Organization and Basis of Presentation - Accumulated Other Comprehensive Loss - Partnership (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	$ 6,292,237
Balance at period end	6,389,003
Essex Portfolio, L.P. [Member] | AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	(29,348)
Other comprehensive income before reclassification	5,864
Amounts reclassified from accumulated other comprehensive loss	(3,651)
Other comprehensive income (loss)	2,213
Balance at period end	(27,135)
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	(30,161)
Other comprehensive income before reclassification	5,685
Amounts reclassified from accumulated other comprehensive loss	(2,046)
Other comprehensive income (loss)	3,639
Balance at period end	(26,522)
Essex Portfolio, L.P. [Member] | Unrealized Gains on Available for Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at period beginning	813
Other comprehensive income before reclassification	179
Amounts reclassified from accumulated other comprehensive loss	(1,605)
Other comprehensive income (loss)	(1,426)
Balance at period end	$ (613)