Organization and Basis of Presentation - Accumulated Other Comprehensive Loss - Partnership (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	$ 6,393,844
Balance at period end	6,415,004
Essex Portfolio, L.P. [Member] | Accumulated Other Comprehensive Loss, Net [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	(9,738)
Cumulative effect upon adoption of ASU No. 2017-12		$ 181
Other comprehensive (loss) income before reclassification	(303)
Amounts reclassified from accumulated other comprehensive loss	(5,892)
Other comprehensive income	(6,014)
Balance at period end	(15,752)
Essex Portfolio, L.P. [Member] | Change in Fair Value and Amortization of Swap Settlements [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	(9,593)
Cumulative effect upon adoption of ASU No. 2017-12		181
Other comprehensive (loss) income before reclassification	(506)
Amounts reclassified from accumulated other comprehensive loss	(5,860)
Other comprehensive income	(6,185)
Balance at period end	(15,778)
Essex Portfolio, L.P. [Member] | Unrealized Gains/(Loss) on Available for Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	(145)
Cumulative effect upon adoption of ASU No. 2017-12		$ 0
Other comprehensive (loss) income before reclassification	203
Amounts reclassified from accumulated other comprehensive loss	(32)
Other comprehensive income	171
Balance at period end	$ 26