SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Mar. 31, 2016
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of NetScout and its wholly-owned subsidiaries. All inter-company transactions and balances have been eliminated in consolidation.
Fiscal Year End	Fiscal Year End The fiscal year end of NetScout and its wholly-owned subsidiaries ends on March 31st, except for Fluke Networks Enterprise business, which ended on April 1, 2016. NetScout’s quarters end on the last calendar day of the months of June, September and December. The fiscal year 2016 quarter end dates of the entities acquired as part of the Communications Business were October 2nd and December 31st. The Company does not adjust for the difference in fiscal periods between the acquired entities and itself, as such difference would be less than 93 days, pursuant to Regulation S-X Rule 3A-02. References herein to Fiscal 2016, 2015 and 2014 refer to the fiscal years ended March 31, 2016, 2015 and 2014, respectively.
Segment Reporting	Segment Reporting The Company reports revenues and income under five operating segments that aggregate under one reportable segment.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Significant estimates in these financial statements include those involving revenue recognition, valuation of goodwill and acquired assets and liabilities, valuation of the pension obligation and share-based compensation. These items are continuously monitored and analyzed by management for changes in facts and circumstances and material changes in these estimates could occur in the future.
Cash and Cash Equivalents and Marketable Securities	Cash and Cash Equivalents and Marketable Securities Under current authoritative guidance, NetScout has classified its investments as “available-for-sale” which are carried at fair value based on quoted market prices and associated unrealized gains or losses are recorded as a separate component of stockholders’ equity until realized. NetScout considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents and those investments with original maturities greater than three months to be marketable securities. At March 31, 2016 and periodically throughout the year, NetScout has maintained cash balances in various operating accounts in excess of federally insured limits. NetScout limits the amount of credit exposure by investing only with credit worthy institutions which we believe are those institutions with an investment grade rating for deposits.
Revenue Recognition	Revenue Recognition The Company exercises judgment and uses estimates in connection with determining the amounts of product and services revenues to be recognized in each accounting period. The Company derives revenues primarily from the sale of network management tools and security solutions for service provider and enterprise customers, which include hardware, software and service offerings. The majority of the Company’s product sales consist of hardware products with embedded software that are essential to providing customers the intended functionality of the solutions. The Company also sells stand-alone software solutions to provide customers with enhanced functionality. In addition, the Company sells hardware bundled with a software license. Product revenue is recognized upon shipment, provided that evidence of an arrangement exists, title and risk of loss have passed to the customer, and in the case of software products, when the customer has the rights and ability to access the software, fees are fixed or determinable and collection of the related receivable is reasonably assured. If any significant obligations to the customer remain post-delivery, typically involving obligations relating to installation and acceptance by the customer, revenue recognition is deferred until such obligations have been fulfilled. Because many of the Company’s solutions are comprised of both hardware and more than incidental software components, the Company recognizes revenue in accordance with authoritative guidance on both hardware and software revenue recognition. The Company’s service offerings include installation, integration, extended warranty and maintenance services, post-contract customer support (PCS), and other professional services including consulting and training. The Company generally provides software and/or hardware support as part of product sales. Revenue related to the initial bundled software and hardware support is recognized ratably over the support period. In addition, customers can elect to purchase extended support agreements for periods after the initial software/hardware warranty expiration. Support services generally include rights to unspecified upgrades (when and if available), telephone and internet-based support, updates and bug fixes. Consulting services are recognized upon delivery or completion of performance. Reimbursements of out-of-pocket expenditures incurred in connection with providing consulting services are included in services revenue, with the offsetting expense recorded in cost of service revenue. Training services include on-site and classroom training. Training revenues are recognized upon delivery of the training. Generally, the Company’s contracts are accounted for individually. However, when contracts are closely interrelated and dependent on each other, it may be necessary to account for two or more contracts as one to reflect the substance of the group of contracts. Multi-element arrangements are concurrent customer purchases of a combination of the Company’s product and service offerings that may be delivered at various points in time. For multi-element arrangements comprised only of hardware products and related services, the Company allocates the total arrangement consideration to the multiple elements based on each element’s fair value compared to the total relative selling price of all the elements. Each element’s selling price is based on management’s best estimate of selling price (BESP) paid by customers based on the element’s historical pricing when vendor-specific objective evidence (VSOE) or third-party evidence (TPE) does not exist. The Company has established BESP for product elements as the average or median selling price the element was recently sold for, whether sold alone or sold as part of a multiple element transaction. The Company also considers its overall pricing objectives and practices across different sales channels and geographies, and market conditions. The Company reviews sales of the product elements on a quarterly basis and updates when appropriate, its BESP for such elements to ensure that it reflects recent pricing experience. The Company has established VSOE for a majority of its service elements based on historical stand-alone sales or by the renewal rate offered to the customer. However certain business units acquired as part of the Transaction are unable to establish VSOE for undelivered elements. This occurs because the pricing for standalone sales does not occur in tight bands around a midpoint, and they are not contractually fixed. In these scenarios the Company has typically established BESP by creating wider bands around a midpoint for standalone transactions or in some cases using cost plus a margin for the underlying services and products. If VSOE of fair value does not exist for a deliverable, the Company uses its BESP for that deliverable. For multi-element arrangements comprised only of software products and related services, the Company allocates a portion of the total arrangement consideration to the undelivered elements, primarily support agreements and professional services, using vendor-specific objective evidence of fair value for the undelivered elements. The remaining portion of the total arrangement consideration is allocated to the delivered software, referred to as the residual method. VSOE of fair value of the undelivered elements is based on the price customers pay when the element is sold separately. The Company reviews the separate sales of the undelivered elements on a regular basis and updates when appropriate, its VSOE of fair value for such elements to ensure that it reflects recent pricing experience. If the Company cannot objectively determine the VSOE of the fair value of any undelivered software element, revenue is deferred until all elements are delivered and services have been performed, or until fair value can objectively be determined for any remaining undelivered elements. However, if the only undelivered element is maintenance and support, the entire arrangement fee is recognized over the service period. For multi-element arrangements comprised of a combination of hardware and software elements, the total arrangement consideration is bifurcated between the hardware and hardware related deliverables and the software and software related deliverables based on the relative selling prices of all deliverables as a group. Then, arrangement consideration for the hardware and hardware-related services is recognized upon delivery or as the related services are provided outlined above and revenue for the software and software-related services is allocated following the residual method and recognized based upon delivery or as the related services are provided. The Company’s products are distributed through its direct sales force and indirect distribution channels through alliances with resellers. Revenue arrangements with resellers are recognized on a sell-in basis; that is, when the Company delivers the product to the reseller. The Company records consideration given to a reseller as a reduction of revenue to the extent the Company has recorded revenue from the reseller. With limited exceptions, the Company’s return policy does not allow product returns for a refund. Returns have been insignificant to date. In addition, the Company has a history of successfully collecting receivables from the resellers.
Commission Expense	Commission Expense The Company recognizes commission expense related to the renewal of maintenance contracts at the time an order is booked. As a result, commission expense can be recognized in full even though the related revenue may not be fully recognized. Base commission expense on product revenue and corresponding new maintenance contracts is recognized in the same period as related product revenue, typically upon shipment.
Uncollected Deferred Product Revenue	Uncollected Deferred Product Revenue Because of NetScout’s revenue recognition policies, there are circumstances for which the Company does not recognize revenue relating to sales transactions that have been billed, but the related account receivable has not been collected. While the receivable represents an enforceable obligation, for balance sheet presentation purposes, the Company has not recognized the deferred revenue or the related account receivable and no amounts appear in the consolidated balance sheets for such transactions.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject us to concentration of credit risk consist primarily of investments, trade accounts receivable and accounts payable. Our cash, cash equivalents, and marketable securities are placed with financial institutions with high credit standings.
Trade Receivable Valuations	Trade Receivable Valuations Accounts receivable are stated at their net realizable value. The allowance against gross trade receivables reflects the best estimate of probable losses inherent in the receivables portfolio determined on the basis of historical experience, specific allowances for known troubled accounts and other currently available information.
Inventories	Inventories Inventories are stated at the lower of actual cost or net realizable value. Cost is determined by using the first-in, first-out (FIFO) method.
Fixed Assets	Fixed Assets Fixed assets are stated at cost and depreciated using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized on a straight-line basis over the shorter of the lease term or anticipated useful life of the improvement. Gains and losses upon asset disposal are recognized in the year of disposition. Expenditures for replacements and building improvements are capitalized, while expenditures for maintenance and repairs are charged against earnings as incurred.
Valuation of Goodwill, Intangible Assets and Other Acquisition Accounting Items	Valuation of Goodwill, Intangible Assets and Other Acquisition Accounting Items The Company amortizes acquired definite-lived intangible assets over their estimated useful lives. Goodwill and other indefinite-lived intangible assets are not amortized but subject to annual impairment tests; more frequently if events or circumstances occur that would indicate a potential decline in their fair value. The Company performs the assessment annually during the fourth quarter and on an interim basis if potential impairment indicators arise. The Company has identified five reporting units: (1) NetScout, (2) Arbor Networks, (3) Tektronix Communications, (4) VSS and (5) FNET and an indefinite-lived trade name. To test impairment, the Company first assesses qualitative factors to determine whether the existence of events and circumstances indicate that it is more likely than not that the intangible asset is impaired. If based on the Company's qualitative assessment it is more likely than not that the fair value of the intangible asset is less than its carrying amount, quantitative impairment testing is required. However, if the Company concludes otherwise, quantitative impairment testing is not required. During fiscal year 2016, the Company performed a quantitative analysis for goodwill and its non-amortizing intangible asset. The Company determined the fair value of the reporting unit's goodwill using established income and market valuation approaches and the fair value of its trade names using a forward-looking relief from royalty model. All goodwill and indefinite-lived intangible assets were estimated to be recoverable as of January 31, 2016. The Company completed one acquisition during the three year period ended March 31, 2016. The acquisition method of accounting requires an estimate of the fair value of the assets and liabilities acquired as part of these transactions. In order to estimate the fair value of acquired intangible assets the Company uses a relief from royalty model which requires management to estimate: future revenues expected to be generated by the acquired intangible assets, a royalty rate which a market participant would pay related to the projected revenue stream, a present value factor which approximates a risk adjusted rate of return for a market participant purchasing the assets, and a technology migration curve representing a period of time over which the technology assets or some portion thereof are still being used. The Company is also required to develop the fair value for customer relationships acquired as part of these transactions which requires that we create estimates for the following items: a projection of future revenues associated with the acquired company’s existing customers, a turnover rate for those customers, a margin related to those sales, and risk adjusted rate of return for a market participant purchasing those relationships. The Transaction contained both contingently returnable consideration and contingent purchase consideration. The contingently returnable consideration represents a contingent right of return from Danaher to reimburse NetScout for certain cash awards to be paid by NetScout to employees of the Communications Business transferred to Newco for post-combination services on various dates through August 4, 2016. The contingently returnable consideration was $16.1 million, net of taxes at March 31, 2016. During the fiscal year ended March 31, 2016, certain post-combination cash retention payments have been disbursed. Danaher will reimburse the Company for those costs and NetScout will reimburse Danaher for the tax benefit. Because the right of offset has not been met, the Company recorded the gross amount of compensation as contingently returnable consideration and the tax benefit of $2.7 million as contingent purchase consideration. For additional information, see Note 7 of the Company's Notes to Consolidated Financial Statements. The acquisition of Simena LLC on November 18, 2011 also contained contingent consideration based on the ultimate settlement of assets and liabilities acquired as part of the transaction, and the former owners' future period of employment with the Company. Contingent consideration accounting requires the Company to estimate the probability of various settlement scenarios, the former owners' expected period of employment with NetScout, and a risk adjusted interest rate to present value the payment streams.
Capitalized Software Development Costs	Capitalized Software Development Costs Costs incurred in the research and development of the Company’s products are expensed as incurred, except for certain software development costs. Costs associated with the development of computer software are expensed prior to the establishment of technological feasibility and capitalized thereafter until the related software products are available for first customer shipment. Such costs are amortized using the straight-line method over the estimated economic life of the product, which generally does not exceed three years. Capitalized software development costs are periodically assessed for recoverability in the event of changes to the anticipated future revenue for the software products or changes in product technologies. Unamortized capitalized software development costs that are determined to be in excess of the net realizable value of the software products would be expensed in the period in which such a determination is made. Typically for accounting purposes, these R&D investments have not been capitalized because of the development methodology employed. The developments are added individually to the core code over a shorter period of time but marketed as a release once all portions are complete.
Derivative Financial Instruments	Derivative Financial Instruments Under authoritative guidance for derivative instruments and hedging activities, all hedging activities must be documented at the inception of the hedge and must meet the definition of highly effective in offsetting changes to future cash flows in order for the derivative to qualify for hedge accounting. Under the guidance, if an instrument qualifies for hedge accounting, the changes in the fair value each period for open contracts, measured at the end of the period, are recorded to other comprehensive income. Otherwise, changes in the fair value are recorded in earnings each period. Management must perform initial and ongoing tests in order to qualify for hedge accounting. In accordance with the guidance, the Company accounts for its instruments under hedge accounting. The effectiveness and a measurement of ineffectiveness of qualifying hedge contracts are assessed by the Company quarterly. The Company records the fair value of its derivatives in prepaid and other current assets and accrued other in the Company's consolidated balance sheet. The effective portion of gains or losses resulting from changes in the fair value of qualifying hedges are recorded in other comprehensive income (loss) until the forecasted transaction occurs, with any ineffective portion classified directly to the Company’s consolidated statement of operations based on the expense categories of the items being hedged. When forecasted transactions occur, unrealized gains or losses associated with the effective portion of the hedge are reclassified to the respective expense categories in the Company’s consolidated statement of operations. Gains or losses related to hedging activity are included as operating activities in the Company’s consolidated statement of cash flows. If the underlying forecasted transactions do not occur, or it becomes probable that they will not occur, the gain or loss on the related cash flow hedge is recognized immediately in earnings.
Contingencies	Contingencies NetScout accounts for claims and contingencies in accordance with authoritative guidance that requires an estimated loss to be recorded from a claim or loss contingency when information available prior to issuance of our consolidated financial statements indicates that it is probable that a liability has been incurred at the date of the consolidated financial statements and the amount of the loss can be reasonably estimated. If NetScout determines that it is reasonably possible but not probable that an asset has been impaired or a liability has been incurred or if the amount of a probable loss cannot be reasonably estimated, then in accordance with the authoritative guidance, we disclose the amount or range of estimated loss if the amount or range of estimated loss is material. Accounting for claims and contingencies requires NetScout to use its judgment. NetScout consults with legal counsel on those issues related to litigation and seeks input from other experts and advisors with respect to matters in the ordinary course of business. See Note 16 for a discussion of contingencies. Contingent liabilities include contingent consideration in connection with the Company’s acquisitions. Contingent consideration represents earnout payments in connection with the Company’s acquisitions and is recognized at fair value on the acquisition date and remeasured each reporting period with subsequent adjustments recognized in the consolidated statements of income. The Company discounts the contingent purchase consideration to present value using a risk adjusted interest rate at each reporting period. Contingent consideration is valued using significant inputs that are not observable in the market which are defined as Level 3 inputs pursuant to fair value measurement accounting. The Company believes its estimates and assumptions are reasonable, however, there is significant judgment involved. Changes in the fair value of contingent liabilities may result from changes in discount periods. The Company reflects changes in fair value due to probability changes in earnings in the consolidated statements of income. Earnout payments are reflected in cash flows from financing activities and the changes in fair value are reflected in cash flows from operating activities in the consolidated statements of cash flows.
Share-based Compensation	Share-Based Compensation NetScout recognizes compensation expense for all share-based payments granted. Under the fair value recognition provisions, share-based compensation is calculated net of an estimated forfeiture rate and compensation cost is only recognized for those shares expected to vest on a straight-line basis over the requisite service period of the award.
Foreign Currency	Foreign Currency NetScout accounts for its reporting of foreign operations in accordance with guidance which establishes guidelines for the determination of the functional currency of foreign subsidiaries. In accordance with the guidance, NetScout has determined its functional currency for those foreign subsidiaries that are an extension of NetScouts U.S. operations to be the U.S. Dollar. Assets and liabilities of subsidiaries operating outside the United States with a functional currency other than U.S. dollars are translated into United States dollars using the period-end exchange rate, and income and expense items are translated using the average exchange rate during the period. Cumulative translation adjustments are reflected as a separate component of stockholders’ equity. NetScout will experience currency exchange risk with respect to foreign currency denominated expenses. In order to partially offset the risks associated with the effects of certain foreign currency exposures, NetScout has established a program that utilizes foreign currency forward contracts. Under this program, increases or decreases in foreign currency exposures are partially offset by gains or losses on forward contracts, to mitigate the impact of foreign currency transaction gains or losses. The Company does not use forward contracts to engage in currency speculation. All outstanding foreign currency forward contracts are recorded at fair value at the end of each fiscal period.
Advertising Expense	Advertising Expense NetScout recognizes advertising expense as incurred.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) is comprised of net income and other comprehensive income (loss). Other comprehensive income (loss) typically consists of unrealized gains and losses on marketable securities, unrealized gain (loss) on hedge contracts, actuarial gains and losses, and foreign currency translation adjustments.
Income Taxes	Income Taxes NetScout accounts for its income taxes under the asset and liability method. Under the asset and liability method, deferred tax assets and liabilities are recognized based on anticipated future tax consequences attributable to differences between financial statement carrying amounts of assets and liabilities and their respective tax basis, as well as the effect of any net operating loss and tax credit carryforwards. Income tax expense is comprised of the current tax liability or benefit and the change in deferred tax assets and liabilities. We evaluate the recoverability of deferred tax assets by considering all positive and negative evidence relating to future profitability. We weigh objective and verifiable evidence more heavily in this analysis. In situations where we conclude that we do not have sufficient objective and verifiable evidence to support the realizability of the deferred tax asset, we create a valuation allowance against it.
Recent Accounting Standards	Recent Accounting Standards In March 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09), which simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures and statutory tax withholding requirements, as well as classification in the statement of cash flows. ASU 2016-09 is effective for the Company beginning April 1, 2017. The Company is currently assessing the potential impact of the adoption of ASU 2016-09 on its consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) Section A - Leases: Amendments to the FASB Accounting Standards Codification (ASU 2016-02), its new standard on accounting for leases. This update requires the recognition of leased assets and lease obligations by lessees for those leases currently classified as operating leases under existing lease guidance. Short term leases with a term of 12 months or less are not required to be recognized. The update also requires disclosure of key information about leasing arrangements to increase transparency and comparability among organizations. ASU 2016-02 is effective for annual reporting periods beginning after December 31, 2018 and interim periods within those fiscal years, and early adoption is permitted. The Company is currently assessing the potential impact of the adoption of ASU 2016-02 on its consolidated financial statements. In November 2015, the FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes (ASU 2015-17), which eliminates the current requirement to present deferred tax liabilities and assets as current and noncurrent in a classified balance sheet. Instead, entities will be required to classify all deferred tax assets and liabilities as noncurrent. The Company adopted this standard prospectively in the third quarter of fiscal year 2016 as early adoption was permitted and prior periods were not retrospectively adjusted. In September 2015, the FASB issued ASU 2015-16, Simplifying the Accounting for Measurement-Period Adjustments (ASU 2015-16), which eliminates the requirement to restate prior financial statements for measurement period adjustments. The new guidance requires that the cumulative impact of a measurement period adjustment be recognized in the reporting period in which the adjustment is identified. The Company adopted this standard in the second quarter of fiscal year 2016 as early adoption was permitted. In August 2015, the FASB issued ASU 2015-15, Interest-Imputation of Interest (Subtopic 835-30): Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-Of-Credit Arrangements and Amendments to SEC Paragraphs Pursuant to Staff Announcement at June 18, 2015 EITF Meeting (ASU 2015-15). The guidance in the previously issued ASU 2015-03, Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs does not address presentation or subsequent measurement of debt issuance costs related to line-of-credit arrangements. Given the absence of authoritative guidance within ASU 2015-03 for debt issuance costs related to line-of-credit arrangements, the SEC staff would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the deferred debt issuance costs ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. The Company adopted this standard in the second quarter of fiscal year 2016 as early adoption was permitted. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers: Topic 606 (ASU 2014-09), to supersede nearly all 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 that is expected to be received for those goods or services. ASU 2014-09 defines a five step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may be required within the revenue recognition process than required under existing GAAP, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. Existing accounting guidance applicable to these transfers has been amended or superseded. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which defers the original effective date of interim and annual reporting periods by one year. As a result, public entities would not be required to apply the new revenue standard until annual reporting periods beginning after December 15, 2017. In March 2016, the FASB issued ASU 2016-08, Principal Versus Agent Considerations (Reporting Revenue Gross Versus Net) (ASU 2016-08) to clarify certain aspects of the principal-versus-agent guidance in its new revenue recognition standard in response to feedback received from the FASB-IASB joint revenue recognition transition resource group. ASU 2016-08 clarifies the implementation guidance on principal-versus-agent considerations regarding how an entity determines whether it is a principal or an agent for each specified good or service promised to the customer and how an entity determines the nature of each specified good or service. ASU 2016-08 also provides clarification regarding the application of the principal-versus-agent guidance. ASU 2016-08 is effective at the same time as ASU 2014-09 (as amended by ASU 2015-14), and will be effective for the Company in the first quarter of its fiscal year 2019. Early adoption is not permitted. The Company is currently assessing the potential impact of the adoption of ASU 2014-09 on its consolidated financial statements.