Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013 Lease
Commitments and Contingencies [Abstract]
Number of non cancelable ground leases	6
Total minimum lease commitments under land leases and operating leases for next five years	$ 1.7

The total of future contractually required payments on leases defined as operating for the next five years.

No definition available.

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