Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities:
Net income	$ 34,834	$ 59,278
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of marketable securities	(886)	(1,767)
Company's share of gain on the sales of co-investment	(3,213)	(2,366)
Gain on the sales of real estate	(8,268)	(1,503)
Gain on early retirement of debt	0	(1,024)
Noncash merger expense	7,562	0
Co-investments, net	(10,719)	(280)
Amortization expense	(846)	5,932
Amortization of discount on notes receivables	0	(844)
Amortization of discount on marketable securities	(3,965)	(2,776)
Depreciation	147,822	95,175
Equity-based compensation	3,625	2,126
Changes in operating assets and liabilities:
Prepaid expenses and other assets	2,425	802
Accounts payable and accrued liabilities	10,086	(2,433)
Other liabilities	665	266
Net cash provided by operating activities	179,122	150,586
Additions to real estate:
Acquisitions of real estate	(93,772)	(175,950)
Improvements to recent acquisitions	(6,148)	(6,288)
Redevelopment	(19,503)	(17,616)
Revenue generating capital expenditures	(11,967)	(742)
Lessor required capital expenditure	(7,562)	(3,557)
Non-revenue generating capital expenditures	(15,048)	(12,349)
Acquisitions of and additions to real estate under development	(58,899)	(9,290)
Advance from insurance claim	10,000	0
Dispositions of real estate	14,123	9,051
BRE merger cash consideration paid	(555,826)	0
Changes in restricted cash and deposits	(3,606)	18,290
Purchases of marketable securities	(14,341)	(14,002)
Sales and maturities of marketable securities	5,192	20,335
Purchases of and advances under notes and other receivables	0	(99,164)
Collections of notes and other receivables	56,750	53,438
Dispositions of co-investments	13,900	0
Contributions to co-investments	(58,029)	(101,295)
Distributions from co-investments	18,467	57,458
Net cash used in investing activities	(726,269)	(281,681)
Cash flows from financing activities:
Borrowings under debt agreements	1,321,044	604,472
Repayment of debt	(1,077,210)	(495,072)
Additions to deferred charges instruments	(16,401)	(3,838)
Equity related issuance cost	(1,093)	(525)
Net proceeds from stock options exercised	5,503	4,190
Net proceeds from issuance of common stock	279,427	122,905
Distributions to noncontrolling interest	(7,510)	(9,811)
Redemption of noncontrolling interest	(2,550)	(2,017)
Common and preferred stock dividends paid	(94,961)	(87,598)
Net cash (used in) provided by financing activities	406,249	132,706
Net increase in cash and cash equivalents	(140,898)	1,611
Cash assumed in the BRE merger	140,353	0
Cash and cash equivalents at beginning of year	18,491	18,606
Cash and cash equivalents at end of period	17,946	20,217
Supplemental disclosure of cash flow information:
Cash paid for interest, net of $11.7 million, and $8.1 million capitalized in 2014 and 2013, respectively	44,437	50,053
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 Operating partner/limited partner common units	(1,419,816)	0
Transfer from real estate under development to land and building	4,580	67
Transfer from real estate under development to co-investments	49,776	0
Mortgage notes assumed in connection with purchases of real estate including the loan premiums recorded	49,009	0
Change in accrual of dividends	35,896	5,436
Change in fair value of derivative liabilities	122	4,820
Change in fair value of marketable securities	3,121	2,256
Change in construction payable	26,654	2,339
Accrued distribution from co-investment	19,836	0
Common stock proceeds receivable	19,970	0
Reclassification to nonredeemable noncontrolling interest	18,766	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Rental properties and real estate under development	5,613,031	0
Real estate held for sale, net	107,772	0
Co-investments	223,438	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
Equity consideration for BRE merger	3,777,646	0
Essex Portfolio, L.P. [Member]
Cash flows from operating activities:
Net income	34,834	59,278
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of marketable securities	(886)	(1,767)
Company's share of gain on the sales of co-investment	(3,213)	(2,366)
Gain on the sales of real estate	(8,268)	(1,503)
Gain on early retirement of debt	0	(1,024)
Noncash merger expense	7,562	0
Co-investments, net	(10,719)	(280)
Amortization expense	(846)	5,932
Amortization of discount on notes receivables	0	(844)
Amortization of discount on marketable securities	(3,965)	(2,776)
Depreciation	147,822	95,175
Equity-based compensation	3,625	2,126
Changes in operating assets and liabilities:
Prepaid expenses and other assets	2,425	802
Accounts payable and accrued liabilities	10,086	(2,433)
Other liabilities	665	266
Net cash provided by operating activities	179,122	150,586
Additions to real estate:
Acquisitions of real estate	(93,772)	(175,950)
Improvements to recent acquisitions	(6,148)	(6,288)
Redevelopment	(19,503)	(17,616)
Revenue generating capital expenditures	(11,967)	(742)
Lessor required capital expenditure	(7,562)	(3,557)
Non-revenue generating capital expenditures	(15,048)	(12,349)
Acquisitions of and additions to real estate under development	(58,899)	(9,290)
Advance from insurance claim	10,000	0
Dispositions of real estate	14,123	9,051
BRE merger cash consideration paid	(555,826)	0
Changes in restricted cash and deposits	(3,606)	18,290
Purchases of marketable securities	(14,341)	(14,002)
Sales and maturities of marketable securities	5,192	20,335
Purchases of and advances under notes and other receivables	0	(99,164)
Collections of notes and other receivables	56,750	53,438
Dispositions of co-investments	13,900	0
Contributions to co-investments	(58,029)	(101,295)
Distributions from co-investments	18,467	57,458
Net cash used in investing activities	(726,269)	(281,681)
Cash flows from financing activities:
Borrowings under debt agreements	1,321,044	604,472
Repayment of debt	(1,077,210)	(495,072)
Additions to deferred charges instruments	(16,401)	(3,838)
Equity related issuance cost	(1,093)	(525)
Net proceeds from stock options exercised	5,503	4,190
Net proceeds from issuance of common stock	279,427	122,905
Distributions to noncontrolling interest	(2,045)	(4,536)
Redemption of noncontrolling interest	(414)	(1,471)
Common and preferred stock dividends paid	(102,562)	(93,419)
Net cash (used in) provided by financing activities	406,249	132,706
Net increase in cash and cash equivalents	(140,898)	1,611
Cash assumed in the BRE merger	140,353	0
Cash and cash equivalents at beginning of year	18,491	18,606
Cash and cash equivalents at end of period	17,946	20,217
Supplemental disclosure of cash flow information:
Cash paid for interest, net of $11.7 million, and $8.1 million capitalized in 2014 and 2013, respectively	44,437	50,053
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 Operating partner/limited partner common units	(1,419,816)	0
Transfer from real estate under development to land and building	4,580	67
Transfer from real estate under development to co-investments	49,776	0
Mortgage notes assumed in connection with purchases of real estate including the loan premiums recorded	49,009	0
Change in accrual of dividends	35,896	5,436
Change in fair value of derivative liabilities	122	4,820
Change in fair value of marketable securities	3,121	2,256
Change in construction payable	26,654	2,339
Accrued distribution from co-investment	19,836	0
Common stock proceeds receivable	19,970	0
Reclassification to nonredeemable noncontrolling interest	18,766	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Rental properties and real estate under development	5,613,031	0
Real estate held for sale, net	107,772	0
Co-investments	223,438	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
Equity consideration for BRE merger	$ 3,777,646	$ 0