Net Income Per Common Share and Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Basic:
Net income available to common stockholders/unitholders	$ 92,275	$ 100,440	$ 211,133	$ 191,358
Weighted average number of shares/common units outstanding during the period (in shares)	65,718,806	66,047,751	65,710,842	66,045,897
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.40	$ 1.52	$ 3.21	$ 2.90
Effect of Dilutive Securities: Stock options (in shares)	103,009	48,598	91,575	42,906
Diluted:
Net income available to common stockholders/unitholders	$ 92,275	$ 100,440	$ 211,133	$ 191,358
Net income available to common stockholders/unitholders, weighted average common shares (in shares)	65,821,815	66,096,349	65,802,417	66,088,803
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.40	$ 1.52	$ 3.21	$ 2.90
Essex Portfolio, L.P. [Member]
Basic:
Net income available to common stockholders/unitholders	$ 95,503	$ 103,900	$ 218,532	$ 197,950
Weighted average number of shares/common units outstanding during the period (in shares)	68,018,090	68,320,849	68,012,999	68,319,151
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.40	$ 1.52	$ 3.21	$ 2.90
Effect of Dilutive Securities: Stock options (in shares)	103,009	48,598	91,575	42,906
Diluted:
Net income available to common stockholders/unitholders	$ 95,503	$ 103,900	$ 218,532	$ 197,950
Net income available to common stockholders/unitholders, weighted average common shares (in shares)	68,121,099	68,369,447	68,104,574	68,362,057
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.40	$ 1.52	$ 3.21	$ 2.90
Convertible Limited Partnership Units [Member]
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	2,299,284	2,273,098	2,302,158	2,273,255
Antidilutive securities excluded from computation of earnings per share, value	$ 3,200	$ 3,500	$ 7,400	$ 6,600
Share-based Payment Arrangement, Option [Member]
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	0	185,181	106,029	185,470
Share-based Payment Arrangement, Option [Member] | Essex Portfolio, L.P. [Member]
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	0	185,181