Description of Business and Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary Of Operations	LivePerson, Inc. (the “Company” or “LivePerson”) was incorporated in the State of Delaware in November 1995 and the LivePerson service was introduced in November 1998. In April 2000, the Company completed an initial public offering and is currently traded on the NASDAQ Global Select Market and the Tel Aviv Stock Exchange. LivePerson is headquartered in New York City with an U.S. office in Alpharetta (Georgia), and international offices in Amsterdam, Berlin, London, Mannheim, Melbourne, Milan, Paris, Ra'anana (Israel), Reading (UK), and Tokyo. LivePerson provides mobile and online business messaging solutions that power digital communication between brands and consumers. LiveEngage, the Company’s enterprise-class, cloud-based platform, enables businesses to create a meaningful connection with consumers via messaging. As consumers have reoriented their digital lives around the smartphone, messaging apps have become their preferred communication channel to connect with each other. LivePerson allows brands to align with this new consumer preference, and deploy messaging at scale for customer care and sales, instead of demanding that consumers use email or call a 1-800 number. LiveEngage was designed to securely deploy messaging at scale for brands with tens of millions of customers and many thousands of customer care agents. Key benefits include a sophisticated proactive targeting engine and a robust suite of text and mobile messaging, real-time chat messaging, content delivery, customer sentiment, and cobrowsing offerings that power intelligent digital engagement with consumers. LiveEngage powers conversations across each of a brand’s primary digital channels, including mobile apps, mobile and desktop web browsers, social media and third-party consumer messaging platforms. LivePerson optimizes campaign outcomes for sales and service transaction by combining website visitor data with other historical, behavioral, and operational information to develop insights into each step of a consumer’s journey. LivePerson’s products, coupled with its domain knowledge, industry expertise and consulting services, have been proven to maximize the effectiveness of consumer engagement. The Company’s primary revenue source is from the sale of LivePerson services to businesses of all sizes. The Company also offers an online marketplace that connects independent service providers (“Experts”) who provide information and knowledge for a fee via real-time chat with individual consumers (“Users”).
Principles Of Consolidation	Principles of Consolidation The consolidated financial statements reflect the operations of LivePerson and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.
Reclassification	Reclassification For comparability, certain 2014 and 2015 amounts have been reclassified where appropriate, to conform to the financial presentation in 2016.
Use Of Estimates	Use of Estimates The preparation of the consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (“GAAP”) requires the Company’s management to make a number of estimates and assumptions relating to the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the period. Significant items subject to such estimates and assumptions include revenue recognition, stock-based compensation, accounts receivable, the valuation of goodwill and intangible assets, income taxes and legal contingencies. Actual results could differ from those estimates.
Concentration Of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable which approximate fair value at December 31, 2016 because of the short-term nature of these instruments. The Company invests its cash and cash equivalents with financial institutions that it believes are of high quality, and the Company performs periodic evaluations of these instruments and the relative credit standings of the institutions with which it invests. At certain times, the Company’s cash balances with any one financial institution may exceed Federal Deposit Insurance Corporation insurance limits. The Company believes it mitigates its risk by depositing its cash balances with high credit, quality financial institutions. The Company’s customers are located primarily in the United States. The Company performs ongoing credit evaluations of its customers’ financial condition (except for customers who purchase the LivePerson services by credit card via Internet download) and has established an allowance for doubtful accounts based upon factors surrounding the credit risk of customers, historical trends and other information. Concentration of credit risk is limited due to the Company’s large number of customers. No single customer accounted for or exceeded 10% of revenue in 2016, 2015 or 2014. No single customer accounted for or exceeded 10% of the Company's total accounts receivable in 2016 and 2015.
Foreign Currency Translation	Foreign Currency Translation The Company's operations are conducted in various countries around the world and the financial statements of its foreign subsidiaries are reported in the applicable foreign currencies (functional currencies). Financial information is translated from the applicable functional currency to the U.S. dollar (the reporting currency) for inclusion in the Company's consolidated financial statements. Income, expenses and cash flows are translated at weighted average exchange rates prevailing during the fiscal period, and assets and liabilities are translated at fiscal period-end exchange rates. Resulting translation adjustments are included as a component of accumulated other comprehensive income (loss) in stockholders' equity. Foreign exchange transaction gain or losses are included in Other Income, net in the accompanying consolidated statements of operations.
Cash And Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid securities with original maturities of 3 months or less when acquired to be cash equivalents. Cash equivalents, which primarily consist of money market funds, are recorded at cost, which approximates fair value.
Accounts Receivable	Accounts Receivable Accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is the Company’s best estimate of the amount of probable credit losses in the Company’s existing accounts receivable. The Company determines the allowance based on historical write-off experience. The Company reviews its allowance for doubtful accounts monthly. Past due balances over 90 days and over a specified amount are reviewed individually for collectability. All other balances are reviewed on a pooled basis. Account balances are charged off against the allowance after all means of collection have been exhausted and the potential for recovery is considered remote. The Company does not have any off-balance sheet credit exposure related to its customers.
Property And Equipment	Property and Equipment Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the related assets, generally three to five years for equipment and software. Leasehold improvements are depreciated using the straight-line method over the shorter of the lease term or the estimated useful life of the asset.
Internal-Use Software Development Costs	Internal-Use Software Development Costs In accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 350-40, Internal-Use Software, the Company capitalizes its costs to develop its internal use software when preliminary development efforts are successfully completed, management has authorized and committed project funding, and it is probable that the project will be completed and the software will be used as intended. These costs are included in property and equipment in the Company's consolidated balance sheets and are amortized on a straight-line basis over the estimated useful life of the related asset, which approximates three years. Costs incurred prior to meeting these criteria, together with costs incurred for training and maintenance, are expensed as incurred.
Goodwill And Intangible Assets	Goodwill and Intangible Assets In accordance with ASC 350, Goodwill and Other Intangible Assets, goodwill and indefinite-lived intangible assets are not amortized, but reviewed for impairment upon the occurrence of events or changes in circumstances that would reduce the fair value below its carrying amount. Goodwill is required to be tested for impairment at least annually. In September 2011, the FASB issued ASU No. 2011-8, “Intangibles — Goodwill and Other (Topic 350).” ASU 2011-8 permits an entity to first assess qualitative factors to determine whether it is “more likely than not” that the fair value of a reporting unit is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step goodwill impairment test described in Topic 350. The more-likely-than-not threshold is defined as having a likelihood of more than 50%. If it is determined that the fair value of a reporting unit is more likely than not to be less than its carrying value (including unrecognized intangible assets) then it is necessary to perform the second step of the goodwill impairment test. The second step of the goodwill impairment test is judgmental in nature and often involves the use of significant estimates and assumptions. Similarly, estimates and assumptions are used in determining the fair value of other intangible assets. These estimates and assumptions could have a significant impact on whether or not an impairment charge is recognized and also the magnitude of any such charge. The Company performs internal valuation analyses and considers other market information that is publicly available. Estimates of fair value are primarily determined using discounted cash flows and market comparisons. These approaches use significant estimates and assumptions including projected future cash flows (including timing), discount rates reflecting the risk inherent in future cash flows, perpetual growth rates, determination of appropriate market comparables and the determination of whether a premium or discount should be applied to comparables. ASC 350-10 also requires that intangible assets with estimable useful lives be amortized over their respective estimated useful lives to their estimated residual values, and reviewed for impairment in accordance with ASC 360-10-35, “Accounting for Impairment or Disposal of Long-Lived Assets.” The Company evaluates for goodwill impairment annually at September 30^th and at the end of the third quarter of 2016, the Company determined that it was not more-likely that the fair value of the reporting units is less than their carrying amount. Accordingly, the Company did not perform the two-step goodwill impairment test on both the Company's Business and Consumer segments. The Company assessed qualitative facts while summarizing the totality of events and circumstances and considered the extent to which adverse events or circumstances could affect the reporting unit's fair value as well as the consideration of positive and mitigating events and circumstances that would affect the determination of whether it was more likely than not that the fair value of a reporting unit is less than its carrying amount.
Impairment Of Long-Lived Assets	Impairment of Long-Lived Assets In accordance with ASC 360-10, “Accounting for the Impairment or Disposal of Long-lived Assets,” long-lived assets, such as property, plant and equipment and purchased intangibles subject to amortization are reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. The amount of any impairment is measured as the difference between the carrying value and the fair value of the impaired asset. During December 31, 2016, the Company determined certain long-lived assets related to the legacy platform and purchased intangibles of technology licenses to be impaired.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The fair value of a financial instrument is the amount at which the instrument could be exchanged in a current transaction between willing parties. Cash and cash equivalents, accounts receivable, security deposits and accounts payable carrying amounts approximate fair value because of the short maturity of these instruments.
Revenue Recognition	Revenue Recognition The majority of the Company’s revenue is generated from monthly service revenues and related professional services from the sale of the LivePerson services. Because the Company provides its application as a service, the Company follows the provisions of FASB Accounting Standards Codification (“ASC”) 605-10-S99, “Revenue Recognition” and ASC 605-25, “Revenue Recognition with Multiple-Element Arrangements.” The Company charges a monthly, quarterly or annual fee, which varies by type of service, the level of customer usage and website traffic, and in some cases, the number of orders placed via the Company’s online engagement solutions. For certain of the Company’s larger customers, the Company may provide call center labor through an arrangement with one or more of several qualified vendors. For most of these customers, the Company passes the fee it incurs with the labor provider and its fee for the hosted services through to its customers in the form of a fixed fee for each order placed via the Company’s online engagement solutions. For these Pay for Performance (“PFP”) arrangements, in accordance with ASC 605-45, “Principal Agent Considerations,” the Company records revenue for transactions in which it acts as an agent on a net basis, and revenue for transactions in which it acts as a principal on a gross basis. The Company also sells certain of the LivePerson services directly via Internet download. These services are marketed as LiveEngage for small to medium-sized businesses (“SMBs”), and are paid for almost exclusively by credit card. Credit card payments accelerate cash flow and reduce the Company’s collection risk, subject to the merchant bank's right to hold back cash pending settlement of the transactions. Sales of LiveEngage may occur with or without the assistance of an online sales representative, rather than through face-to-face or telephone contact that is typically required for traditional direct sales. The Company recognizes monthly service revenue based upon the fee charged for the LivePerson services, provided that there is persuasive evidence of an arrangement, no significant Company obligations remain, collection of the resulting receivable is probable and the amount of fees to be paid is fixed or determinable. The Company’s service agreements typically have 12 month terms and, in some cases, are terminable or may terminate upon 30 to 90 days’ notice without penalty. When professional service fees add value to the customer on a standalone basis, the Company recognizes professional service fees upon completion of services and customer acceptance. This guidance establishes a selling price hierarchy for determining the selling price of a deliverable, which is based on: (a) vendor-specific objective evidence; (b) third-party evidence; or (c) best estimated selling price. If a professional services arrangement does not qualify for separate accounting, the Company recognizes the fees, and the related labor costs, ratably over the contracted period. For revenue from our Consumer segment generated from online transactions between Experts and Users, the Company recognizes revenue net of the Expert fees in accordance with ASC 605-45, “Principal Agent Considerations,” due primarily to the fact that the Expert is the primary obligor. Additionally, the Company performs as an agent without any risk of loss for collection, and is not involved in selecting the Expert or establishing the Expert’s fee. The Company collects a fee from the User and retains a portion of the fee, and then remits the balance to the Expert. Revenue from these transactions is recognized when there is persuasive evidence of an arrangement, no significant Company obligations remain, collection of the resulting receivable is probable and the amount of fees to be paid is fixed and determinable.
Advertising Costs	Advertising Costs The Company expenses the cost of advertising and promoting its services as incurred.
Stock-Based Compensation	Stock-based Compensation In accordance with ASC Topic 718 -10, "Stock Compensation", the Company measures stock based awards at fair value and recognizes compensation expense for all share-based payment awards made to its employees and directors, including employee stock options. The Company estimates the fair value of stock options granted using the Black-Scholes valuation model. This model requires the Company to make estimates and assumptions including, among other things, estimates regarding the length of time an employee will retain vested stock options before exercising them, the estimated volatility of its common stock price and the number of options that will be forfeited prior to vesting. The fair value is then recognized on a straight line basis over the requisite service period of the award, which is generally four years. Changes in these estimates and assumptions can materially affect the determination of the fair value of the stock-based compensation and consequently, the related amount recognized in the consolidated statement of operations.
Deferred Rent	Deferred Rent The Company records rent expense on a straight-line basis over the term of the related lease. The difference between the rent expense recognized for financial reporting purposes and the actual payments made in accordance with the lease agreement is recognized as deferred rent liability included in other liabilities on the Company’s consolidated balance sheets.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in results of operations in the period that the tax change occurs. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized.
Comprehensive Income (Loss)	Comprehensive Loss In accordance with ASC 220, Comprehensive Income, the Company reports by major components and as a single total, the change in its net assets during the period from non-owner sources. Comprehensive income (loss) consists of net income (loss), and accumulated other comprehensive income (loss), which includes certain changes in equity that are excluded from net income (loss). The Company’s comprehensive loss for all periods presented is related to the effect of foreign currency translation.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2017-04, "Intangibles —Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment" (“ASU 2017-04”). This update addresses concerns over the cost and complexity of the two-step goodwill impairment test. The amendments in this update remove the second step of the test. An entity will apply a one-step quantitative test and record the amount of goodwill impairment as the excess of a reporting unit's carrying amount over its fair value, not to exceed the total amount of goodwill allocated to the reporting unit. The new guidance does not amend the optional qualitative assessment of goodwill impairment. ASU 2017-04 is effective for financial statements issued for annual periods beginning after December 15, 2019, and interim periods within those annual periods. The Company does not expect the adoption of ASU 2017-04 to have a material effect on its financial position, results of operations or cash flows. In January 2017, the FASB issued Accounting Standards Update No. 2017-01, "Business Combinations (Topic 805): Clarifying the Definition of a Business" (“ASU 2017-01”). This update clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of businesses. The amendments in this update provide a screen to determine when a set is not a business. If the screen is not met, it (1) requires that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output and (2) removes the evaluation of whether a market participant could replace the missing elements. ASU 2017-01 is effective for financial statements issued for annual periods beginning after December 15, 2017, and interim periods within those annual periods. The Company does not expect the adoption of ASU 2017-01 to have a material effect on its financial position, results of operations or cash flows. In March 2016, the FASB issued Accounting Standards Update No. 2016-09, “Compensation -Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting” (“ASU 2016-09”). This update is intended to improve the accounting for employee share-based payments and affects all organizations that issue share-based payment awards to their employees. Several aspects of the accounting for share-based payment award transactions are simplified, including:(a) income tax consequences; (b) classification of awards as either equity or liabilities; and(c)classification on the statement of cash flows. ASU 2016-09 is effective for financial statements issued for annual periods beginning after December 15, 2016. The Company does not expect the adoption of ASU 2016-09 to have a material effect on its financial position, results of operations or cash flows. On February 2016, the FASB issued Accounting Standards Update No. 2016-02, "Leases" ("ASU 2016-02"). ASU 2016-02 requires lessees to recognize the following for all leases (with the exception of short-term leases) at the commencement date: a lease liability, which is a lessee‘s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. Under the new guidance, lessor accounting is largely unchanged. Certain targeted improvements were made to align, where necessary, lessor accounting with the lessee accounting model and Topic 606, Revenue from Contracts with Customers. The new lease guidance also simplified the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off-balance sheet financing. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. ASU 2016-02 is effective for financial statements issued for annual periods beginning after December 15, 2018. While the Company is currently assessing the impact ASU 2016-02 will have on the consolidated financial statements, the Company expects the primary impact to its consolidated financial position upon adoption will be the recognition, on a discounted basis, of its minimum commitments under non-cancelable operating leases on the consolidated balance sheets resulting in the recording of right of use assets and lease obligations. The Company's current minimum commitments under noncancelable operating leases are disclosed in Note 10. In May 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”), which supersedes most existing revenue recognition guidance under GAAP. The core principle of ASU 2014-09 is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration to which an entity expects to be entitled for those goods or services. ASU 2014-09 defines a five step process to achieve this core principle and, in doing so, more judgment and estimates may be required within the revenue recognition process than are required under existing GAAP. The standard is effective for annual periods beginning after December 15, 2017, and interim periods therein, using either of the following transition methods: (i) a full retrospective approach reflecting the application of the standard in each prior reporting period with the option to elect certain practical expedients, or (ii) a retrospective approach with the cumulative effect of initially adopting ASU 2014-09 recognized at the date of adoption (which includes additional footnote disclosures). In March 2016, the FASB issued implementation guidance that clarified the considerations in principal versus agent determination. In April 2016, FASB issued guidance that clarified identifying performance obligations and licensing implementation guidance contained in the new revenue recognition standard. In May 2016, FASB issued guidance that addresses narrow-scope improvements to the guidance on collectability, noncash consideration, and completed contracts at transition. In December 2016, FASB issued guidance to make minor corrections or minor improvements to the Codification that are not expected to have a significant effect on current accounting practice or create a significant administrative cost to most entities. The Company's current revenue policy meets five core principles of ASU 2014-09 and the Company currently capitalizes the contract costs over the contracted period also in accordance with ASU 2014-09. The Company is still analyzing the impact of this ASU, but based on the current work to date the Company believes that the current revenue recognition policy currently in place already depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services and as a result the adoption of this ASU is not expected to have a material impact on the Company's financial statements.