Organization and Basis of Presentation - Accumulated Other Comprehensive Loss - Partnership (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	$ 6,393,844
Cumulative effect upon adoption of ASU		$ 181
Balance at period end	6,317,195
Essex Portfolio, L.P. [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect upon adoption of ASU		181
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 income (loss) before reclassification	95
Amounts reclassified from accumulated other comprehensive loss	(1,932)
Other comprehensive income	(1,656)
Balance at period end	(11,394)
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 income (loss) before reclassification	(28)
Amounts reclassified from accumulated other comprehensive loss	(1,965)
Other comprehensive income	(1,812)
Balance at period end	(11,405)
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 income (loss) before reclassification	123
Amounts reclassified from accumulated other comprehensive loss	33
Other comprehensive income	156
Balance at period end	$ 11