SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Mar. 31, 2015
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.
Segment Reporting	Segment Reporting The Company reports as a single operating segment with the Chief Executive Officer (CEO) being the Company’s chief operating decision maker. The Company’s CEO reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. Accordingly, the Company has one business activity and there are no segment managers who are held accountable for operations, operating results or components below the consolidated unit level.
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 revenue recognition, valuation of goodwill and acquired intangible assets 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, 2015 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.
Revenue Recognition	Revenue Recognition We exercise judgment and use estimates in connection with determining the amounts of product and services revenues to be recognized in each accounting period. Product revenue consists of sales of NetScout’s hardware products (which include required embedded software that works together with the hardware to deliver the hardware’s essential functionality), licensing of its software products, and sale of 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, fees are fixed or determinable and collection of the related receivable is probable. Because many of NetScout’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. Service revenue consists primarily of fees from customer support agreements, consulting and training. NetScout generally provides software and 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 warranty expiration. Support services generally include rights to unspecified upgrades (when and if available), telephone and internet-based support, updates and bug fixes. 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 as the related training services are provided. 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 NetScout’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 selling price 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 VSOE or third party evidence (TPE) does not exist. The Company has established BESP for product elements as the average selling price the element was sold for over the past six quarters, whether sold alone or sold as part of a multiple element transaction. The Company’s internal list price for products, reviewed quarterly by senior management, with consideration in regards to changing factors in its technology and in the marketplace, is generated to target the desired gross margin from sales of product after analyzing historical discounting trends. 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 services related undelivered elements based on historical stand-alone sales. 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 training, 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 quarterly 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. 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 NetScout 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. The Company does not offer contractual rights of return, stock balancing, or price protection to its resellers, and actual product returns from them have been insignificant to date. In addition, the Company has a history of successfully collecting receivables from the resellers. As a result, the Company does not maintain reserves for reseller product returns.
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 has two reporting units: (1) Unified Service Delivery and (2) Test Optimization. Goodwill is tested for impairment at a reporting unit level at least annually, or on an interim basis if an event occurs or circumstances change that would, more likely than not, reduce the fair value of the reporting segment below its carrying value. The Company performed the qualitative Step 0 assessment on its Unified Service Delivery reporting unit. In performing the qualitative Step 0 assessment, the Company considered certain events and circumstances specific to the entity at the reporting unit level, such as macroeconomic conditions, industry and market considerations, overall financial performance and cost factors when evaluating whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. No indicators of impairment were noted at January 31, 2015. The Company performed the quantitative Step 1 assessment on its Test Optimization reporting unit. If the reporting unit’s carrying value exceeds its fair value, the Company would record an impairment loss equal to the difference between the carrying value of goodwill and its implied fair value. The Company estimates the fair values of its reporting units using discounted cash flow valuation models. Those models require estimates of future revenues, profits, capital expenditures, working capital, terminal values based on revenue multiples, and discount rates for each reporting unit. The Company estimates these amounts by evaluating historical trends, current budgets, operating plans and industry data. The estimated fair value of the Test Optimization reporting unit was approximately 120 percent greater than its carrying value as of January 31, 2015. Additionally, the market capitalization of NetScout as a whole significantly exceeded its carrying value. Indefinite-lived assets are tested for impairment at a reporting unit level at least annually, or on an interim basis if an event occurs or circumstances change that would, more likely than not, reduce the fair value of the reporting segment below its carrying value. 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 indefinite-lived intangible asset is impaired. If based on the Company's qualitative assessment that it is more likely than not that the fair value of an indefinite-lived 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. NetScout amortizes acquired intangible assets over their estimated useful lives, except for an acquired tradename which has an indefinite life and thus, is not amortized. The carrying value of the indefinite lived tradename is evaluated annually or more frequently if events or changes in circumstances indicate that the asset might be impaired. The Company completed its annual impairment test of the indefinite lived intangible at January 31, 2015 using the qualitative Step 0 assessment described above, which largely mirrors the Unified Service Delivery goodwill impairment assessment, as the tradenames apply to a majority of the products and branding within that reporting unit. No impairment indicators were identified at January 31, 2015. The Company acquired two companies during the three year period ended March 31, 2015. 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 acquisition of Simena LLC on November 18, 2011 also contained contingent features 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 to 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. 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 17 for a discussion of contingencies. Contingent liabilities includes contingent consideration in connection with the Company’s acquisitions and contingent contractual non-compliance liability. 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. A majority of NetScout’s foreign subsidiaries are an extension of NetScout’s U.S. operations. In accordance with the guidance, NetScout has determined its functional currency for those foreign subsidiaries to be the U.S. Dollar. Foreign subsidiary expenses that are denominated in a currency other than the U.S. Dollar functional currency are translated at the foreign exchange rate in effect at the time the transaction is recorded. The Company does consolidate European subsidiaries which use the Euro as a functional currency. Accordingly, the assets and liabilities of those entities 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. Foreign currency transaction gains and losses associated with non-Euro denominated balances held by those entities are charged to operations. 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	Comprehensive Income Comprehensive income is comprised of net income and other comprehensive income (loss). Other comprehensive income (loss) typically consists of unrealized gains and losses on marketable securities and restricted investments, unrealized gain (loss) on hedge contracts 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 bases, 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 asset, we create a valuation allowance against it.
Recent Accounting Standards	Recent Accounting Standards In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers: Topic 606 (ASU 2014-09), to supersede nearly all existing revenue recognition guidance under U.S. 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 U.S. 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. In April 2015, the FASB issued an exposure draft to propose a delay of the effective date for one year, which would make the effective date for the Company in its first quarter of fiscal year 2019 using either of two methods: (i) retrospective to each prior reporting period presented with the option to elect certain practical expedients as defined within ASU 2014-09; or (ii) retrospective with the cumulative effect of initially applying ASU 2014-09 recognized at the date of initial application and providing certain additional disclosures as defined per ASU 2014-09. The Company is currently evaluating the impact of its pending adoption of ASU 2014-09 on its consolidated financial statements.