Organization and Basis of Presentation - Accumulated Other Comprehensive Loss - Partnership (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 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	6,345,116
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		$ 181
Other comprehensive (loss) income before reclassification	(2,207)
Amounts reclassified from accumulated other comprehensive loss	(3,951)
Other comprehensive income	(5,977)
Balance at period end	(15,715)
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		181
Other comprehensive (loss) income before reclassification	(2,435)
Amounts reclassified from accumulated other comprehensive loss	(3,919)
Other comprehensive income	(6,173)
Balance at period end	(15,766)
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		$ 0
Other comprehensive (loss) income before reclassification	228
Amounts reclassified from accumulated other comprehensive loss	(32)
Other comprehensive income	196
Balance at period end	$ 51