Summary of Critical and Significant Accounting Policies - AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Jan. 01, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2018	$ 6,267,073
Other comprehensive income before reclassification	8,108
Amounts reclassified from accumulated other comprehensive loss	(8,954)
Other comprehensive income (loss)	(671)
Balance at December 31, 2019	6,220,427
Change in Fair Value and Amortization of Swap Agreements
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2018	(13,077)
Cumulative effect upon adoption of ASU No. 2017-12		$ 175
Other comprehensive income before reclassification	7,836
Amounts reclassified from accumulated other comprehensive loss	(8,923)
Other comprehensive income (loss)	(912)
Balance at December 31, 2019	(13,989)
Unrealized Gains on Available for Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2018	(140)
Cumulative effect upon adoption of ASU No. 2017-12		0
Other comprehensive income before reclassification	272
Amounts reclassified from accumulated other comprehensive loss	(31)
Other comprehensive income (loss)	241
Balance at December 31, 2019	101
Accumulated Other Comprehensive Loss, Net
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2018	(13,217)
Cumulative effect upon adoption of ASU No. 2017-12		175
Balance at December 31, 2019	(13,888)
Essex Portfolio, L.P.
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income before reclassification	8,392
Amounts reclassified from accumulated other comprehensive loss	(9,267)
Other comprehensive income (loss)	(694)
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, 2018	(9,593)
Cumulative effect upon adoption of ASU No. 2017-12		181
Other comprehensive income before reclassification	8,111
Amounts reclassified from accumulated other comprehensive loss	(9,235)
Other comprehensive income (loss)	(943)
Balance at December 31, 2019	(10,536)
Essex Portfolio, L.P. | Unrealized Gains on Available for Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2018	(145)
Cumulative effect upon adoption of ASU No. 2017-12		0
Other comprehensive income before reclassification	281
Amounts reclassified from accumulated other comprehensive loss	(32)
Other comprehensive income (loss)	249
Balance at December 31, 2019	104
Essex Portfolio, L.P. | Accumulated Other Comprehensive Loss, Net
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2018	(9,738)
Cumulative effect upon adoption of ASU No. 2017-12		$ 181
Balance at December 31, 2019	$ (10,432)