Summary of Critical and Significant Accounting Policies - AOCI (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2019	$ 6,220,427
Other comprehensive income before reclassification	4,215
Amounts reclassified from accumulated other comprehensive loss	(5,056)
Other comprehensive loss	(841)
Balance at December 31, 2020	6,000,410
Change in Fair Value and Amortization of Swap Agreements
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2019	(13,989)
Other comprehensive income before reclassification	4,274
Amounts reclassified from accumulated other comprehensive loss	(5,056)
Other comprehensive loss	(782)
Balance at December 31, 2020	(14,771)
Unrealized Gains on Available for Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2019	101
Other comprehensive income before reclassification	(59)
Amounts reclassified from accumulated other comprehensive loss	0
Other comprehensive loss	(59)
Balance at December 31, 2020	42
Accumulated other comprehensive loss, net
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2019	(13,888)
Balance at December 31, 2020	(14,729)
Essex Portfolio, L.P.
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income before reclassification	4,363
Amounts reclassified from accumulated other comprehensive loss	(5,234)
Other comprehensive loss	(871)
Essex Portfolio, L.P. | Change in Fair Value and Amortization of Swap Agreements
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2019	(10,536)
Other comprehensive income before reclassification	4,424
Amounts reclassified from accumulated other comprehensive loss	(5,234)
Other comprehensive loss	(810)
Balance at December 31, 2020	(11,346)
Essex Portfolio, L.P. | Unrealized Gains on Available for Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2019	104
Other comprehensive income before reclassification	(61)
Amounts reclassified from accumulated other comprehensive loss	0
Other comprehensive loss	(61)
Balance at December 31, 2020	43
Essex Portfolio, L.P. | Accumulated other comprehensive loss, net
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2019	(10,432)
Balance at December 31, 2020	$ (11,303)