ 224,467	$ 224,130
Weighted average interest rate	2.40%	2.40%
Debt instruments, maturity period	10 months 24 days
Fixed Rate Bond Two [Member]
Debt Instrument [Line Items]
Unsecured debt, net	$ 2,400,322	$ 1,915,975
Weighted average interest rate	3.60%	3.60%
Debt instruments, maturity period	6 years 8 months 12 days
Unsecured Line of Credit [Member]
Debt Instrument [Line Items]
Unsecured debt, net	$ 11,707	$ 242,824
Weighted average interest rate	1.90%	1.80%

Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer) and the carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

No definition available.

Name:	ess_UnsecuredDebtAndLineOfCredit
Namespace Prefix:	ess_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant