Organization and Basis of Presentation - Accumulated Other Comprehensive Loss - Partnership (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	$ 6,237,733
Balance at period end	6,141,992
Essex Portfolio, L.P. [Member] | AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	(39,598)
Other comprehensive income (loss) before reclassification	(4,278)
Amounts reclassified from accumulated other comprehensive loss	2,067
Other comprehensive loss	(2,211)
Balance at period end	(41,809)
Essex Portfolio, L.P. [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	(46,087)
Other comprehensive income (loss) before reclassification	(4,595)
Amounts reclassified from accumulated other comprehensive loss	2,067
Other comprehensive loss	(2,528)
Balance at period end	(48,615)
Essex Portfolio, L.P. [Member] | Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	6,489
Other comprehensive income (loss) before reclassification	317
Amounts reclassified from accumulated other comprehensive loss	0
Other comprehensive loss	317
Balance at period end	$ 6,806