Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net income	$ 89,312	$ 135,153
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	254,211	143,662
Amortization of discount on marketable securities	(6,555)	(4,664)
Amortization of premium and debt financing costs, net	(4,987)	8,111
Gain on sale of marketable securities	(886)	(1,767)
Company's/Operating Partnership's share of gain on the sales of co-investment	(3,213)	(41,252)
Gain on the sales of real estate and land	(39,640)	(14,161)
Non-cash merger expense	7,562	0
Equity in income in co-investments, net	(14,903)	(1,892)
Equity-based compensation	4,996	3,137
Gain on early retirement of debt	0	(846)
Changes in operating assets and liabilities:
Acquired in place lease value and other assets	8,923	(19,689)
Accounts payable and accrued liabilities	44,775	19,091
Other liabilities	1,393	199
Net cash provided by operating activities	340,988	225,082
Additions to real estate:
Acquisitions of real estate	(409,018)	(205,539)
Improvements to recent acquisitions	(13,512)	(14,374)
Redevelopment	(35,361)	(32,488)
Revenue generating capital expenditures	(20,560)	(2,165)
Lessor required capital expenditure	(7,562)	(4,320)
Non-revenue generating capital expenditures	(29,070)	(21,885)
Acquisitions of and additions to real estate under development	(108,659)	(13,963)
Proceeds from insurance claim for property damage	29,160	0
BRE merger cash consideration paid	(555,826)	0
Dispositions of real estate	61,331	33,666
Dispositions of co-investments	13,900	0
Contributions to co-investments	(128,268)	(150,852)
Distributions from co-investments	40,421	117,103
Changes in restricted cash and deposits	(39,482)	(17,246)
Purchases of marketable securities	(15,516)	(16,442)
Sales and maturities of marketable securities	6,275	22,830
Purchases of and advances under notes and other receivables	0	(56,750)
Collections of notes and other receivables	76,585	53,438
Net cash used in investing activities	(1,135,162)	(308,987)
Cash flows from financing activities:
Borrowings under debt agreements	1,737,322	641,892
Principal repayment of debt	(1,327,840)	(536,926)
Additions to deferred and financing costs	(16,941)	(3,836)
Equity related issuance cost of common stock	(1,348)	(616)
Proceeds from stock options exercises	6,526	4,756
Net proceeds from issuance of common units	450,812	122,905
Distributions to noncontrolling interest	(13,217)	(14,108)
Redemption of noncontrolling interest	(4,707)	(5,113)
Common units and preferred units and preferred interests distributions paid	(177,400)	(134,146)
Net cash provided by financing activities	653,207	74,808
Net decrease in cash and cash equivalents-unrestricted	(140,967)	(9,097)
Cash acquired in the BRE merger	140,353	0
Cash and cash equivalents-unrestricted at beginning of period	18,491	18,606
Cash and cash equivalents-unrestricted at end of period	17,877	9,509
Supplemental disclosure of cash flow information:
Cash paid for interest	93,342	76,596
Supplemental disclosure of noncash investing and financing activities:
Issuance of Operating partner/limited partner common units for contributed properties	1,419,816	0
Retirement of limited partner common units	(1,419,816)	0
Transfer from real estate under development to land and building	71,496	68
Transfer from real estate under development to co-investments	81,332	27,906
Mortgage notes (excluding BRE merger) assumed in connection with purchases of real estate including the loan premiums recorded	70,480	0
Change in accrual of dividends	45,605	5,434
Change in fair value of derivative liabilities	(1,175)	3,649
Change in fair value of marketable securities	2,186	2,958
Change in construction payable	30,405	1,544
Reclassification to redeemable noncontrolling interest from additional paid in capital and noncontrolling interest	18,764	0
Assets acquired and liabilities assumed in BRE merger:
Cash assumed in merger	140,353	0
Rental properties and real estate under development	5,618,067	0
Real estate held for sale, net	107,772	0
Co-investments	218,402	0
Acquired in-place lease value	80,358	0
Other assets	15,676	0
Mortgage notes payable and unsecured debt	1,747,382	0
Other liabilities	94,976	0
Redeemable noncontrolling interest	4,798	0
Consideration issued	3,777,646	0
Essex Portfolio, L.P. [Member]
Cash flows from operating activities:
Net income	89,312	135,153
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	254,211	143,662
Amortization of discount on marketable securities	(6,555)	(4,664)
Amortization of premium and debt financing costs, net	(4,987)	8,111
Gain on sale of marketable securities	(886)	(1,767)
Company's/Operating Partnership's share of gain on the sales of co-investment	(3,213)	(41,252)
Gain on the sales of real estate and land	(39,640)	(14,161)
Non-cash merger expense	7,562	0
Equity in income in co-investments, net	(14,903)	(1,892)
Equity-based compensation	4,996	3,137
Gain on early retirement of debt	0	(846)
Changes in operating assets and liabilities:
Acquired in place lease value and other assets	8,923	(19,689)
Accounts payable and accrued liabilities	44,775	19,091
Other liabilities	1,393	199
Net cash provided by operating activities	340,988	225,082
Additions to real estate:
Acquisitions of real estate	(409,018)	(205,539)
Improvements to recent acquisitions	(13,512)	(14,374)
Redevelopment	(35,361)	(32,488)
Revenue generating capital expenditures	(20,560)	(2,165)
Lessor required capital expenditure	(7,562)	(4,320)
Non-revenue generating capital expenditures	(29,070)	(21,885)
Acquisitions of and additions to real estate under development	(108,659)	(13,963)
Proceeds from insurance claim for property damage	29,160	0
BRE merger cash consideration paid	(555,826)	0
Dispositions of real estate	61,331	33,666
Dispositions of co-investments	13,900	0
Contributions to co-investments	(128,268)	(150,852)
Distributions from co-investments	40,421	117,103
Changes in restricted cash and deposits	(39,482)	(17,246)
Purchases of marketable securities	(15,516)	(16,442)
Sales and maturities of marketable securities	6,275	22,830
Purchases of and advances under notes and other receivables	0	(56,750)
Collections of notes and other receivables	76,585	53,438
Net cash used in investing activities	(1,135,162)	(308,987)
Cash flows from financing activities:
Borrowings under debt agreements	1,737,322	641,892
Principal repayment of debt	(1,327,840)	(536,926)
Additions to deferred and financing costs	(16,941)	(3,836)
Equity related issuance cost of common stock	(1,348)	(616)
Proceeds from stock options exercises	6,526	4,756
Net proceeds from issuance of common units	450,812	122,905
Distributions to noncontrolling interest	(3,462)	(6,234)
Redemption of noncontrolling interest	(308)	(1,819)
Common units and preferred units and preferred interests distributions paid	(191,554)	(145,314)
Net cash provided by financing activities	653,207	74,808
Net decrease in cash and cash equivalents-unrestricted	(140,967)	(9,097)
Cash acquired in the BRE merger	140,353	0
Cash and cash equivalents-unrestricted at beginning of period	18,491	18,606
Cash and cash equivalents-unrestricted at end of period	17,877	9,509
Supplemental disclosure of cash flow information:
Cash paid for interest	93,342	76,596
Supplemental disclosure of noncash investing and financing activities:
Issuance of Operating partner/limited partner common units for contributed properties	1,419,816	0
Retirement of limited partner common units	(1,419,816)	0
Transfer from real estate under development to land and building	71,496	68
Transfer from real estate under development to co-investments	81,332	27,906
Mortgage notes (excluding BRE merger) assumed in connection with purchases of real estate including the loan premiums recorded	70,480	0
Change in accrual of dividends	45,605	5,434
Change in fair value of derivative liabilities	(1,175)	3,649
Change in fair value of marketable securities	2,186	2,958
Change in construction payable	30,405	1,544
Reclassification to redeemable noncontrolling interest from additional paid in capital and noncontrolling interest	(18,764)	0
Assets acquired and liabilities assumed in BRE merger:
Cash assumed in merger	140,353	0
Rental properties and real estate under development	5,618,067	0
Real estate held for sale, net	107,772	0
Co-investments	218,402	0
Acquired in-place lease value	80,358	0
Other assets	15,676	0
Mortgage notes payable and unsecured debt	1,747,382	0
Other liabilities	94,976	0
Redeemable noncontrolling interest	4,798	0
Consideration issued	$ 3,777,646	$ 0