Organization and Basis of Presentation (Policies)	9 Months Ended
Organization and Basis of Presentation (Policies)	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Consolidation Policy	The accompanying unaudited condensed consolidated financial statements present the accounts of Essex Property Trust, Inc. (“Essex” or the “Company”), which include the accounts of the Company and Essex Portfolio, L.P. and its subsidiaries (the “Operating Partnership,” which holds the operating assets of the Company), prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information and in accordance with the instructions to Form 10-Q. In the opinion of management, all adjustments necessary for a fair presentation of the financial position, results of operations, and cash flows for the periods presented have been included and are normal and recurring in nature. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements included in the Company's annual report on Form 10-K for the year ended December 31, 2017. All significant intercompany accounts and transactions have been eliminated in the unaudited condensed consolidated financial statements. Certain reclassifications have been made to conform to the current year’s presentation, including the reclassification of corporate-level property management expenses out of property operating, excluding real estate taxes to its own line item on the Company's condensed consolidated statements of income and comprehensive income.
Accounting Pronouncement Adopted in the Current Year and Recent Accounting Pronouncements	Accounting Pronouncements Adopted in the Current Year In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09 “Revenue from Contracts with Customers.” The new standard provides a single comprehensive revenue recognition model for contracts with customers (excluding certain contracts, such as lease contracts) to improve comparability within industries. The new standard requires an entity to recognize revenue to reflect the transfer of goods or services to customers at an amount the entity expects to be paid in exchange for those goods and services and provide enhanced disclosures, all to provide more comprehensive guidance for transactions such as service revenue and contract modifications. The new standard is effective for interim and annual periods beginning after December 15, 2017. The new standard may be applied using either a full retrospective or a modified approach upon adoption. The Company adopted ASU No. 2014-09 as of January 1, 2018 using the modified retrospective approach. See Note 3, Revenues, for further details. In January 2016, the FASB issued ASU No. 2016-01 “Recognition and Measurement of Financial Assets and Financial Liabilities,” which requires changes to the classification and measurement of investments in certain equity securities and to the presentation of certain fair value changes for financial liabilities measured at fair value. The new standard is effective for interim and annual periods beginning after December 15, 2017. The Company adopted ASU No. 2016-01 as of January 1, 2018 using the modified retrospective method by applying a cumulative effect adjustment to retained earnings and partners' capital of $2.2 million, representing accumulated net unrealized gains of certain equity securities held by the Company. Furthermore, as a result of the adoption of this standard, the Company will recognize changes in the fair value of equity investments with readily determinable fair values through net income as opposed to comprehensive income. In August 2016, the FASB issued ASU No. 2016-15 “Classification of Certain Cash Receipts and Cash Payments,” which requires entities to adhere to a uniform classification and presentation of certain cash receipts and cash payments in the statement of cash flows. The amendments in this update provide guidance on eight specific cash flow issues. The new standard is effective for interim and annual periods beginning after December 15, 2017. The Company adopted ASU No. 2016-15 as of January 1, 2018 using the retrospective transition method. This amendment did not have a material impact on the Company's consolidated results of operations or financial position. In November 2016, the FASB issued ASU No. 2016-18 “Statement of Cash Flows,” which requires entities to include restricted cash and restricted cash equivalents in the reconciliation of beginning-of-period to the end-of-period of cash and cash equivalents in the statement of cash flows. This new standard seeks to eliminate the current diversity in practice in how changes in restricted cash and restricted cash equivalents is presented in the statement of cash flows. The new standard is effective for interim and annual periods beginning after December 15, 2017. The Company adopted ASU No. 2016-18 as of January 1, 2018 using the retrospective transition method. This amendment did not have a material impact on the Company's consolidated results of operations or financial position. In January 2017, the FASB issued ASU No. 2017-01 “Business Combinations: Clarifying the Definition of a Business,” which provides a new framework for determining whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. Previously, U.S. GAAP did not specify the minimum inputs and processes required for an integrated set of assets and activities to meet the definition of a business, causing a broad interpretation of the definition of a business. The new standard is effective for interim and annual periods beginning after December 15, 2017. The Company adopted ASU No. 2017-01 as of January 1, 2018 prospectively. The Company expects that substantially all of its acquisitions of communities will qualify as asset acquisitions and transaction costs related to these acquisitions will be capitalized upon adoption. In February 2017, the FASB issued ASU No. 2017-05 “Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets,” which adds guidance for partial sales of nonfinancial assets, including partial sales of real estate. Historically, U.S. GAAP contained several different accounting models to evaluate whether the transfer of certain assets qualified for sale treatment. This new standard reduces the number of potential accounting models that might apply and clarifies which model does apply in various circumstances. Partial sales of nonfinancial assets are common in the real estate industry and include transactions in which the seller retains an equity interest in the entity that owns the assets or has an equity interest in the buyer. The new standard is effective for interim and annual periods beginning after December 15, 2017. Management performed an evaluation of all of the Company's contracts that may be affected by the new standard. The Company adopted ASU No. 2017-05 concurrently with the adoption of ASU No. 2014-09 “Revenue from Contracts with Customers” as of January 1, 2018 using the modified-retrospective method by applying a cumulative effect adjustment to retained earnings and partners' capital of $123.7 million, representing the partial sale of its membership interest in BEX II, LLC (“BEX II”) during the fourth quarter of 2016. Recent Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02 “Leases,” which requires an entity that is a lessee to classify leases as either finance or operating and to recognize a lease liability and a right-of-use asset for all leases that have a duration of greater than 12 months. Leases of 12 months or less will be accounted for similar to existing guidance for operating leases today. For lessors, accounting for leases under the new standard will be substantially the same as existing guidance for sales-type leases, direct financing leases, and operating leases, but eliminates current real estate specific provisions and changes the treatment of initial direct costs. The Company expects that its residential and commercial leases, where it is the lessor, will continue to be accounted for as operating leases under the new standard. In July 2018, the FASB issued ASU No. 2018-11 “Leases (Topic 842): Targeted Improvements,” which includes a practical expedient that allows lessors to not separate nonlease components from the associated lease component. This provides the Company with the option of not bifurcating certain common area maintenance recoveries as a non-lease component, if certain requirements are met. The Company expects to elect this practical expedient, which would result in minimum rents and expense recoveries being presented as a single revenue line item in the consolidated statement of income and comprehensive income. For leases where the Company is the lessee, which includes various corporate office and ground leases, the Company will be required to recognize a right of use asset and related lease liability on its consolidated balance sheets upon adoption. The Company expects that its corporate office leases, where it is the lessee, will continue to be accounted for as operating leases. The Company also expects to elect a package of practical expedients, under which the Company would not be required to reassess the classification of existing ground leases. The new standards will be effective for the Company beginning January 1, 2019 and early adoption is permitted, including adoption in an interim period. The Company currently anticipates adopting the new standards on the effective date. The Company expects to apply the new standard on January 1, 2019 and is continuing to evaluate the impact of these amendments on its consolidated results of operations and financial position. In June 2016, the FASB issued ASU No. 2016-13 “Measurement of Credit Losses on Financial Instruments,” which amends the current approach to estimate credit losses on certain financial assets, including trade and other receivables, available-for-sale securities, and other financial instruments. Generally, this amendment requires entities to establish a valuation allowance for the expected lifetime losses of these certain financial assets. Subsequent changes in the valuation allowance are recorded in current earnings and reversal of previous losses are permitted. Currently, U.S. GAAP requires entities to write down credit losses only when losses are probable and loss reversals are not permitted. The new standard will be effective for the Company beginning January 1, 2020 and early adoption is permitted. The Company is currently evaluating the impact of this amendment on its consolidated results of operations and financial position. In August 2017, the FASB issued ASU No. 2017-12 “Derivatives and Hedging - Targeted Improvements to Accounting for Hedging Activities,” which, among other things, requires entities to present the earnings effect of hedging instruments in the same income statement line item in which the earnings effect of the hedged item is reported. The new standard also adds new disclosure requirements. This new standard will be effective for the Company beginning January 1, 2019 and early adoption is permitted. The Company is currently evaluating the impact of this amendment on its consolidated results of operations and financial position. In August 2018, the FASB issued ASU No. 2018-13 "Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement," which eliminates certain disclosure requirements affecting all levels of measurements, and modifies and adds new disclosure requirements for Level 3 measurements. The new standard will be effective for the Company beginning January 1, 2020 and early adoption is permitted. The Company is currently evaluating the impact of this amendment on its disclosures.
Marketable Securities	Marketable Securities The Company reports its equity securities and available for sale debt securities at fair value, based on quoted market prices (Level 1 for the common stock and investment funds, Level 2 for the unsecured bonds and Level 3 for investments in mortgage backed securities, as defined by the FASB standard for fair value measurements). Any unrealized gain or loss in debt securities classified as available for sale is recorded as other comprehensive income. Unrealized gains and losses in equity securities, realized gains and losses in debt securities, interest income, and amortization of purchase discounts are included in interest and other income on the condensed consolidated statements of income and comprehensive income. As of September 30, 2018 and December 31, 2017, equity securities and available for sale debt securities consisted primarily of investment-grade unsecured bonds, common stock and stock funds, investments in mortgage backed securities, and investment funds that invest in U.S. treasury or agency securities. As of September 30, 2018 and December 31, 2017, the Company classified its investments in mortgage backed securities, which mature in November 2019 and September 2020, as held to maturity, and accordingly, these securities are stated at their amortized cost. The discount on the mortgage backed securities is being amortized to interest income based on an estimated yield and the maturity date of the securities.
Variable Interest Entities	Variable Interest Entities In accordance with accounting standards for consolidation of variable interest entities (“VIEs”), the Company consolidates the Operating Partnership, 16 limited partnerships, comprising eight communities, (the “DownREIT limited partnerships”) and eight co-investments as of September 30, 2018. The Company consolidates these entities because it is deemed the primary beneficiary. Essex has no assets or liabilities other than its investment in the Operating Partnership. The consolidated total assets and liabilities related to the eight consolidated co-investments and 16 DownREIT limited partnerships, net of intercompany eliminations, were approximately $839.1 million and $264.1 million, respectively, as of September 30, 2018 and $837.7 million and $265.5 million, respectively, as of December 31, 2017. Noncontrolling interests in these entities were $64.6 million and $66.7 million as of September 30, 2018 and December 31, 2017, respectively. The Company's financial risk in each VIE is limited to its equity investment in the VIE. As of September 30, 2018 and December 31, 2017, the Company did not have any other VIEs of which it was deemed to be the primary beneficiary and did not have any VIEs of which it was not deemed to be the primary beneficiary.
Equity-based Compensation	Equity-based Compensation The cost of share- and unit-based compensation awards is measured at the grant date based on the estimated fair value of the awards. The estimated fair value of stock options and restricted stock granted by the Company are being amortized over the vesting period. The estimated grant date fair values of the long term incentive plan units (discussed in Note 12, “Equity Based Compensation Plans,” in the Company’s annual report on Form 10-K for the year ended December 31, 2017) are being amortized over the expected service periods.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Management believes that the carrying amounts of the outstanding balances under its lines of credit, and notes and other receivables approximate fair value as of September 30, 2018 and December 31, 2017, because interest rates, yields, and other terms for these instruments are consistent with yields and other terms currently available for similar instruments. Management has estimated that the fair value of the Company’s fixed rate debt with a carrying value of $5.0 billion and $4.9 billion, including premiums, discounts and debt financing costs, at both September 30, 2018 and December 31, 2017, was approximately $5.0 billion. Management has estimated that the fair value of the Company’s $612.7 million and $792.9 million of variable rate debt, net of debt financing costs, at September 30, 2018 and December 31, 2017, respectively, was approximately $615.3 million and $793.9 million based on the terms of existing mortgage notes payable, unsecured debt, and variable rate demand notes compared to those available in the marketplace. Management believes that the carrying amounts of cash and cash equivalents, restricted cash, accounts payable and accrued liabilities, construction payables, other liabilities, and dividends payable approximate fair value as of September 30, 2018 and December 31, 2017 due to the short-term maturity of these instruments. Marketable securities, except mortgage backed securities, and derivatives are carried at fair value as of September 30, 2018 and December 31, 2017. At September 30, 2018, the Company’s investments in mortgage backed securities had a carrying value of $122.5 million and the Company estimated the fair value to be approximately $130.6 million. At December 31, 2017, the Company’s investments in mortgage backed securities had a carrying value of $109.5 million and the Company estimated the fair value to be approximately $120.7 million. The Company determines the fair value of the mortgage backed securities based on unobservable inputs (level 3 of the fair value hierarchy) considering the assumptions that market participants would make in valuing these securities. Assumptions such as estimated default rates and discount rates are used to determine the expected discounted cash flows to estimate fair value.
Capitalization of Costs	Capitalization of Costs The Company’s capitalized internal costs related to development and redevelopment projects were comprised primarily of employee compensation and totaled $4.7 million and $4.6 million during the three months ended September 30, 2018 and 2017, respectively, and $14.2 million and $14.0 million for the nine months ended September 30, 2018 and 2017, respectively. The Company capitalizes leasing commissions associated with the lease-up of development communities and amortizes the costs over the life of the leases. The amounts capitalized for leasing commissions are immaterial for all periods presented.
Co-investments	Co-investments The Company owns investments in joint ventures and preferred equity investments, (collectively, “co-investments”) in which it has significant influence, but its ownership interest does not meet the criteria for consolidation in accordance with U.S. GAAP. Therefore, the Company accounts for co-investments using the equity method of accounting. Under the equity method of accounting, the investment is carried at the cost of assets contributed, plus the Company's equity in earnings less distributions received and the Company's share of losses. The significant accounting policies of the Company’s co-investment entities are consistent with those of the Company in all material respects. Upon the acquisition of a controlling interest of a co-investment, the co-investment entity is consolidated and the transaction will be accounted for as a business combination if the entity meets the definition of a business pursuant to ASU No. 2017-01, or an asset acquisition if the entity is not determined to be a business. A majority of the co-investments, excluding the preferred equity investments, compensate the Company for its asset management services and some of these investments may provide promote income if certain financial return benchmarks are achieved. Asset management fees are recognized when earned, and promote fees are recognized when the earnings events have occurred and the amount is determinable and collectible. Any promote fees are reflected in equity income from co-investments. The Company reports investments in co-investments where accumulated distributions have exceeded the Company’s investment as distributions in excess of investments in co-investments in the accompanying condensed consolidated balance sheets. As of December 31, 2017, the net investment of one of the Company’s co-investments was less than zero as a result of financing distributions in excess of the Company's investment in that co-investment. As a result of the Company's adoption of ASU No. 2017-05 on January 1, 2018, the carrying value of this co-investment was greater than zero as of September 30, 2018.
Changes in Accumulated Other Comprehensive Loss	Amounts reclassified from accumulated other comprehensive loss in connection with derivatives are recorded in interest expense on the condensed consolidated statements of income and comprehensive income. Realized gains and losses on available for sale debt securities are included in interest and other income on the condensed consolidated statements of income and comprehensive income.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash Highly liquid investments with original maturities of three months or less when purchased are classified as cash equivalents. Restricted cash balances relate primarily to reserve requirements for capital replacement at certain communities in connection with the Company’s mortgage debt.
Accounting Estimates	Accounting Estimates The preparation of condensed consolidated financial statements, in accordance with U.S. GAAP, requires the Company to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosures of contingent assets and liabilities. On an on-going basis, the Company evaluates its estimates, including those related to acquiring, developing and assessing the carrying values of its real estate portfolio, its investments in and advances to joint ventures and affiliates, its notes receivables, and its qualification as a real estate investment trust (“REIT”). The Company bases its estimates on historical experience, current market conditions, and on various other assumptions that are believed to be reasonable under the circumstances. Actual results may vary from those estimates and those estimates could be different under different assumptions or conditions.