NetScout Systems (NTCT) 10-K 20 May 21 2021 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Mar. 31, 2021	May 10, 2021	Sep. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Mar. 31, 2021
Current Fiscal Year End Date	--03-31
Document Transition Report	false
Entity File Number	000-26251
Entity Registrant Name	NETSCOUT SYSTEMS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-2837575
Entity Address, Address Line One	310 Littleton Road
Entity Address, City or Town	Westford
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01886
City Area Code	978
Local Phone Number	614-4000
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	NTCT
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1,546,085,584
Entity Common Stock, Shares Outstanding (in shares)		73,752,519
Documents Incorporated by Reference	Portions of the registrant's definitive Proxy Statement for the 2021 Annual Meeting of Stockholders to be filed with the U.S. Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after the end of the fiscal year covered by this Annual Report on Form 10-K are incorporated by reference in Part III, Items 10-14 of this Annual Report on Form 10-K.
Entity Central Index Key	0001078075
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Current assets:
Cash and cash equivalents	$ 467,176	$ 338,489
Marketable securities	9,277	47,969
Accounts receivable and unbilled costs, net of allowance for doubtful accounts of $416 and $1,350 at March 31, 2021 and 2020, respectively	197,717	213,514
Inventories and deferred costs	22,813	22,227
Prepaid income taxes	1,906	13,505
Prepaid expenses and other current assets	23,583	24,039
Total current assets	722,472	659,743
Fixed assets, net	48,474	57,715
Operating lease right-of-use assets	61,512	68,583
Goodwill	1,717,554	1,725,680
Intangible assets, net	511,866	582,179
Deferred income taxes	8,096	6,220
Long-term marketable securities	0	2,613
Other assets	15,064	17,770
Total assets	3,085,038	3,120,503
Current liabilities:
Accounts payable	17,964	20,004
Accrued compensation	83,057	75,632
Accrued other	21,127	21,840
Income taxes payable	7,025	903
Deferred revenue and customer deposits	269,748	270,281
Current portion of operating lease liabilities	12,354	10,337
Total current liabilities	411,275	398,997
Other long-term liabilities	21,641	10,039
Deferred tax liability	92,287	114,394
Accrued long-term retirement benefits	39,479	34,256
Long-term deferred revenue and customer deposits	103,310	104,240
Operating lease liabilities, net of current portion	61,267	70,658
Long-term debt	350,000	450,000
Total liabilities	1,079,259	1,182,584
Commitments and contingencies (Note 19)
Stockholders’ equity:
Preferred stock, $0.001 par value: 5,000,000 shares authorized; no shares issued or outstanding at March 31, 2021 and 2020	0	0
Common stock, $0.001 par value: 300,000,000 shares authorized; 124,197,974 and 122,006,077 shares issued and 73,751,615 and 72,220,906 shares outstanding at March 31, 2021 and 2020, respectively	124	122
Additional paid-in capital	2,955,400	2,891,553
Accumulated other comprehensive loss	(1,940)	(3,160)
Treasury stock at cost, 50,446,359 and 49,785,171 shares at March 31, 2021 and 2020, respectively	(1,322,496)	(1,305,935)
Retained earnings	374,691	355,339
Total stockholders’ equity	2,005,779	1,937,919
Total liabilities and stockholders’ equity	$ 3,085,038	$ 3,120,503

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 416	$ 1,350
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	124,197,974	122,006,077
Common stock, shares outstanding (in shares)	73,751,615	72,220,906
Treasury stock (in shares)	50,446,359	49,785,171

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Revenue:
Total revenue	$ 831,282	$ 891,820	$ 909,918
Cost of revenue:
Total cost of revenue	222,097	242,192	254,127
Gross profit	609,185	649,628	655,791
Operating expenses:
Research and development	179,163	188,294	203,588
Sales and marketing	242,730	276,523	291,870
General and administrative	88,969	99,994	93,572
Amortization of acquired intangible assets	61,131	64,505	74,305
Restructuring charges	62	2,674	18,693
Impairment of intangible assets	0	0	35,871
Loss on divestiture of business	0	0	9,472
Total operating expenses	572,055	631,990	727,371
Income (loss) from operations	37,130	17,638	(71,580)
Interest and other expense, net:
Interest income	646	4,528	5,245
Interest expense	(10,879)	(20,597)	(26,143)
Other income (expense), net	(4,593)	355	(434)
Total interest and other expense, net	(14,826)	(15,714)	(21,332)
Income (loss) before income tax expense (benefit)	22,304	1,924	(92,912)
Income tax expense (benefit)	2,952	4,678	(19,588)
Net income (loss)	$ 19,352	$ (2,754)	$ (73,324)
Basic net income (loss) per share (in dollars per share)	$ 0.26	$ (0.04)	$ (0.93)
Diluted net income (loss) per share (in dollars per share)	$ 0.26	$ (0.04)	$ (0.93)
Weighted average common shares outstanding used in computing:
Net income (loss) per share-basic (in shares)	73,103	75,162	78,617
Net income (loss) per share-diluted (in shares)	73,822	75,162	78,617
Product
Revenue:
Total revenue	$ 377,721	$ 438,341	$ 467,289
Cost of revenue:
Total cost of revenue	95,965	122,832	140,938
Service
Revenue:
Total revenue	453,561	453,479	442,629
Cost of revenue:
Total cost of revenue	$ 126,132	$ 119,360	$ 113,189

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 19,352	$ (2,754)	$ (73,324)
Other comprehensive income (loss):
Cumulative translation adjustments	2,926	(1,644)	(3,229)
Recognition of actuarial net (losses) gains from pension and other post-retirement plans, net of (benefit) tax of ($657), $590, and ($976)	(1,548)	1,054	(2,278)
Changes in market value of investments:
Changes in unrealized (losses) gains, net of (benefit) tax of ($41), $39, and $19	(130)	126	60
Total net change in market value of investments	(130)	126	60
Changes in market value of derivatives:
Changes in market value of derivatives, net of tax (benefit) of $66, ($25), and ($172)	208	(78)	(524)
Reclassification adjustment for net (loss) gain included in net income (loss), net of (benefit) tax of ($73), $7, and $138	(236)	21	437
Total net change in market value of derivatives	(28)	(57)	(87)
Other comprehensive income (loss)	1,220	(521)	(5,534)
Total comprehensive income (loss)	$ 20,572	$ (3,275)	$ (78,858)

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Recognition of actuarial net gain from pension and other post-retirement plans, tax expense (benefit)	$ (657)	$ 590	$ (976)
Changes in unrealized (losses) gains, taxes	(41)	39	19
Changes in market value of derivatives, taxes (benefit)	66	(25)	(172)
Reclassification adjustment for net gains included in net income, taxes	$ (73)	$ 7	$ 138

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common stock Voting	Additional Paid In Capital	Accumulated Other Comprehensive Income (Loss)	Treasury stock	Retained Earnings	Retained EarningsCumulative Effect, Period of Adoption, Adjustment
Beginning balance (in shares) at Mar. 31, 2018			117,744,913			(37,474,890)
Beginning balance at Mar. 31, 2018	$ 2,068,782	$ 34,924	$ 117	$ 2,665,120	$ 2,895	$ (995,843)	$ 396,493	$ 34,924
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(73,324)						(73,324)
Unrealized net investment gains (losses)	60				60
Unrealized net losses on derivative financial instruments	(87)				(87)
Cumulative translation adjustments	(3,229)				(3,229)
Recognition of actuarial net gains (losses) from pension and other post-retirement plan	(2,278)				(2,278)
Issuance of common stock pursuant to vesting of restricted stock units (in shares)			1,438,219
Issuance of common stock pursuant to vesting of restricted stock units	3		$ 3
Stock-based compensation expense for restricted stock units granted to employees	51,945			51,945
Issuance of common stock under employee stock purchase plan (in shares)			577,000
Issuance of common stock under employee stock purchase plan	15,074			15,074
Repurchase of treasury stock (in shares)						4,674,881
Repurchase of treasury stock	(26,437)			96,783		$ (123,220)
Ending balance (in shares) at Mar. 31, 2019			119,760,132			(42,149,771)
Ending balance at Mar. 31, 2019	2,065,433		$ 120	2,828,922	(2,639)	$ (1,119,063)	358,093
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(2,754)						(2,754)
Unrealized net investment gains (losses)	126				126
Unrealized net losses on derivative financial instruments	(57)				(57)
Cumulative translation adjustments	(1,644)				(1,644)
Recognition of actuarial net gains (losses) from pension and other post-retirement plan	1,054				1,054
Issuance of common stock pursuant to vesting of restricted stock units (in shares)			1,651,284
Issuance of common stock pursuant to vesting of restricted stock units	2		$ 2
Stock-based compensation expense for restricted stock units granted to employees	48,404			48,404
Issuance of common stock under employee stock purchase plan (in shares)			594,661
Issuance of common stock under employee stock purchase plan	14,227			14,227
Repurchase of treasury stock (in shares)						7,635,400
Repurchase of treasury stock	(186,872)					$ (186,872)
Ending balance (in shares) at Mar. 31, 2020			122,006,077			(49,785,171)
Ending balance at Mar. 31, 2020	1,937,919		$ 122	2,891,553	(3,160)	$ (1,305,935)	355,339
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	19,352						19,352
Unrealized net investment gains (losses)	(130)				(130)
Unrealized net losses on derivative financial instruments	(28)				(28)
Cumulative translation adjustments	2,926				2,926
Recognition of actuarial net gains (losses) from pension and other post-retirement plan	(1,548)				(1,548)
Issuance of common stock pursuant to vesting of restricted stock units (in shares)			1,630,228
Issuance of common stock pursuant to vesting of restricted stock units	2		$ 2
Stock-based compensation expense for restricted stock units granted to employees	49,418			49,418
Issuance of common stock under employee stock purchase plan (in shares)			561,669
Issuance of common stock under employee stock purchase plan	14,429			14,429
Repurchase of treasury stock (in shares)						661,188
Repurchase of treasury stock	(16,561)					$ (16,561)
Ending balance (in shares) at Mar. 31, 2021			124,197,974			(50,446,359)
Ending balance at Mar. 31, 2021	$ 2,005,779		$ 124	$ 2,955,400	$ (1,940)	$ (1,322,496)	$ 374,691

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income (loss)	$ 19,352	$ (2,754)	$ (73,324)
Adjustments to reconcile net income (loss) to cash provided by operating activities, net of the effects of acquisitions:
Depreciation and amortization	105,828	116,104	137,878
Operating lease right-of-use assets	10,004	10,504
Loss on divestiture of business	0	0	7,660
Loss on disposal of fixed assets	236	16	260
Deal related compensation expense and accretion charges	0	0	102
Share-based compensation expense associated with equity awards	51,892	50,861	56,328
Net change in fair value of contingent and contractual liabilities	0	798	1,614
Accretion of contingent consideration	0	(36)	(119)
Impairment charge	0	0	35,871
Deferred income taxes	(23,804)	(9,821)	(33,442)
Other gains	(196)	(152)	(152)
Changes in assets and liabilities
Accounts receivable and unbilled costs	16,878	21,472	(22,180)
Due from related party	0	0	172
Inventories	(2,043)	1,501	5,321
Prepaid expenses and other assets	11,483	13,839	3,034
Accounts payable	(1,734)	(4,288)	(3,876)
Accrued compensation and other expenses	31,955	32,812	19,964
Operating lease liabilities	(10,307)	(13,077)
Due to related party	0	0	234
Income taxes payable	6,684	(919)	(639)
Deferred revenue	(2,307)	8,163	15,132
Net cash provided by operating activities	213,921	225,023	149,838
Cash flows from investing activities:
Purchase of marketable securities	(15,673)	(117,383)	(229,769)
Proceeds from maturity of marketable securities	56,806	144,322	230,433
Purchase of fixed assets	(11,986)	(19,922)	(23,392)
Purchase of intangible assets	(4,537)	0	0
Payments related to the divestiture of business	0	0	(3,293)
Acquisition of businesses, net of cash acquired	0	(11,347)	0
Decrease (increase) in deposits	88	(31)	(97)
Collection of contingent consideration	0	52	0
Capitalized software development costs	0	0	(134)
Net cash provided by (used in) investing activities	24,698	(4,309)	(26,252)
Cash flows from financing activities:
Issuance of common stock under stock plans	2	2	3
Payment of contingent consideration	(1,748)	0	(2,851)
Treasury stock repurchases	(3,275)	(175,000)	(14,468)
Tax withholding on restricted stock units	(13,286)	(11,872)	(11,969)
Repayment of long-term debt	(100,000)	(100,000)	(50,000)
Net cash used in financing activities	(118,307)	(286,870)	(79,285)
Effect of exchange rate changes on cash and cash equivalents	6,627	(3,427)	(5,212)
Net increase (decrease) in cash and cash equivalents	126,939	(69,583)	39,089
Cash and cash equivalents and restricted cash, beginning of year	340,237	409,820	370,731
Cash and cash equivalents and restricted cash, end of year	467,176	340,237	409,820
Supplemental disclosures of cash flow information:
Cash paid for interest	7,685	17,644	23,281
Cash paid for income taxes	11,472	13,061	13,381
Non-cash transactions:
Transfers of inventory to fixed assets	1,530	2,290	2,152
Additions to property, plant and equipment included in accounts payable	333	255	455
Issuance of common stock under employee stock purchase plans	14,429	14,227	15,074
Contingent consideration related to acquisition, included in accrued other	0	1,800	0
Tenant improvement allowance	0	0	10,171
Initial fair value of contingent consideration received as partial consideration for divestiture of business	$ 0	$ 0	$ 2,257

NATURE OF BUSINESS

NATURE OF BUSINESS	12 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
NATURE OF BUSINESS	NATURE OF BUSINESSNetScout Systems, Inc., or NetScout or the Company, has been a technology innovator for three-plus decades since its founding in 1984. The Company's solutions, based on patented Adaptive Service Intelligence (ASI) technology, help customers identify network and application performance issues, defend their networks from denial of service (DDoS) attacks, and rapidly find and isolate advanced network threats. As a result, customers can quickly resolve issues that cause business disruptions, downtime, poor service quality or compromised security, thereby driving compelling returns on their investments in their network and broader information technology (IT) initiatives.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Principles of Consolidation The consolidated financial statements include the accounts of NetScout and its wholly owned subsidiaries. Inter-company transactions and balances have been eliminated in consolidation. Segment Reporting The Company's operating segments are determined based on the units that constitute a business for which financial information is available and for which operating results are regularly reviewed by the Chief Operating Decision Maker (CODM). The Company reports revenue and income in one reportable segment. 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, valuation of contingent consideration 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. The Company considered the impact of the COVID-19 pandemic on the use of estimates and assumptions used for financial reporting. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company's business, results of operations and financial condition, including sales, expenses, reserves and allowances, manufacturing, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain it or treat COVID-19, as well as the economic impact on local, regional, national and international customers and markets. The Company has made estimates within our financial statements and there may be changes to those estimates in future periods. Actual results may differ from these estimates. COVID-19 Risks and Uncertainties The Company is closely monitoring the impact of the COVID-19 pandemic on all aspects of its business. COVID-19 was declared a global pandemic by the World Health Organization on March 11, 2020 and the President of the United States declared the COVID-19 outbreak a national emergency. The future impacts of the pandemic and any resulting economic impact on the Company's operations are largely unknown and rapidly evolving. It is possible that the COVID-19 pandemic, the measures taken by the governments of countries affected and the resulting economic impact may materially and adversely affect the Company’s results of operations, cash flows and financial position as well as its customers. Under Accounting Standards Update (ASU) 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40), or ASC 205-40, the Company has the responsibility to evaluate whether conditions and/or events raise substantial doubt about its ability to meet its future financial obligations as they become due within one year after the date that the financial statements are issued. The Company is taking precautionary actions to reduce costs and spending across the organization. This includes limiting discretionary spending and reducing hiring activities. In addition, based on covenant levels at March 31, 2021, the Company has an incremental $336 million available under its $1.0 billion revolving credit facility. On March 27, 2020, the Coronavirus Aid, Relief and Economic Security Act (the CARES Act) was enacted. The CARES Act, among other things, includes provisions relating to refundable payroll tax credits, deferment of employer social security payments, net operating loss carryback periods, alternative minimum tax credit refunds, modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property. The Company has elected to defer the employer-paid portion of social security taxes. As of March 31, 2021, the Company had deferred $8.9 million of employer payroll taxes, of which 50% are required to be deposited by December 2021 and the remaining 50% by December 2022. The balance of $4.5 million was included as accrued other and a balance of $4.4 million was included as other long-term liabilities in the Company's consolidated balance sheet at March 31, 2021. The Company expects net cash provided by operations combined with cash, cash equivalents, and marketable securities and borrowing availability under the revolving credit facility to provide sufficient liquidity to fund current obligations, capital spending, debt service requirements and working capital requirements over at least the next twelve months. 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 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, 2021 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 the Company believes are those institutions with an investment grade rating for deposits. Revenue Recognition The Company accounts for revenue in accordance with ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which was adopted on April 1, 2018 using the modified retrospective transition method. For further discussion of the Company's accounting policies related to revenue see Note 3, "Revenue Recognition." Commission Expense Sales commissions are recorded as an asset when the initial contract's duration is longer than 12 months and amortized to expense ratably over the remaining performance periods of the related contracts. Uncollected Deferred 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 because control of the underlying deliverable has not transferred. The aggregate amount of unrecognized accounts receivable and deferred revenue was $7.1 million and $11.1 million at March 31, 2021 and 2020, respectively. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentration of credit risk consist primarily of investments, trade accounts receivable and accounts payable. NetScout's cash, cash equivalents, and marketable securities are placed with financial institutions with high credit standings. At March 31, 2021 , the Company had one direct customer who accounted for more than 10% of the accounts receivable balance, while no indirect channel partners accounted for more than 10% of the accounts receivable balance. At March 31, 2020 , the Company had no direct customers or indirect channel partners which accounted for more than 10% of the accounts receivable balance. During the fiscal ye ars ended March 31, 2021, 2020 and 2019 respectively, no direct customers or indirect channel partners accounted for more than 10% of total rev enue. Historically, the Company has not experienced any significant failure of its customers to meet their payment obligations nor does the Company anticipate material non-performance by its customers in the future; accordingly, the Company does not require collateral from its customers. However, if the Company’s assumptions are incorrect, there could be an adverse impact on its allowance for doubtful accounts. 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 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 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. Leases The Company accounts for leases in accordance with ASU No. 2016-02, Leases (Topic 842), which was adopted April 1, 2019. Prior to the adoption of Topic 842, the Company followed the guidance for leases under Topic 840, Leases. For further discussion of the Company's policies related to leases see Note 18, "Leases." The Company has operating leases for administrative, research and development, sales and marketing and manufacturing facilities and equipment under various non-cancelable lease agreements. Lease commencement occurs on the date the Company takes possession or control of the property or equipment. The Company's lease terms may include options to extend or terminate the lease where it is reasonably certain that the Company will exercise those options. The Company considers several economic factors when making this determination, including but not limited to, the significance of leasehold improvements incurred in the office space, the difficulty in replacing the asset, underlying contractual obligations, or specific characteristics unique to a particular lease. The Company's lease agreements do not contain any material residual value guarantees or material restrictive covenants. Valuation of Goodwill, Intangible Assets and Other Acquisition and Divestiture 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. Reporting units are determined based on the components of a Company's operating segments that constitute a business for which financial information is available and for which operating results are regularly reviewed by segment management. The Company has one reporting unit. 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 fourth quarter of fiscal year 2021, the Company performed its annual impairment analysis for goodwill as of January 31, 2021, using the qualitative Step 0 assessment as the Company concluded that it was more likely than not that the fair value of the reporting unit exceeded its carrying value. Indefinite-lived intangible assets are tested for impairment 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 indefinite-lived intangible assets 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 is impaired. If based on the Company's qualitative assessment, the Company concludes that it is more likely than not that the fair value of the indefinite- lived 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 the fourth quarter of fiscal year 2021, the Company completed its annual impairment test of the indefinite-lived intangible at January 31, 2021, using the qualitative Step 0 assessment as the Company concluded that it was more likely than not that the fair value of the indefinite-lived asset exceeded its carrying value. The Company completed two acquisitions and one divestiture during the three-year period ended March 31, 2021. 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 either an income, market or cost method approach. The Company's level 3 liabilities at March 31, 2020 consisted of contingent purchase consideration related to the two acquisitions that occurred during the fiscal year 2020. The contingent purchase consideration related to the two acquisitions represent amounts deposited into escrow accounts, which were established to cover damages NetScout may have suffered related to any liabilities that NetScout did not agree to assume or as a result of the breach of representations and warranties of the sellers as described in the acquisition agreements. The contingent purchase consideration of $0.7 million and $1.0 million related to the Gigavation Incorporated (Gigavation) and Eastwind Networks, Inc. (Eastwind) acquisitions, respectively are included as accrued other in the Company's consolidated balance sheet at March 31, 2020. The $0.7 million related to the Gigavation acquisition was paid to the seller in February 2021. The $1.0 million related to the Eastwind acquisition was paid to the seller in April 2020. During fiscal year 2019, the Company recorded a contingent consideration related to the divestiture of the Company's handheld network test (HNT) tools business in September 2018. The contingent consideration represented potential future earnout payments to the Company of up to $4.0 million over two years that were contingent on the HNT tools business achieving certain milestones. The fair value of the contingent consideration of $2.3 million was recognized on the divestiture date and was measured using unobservable (Level 3) inputs. The Company recorded an $0.8 million and a $1.6 million change in the fair value of the contingent consideration, which is included in other expense, net within the Company's consolidated statement of operations for the years ended March 31, 2020 and 2019. 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. Amortization included as cost of product revenue was $0.1 million, $0.5 million, and $1.1 million for the fiscal years ended March 31, 2021, 2020, and 2019, respectively. The Company did not capitalize software development costs in the fiscal years ended March 31, 2021 or 2020. 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 expenses 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. NetScout also periodically enters into forward contracts to manage exchange rate risk associated with certain third-party transactions and for which the Company does not elect hedge accounting treatment as there is no difference in the timing of gain or loss recognition on the hedge instrument and the hedged item. 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 its 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, Netscout discloses 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. Contingent assets and liabilities include contingent consideration in connection with the Company's acquisitions and divestitures. Contingent consideration represents earnout payments in connection with the Company's acquisitions and divestitures 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 assets and 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 both cash flows from operating and 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 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 expected requisite service period of the award. 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 NetScout's 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 U.S. 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. The Company had foreign currency losse s of $5.5 million , $0.7 million and $2.0 million for the fiscal years ended March 31, 2021, 2020 and 2019, respectively. These amounts are included in other expense, net. Advertising Expense NetScout recognizes advertising expense as incurred. Advertising expense was $8.7 million, $8.3 million and $9.4 million for the fiscal years ended March 31, 2021, 2020 and 2019, respectively. Comprehensive Income (Loss) Comprehensive income (loss) consists of net income (loss) and other comprehensive income (loss). Other comprehensive income (loss) typically consists of unrealized gains and losses on marketable securities, unrealized gain and losses on hedge contracts, actuarial gains and losses, and foreign currency translation adjustments. 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. NetScout evaluates the recoverability of deferred tax assets by considering all positive and negative evidence relating to future profitability. NetScout weighs objective and verifiable evidence more heavily in this analysis. In situations where NetScout concludes that it does not have sufficient objective and verifiable evidence to support the realizability of the deferred tax asset, NetScout creates a valuation allowance against it. Recent Accounting Standards In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. The amendments provide optional guidance for a limited time to ease the potential burden in accounting for reference rate reform. The new guidance provides optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. The amendments apply only to contracts and hedging relationships that reference LIBOR or another reference rate expected to be discontinued due to reference rate reform. In January 2021, the FASB issued ASU 2021-01, Reference Rate Reform, which clarifies the scope and application of certain optional expedients and exceptions regarding the original guidance. ASU 2021-01 may be applied prospectively through December 31, 2022. The expedients and exceptions provided by the amendments do not apply to contract modifications made and hedging relationships entered into or evaluated after December 31, 2022, that an entity has elected certain optional expedients for and that are retained through the end of the hedging relationship. The adoption is not expected to have a material impact on the Company's financial position, results of operations, and disclosures. In January 2020, the FASB issued ASU 2020-01, Investments-Equity Securities (Topic 321), Investments-Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815) - Clarifying the Interactions between Topic 321, Topic 323, and Topic 815. This guidance addresses accounting for the transition into and out of the equity method and provides clarification of the interaction of rules for equity securities, the equity method of accounting, and forward contracts and purchase options on certain types of securities. This standard is effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2020. Early adoption is permitted. ASU 2020-01 is effective for NetScout beginning April 1, 2021. The adoption is not expected to have a material impact on the Company's financial position, results of operations, and disclosures. In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes. ASU 2019-12 simplifies the accounting for income taxes, eliminates certain exceptions within ASC 740, Income Taxes, and clarifies certain aspects of the current guidance to promote consistency among reporting entities. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020. ASU 2019-12 is effective for NetScout beginning April 1, 2021. Most amendments within the standard are required to be applied on a prospective basis, while certain amendments must be applied on a retrospective or modified retrospective basis. The adoption is not expected to have a material impact on the Company's financial position, results of operations, and disclosures. In August 2018, the FASB issued ASU 2018-14, Compensation – Retirement Benefits – Defined Benefit Plans – General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans. This ASU adds, modifies and clarifies several disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The Company adopted the guidance as of April 1, 2020. The adoption did not have a material impact on the Company's consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. ASU 2018-13 adds, modifies and removes several disclosure requirements relative to the three levels of inputs used to measure fair value in accordance with Topic 820, Fair Value Measurement. The Company adopted the guidance as of April 1, 2020. The adoption did not have a material impact on the Company's consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13) and also issued subsequent amendments to the initial guidance: ASU 2018-19, ASU 2019-04, ASU 2019-05, ASU 2019-11 and ASU 2020-02 (collectively, Topic 326). Topic 326 requires measurement and recognition of expected credit losses for financial assets held. Topic 326 replaces the existing incurred loss impairment model with an expected loss methodology, which will result in more timely recognition of credit losses. The Company adopted the guidance prospectively as of April 1, 2020. The adoption did not result in a cumulative adjustment to retained earnings and did not have an impact on the Company's consolidated financial statements other than with respect to the updated disclosure requirements.

REVENUE RECOGNITION

REVENUE RECOGNITION	12 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
REVENUE RECOGNITION	REVENUE RECOGNITION Revenue from Contracts with Customers In May 2014, the FASB issued Topic 606, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. Topic 606 replaced most existing revenue recognition guidance under GAAP. The new standard introduces a five-step process to be followed in determining the amount and timing of revenue recognition. It also provides guidance on accounting for costs incurred to obtain or fulfill contracts with customers and establishes disclosure requirements which are more extensive than those required under prior GAAP. Topic 606 became effective for the Company on April 1, 2018. The Company elected to use the modified retrospective transition approach. Therefore, the comparative financial information has not been restated and continues to be reported under the accounting standards in effect for those periods. Revenue Recognition Policy The Company exercises judgment and uses estimates in connection with determining the amounts of product and service 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 Company's product sales consist of software only offerings and offerings which include hardware appliances with embedded software that are essential to providing customers the intended functionality of the solutions. The Company accounts for revenue once a legally enforceable contract with a customer has been approved by the parties and the related promises to transfer products or services have been identified. A contract is defined by the Company as an arrangement with commercial substance identifying payment terms, each party’s rights and obligations regarding the products or services to be transferred and the amount the Company deems probable of collection. Customer contracts may include promises to transfer multiple products and services to a customer. Determining whether the products and services are considered distinct performance obligations that should be accounted for separately or as one combined performance obligation may require significant judgment. Revenue is recognized when control of the products or services are transferred to the Company's customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for products and services. Product revenue is typically recognized upon shipment, provided a legally enforceable contract exists, control has passed to the customer, and in the case of software products, when the customer has the rights and ability to access the software; and collection of the related receivable is probable. 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. The Company's service offerings include installation, integration, extended warranty and maintenance services, post-contract customer support, stand-ready software-as-a-service (SAAS) 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, bug fixes and hardware repair and replacement. Consulting services are recognized upon delivery or completion of performance depending on the terms of the underlying contract. 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. Bundled 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. The Company allocates the transaction price among the performance obligations in an amount that depicts the relative standalone selling prices (SSP) of each obligation. Judgment is required to determine the SSP for each distinct performance obligation. The Company uses a range of amounts to estimate SSP when it sells each of the products and services separately based on the element’s historical pricing. The Company also considers its overall pricing objectives and practices across different sales channels and geographies, and market conditions. Generally, the Company has established SSP for a majority of its service elements based on historical standalone sales. In certain instances, the Company has established SSP for services based upon an estimate of profitability and the underlying cost to fulfill those services. Further, for certain service engagements, the Company considers quoted prices as part of multi-element arrangements of those engagements as a basis for establishing SSP. SSP has been established 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 reviews sales of the product elements on a quarterly basis and updates, when appropriate, its SSP for such elements to ensure that it reflects recent pricing experience. The Company's products are distributed through its direct sales force and indirect distribution channels through alliances with resellers and distributors. Revenue arrangements with resellers and distributors are recognized on a sell-in basis; that is, when control of the product transfers to the reseller or distributor. The Company records consideration given to a customer as a reduction of revenue to the extent they have recorded revenue from the customer. 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 its resellers and distributors. During the fiscal year ended March 31, 2021, the Company recognized reven ue of $262.5 million rela ted to the Company's deferred revenue balance reported at March 31, 2020. Performance Obligations Customer contracts may include promises to transfer multiple products and services to a customer. Determining whether the products and services are considered distinct performance obligations that should be accounted for separately or as one combined performance obligation may require significant judgment. The transaction price is allocated among performance obligations in bundled contracts in an amount that depicts the relative standalone selling prices of each obligation. For contracts involving distinct hardware and software licenses, the performance obligations are satisfied at a point in time when control is transferred to the customer. For standalone maintenance and post-contract support (PCS) the performance obligation is satisfied ratably over the contract term as a stand-ready obligation. For consulting and training services, the performance obligation may be satisfied over the contract term as a stand-ready obligation, satisfied over a period of time as those services are delivered, or satisfied at the completion of the service when control has transferred, or the services have expired unused. Payments for hardware, software licenses, one-year maintenance, PCS and consulting services, are typically due up front with payment terms of 30 to 90 days. However, the Company does have contracts pursuant to which billings occur ratably over a period of years following the transfer of control for the contracted performance obligations. Payments on multi-year maintenance, PCS and consulting services are typically due in annual installments over the contract term. The Company did not have any material variable consideration such as obligations for returns, refunds or warranties at March 31, 2021. At March 31, 2021, the Company had total deferred revenue of $373.1 million, which represents the aggregate total contract price allocated to undelivered performance obligations. The Company expects to recognize $269.8 million, or 72%, of this revenue during the next 12 months, and expects to recognize the remaining $103.3 million, or 28%, of this revenue thereafter. NetScout expects that the amount of billed and unbilled deferred revenue will change from quarter to quarter for several reasons, including the specific timing, duration and size of large customer support and service agreements, varying billing cycles of such agreements, the specific timing of customer renewals, and foreign currency fluctuations. The Company did not have material significant financing components, or variable consideration or performance obligations satisfied in a prior period recognized during the twelve months ended March 31, 2021. Contract Balances The Company may receive payments from customers based on billing schedules as established by the Company's contracts. Contract assets relate to performance obligations where control has transferred to the customer in advance of scheduled billings. The Company records unbilled accounts receivable representing the right to consideration in exchange for goods or services that have been transferred to a customer conditional on the passage of time. Deferred revenue relates to scenarios where billings occur before all performance obligations are delivered or payments are received in advance of performance under the contract. Costs to Obtain Contracts The Company has determined that the only significant incremental costs incurred to obtain contracts with customers within the scope of Topic 606 are sales commissions paid to its employees. Sales commissions are recorded as an asset and amortized to expense ratably over the remaining performance periods of the related contracts with remaining performance obligations. The Company expenses costs as incurred for sales commissions when the amortization period would have been one year or less. At March 31, 2021, the consolidated balance sheet inclu ded $7.4 million in assets related to sales commissions to be expensed in future periods. A balance of $4.1 million wa s included in prepaid expenses and other current assets, and a balance of $3.3 million was included as other assets in the Company's consolidated balance sheet at March 31, 2021. At March 31, 2020, the consolidated balance sheet included $7.2 million in assets related to sales commissions to be expensed in future periods. A balance of $3.9 million was included in prepaid expenses and other current assets, and a balance of $3.3 million was included in other assets in the Company's consolidated balance sheet at March 31, 2020. During the twelve months ended March 31, 2021 and 2020, the Company recognized $6.3 million and $6.5 million of amortization related to this sales commission asset, which is included in the sales and marketing expense line in the Company's consolidated statements of operations. Allowance for Credit Losses The Company continually monitors collections from its customers. The Company evaluates the collectability of its accounts receivable and determines the appropriate allowance for credit losses based on a combination of factors, including but not limited to, analysis of the aging schedules, past due balances, historical collection experience and prevailing economic conditions. The following table summarizes the activity in the allowance for credit losses (in thousands): Balance at March 31, 2020 $ 1,350 Provision for allowance for credit losses 48 Recoveries and other adjustments (733) Write off charged against the allowance for credit losses (249) Balance at March 31, 2021 $ 416

CASH, CASH EQUIVALENTS AND MARK

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES	12 Months Ended
	Mar. 31, 2021
Cash and Cash Equivalents [Abstract]
CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES	CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES Cash and cash equivalents mainly consisted of U.S government and municipal obligations, commercial paper, corporate bonds, money market instruments and cash maintained with various financial institutions at March 31, 2021 and 2020. Cash, Cash Equivalents and Restricted Cash The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the consolidated statements of cash flows (in thousands): March 31, 2021 March 31, 2020 March 31, 2019 March 31, 2018 Cash and cash equivalents $ 467,176 $ 338,489 $ 409,632 $ 369,821 Restricted cash $ — 1,748 188 910 Total cash, cash equivalents and restricted cash $ 467,176 $ 340,237 $ 409,820 $ 370,731 The Company's restricted cash includes cash balances which are legally or contractually restricted. The Company's restricted cash is included within prepaid and other current assets and consists of amounts related to holdbacks associated with prior acquisitions. Marketable Securities The following is a summary of marketable securities held by NetScout at March 31, 2021 classified as short-term and long-term (in thousands): Amortized Unrealized Fair Type of security: U.S. government and municipal obligations $ 3,571 $ 7 $ 3,578 Commercial paper 5,699 — 5,699 Total short-term marketable securities 9,270 7 9,277 Total long-term marketable securities — — — Total marketable securities $ 9,270 $ 7 $ 9,277 The following is a summary of marketable securities held by NetScout at March 31, 2020, classified as short-term and long-term (in thousands): Amortized Unrealized Fair Type of security: U.S. government and municipal obligations $ 28,621 $ 107 $ 28,728 Commercial paper 14,644 — 14,644 Corporate bonds 4,587 10 4,597 Total short-term marketable securities 47,852 117 47,969 U.S. government and municipal obligations 2,562 51 2,613 Total long-term marketable securities 2,562 51 2,613 Total marketable securities $ 50,414 $ 168 $ 50,582 Contractual maturities of the Company's marketable securities held at March 31, 2021 and 2020 (in thousands) were as follows: March 31, March 31, Available-for-sale securities: Due in 1 year or less $ 9,277 $ 47,969 Due after 1 year through 5 years — 2,613 $ 9,277 $ 50,582

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The fair value hierarchy has three levels based on the reliability of the inputs used to determine fair value. Level 1 refers to fair values determined based on quoted prices in active markets for identical assets. Level 2 refers to fair values estimated using significant other observable inputs, and Level 3 includes fair values estimated using significant unobservable inputs. The following tables present the Company's financial assets and liabilities measured on a recurring basis using the fair value hierarchy at March 31, 2021 and 2020 (in thousands): Fair Value Measurements at March 31, 2021 Level 1 Level 2 Level 3 Total ASSETS: Cash and cash equivalents $ 467,176 $ — $ — $ 467,176 U.S. government and municipal obligations 2,539 1,039 — 3,578 Commercial paper — 5,699 — 5,699 Derivative financial instruments — 57 — 57 $ 469,715 $ 6,795 $ — $ 476,510 LIABILITIES: Derivative financial instruments — (191) — (191) $ — $ (191) $ — $ (191) Fair Value Measurements at March 31, 2020 Level 1 Level 2 Level 3 Total ASSETS: Cash and cash equivalents $ 338,489 $ — $ — $ 338,489 U.S. government and municipal obligations 31,341 — — 31,341 Commercial paper — 14,644 — 14,644 Corporate bonds 4,597 — — 4,597 $ 374,427 $ 14,644 $ — $ 389,071 LIABILITIES: Contingent purchase consideration $ — $ — $ (1,748) $ (1,748) Derivative financial instruments — (49) — (49) $ — $ (49) $ (1,748) $ (1,797) This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. On a recurring basis, the Company measures certain financial assets and liabilities at fair value, including marketable securities and derivative financial instruments. The Company's Level 1 investments are classified as such because they are valued using quoted market prices or alternative pricing sources with reasonable levels of price transparency. The Company's Level 2 investments are classified as such because fair value is calculated using market observable data for similar but not identical instruments, or a discounted cash flow model using the contractual interest rate as compared to the underlying interest yield curve. The Company classifies municipal obligations as Level 2 because the fair values are determined using quoted prices from markets the Company considers to be inactive. Commercial paper is classified as Level 2 because the Company uses market information from similar but not identical instruments and discounted cash flow models based on interest rate yield curves to determine fair value. The Company's derivative financial instruments consist of forward foreign exchange contracts and are classified as Level 2 because the fair values of these derivatives are determined using models based on market observable inputs, including spot prices for foreign currencies and credit derivatives, as well as an interest rate factor. The Company's Level 3 liabilities at March 31, 2020 consisted of contingent purchase consideration related to the two acquisitions that occurred during the fiscal year 2020. The contingent purchase consideration related to the two acquisitions represented amounts deposited into escrow accounts, which were established to cover damages NetScout may have suffered related to any liabilities that NetScout did not agree to assume or as a result of the breach of representations and warranties of the sellers as described in the acquisition agreements. The contingent purchase consideration of $0.7 million and $1.0 million related to the Gigavation and Eastwind acquisitions, respectively were included as accrued other in the Company's consolidated balance sheet at March 31, 2020. The $0.7 million related to the Gigavation acquisition was paid to the seller in February 2021. The $1.0 million related to the Eastwind acquisition was paid to the seller in April 2020. During fiscal year 2019, the Company recorded a contingent consideration related to the divestiture of the Company's handheld network test (HNT) tools business in September 2018. The contingent consideration represented potential future earnout payments to the Company of up to $4.0 million over two years that were contingent on the HNT tools business achieving certain milestones. The fair value of the contingent consideration of $2.3 million was recognized on the divestiture date and was measured using unobservable (Level 3) inputs. The Company recorde d an $0.8 million and a $1.6 million change in the fair value of the contingent consideration, which is included in other expense, net within the Company's consolidated statement of operations for the years ended March 31, 2020 and 2019. The following table sets forth a reconciliation of changes in the fair value of the Company’s Level 3 financial liabilities for the fiscal year ended March 31, 2021 (in thousands): Contingent Balance at March 31, 2020 $ (1,748) Additions to Level 3 — Payments made 1,748 Balance at March 31, 2021 $ — The following table sets forth a reconciliation of changes in the fair value of the Company’s Level 3 financial assets and liabilities for the fiscal year ended March 31, 2020 (in thousands): Contingent Contingent Balance at March 31, 2019 $ — $ 762 Additions to Level 3 (1,800) — Change in fair value of contingent consideration — (762) Payments received 52 — Balance at March 31, 2020 $ (1,748) $ — Accretion income related to the contingent consideration received as partial consideration for the divestiture of the HNT tools business for the fiscal year ended March 31, 2020 was $36 thousand and was included within interest income.

INVENTORIES

INVENTORIES	12 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
INVENTORIES	INVENTORIES Inventories are stated at the lower of actual cost or net realizable value. Cost is determined by using the FIFO method. Inventories consisted of the following (in thousands): March 31, 2021 2020 Raw materials $ 13,189 $ 15,311 Work in process 16 819 Finished goods 6,168 5,376 Deferred costs 3,440 721 $ 22,813 $ 22,227

FIXED ASSETS

FIXED ASSETS	12 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
FIXED ASSETS	FIXED ASSETS Fixed assets consisted of the following (in thousands): Estimated Useful Life in Years March 31, 2021 2020 Furniture and fixtures 3-7 $ 9,742 $ 9,561 Computer equipment and internal use software 3-5 177,098 170,518 Leasehold improvements (1) up to 12 53,980 51,910 Demonstration and spare part units 2-5 17,968 19,626 258,788 251,615 Less – accumulated depreciation (210,314) (193,900) $ 48,474 $ 57,715 (1) Leasehold improvements are depreciated over the shorter of the lease term or anticipated useful life of the improvement. A typographical error in the prior year presentation of the above disclosure has been corrected in the current period. Depreciation expense was $22.4 million, $23.4 million and $27.4 million for the fiscal years ended March 31, 2021, 2020 and 2019, respectively.

ACQUISITIONS & DIVESTITURES

ACQUISITIONS & DIVESTITURES	12 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
ACQUISITIONS & DIVESTITURES	ACQUISITIONS & DIVESTITURES Gigavation Acquisition On February 5, 2020 (the Gigavation Closing Date), the Company acquired 100% of the common stock of Gigavation Incorporated, a cybersecurity company for $8.0 million. Gigavation's solutions provide security to device communication protocols, end point protection and security analytics. The Gigavation technology and engineering talent have been integrated into our service assurance products in order to support the ongoing enhancement of that portfoli o. The Company completed the accounting related to the Gigavation acquisition as of March 31, 2020. Goodwill and intangible assets recorded as part of the acquisition are not deductible for tax purposes. The Company determined Gigavation's results of operations are not material. As such, the pro forma information is not required. The following table summarizes the allocation of the purchase price (in thousands): Initial cash payment $ 7,200 Estimated fair value of contingent purchase consideration 800 Estimated purchase price $ 8,000 The following table reflects the estimated fair value of assets acquired and liabilities assumed (in thousands): Cash $ 7 Accounts receivable 209 Prepaid and other current assets 5 Intangible assets 4,760 Deferred tax liability (693) Accounts payable (50) Accrued other liabilities (54) Goodwill $ 3,816 Of the total consideration, $0.8 million was deposited into an escrow account. The escrow account was established to cover damages NetScout may have suffered related to any liabilities that NetScout did not agree to assume or as a result of the breach of representations and warranties of the seller as described in the acquisition agreement. Generally, indemnification claims that Gigavation would be liable for are limited to the total amount of the escrow account, which shall be the sole source for the satisfaction of any damages to the Company for such claims, but such limitation does not apply with respect to the seller's breach of certain fundamental representations or related to other specified indemnity items, for which certain of Gigavation's shareholders may be liable for additional amounts in excess of the escrow amount. During the fiscal year ended March 31, 2020, $0.1 million was withdrawn from the escrow account to satisfy an indemnification claim. The remaining $0.7 million was paid to the seller in February 2021. In connection with the Gigavation acquisition, certain former employees of Gigavation received restricted stock units. The restricted stock units issued are considered new share-based payment awards granted by NetScout to the former employees of Gigavation. NetScout accounted for these new awards separately from the business combination. The Company recognized share-based compensation net of an estimated forfeiture rate and only recognized compensation cost for those shares expected to vest on a straight-line basis over the requisite service period of the award. The fair value of the intangible asset was based on a valuation using an income approach. The underlying assumptions include the estimated cash flows to be generated by the technology purchased as part of the acquisition less any returns on contributory assets, if any. This fair value measurement was based on significant inputs not observable in the market and thus represents Level 3 fair value measurements. The following table reflects the fair value of the acquired identifiable intangible asset and related estimated useful life (in thousands): Fair Value Useful Life (Years) Developed technology $ 4,760 10 The weighted average useful life of the developed technology acquired from Gigavation is 10 years. Eastwind Acquisition On April 3, 2019 (the Eastwind Closing Date), the Company completed the acquisition of certain assets and liabilities of Eastwind for $5.2 million. Eastwind's breach analytics cloud analyzes data to identify malicious activity, insider threats and data leakage. The Company completed the purchase accounting related to the Eastwind acquisition as of June 30, 2019. Goodwill and intangible assets recorded as part of the acquisition are deductible for tax purposes. The Company determined Eastwind's results of operations are not material. As such, the pro forma information is not required. Initial cash payment $ 4,154 Estimated fair value of contingent purchase consideration 1,000 Estimated purchase price $ 5,154 The following table reflects the estimated fair value of assets acquired and liabilities assumed (in thousands): Property, plant and equipment $ 17 Intangible assets 4,230 Accrued other liabilities (96) Goodwill $ 1,003 Of the total consideration, $1.0 million was deposited into an escrow account. The escrow account was established to cover damages NetScout may have suffered related to any liabilities that NetScout did not agree to assume or as a result of the breach of representations and warranties of the seller as described in the acquisition agreement. Generally, indemnification claims that Eastwind would be liable for are limited to the total amount of the escrow account, which shall be the sole source for the satisfaction of any damages to the Company for such claims, but such limitation does not apply with respect to the seller's breach of certain fundamental representations or related to other specified indemnity items, for which certain of Eastwind's shareholders may be liable for additional amounts in excess of the escrow amount. The contingent purchase consideration of $1.0 million was paid to the seller in April 2020. In connection with the Eastwind acquisition, certain former employees of Eastwind received cash retention payments totaling $0.3 million on the Eastwind Closing Date. Because these employees were not required to provide future services to the Company, the cash retention payments were accounted for as part of the purchase price. These former Eastwind employees will also receive cash retention payments subject to such employee's continued employment with the Company through the next regularly scheduled payroll dates following each of the first and second anniversaries of the Eastwind Closing Date. The cash retention payment liability related to these future cash retention payments were accounted for separately from the business combination as the cash retention payment is automatically forfeited upon termination of employment. The Company recorded the liability over the period it was earned as compensation expense for post-combination services. The fair value of intangible asset was based on a valuation using a cost method approach. The underlying assumptions include estimates of cost to replace or reproduce the asset, less adjustments for physical deterioration and functional obsolescence, if relevant. This fair value measurement was based on significant inputs not observable in the market and thus represents Level 3 fair value measurements. The following table reflects the fair value of the acquired identifiable intangible asset and related estimated useful life (in thousands): Fair Value Useful Life (Years) Developed technology $ 4,230 10 The average useful life of the developed technology acquired from Eastwind is 10 years. HNT Tools Business Divestiture On September 14, 2018 (the HNT Divestiture Date), the Company divested its handheld network test (HNT) tools business for cash proceeds of $1.3 million and potential future earnout payments of up to $4.0 million over two years that were contingent on the HNT tools business achieving certain milestones. The fair value of the contingent consideration in the amount of $2.3 million was recognized on the HNT Divestiture Date and was measured using unobservable (Level 3) inputs. The contingent consideration was presented as a non-cash investing activity on the consolidated statement of cash flows. The Company transferred $4.6 million of consideration along with net liabilities of the HNT tools business related to a working capital adjustment during the fiscal year ended March 31, 2019. The Company recorded a loss on the divestiture for the year ended March 31, 2019 totaling $9.5 million, which included $1.3 million of transaction costs and $0.5 million of incentive compensation payable to the HNT tools business employees negotiated as part of the sale. In connection with the divestiture, the Company had entered into a transitional services agreement with the buyer to provide certain services for a period of up to eighteen months. Income associated with the transitional services agreement for the fiscal years ended March 31, 2021 and 2020 was $0.2 million and $1.2 million, respectively, and is included within other expense, net in the Company's consolidated statement of operations.

GOODWILL & INTANGIBLE ASSETS

GOODWILL & INTANGIBLE ASSETS	12 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL & INTANGIBLE ASSETS	GOODWILL & INTANGIBLE ASSETS Goodwill The Company has one reporting unit. Goodwill is tested for impairment at a reporting unit level at least annually, as of January 31, 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 unit below its carrying value. At March 31, 2021 and 2020, the carrying amount of goodwill was $1.7 billion. During fiscal years 2021 and 2020, the Company's annual impairment tests indicated that goodwill was not impaired. In the fourth quarter of fiscal year 2021, the Company completed its annual goodwill impairment test at January 31, 2021, using the qualitative Step 0 assessment as the Company concluded that it was more likely than not that the fair value of the reporting unit exceeded its carrying value . The change in the carrying amount of goodwill for the fiscal year ended March 31, 2021 is due to the impact of foreign currency translation adjustments related to asset balances that are recorded in currencies other than the U.S. Dollar. The changes in the carrying amount of goodwill for the fiscal years ended March 31, 2021 and 2020 are as follows (in thousands): Balance at March 31, 2019 $ 1,715,485 Goodwill attributed to the Eastwind acquisition 1,003 Goodwill attributed to the Gigavation acquisition 3,816 Foreign currency translation impact 5,376 Balance at March 31, 2020 $ 1,725,680 Foreign currency translation impact (8,126) Balance at March 31, 2021 $ 1,717,554 Intangible Assets The net carrying amounts of intangible assets were $511.9 million and $582.2 million at March 31, 2021 and 2020, respectively. Intangible assets acquired in a business combination are recorded under the acquisition method of accounting at their estimated fair values at the date of acquisition. The Company amortizes intangible assets over their estimated useful lives, except for the acquired trade name which resulted from the Network General acquisition, which has an indefinite life and thus is not amortized. The carrying value of the indefinite lived trade name is evaluated for potential impairment annually or more frequently if events or changes in circumstances indicate that the asset might be impaired. During fiscal year 2019, the Company performed a quantitative analysis on certain intangible assets related to the HNT tools business, which has since been divested. The fair value for the intangible assets related to the HNT tools business was calculated considering a range of potential transaction prices which the Company considers to be a Level 3 measurement. The fair value of these intangible assets was determined to be less than the carrying value, and as a result, the Company recognized an impairment charge of $35.9 million in the twelve months ended March 31, 2019. The impairment charge was recorded within a separate operating expense line item in the Company's consolidated statements of operations during the twelve months ended March 31, 2019. During fiscal year 2021 and 2020, the Company's annual impairment tests indicated that the acquired trade name was not impaired. In the fourth quarter of fiscal year 2021, the Company completed its annual impairment test of the indefinite lived intangible at January 31, 2021 using the qualitative Step 0 assessment as the Company concluded that it was more likely than not that the fair value of the indefinite-lived asset exceeded its carrying value. During the fiscal year ended March 31, 2021, the Company acquired $4.5 million of technology licenses. These amounts are included within distributor relationships and are being amortizing using the economic benefit method over useful lives of between three Intangible assets include the indefinite lived trade name with a carrying value of $18.6 million and the following amortizable intangible assets at March 31, 2021 (in thousands): Cost Accumulated Net Developed technology $ 252,071 $ (212,688) $ 39,383 Customer relationships 775,898 (333,903) 441,995 Distributor relationships and technology licenses 11,469 (7,829) 3,640 Definite-lived trademark and trade name 39,434 (31,467) 7,967 Core technology 7,192 (7,192) — Net beneficial leases 336 (336) — Non-compete agreements 292 (292) — Capitalized software 3,317 (3,281) 36 Other 1,208 (963) 245 $ 1,091,217 $ (597,951) $ 493,266 Intangible assets include the indefinite lived trade name with a carrying value of $18.6 million and the following amortizable intangible assets at March 31, 2020 (in thousands): Cost Accumulated Net Developed technology $ 249,675 $ (191,876) $ 57,799 Customer relationships 767,366 (275,361) 492,005 Distributor relationships and technology licenses 6,785 (6,321) 464 Definite-lived trademark and trade name 39,059 (26,246) 12,813 Core technology 7,192 (7,074) 118 Net beneficial leases 336 (336) — Non-compete agreements 292 (292) — Leasehold interest 500 (500) — Backlog 16,223 (16,223) — Capitalized software 3,317 (3,202) 115 Other 1,208 (943) 265 $ 1,091,953 $ (528,374) $ 563,579 Amortization included as cost of product revenue consists of amortization of developed technology, distributor relationships and technology licenses, core technology and software. Amortization included as operating expense consists of all other intangible assets. The following table provides a summary of amortization expense during the fiscal years ended March 31, 2021, 2020, and 2019 (in thousands). Years Ended March 31, 2021 2020 2019 Amortization of intangible assets included as: Cost of product revenue 20,457 26,664 34,039 Operating expense 61,151 64,525 74,325 $ 81,608 $ 91,189 $ 108,364 The following is the expected future amortization expense at March 31, 2021 for the fiscal years ended March 31 (in thousands): 2022 $ 71,540 2023 63,799 2024 55,547 2025 48,476 2026 44,386 Thereafter 209,518 Total $ 493,266 The weighted average amortization period of developed technology and core t echnology is 11.2 year s. The weighted average amortization period for customer and distributor relationships is 15.9 years. The weighted average amortization period for trademarks and trade names is 8.6 years. The weighted average amortization period for capitalized software is 3.0 years. The weighted average amortization period for all amortizing intangible assets is 14.6 years.

DERIVATIVE INSTRUMENTS AND HEDG

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	12 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIESNetScout operates internationally and, in the normal course of business, is exposed to fluctuations in foreign currency exchange rates. The exposures result from costs that are denominated in currencies other than the U.S. Dollar, primarily the Euro, British Pound, Canadian Dollar, and Indian Rupee. The Company manages its foreign cash flow risk by hedging forecasted cash flows for operating expenses denominated in foreign currencies for up to twelve months, within specified guidelines through the use of forward contracts. The Company enters into foreign currency exchange contracts to hedge cash flow exposures from costs that are denominated in currencies other than the U.S. Dollar. These hedges are designated as cash flow hedges at inception. NetScout also periodically enters into forward contracts to manage exchange rate risk associated with certain third-party transactions and for which the Company does not elect hedge accounting treatment as there is no difference in the timing of gain or loss recognition on the hedge instrument and the hedged item. All of the Company's derivative instruments are utilized for risk management purposes, and the Company does not use derivatives for speculative trading purposes. These contracts will mature over the next twelve months and are expected to impact earnings on or before maturity. The notional amounts and fair values of derivative instruments in the consolidated balance sheets at March 31, 2021 and 2020 were as follows (in thousands): Notional Amounts (a) Prepaid Expenses and Other Current Assets Accrued Other March 31, 2021 March 31, 2020 March 31, 2021 March 31, 2020 March 31, 2021 March 31, 2020 Derivatives Designated as Hedging Instruments: Forward contracts $ 11,037 $ 1,722 $ 57 $ — $ 152 $ 49 Derivatives Not Designated as Hedging Instruments: Forward contracts 6,373 — — — 39 — $ 57 $ — $ 191 $ 49 Notional amounts represent the gross contract/notional amount of the derivatives outstanding. The following table provides the effect foreign exchange forward contracts had on other comprehensive income (loss), (OCI) and results of operations during the fiscal years ended March 31, 2021 and 2020 (in thousands): Gain (Loss) Recognized Gain (Loss) Reclassified from March 31, March 31, March 31, March 31, 2021 2020 Location 2021 2020 Forward contracts $ 274 $ (103) Research and development $ (57) $ (19) Sales and marketing (252) 47 $ 274 $ (103) $ (309) $ 28 (a) The amount represents the change in fair value of derivative contracts due to changes in spot rates. (b) The amount represents reclassification from other comprehensive income to earnings that occurs when the hedged item affects earnings. The following table provides the effect foreign exchange forward contracts not designated as hedging instruments had on the Company's results of operations during the fiscal years ended March 31, 2021 and 2020 (in thousands): Gain Recognized in Income March 31, March 31, Location 2021 2020 Forward contracts General and administrative $ 115 $ — $ 115 $ — (a) The amount represents the change in fair value of derivative contracts due to changes in spot rates.

RESTRUCTURING CHARGES

RESTRUCTURING CHARGES	12 Months Ended
	Mar. 31, 2021
Restructuring and Related Activities [Abstract]
RESTRUCTURING CHARGES	RESTRUCTURING CHARGES During the fiscal year ended March 31, 2018, the Company restructured certain departments to better align functions. As a result of the workforce reduction, during the fiscal year ended March 31, 2018, the Company recorded a restructuring charge totaling $5.1 million related to one-time termination benefits for the employees that were notified during the period. Additional one-time termination benefit charges and facility-related costs of $1.7 million were recorded during the fiscal year ended March 31, 2019. The one-time termination benefits and facility-related costs related to this plan were paid in full during the fiscal year ended March 31, 2019. During the fiscal year ended March 31, 2019, the Company implemented a voluntary separation program (VSP) for employees who met certain requirements to reduce overall headcount. As a result of the related workforce reduction, the Company recorded restructuring charges totaling $17.2 million related to one-time termination benefits for employees who voluntarily terminated their employment with the Company during the period. Additional one-time termination benefit charges of $0.1 million were recorded in the fiscal year ended March 31, 2020. The one-time termination benefits were paid in full during the fiscal year ended March 31, 2020. During the fiscal year ended March 31, 2020, the Company approved two restructuring plans. During the second quarter of the fiscal year ended March 31, 2020, the Company restructured certain departments to better align functions. As a result of the workforce reduction, the Company recorded a restructuring charge totaling $0.5 million during the fiscal year ended March 31, 2020. The one-time termination benefits were paid in full during the first quarter of the fiscal year ending March 31, 2021. During the fourth quarter of the fiscal year ended March 31, 2020, the Company restructured certain departments to better align functions. As a result of the workforce reduction, the Company recorded a restructuring charge totaling $2.1 million during the fiscal year ended March 31, 2020 and an additional $0.1 million during the fiscal year ended March 31, 2021. The one-time termination benefits were paid in full by the end of the second quarter of the fiscal year ending March 31, 2021. The following table provides a summary of the activity related to the restructuring plans and the related restructuring liability (in thousands): FY2018 Plan VSP Q2 FY20 Plan Q4 FY20 Plan Employee-Related Facilities Related Employee-Related Employee-Related Employee-Related Total Balance at March 31, 2018 $ 3,696 $ — $ — $ — $ — $ 3,696 Restructuring charges to operations 1,017 643 17,248 — — 18,908 Cash payments (4,240) (458) (17,329) — — (22,027) Other adjustments (473) (185) 81 — — (577) Balance at March 31, 2019 $ — $ — $ — $ — $ — $ — Restructuring charges to operations — — 123 465 2,069 2,657 Cash payments — — (123) (434) (339) (896) Other adjustments — — — (28) (13) (41) Balance at March 31, 2020 $ — $ — $ — $ 3 $ 1,717 $ 1,720 Restructuring charges to operations — — — — 62 62 Cash payments — — — (3) (1,860) (1,863) Other adjustments — — — — 81 81 Balance at March 31, 2021 $ — $ — $ — $ — $ — $ —

LONG-TERM DEBT

LONG-TERM DEBT	12 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT On January 16, 2018, the Company amended and expanded its existing credit agreement (Amended Credit Agreement) with a syndicate of lenders by and among: the Company; JPMorgan Chase Bank, N.A. (JPMorgan), as administrative agent and collateral agent; J.P. Morgan Securities LLC, KeyBanc Capital Markets, Merrill Lynch, Pierce, Fenner & Smith Incorporated, RBC Capital Markets and Wells Fargo Securities, LLC, as joint lead arrangers and joint bookrunners; Fifth Third Bank, Santander Bank, N.A., SunTrust Bank, N.A. and U.S. Bank National Association, as co-documentation agents; and the lenders party thereto. The Amended Credit Agreement provides for a five-year, $1.0 billion senior secured revolving credit facility, including a letter of credit sub-facility of up to $75.0 million. The Company may elect to use the new credit facility for general corporate purposes or to finance the repurchase of up to twenty-five million shares of the Company's common stock under the Company's common stock repurchase plan. The commitments under the Amended Credit Agreement will expire on January 16, 2023, and any outstanding loans will be due on that date. During the fiscal year ended March 31, 2021, the Company repaid $100.0 million of borrowings under the Amended Credit Agreement. At March 31, 2021, $350 million was outstanding under the Amended Credit Agreement. At the Company's election, revolving loans under the Amended Credit Agreement bear interest at either (a) an Alternate Base Rate per annum equal to the greatest of (1) JPMorgan's prime rate, (2) 0.50% in excess of the New York Federal Reserve Bank (NYFRB) rate, or (3) an adjusted one month LIBOR rate plus 1%; or (b) such adjusted LIBOR rate (for the interest period selected by the Company), in each case plus an applicable margin. For the period from the delivery of the Company's financial statements for the quarter ended December 31, 2020, until the Company has delivered financial statements for the quarter ended March 31, 2021, the applicable margin will be 1.50% per annum for LIBOR loans and 0.50% per annum for Alternate Base Rate loans, and thereafter the applicable margin will vary depending on the Company's leverage ratio, ranging from 0.75% per annum for Base Rate loans and 1.75% per annum for LIBOR loans if the Company's consolidated leverage ratio is less than or equal to 3.50 to 1.00, down to 0.00% per annum for Alternate Base Rate loans and 1.00% per annum for LIBOR loans if the Company's consolidated leverage ratio is equal to or less than 1.50 to 1.00. As of March 31, 2021, the Company’s maximum allowed consolidated leverage ratio is 3.50 to 1.00. On July 27, 2017, the U.K. Financial Conduct Authority (FCA) announced that it will no longer require banks to submit rates for the calculation of LIBOR after 2021. On March 5, 2021, the Intercontinental Exchange Benchmark Administration (IBA), the FCA-regulated and authorized administrator of LIBOR, announced, and the FCA confirmed, that one week and two-month USD LIBOR settings will cease on December 31, 2021, and that the USD LIBOR panel will cease on June 30, 2023. IBA notes that any publication of the Overnight and 1, 3, 6 and 12 Months USD LIBOR settings based on panel bank submissions beyond December 31, 2021 will need to comply with applicable regulations, including as to representativeness. Based on current information from panel banks, IBA anticipates there being a representative panel for the continuation of these USD LIBOR settings through to June 30, 2023. The Company's Amended Credit Agreement, which matures on January 16, 2023 prior to the June 30, 2023 cessation of USD LIBOR publications, provides for the Administrative Agent to determine if (i) adequate and reasonable means do not exist for ascertaining the LIBOR rate or (ii) the FCA or Government Authority having jurisdiction over the Administrative Agent has made a public statement identifying a specific date after which the LIBOR rate shall no longer be used for determining interest rates for loans and the Administrative Agent determines that (i) and (ii) above are unlikely to be temporary, then the Administrative Agent and the Company would agree to transition to an Alternate Base Rate borrowing as described above or amend the Credit Agreement to establish an alternate rate of interest to LIBOR that gives due consideration to the then prevailing market convention for determining a rate of interest for syndicated loans in the United States at such time. The Company's consolidated leverage ratio is the ratio of its total funded debt compared to its consolidated adjusted EBITDA. Consolidated adjusted EBITDA includes certain adjustments, including, without limitation, adjustments relating to extraordinary, unusual or non-recurring charges, certain restructuring charges, non-cash charges, certain transaction costs and expenses and certain pro forma adjustments in connection with material acquisitions and dispositions, all as set forth in detail in the definition of consolidated adjusted EBITDA in the Amended Credit Agreement. Commitment fees will accrue on the daily unused amount of the credit facility. For the period from the delivery of the Company's financial statements for the quarter ended December 31, 2020 until the Company has delivered financial statements for the quarter ended March 31, 2021, the commitment fee will be 0.25% per annum, and thereafter the commitment fee will vary depending on the Company's consolidated leverage ratio, ranging from 0.30% per annum if the Company's consolidated leverage ratio is greater than 2.75 to 1.00, down to 0.15% per annum if the Company's consolidated leverage ratio is equal to or less than 1.50 to 1.00. Letter of credit participation fees are payable to each lender on the amount of such lender’s letter of credit exposure, during the period from the closing date of the Amended Credit Agreement to but excluding the date which is the later of (i) the date on which such lender’s commitment terminates or (ii) the date on which such lender ceases to have any letter of credit exposure, at a rate per annum equal to the applicable margin for LIBOR loans. Additionally, the Company will pay a fronting fee to each issuing bank in amounts to be agreed to between the Company and the applicable issuing bank. Interest on Alternate Base Rate loans is payable at the end of each calendar quarter. Interest on LIBOR loans is payable at the end of each interest rate period or at the end of each three-month interval within an interest rate period if the period is longer than three months. The Company may also prepay loans under the Amended Credit Agreement at any time, without penalty, subject to certain notice requirements. Debt is recorded at the amount drawn on the revolving credit facility plus interest based on floating rates reflective of changes in the market which approximates fair value. The loans and other obligations under the credit facility are (a) guaranteed by each of the Company's wholly owned material domestic restricted subsidiaries, subject to certain exceptions, and (b) are secured by substantially all of the assets of the Company and the subsidiary guarantors, including a pledge of all the capital stock of material subsidiaries held directly by the Company and the subsidiary guarantors (which pledge, in the case of any foreign subsidiary, is limited to 65% of the voting stock), subject to certain customary exceptions and limitations. The Amended Credit Agreement generally prohibits any other liens on the assets of the Company and its restricted subsidiaries, subject to certain exceptions as described in the Amended Credit Agreement. The Amended Credit Agreement contains certain covenants applicable to the Company and its restricted subsidiaries, including, without limitation, limitations on additional indebtedness, liens, various fundamental changes, dividends and distributions, investments (including acquisitions), transactions with affiliates, asset sales, including sale-leaseback transactions, speculative hedge agreements, payment of junior financing, changes in business and other limitations customary in senior secured credit facilities. In addition, the Company is required to maintain certain consolidated leverage and interest coverage ratios. These covenants and limitations are more fully described in the Amended Credit Agreement. At March 31, 2021, the Company was in compliance with all of these covenants. The Amended Credit Agreement provides that events of default will exist in certain circumstances, including failure to make payment of principal or interest on the loans when required, failure to perform certain obligations under the Amended Credit Agreement and related documents, defaults under certain other indebtedness, certain insolvency events, certain events arising under ERISA, a change of control and certain other events. Upon an event of default, the administrative agent with the consent of, or at the request of, the holders of more than 50% in principal amount of the loans and commitments may terminate the commitments and accelerate the maturity of the loans and enforce certain other remedies under the Amended Credit Agreement and the other loan documents. In connection with the Company's Amended Credit Agreement described above, the Company terminated its previous term loan dated as of July 14, 2015, by and among the Company; JPMorgan Chase Bank, N.A. (JPMorgan), as administrative agent and collateral agent; J.P. Morgan Securities LLC, KeyBanc Capital Markets, Merrill Lynch, Pierce, Fenner & Smith Incorporated, RBC Capital Markets and Wells Fargo Securities, LLC, as joint lead arrangers and joint bookrunners; Santander Bank, N.A., SunTrust Bank, N.A. and U.S. Bank National Association, as co-documentation agents; and the lenders party thereto.

NET INCOME (LOSS) PER SHARE

NET INCOME (LOSS) PER SHARE	12 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
NET INCOME (LOSS) PER SHARE	NET INCOME (LOSS) PER SHARE Calculations of the basic and diluted net income (loss) per share and potential common shares are as follows (in thousands, except for per share data): Fiscal Year Ended March 31, 2021 2020 2019 Numerator: Net income (loss) $ 19,352 $ (2,754) $ (73,324) Denominator: Denominator for basic net income (loss) per share - weighted average common shares outstanding 73,103 75,162 78,617 Dilutive common equivalent shares: Weighted average restricted stock units 719 — — Denominator for diluted net income (loss) per share - weighted average shares outstanding 73,822 75,162 78,617 Net income (loss) per share: Basic net income (loss) per share $ 0.26 $ (0.04) $ (0.93) Diluted net income (loss) per share $ 0.26 $ (0.04) $ (0.93) The following table sets forth restricted stock units excluded from the calculation of diluted net income per share, since their inclusion would be antidilutive (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Restricted stock units 2,864 675 706

TREASURY STOCK

TREASURY STOCK	12 Months Ended
	Mar. 31, 2021
Equity [Abstract]
TREASURY STOCK	TREASURY STOCK On October 24, 2017, the Company’s Board of Directors approved a share repurchase program that enables the Company to repurchase up to twenty-five million shares of its common stock. This program became effective once the Company’s previously disclosed twenty million share repurchase program was completed. The Company is not obligated to acquire any specific amount of common stock within any particular timeframe as a result of this share repurchase program. On February 1, 2018, the Company entered into ASR agreements with two third-party financial institutions to repurchase an aggregate of $300 million of the Company's common stock via accelerated stock repurchase transactions under the Company’s twenty million share repurchase program and the twenty-five million share repurchase program. During the fiscal year ended March 31, 2018, the Company received an initial delivery of 7,387,862 shares for $210.0 million, of which 970,650 shares were deducted from the twenty million share repurchase program and 6,417,212 shares were deducted from the twenty-five million share repurchase program. During the fiscal year ended March 31, 2019, final settlement of the ASR agreements was completed and as a result, the Company received an additional 3,679,947 shares of its common stock for $96.8 million, which reduced the number of shares available to be purchased from the twenty-five million share repurchase program during the fiscal year ended March 31, 2019. In total, 11,067,809 shares of the Company's common stock were repurchased under the ASR at an average cost per share of $27.11. The Company repurchased an additional 154,271 shares for $3.3 million, 7,116,159 shares for $175.0 million, and 543,251 shares for $14.5 million under the twenty-five million share repurchase program during the fiscal years ended March 31, 2021, 2020 and 2019, respectively. At March 31, 2021, 7,089,160 shares of common stock remained available to be purchased under the current repurchase program. In connection with the vesting and release of the restriction on previously vested shares of restricted stock, the Company repurchased 506,917 shares for $13.3 million, 519,241 shares for $11.9 million and 451,683 shares for $11.9 million related to minimum statutory tax withholding requirements on these restricted stock units during the fiscal years ended March 31, 2021, 2020 and 2019, respectively. These repurchase transactions do not fall under the repurchase program described above, and therefore do not reduce the amount that is available for repurchase under those programs.

STOCK PLANS

STOCK PLANS	12 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
STOCK PLANS	STOCK PLANS 2011 Employee Stock Purchase Plan On September 7, 2011, the Company's stockholders approved the 2011 Employee Stock Purchase Plan (the ESPP), under which 2,500,000 shares of the Company's common stock have been reserved for issuance. On November 8, 2018, the Company increased the number of shares available under the ESPP by an additional 3,000,000 shares. The Company implemented the ESPP on March 1, 2012. Eligible employees may purchase shares of the Company's common stock through regular payroll deductions of up to 20% of their eligible compensation. Under the terms of the offering under the ESPP, the number of shares of the Company's common stock which a participant could purchase during any purchase period is limited to 2,000. In addition, the fair market value of shares purchased by an individual participant in the plan may not exceed $25,000 if the contribution period is within any calendar year. However, if contribution periods overlap calendar years, an individual participant is eligible to utilize the unused portion of the $25,000 limit from the subsequent purchase in the current purchase up to $50,000. Under the ESPP, shares of the Company's common stock may be purchased on the last day of each bi-annual offering period at 85% of the fair market value on the last day of such offering period. The offering periods run from March 1 through August 31 and from September 1 through the last day of February of each year. During the fiscal year ended March 31, 2021, employees purchased 561,669 shares under the ESPP with a weighted average purchase price per share of $25.69. At March 31, 2021, 1,751,813 shares were available for future issuance under the ESPP. 2019 Equity Incentive Plan On September 12, 2019, the Company's stockholders approved the 2019 Equity Incentive Plan (2019 Plan), which replaced the Company's Amended 2007 Plan. The 2019 Plan permits the granting of incentive and nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, and other stock awards, collectively referred to as "share-based awards." Periodically, the Company grants share-based awards to employees and officers of the Company and its subsidiaries. The Company accounts for these share-based awards in accordance with GAAP, which requires the measurement and recognition of compensation expense based on estimated fair values for all share-based payment awards made to its employees and directors. Share-based award grants are generally measured at fair value on the date of grant based on the number of shares granted and the quoted price of the Company's common stock. Such value is recognized as a cost of revenue or an operating expense over the corresponding vesting period. At September 12, 2019, there was a total of 6,794,651 shares reserved for issuance under the 2019 Plan, which consisted of 5,500,000 new shares plus 1,294,651 shares that remained available for grant under the Amended 2007 Plan as of September 12, 2019, the effective date of the 2019 Plan. On September 10, 2020, the Company's stockholders approved an amendment to the 2019 Equity Incentive Plan (2019 Amended Plan). The amendment increased the number of shares reserved for issuance by 4,700,000 shares, established a one-year minimum vesting requirement for awards granted on or after September 10, 2020, and changed the factor used to calculate the increase or reduction in the number of shares available for issuance under the 2019 Amended Plan. At September 10, 2020, there was a total of 7,667,262 shares reserved for issuance under the 2019 Amended Plan, which consisted of 4,700,000 new shares plus 2,967,262 shares that remained available for grant under the 2019 Plan as of September 10, 2020, the effective date of the 2019 Amended Plan. The aggregate number of shares available for issuance under the 2019 Amended Plan will increase by 1.00 share for each share of common stock returned to the 2019 Amended Plan pursuant to a stock option or stock appreciation right and increase for each share: (i) subject to an award granted under the Amended 2007 Plan or 2019 Amended Plan that are not issued because such award expires or otherwise terminates without all of the shares covered by such award having been issued; (ii) any shares subject to an award under the Amended 2007 Plan or 2019 Amended Plan that are not issued because such award is settled in cash; (iii) any shares issued pursuant to an award granted under the Amended 2007 Plan or 2019 Amended Plan that are forfeited back to or repurchased by the Company because of failure to vest; and (iv) any shares that are reacquired or withheld by the Company to satisfy tax withholding obligations in connection with common stock issued pursuant to restricted stock, restricted stock units, performance stock awards, or other stock awards granted under the Amended 2007 Plan and 2019 Amended Plan by 2.76 for awards that are returned to the 2019 Amended Plan prior to September 10, 2020 and by 2.32 shares for awards that are returned to the 2019 Amended Plan on or after September 10, 2020. Furthermore, the share reserve under the 2019 Amended Plan is reduced by one share for each share of common stock issued pursuant to a stock option or stock appreciation right, 2.76 shares for each share of common stock issued pursuant to restricted stock, restricted stock units, performance stock awards, or other stock awards granted under the 2019 Amended Plan on or after September 12, 2019 but prior to September 10, 2020 and 2.32 shares for each share of common stock issued pursuant to restricted stock, restricted stock units, performance stock awards, or other stock awards after September 10, 2020. At March 31, 2021, an aggregate of 4,495,613 shares of unvested equity awards were outstanding under the 2019 Amended Plan. The 2019 Amended Plan is administered by the Compensation Committee of the Board of Directors. The Compensation Committee operates under guidelines established by the Board of Directors. The Compensation Committee has the authority to select the employees and consultants to whom awards are granted (except for directors and executive officers) and determine the terms of each award, including the number of shares of common stock subject to the award. Share-based awards generally vest over four years. The exercise price of stock options shall not be less than 100% of the fair market value of the common stock at the date of grant (110% for incentive stock options granted to holders of more than 10% of the voting stock of NetScout). The term of stock options granted cannot exceed seven years (five years for incentive stock options granted to holders of more than 10% of the voting stock of NetScout). Based on historical experience, the Company assumed an annualized forfeiture rate of 0% for awards granted to its independent directors, approximately 2% for awards granted to its senior executives, and approximately 5% granted to all remaining employees during the fiscal years ended March 31, 2021, 2020 and 2019. The following is a summary of share-based compensation expense including restricted stock units and employee stock purchases made under the Company's employee stock purchase plan (ESPP) based on estimated fair values within the applicable cost and expense lines identified below (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Cost of product revenue $ 1,038 $ 1,069 $ 1,463 Cost of service revenue 5,823 5,774 5,959 Research and development 16,138 15,511 17,321 Sales and marketing 17,328 17,085 18,923 General and administrative 11,565 11,422 12,662 $ 51,892 $ 50,861 $ 56,328 Transactions under the Amended 2007, 2019 Plan and 2019 Amended Plan during the fiscal years ended March 31, 2021, 2020 and 2019 are summarized in the table below. Restricted Stock Units Number of Weighted Outstanding – March 31, 2018 4,078,780 $ 31.77 Granted 2,178,339 30.10 Vested (1,438,219) 32.49 Canceled (608,245) 30.52 Outstanding – March 31, 2019 4,210,655 $ 30.84 Granted 2,062,110 26.32 Vested (1,651,284) 31.03 Canceled (347,008) 29.74 Outstanding – March 31, 2020 4,274,473 $ 28.68 Granted 2,038,681 27.42 Vested (1,630,228) 28.63 Canceled (187,313) 28.28 Outstanding – March 31, 2021 4,495,613 $ 28.14 At March 31, 2021, there were 7,868,290 shares of common stock available for grant under the 2019 Amended Plan. The Company does not currently expect to repurchase shares from any source to satisfy its obligations under the 2019 Amended Plan. The aggregate intrinsic value of stock options exercised and the fair value of restricted stock units vested at March 31, 2021, 2020 and 2019 were as follows (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Total fair value of restricted stock unit awards vested $ 42,510 $ 37,783 $ 38,070 At March 31, 2021, the total unrecognized compensation cost related to restricted stock unit awards was $94.8 million, which is expected to be amortized over a weighted-average period of 1.3 years.

PENSION BENEFIT PLANS

PENSION BENEFIT PLANS	12 Months Ended
	Mar. 31, 2021
Retirement Benefits [Abstract]
PENSION BENEFIT PLANS	PENSION BENEFIT PLANS 401(k) Plan The Company has a defined contribution program for certain employees that is qualified under Section 401(k) of the Internal Revenue Code of 1986, as amended. The Company matches 50% of the employee's contribution up to 6% of the employee’s salary. NetScout contributions vest at a rate of 25% per year of service. NetScout made matching contributions of $6.7 million, $6.7 million and $6.6 million to the plan for the fiscal years ended March 31, 2021, 2020 and 2019, respectively. Defined Benefit Pension Plan Certain of the Company's non-U.S. employees participate in certain noncontributory defined benefit pension plans. None of the Company's employees in the U.S. participate in any noncontributory defined benefit pension plans. In general, these plans are funded based on considerations relating to legal requirements, underlying asset returns, the plan's funded status, the anticipated deductibility of the contribution, local practices, market conditions, interest rates and other factors. The components of the change in benefit obligation of the pension plan is as follows (in thousands): March 31, March 31, 2021 2020 Benefit obligation, at beginning of year $ 32,805 $ 34,895 Service cost 333 341 Interest cost 667 603 Benefits paid and other (400) (359) Actuarial loss (gain) 2,205 (1,644) Foreign exchange rate impact 1,976 (1,031) Benefit obligation, at end of year $ 37,586 $ 32,805 The reconciliation of the beginning and ending balances of the fair value of the assets of the pension plan is as follows (in thousands): March 31, March 31, 2021 2020 Fair value of plan assets, at beginning of year $ — $ — Employer direct benefit payments 400 359 Benefits paid and other (400) (359) Fair value of plan assets, at end of year $ — $ — The following sets forth the components of the Company's net periodic pension cost of the noncontributory defined benefit pension plans for the fiscal years ended March 31, 2021, 2020, and 2019 (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Service cost $ 333 $ 341 $ 304 Interest cost 667 603 704 Net periodic pension cost $ 1,000 $ 944 $ 1,008 Weighted average assumptions used to determine net periodic pension cost at date of measurement: March 31, March 31, March 31, 2021 2020 2019 Discount rate 1.60 % 1.90 % 1.80 % Rate of compensation increase 3.00 % 3.00 % 3.00 % As of March 31, 2021, unrecognized actuarial loss of $2.2 million ($1.5 million, net of tax) which have not yet been recognized in net periodic pension cost are included in accumulated other comprehensive income (loss). The unrecognized actuarial gains and losses are calculated as the difference between the actuarially determined projected benefit obligation and the value of the plan assets less accrued pension costs. None of this amount is expected to be recognized in net periodic pension costs during the fiscal year ending March 31, 2021. No plan assets are expected to be returned to the Company during the fiscal year ending March 31, 2021. Expected Contributions During the fiscal year ended March 31, 2021, the Company contributed $400 thousand to its defined benefit pension plan. The following sets forth benefit payments, which reflect expected future service, as appropriate, expected to be paid by the plan in the periods indicated (in thousands): 2022 $ 485 2023 $ 553 2024 $ 605 2025 $ 716 2026 $ 932 2027 - 2031 $ 5,656

INCOME TAXES

INCOME TAXES	12 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Income (loss) before income tax expense (benefit) consisted of the following (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Domestic $ 4,985 $ (1,502) $ (107,088) Foreign 17,319 3,426 14,176 $ 22,304 $ 1,924 $ (92,912) The components of the income tax expense (benefit) are as follows (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Current income tax expense: Federal $ 14,701 $ 2,817 $ 3,902 State 2,426 1,850 (136) Foreign 9,902 9,712 10,618 27,029 14,379 14,384 Deferred income tax benefit: Federal (18,190) (5,287) (25,347) State (3,404) (2,897) (3,845) Foreign (2,483) (1,517) (4,780) (24,077) (9,701) (33,972) $ 2,952 $ 4,678 $ (19,588) The income tax expense (benefit) computed using the federal statutory income tax rate differs from NetScout's effective tax rate primarily due to the following: Fiscal Year Ended March 31, 2021 2020 2019 Statutory U.S. federal tax rate 21.0 % 21.0 % 21.0 % State taxes, net of federal tax effect 2.1 (47.8) 3.4 U.S. research and development tax credits (23.7) (245.9) 7.1 Effect of foreign operations (5.3) (66.9) (0.1) Meals and entertainment 0.7 43.7 (1.0) Change in valuation allowance 24.0 250.0 2.2 Internal restructuring charges — 196.5 — Stock compensation 5.2 172.1 (2.6) Divestiture — — (1.0) GILTI/FDII (20.2) (174.3) 2.9 BEAT — — (7.0) 2017 Tax Act (transition tax and re-measurement of deferreds) — — 0.4 Foreign withholding 13.8 220.6 (3.1) Provision to return (2.3) (152.8) (1.0) Other permanent differences (2.1) 26.9 (0.1) 13.2 % 243.1 % 21.1 % The components of net deferred tax assets and liabilities are as follows (in thousands): Fiscal Year Ended March 31, 2021 2020 Deferred tax assets: Accrued expenses $ 8,480 $ 5,060 Deferred revenue 17,648 14,420 Reserves 2,898 3,216 Pension and other retiree benefits 6,160 5,078 Net operating loss carryforwards 11,526 12,443 Tax credit carryforwards 19,432 14,138 Share-based compensation 5,397 4,534 Operating lease liability 17,333 18,213 Other deferred tax assets 2,116 20 Total gross deferred tax assets 90,990 77,122 Valuation allowance (11,406) (5,641) Net deferred tax assets 79,584 71,481 Deferred tax liabilities: Intangible assets (132,635) (146,950) Other deferred tax liabilities (8,848) (8,061) Operating lease right-of-use asset (14,474) (15,152) Depreciation (7,818) (9,492) Total deferred tax liability $ (84,191) $ (108,174) Deferred tax assets and liabilities are recognized based on the anticipated future tax consequences, attributable to differences between financial statement carrying amounts of assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates in effect for the year in which the differences are expected to reverse. The Company evaluates the recoverability of deferred tax assets by considering all positive and negative evidence relating to future profitability. The Company weighs objective and verifiable evidence more heavily in this analysis. In situations where the Company concludes that it does not have sufficient objective and verifiable evidence to support the realizability of the asset it creates a valuation allowance against it. As a result, the Company established a valuation allowance of $5.6 million as of March 31, 2020 and $11.4 million as of March 31, 2021, repres enting an increase of $5.8 million. The increase in the valuation allowance as of March 31, 2021, as compared to March 31, 2020, is primarily due to deferred tax assets related to U.S. foreign tax credits that the Company believes are not more likely than not to be realized. If it is later determined the Company is able to use all or a portion of the deferred tax assets for which a valuation allowance has been established, then the Company may be required to recognize these deferred tax assets as a tax benefit recorded in the period such determination is made. At March 31, 2021, the Company had U.S. federal net operating loss carry forwards of approximately $11 million, state net operating loss carryforwards of approximately $44 million and tax credit carryforwards of approximately $15 million. The net operating loss and credit carryforwards will expire at various dates beginning in 2026. The Company also had foreign net operating loss carryforwards of approximately $45 million at March 31, 2021 and foreign tax credit carryforwards of approximately $7 million. The majority of foreign net operating losses have no expiration dates. Utilization of the U.S. net operating losses and credits are subject to an annual limitation due to the ownership change limitations provided by the Internal Revenue Code of 1986, as amended, and similar state tax provisions. The Company files U.S. federal tax returns and files returns in various state, local and foreign jurisdictions. With respect to the U.S. federal and primary state jurisdictions, the Company is no longer subject to examinations by tax authorities for tax years before 2016, although carryforward attributes that were generated prior to 2016 may still be adjusted upon examination if they either have been or will be used in a future period. The Company also receives inquiries from various tax jurisdictions during the year, and some of those inquiries may include an audit of the tax return previously filed. In the normal course of business, NetScout and its subsidiaries are examined by various taxing authorities, including the IRS in the United States. A reconciliation of the beginning and ending amount of gross unrecognized tax benefits, excluding interest and penalties, for the fiscal years ended March 31, 2021, 2020 and 2019 is as follows (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Balance at April 1, $ 1,151 $ 1,314 $ 2,215 Additions based on tax positions related to the current year 48 49 28 Release of tax positions of prior years (286) (212) (194) Decrease relating to settlements with taxing authorities — — (735) Balance at March 31, $ 913 $ 1,151 $ 1,314 The Company is unable to make a reliable estimate when cash settlement, if any, will occur with a tax authority as the timing of examinations and ultimate resolution of those examinations is uncertain. All of the unrecognized tax benefits would affect the effective tax rate if recognized. The Company includes interest and penalties accrued in the consolidated financial statements as a component of the tax provision. During fiscal year 2019, the Company completed its analysis and recording of all the tax effects related to the Tax Cuts and Jobs Act (TCJA), as required under SAB 118, and recorded a benefit of $87.0 million due to the re-measurement of its deferred taxes and a $2.0 million one-time transition tax. The Company is subject to a territorial tax system under the TCJA, in which we are required to provide for tax on Global Intangible Low-Taxed Income (GILTI) earned by certain foreign subsidiaries. The Company has established an accounting policy to provide for GILTI as a tax expense in the year incurred. The Company continues to assert that certain historical book over tax outside basis differences primarily related to foreign unremitted earnings and cumulative translation adjustments are permanently reinvested. The determination of the amount of unrecognized deferred tax liability related to such outside basis differences is not practicable due to the uncertainty in the manner and timing in which such differences become taxable and is dependent upon various circumstances and factors, including availability of tax planning. The Company's intent is to only make distributions from its foreign subsidiaries in the future when they can be made at no or immaterial net tax cost.

LEASES

LEASES	12 Months Ended
	Mar. 31, 2021
Leases [Abstract]
LEASES	LEASES In February 2016, the FASB issued ASC 842 to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The Company adopted the guidance on April 1, 2019 using the modified retrospective method and as a result did not adjust comparative periods or modify disclosures in those comparative periods. The new guidance provides a number of optional practical expedients in transition. The Company elected the package of practical expedients, which does not require the reassessment of prior conclusions about lease identification, lease classification and initial direct costs. Further, the Company elected the practical expedients to combine lease and non-lease components, and to not recognize right-of-use (ROU) assets and lease liabilities for short-term leases. Leases with an initial term of 12 months or less are classified as short-term leases. The Company did not elect the hindsight practical expedient to determine the lease term for existing leases. The adoption of ASC 842 on April 1, 2019 resulted in the recognition of operating lease ROU assets of approximately $68.2 million, operating lease liabilities of approximately $83.2 million and the elimination of deferred rent of approximately $15.0 million. Operating leases are included in operating lease ROU assets and lease liabilities on the Company’s balance sheets. The adoption of ASC 842 did not have a material impact on the Company’s consolidated statement of operations, consolidated statement of stockholders' equity, consolidated statement of comprehensive income (loss) or consolidated statement of cash flows. The new standard had no material impact on liquidity and had no impact on the Company’s debt-covenant compliance under its current debt agreements. The Company determines if an arrangement is a lease at inception. Right-of-use (ROU) assets represent the Company's right to use an underlying asset for the duration of the lease term. Lease liabilities represent the Company's contractual obligation to make lease payments over the lease term. ROU assets are recorded and recognized at commencement for the lease liability amount, plus initial direct costs incurred less lease incentives received. Lease liabilities are recorded at the present value of future lease payments over the lease term at commencement. The discount rate used is generally the Company's estimated incremental borrowing rate unless the lessor's implicit rate is readily determinable. Incremental borrowing rates are calculated periodically to estimate the rate the Company would pay to borrow the funds necessary to obtain an asset of similar value over a similar term. Lease expenses relating to operating leases are recognized on a straight-line basis over the lease term. The Company has operating leases for administrative, research and development, sales and marketing and manufacturing facilities and equipment under various non-cancelable lease agreements. The Company's leases have remaining lease terms ranging from 1 year to 10 years. The Company's lease terms may include options to extend or terminate the lease where it is reasonably certain that the Company will exercise those options. The Company considers several economic factors when making this determination, including but not limited to, the significance of leasehold improvements incurred in the office space, the difficulty in replacing the asset, underlying contractual obligations, or specific characteristics unique to a particular lease. The Company's lease agreements do not contain any material residual value guarantees or material restrictive covenants. Most of the Company's lease agreements contain variable payments, primarily for common area maintenance (CAM), which are expensed as incurred and not included in the measurement of the ROU assets and lease liabilities. The components of operating lease cost for the fiscal years ended March 31, 2021 and 2020 were as follows (in thousands): Fiscal Year Ended March 31, 2021 2020 Lease cost under long-term operating leases $ 13,092 $ 13,318 Lease cost under short-term operating leases 3,678 4,172 Variable lease cost under short-term and long-term operating leases 3,800 4,259 Total operating lease cost $ 20,570 $ 21,749 The table below presents supplemental cash flow information related to leases during the fiscal years ended March 31, 2021 and 2020 (in thousands): Fiscal Year Ended March 31, 2021 2020 Right-of-use assets obtained in exchange for new operating lease liabilities $ 2,492 $ 11,127 At March 31, 2021 and 2020, the weighted average remaining lease term in years and weighted average discount rate were as follows: March 31, 2021 March 31, 2020 Weighted average remaining lease term in years - operating leases 7.70 8.59 Weighted average discount rate - operating leases 4.1 % 4.1 % Future minimum payments under non-cancellable leases at March 31, 2021 are as follows (in thousands): Year Ending March 31, 2022 $ 14,085 2023 12,890 2024 10,299 2025 10,098 2026 9,087 Thereafter 29,286 Total lease payments $ 85,745 Less imputed interest (12,124) Present value of lease liabilities $ 73,621

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Acquisition- and Divestiture-Related The Company's Level 3 liabilities at March 31, 2021 consisted of contingent purchase consideration related to the two acquisitions that occurred during the fiscal year 2020. The contingent purchase consideration related to the two acquisitions represent amounts deposited into escrow accounts, which were established to cover damages NetScout may have suffered related to any liabilities that NetScout did not agree to assume or as a result of the breach of representations and warranties of the sellers as described in the acquisition agreements. The contingent purchase consideration of $0.7 million and $1.0 million related to the Gigavation and Eastwind acquisitions, respectively were included as accrued other in the Company's consolidated balance sheet at March 31, 2020. The $0.7 million related to the Gigavation acquisition was paid to the seller in February 2021. The $1.0 million related to the Eastwind acquisition was paid to the seller in April 2020. During fiscal year 2019, the Company paid $0.5 million and $5.0 million of contingent liabilities to the sellers of Efflux Systems, Inc. (Efflux) and Simena, LLC (Simena), respectively related to prior acquisitions. Legal From time to time, NetScout is subject to legal proceedings and claims in the ordinary course of business. In the opinion of management, the amount of ultimate expense with respect to any current legal proceedings and claims, if determined adversely, will not have a material adverse effect on the Company's financial condition, results of operations or cash flows. As previously disclosed, in March 2016, Packet Intelligence LLC (Packet Intelligence or Plaintiff) filed a Complaint against NetScout and two subsidiary entities in the United States District Court for the Eastern District of Texas asserting infringement of five United States patents. Plaintiff's Complaint alleged that legacy Tektronix GeoProbe products, including the G10 and GeoBlade products, infringed these patents. NetScout filed an Answer denying Plaintiff's allegations and asserting that Plaintiff's patents were, among other things, invalid, not infringed, and unenforceable due to inequitable conduct. In October 2017, a jury trial was held to address the parties' claims and counterclaims regarding infringement of three patents by the G10 and GeoBlade products, invalidity of these patents, and damages. On October 13, 2017, the jury rendered a verdict finding in favor of the Plaintiff and that Plaintiff was entitled to $3,500,000 for pre-suit damages and $2,250,000 for post-suit damages. The jury indicated that the awarded damages amounts were intended to reflect a running royalty. In September 2018, the Court entered judgment and "enhanced" the jury verdict in the amount of $2.8 million as a result of a jury finding. The judgment also awards pre- and post-judgment interest, and a running royalty on the G10 and GeoBlade products until the expiration of the patents at issue, the last date being June 2022. Following the entry of final judgment, on June 12, 2019, NetScout filed its Notice of Appeal. On July 14, 2020, the Court of Appeals for the Federal Circuit issued a decision vacating the $3,500,000 pre-suit damages award, affirming the $2,250,000 post-suit damages award, and remanding to the district court to determine what, if any, enhancement should be awarded. On March 15, 2021, NetScout filed a petition for a writ of certiorari to the United States Supreme Court, which was subsequently denied, challenging, among other issues, the basis for enhanced damages and the patentability of the claimed technology. NetScout continues to avail itself of its legal options. NetScout has concluded that the risk of loss associated with the post-suit damages award is "probable" in accounting terms, regardless of the options NetScout may pursue, and that the risk of loss associated with pre-suit damages is now remote. Accounting rules require NetScout to provide an estimate for the range of potential liability. NetScout currently estimates that the range of liability is the sum of post-suit damages, plus pre- and post-judgment interest amounts and royalties owed on post-trial sales of the accused G10 and GeoBlade products. Any potential enhancement is not reasonably estimable but is likely within the range of $0 to $2,800,000. Unconditional Purchase Obligations

SEGMENT AND GEOGRAPHIC INFORMAT

SEGMENT AND GEOGRAPHIC INFORMATION	12 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
SEGMENT AND GEOGRAPHIC INFORMATION	SEGMENT AND GEOGRAPHIC INFORMATION The Company manages its business in the following geographic areas: United States, Europe, Asia and the rest of the world. The Company's policies mandate compliance with economic sanctions and export controls. The Company reports revenues and income under one reportable segment. Total revenue by geography is as follows (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 United States $ 484,129 $ 545,620 $ 553,267 Europe 160,372 154,510 148,036 Asia 56,562 59,939 72,355 Rest of the world 130,219 131,751 136,260 $ 831,282 $ 891,820 $ 909,918 The United States revenue includes sales to resellers in the United States. These resellers fulfill customer orders and may subsequently ship the Company's products to international locations. Further, the Company determines the geography of its sales after considering where the contract originated. A majority of revenue attributable to locations outside of the United States is a result of export sales. Substantially all of the Company's identifiable assets are located in the United States.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Mar. 31, 2021
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	NetScout Systems, Inc. Schedule II—Valuation and Qualifying Accounts (in thousands) Balance at Additions Charges to Deductions Balance at Fiscal year ended March 31, 2019 Allowance for credit losses $ 1,991 $ 826 $ (464) $ (770) $ 1,583 Deferred tax asset valuation allowance $ 3,108 $ 905 $ — $ (3,178) $ 835 Fiscal year ended March 31, 2020 Allowance for credit losses $ 1,583 $ 1,450 $ (1,202) $ (481) $ 1,350 Deferred tax asset valuation allowance $ 835 $ 4,806 $ — $ — $ 5,641 Fiscal year ended March 31, 2021 Allowance for credit losses $ 1,350 $ 48 $ (733) $ (249) $ 416 Deferred tax asset valuation allowance $ 5,641 $ 5,765 $ — $ — $ 11,406

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Principles of Consolidation	Principles of ConsolidationThe consolidated financial statements include the accounts of NetScout and its wholly owned subsidiaries. Inter-company transactions and balances have been eliminated in consolidation.
Segment Reporting	Segment Reporting The Company's operating segments are determined based on the units that constitute a business for which financial information is available and for which operating results are regularly reviewed by the Chief Operating Decision Maker (CODM). The Company reports revenue and income in 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, valuation of contingent consideration 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. The Company considered the impact of the COVID-19 pandemic on the use of estimates and assumptions used for financial reporting. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company's business, results of operations and financial condition, including sales, expenses, reserves and allowances, manufacturing, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain it or treat COVID-19, as well as the economic impact on local, regional, national and international customers and markets. The Company has made estimates within our financial statements and there may be changes to those estimates in future periods. Actual results may differ from these estimates.
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 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, 2021 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 the Company believes are those institutions with an investment grade rating for deposits.
Revenue Recognition	Revenue RecognitionThe Company accounts for revenue in accordance with ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which was adopted on April 1, 2018 using the modified retrospective transition method. Revenue from Contracts with Customers In May 2014, the FASB issued Topic 606, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. Topic 606 replaced most existing revenue recognition guidance under GAAP. The new standard introduces a five-step process to be followed in determining the amount and timing of revenue recognition. It also provides guidance on accounting for costs incurred to obtain or fulfill contracts with customers and establishes disclosure requirements which are more extensive than those required under prior GAAP. Topic 606 became effective for the Company on April 1, 2018. The Company elected to use the modified retrospective transition approach. Therefore, the comparative financial information has not been restated and continues to be reported under the accounting standards in effect for those periods. Revenue Recognition Policy The Company exercises judgment and uses estimates in connection with determining the amounts of product and service 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 Company's product sales consist of software only offerings and offerings which include hardware appliances with embedded software that are essential to providing customers the intended functionality of the solutions. The Company accounts for revenue once a legally enforceable contract with a customer has been approved by the parties and the related promises to transfer products or services have been identified. A contract is defined by the Company as an arrangement with commercial substance identifying payment terms, each party’s rights and obligations regarding the products or services to be transferred and the amount the Company deems probable of collection. Customer contracts may include promises to transfer multiple products and services to a customer. Determining whether the products and services are considered distinct performance obligations that should be accounted for separately or as one combined performance obligation may require significant judgment. Revenue is recognized when control of the products or services are transferred to the Company's customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for products and services. Product revenue is typically recognized upon shipment, provided a legally enforceable contract exists, control has passed to the customer, and in the case of software products, when the customer has the rights and ability to access the software; and collection of the related receivable is probable. 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. The Company's service offerings include installation, integration, extended warranty and maintenance services, post-contract customer support, stand-ready software-as-a-service (SAAS) 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, bug fixes and hardware repair and replacement. Consulting services are recognized upon delivery or completion of performance depending on the terms of the underlying contract. 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. Bundled 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. The Company allocates the transaction price among the performance obligations in an amount that depicts the relative standalone selling prices (SSP) of each obligation. Judgment is required to determine the SSP for each distinct performance obligation. The Company uses a range of amounts to estimate SSP when it sells each of the products and services separately based on the element’s historical pricing. The Company also considers its overall pricing objectives and practices across different sales channels and geographies, and market conditions. Generally, the Company has established SSP for a majority of its service elements based on historical standalone sales. In certain instances, the Company has established SSP for services based upon an estimate of profitability and the underlying cost to fulfill those services. Further, for certain service engagements, the Company considers quoted prices as part of multi-element arrangements of those engagements as a basis for establishing SSP. SSP has been established 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 reviews sales of the product elements on a quarterly basis and updates, when appropriate, its SSP for such elements to ensure that it reflects recent pricing experience. The Company's products are distributed through its direct sales force and indirect distribution channels through alliances with resellers and distributors. Revenue arrangements with resellers and distributors are recognized on a sell-in basis; that is, when control of the product transfers to the reseller or distributor. The Company records consideration given to a customer as a reduction of revenue to the extent they have recorded revenue from the customer. 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 its resellers and distributors.
Commission Expense	Commission Expense Sales commissions are recorded as an asset when the initial contract's duration is longer than 12 months and amortized to expense ratably over the remaining performance periods of the related contracts.
Uncollected Deferred Revenue	Uncollected Deferred RevenueBecause 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 because control of the underlying deliverable has not transferred.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentration of credit risk consist primarily of investments, trade accounts receivable and accounts payable. NetScout's cash, cash equivalents, and marketable securities are placed with financial institutions with high credit standings. At March 31, 2021 , the Company had one direct customer who accounted for more than 10% of the accounts receivable balance, while no indirect channel partners accounted for more than 10% of the accounts receivable balance. At March 31, 2020 , the Company had no direct customers or indirect channel partners which accounted for more than 10% of the accounts receivable balance. During the fiscal ye ars ended March 31, 2021, 2020 and 2019 respectively, no direct customers or indirect channel partners accounted for more than 10% of total rev enue. Historically, the Company has not experienced any significant failure of its customers to meet their payment obligations nor does the Company anticipate material non-performance by its customers in the future; accordingly, the Company does not
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.
Leases	Leases The Company accounts for leases in accordance with ASU No. 2016-02, Leases (Topic 842), which was adopted April 1, 2019. Prior to the adoption of Topic 842, the Company followed the guidance for leases under Topic 840, Leases. For further discussion of the Company's policies related to leases see Note 18, "Leases." The Company has operating leases for administrative, research and development, sales and marketing and manufacturing facilities and equipment under various non-cancelable lease agreements. Lease commencement occurs on the date the Company takes possession or control of the property or equipment. The Company's lease terms may include options to extend or terminate the lease where it is reasonably certain that the Company will exercise those options. The Company considers several economic factors when making this determination, including but not limited to, the significance of leasehold improvements incurred in the office space, the difficulty in replacing the asset, underlying contractual obligations, or specific characteristics unique to a particular lease. The Company's lease agreements do not contain any material residual value guarantees or material restrictive covenants.
Valuation of Goodwill, Intangible Assets and Other Acquisition and Divestiture Accounting Items	Valuation of Goodwill, Intangible Assets and Other Acquisition and Divestiture 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. Reporting units are determined based on the components of a Company's operating segments that constitute a business for which financial information is available and for which operating results are regularly reviewed by segment management. The Company has one reporting unit. 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 fourth quarter of fiscal year 2021, the Company performed its annual impairment analysis for goodwill as of January 31, 2021, using the qualitative Step 0 assessment as the Company concluded that it was more likely than not that the fair value of the reporting unit exceeded its carrying value. Indefinite-lived intangible assets are tested for impairment 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 indefinite-lived intangible assets 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 is impaired. If based on the Company's qualitative assessment, the Company concludes that it is more likely than not that the fair value of the indefinite- lived 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 the fourth quarter of fiscal year 2021, the Company completed its annual impairment test of the indefinite-lived intangible at January 31, 2021, using the qualitative Step 0 assessment as the Company concluded that it was more likely than not that the fair value of the indefinite-lived asset exceeded its carrying value. The Company completed two acquisitions and one divestiture during the three-year period ended March 31, 2021. 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 either an income, market or cost method approach. The Company's level 3 liabilities at March 31, 2020 consisted of contingent purchase consideration related to the two acquisitions that occurred during the fiscal year 2020. The contingent purchase consideration related to the two acquisitions represent amounts deposited into escrow accounts, which were established to cover damages NetScout may have suffered related to any liabilities that NetScout did not agree to assume or as a result of the breach of representations and warranties of the sellers as described in the acquisition agreements. The contingent purchase consideration of $0.7 million and $1.0 million related to the Gigavation Incorporated (Gigavation) and Eastwind Networks, Inc. (Eastwind) acquisitions, respectively are included as accrued other in the Company's consolidated balance sheet at March 31, 2020. The $0.7 million related to the Gigavation acquisition was paid to the seller in February 2021. The $1.0 million related to the Eastwind acquisition was paid to the seller in April 2020. During fiscal year 2019, the Company recorded a contingent consideration related to the divestiture of the Company's handheld network test (HNT) tools business in September 2018. The contingent consideration represented potential future earnout payments to the Company of up to $4.0 million over two years that were contingent on the HNT tools business achieving certain milestones. The fair value of the contingent consideration of $2.3 million was recognized on the divestiture date and was measured using unobservable (Level 3) inputs. The Company recorded an $0.8 million and a $1.6 million change in the fair value of the contingent consideration, which is included in other expense, net within the Company's consolidated statement of operations for the years ended March 31, 2020 and 2019.
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 expenses 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. NetScout also periodically enters into forward contracts to manage exchange rate risk associated with certain third-party transactions and for which the Company does not elect hedge accounting treatment as there is no difference in the timing of gain or loss recognition on the hedge instrument and the hedged item.
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 its 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, Netscout discloses 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. Contingent assets and liabilities include contingent consideration in connection with the Company's acquisitions and divestitures. Contingent consideration represents earnout payments in connection with the Company's acquisitions and divestitures 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.
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 expected 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 NetScout's 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 U.S. 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.
Advertising Expense	Advertising ExpenseNetScout recognizes advertising expense as incurred.
Comprehensive Income (Loss)	Comprehensive Income (Loss)Comprehensive income (loss) consists of net income (loss) and other comprehensive income (loss). Other comprehensive income (loss) typically consists of unrealized gains and losses on marketable securities, unrealized gain and losses 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. NetScout evaluates the recoverability of deferred tax assets by considering all positive and negative evidence relating to future profitability. NetScout weighs objective and verifiable evidence more heavily in this analysis. In situations where NetScout concludes that it does not have sufficient objective and verifiable evidence to support the realizability of the deferred tax asset, NetScout creates a valuation allowance against it.
Recent Accounting Standards	Recent Accounting Standards In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. The amendments provide optional guidance for a limited time to ease the potential burden in accounting for reference rate reform. The new guidance provides optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. The amendments apply only to contracts and hedging relationships that reference LIBOR or another reference rate expected to be discontinued due to reference rate reform. In January 2021, the FASB issued ASU 2021-01, Reference Rate Reform, which clarifies the scope and application of certain optional expedients and exceptions regarding the original guidance. ASU 2021-01 may be applied prospectively through December 31, 2022. The expedients and exceptions provided by the amendments do not apply to contract modifications made and hedging relationships entered into or evaluated after December 31, 2022, that an entity has elected certain optional expedients for and that are retained through the end of the hedging relationship. The adoption is not expected to have a material impact on the Company's financial position, results of operations, and disclosures. In January 2020, the FASB issued ASU 2020-01, Investments-Equity Securities (Topic 321), Investments-Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815) - Clarifying the Interactions between Topic 321, Topic 323, and Topic 815. This guidance addresses accounting for the transition into and out of the equity method and provides clarification of the interaction of rules for equity securities, the equity method of accounting, and forward contracts and purchase options on certain types of securities. This standard is effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2020. Early adoption is permitted. ASU 2020-01 is effective for NetScout beginning April 1, 2021. The adoption is not expected to have a material impact on the Company's financial position, results of operations, and disclosures. In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes. ASU 2019-12 simplifies the accounting for income taxes, eliminates certain exceptions within ASC 740, Income Taxes, and clarifies certain aspects of the current guidance to promote consistency among reporting entities. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020. ASU 2019-12 is effective for NetScout beginning April 1, 2021. Most amendments within the standard are required to be applied on a prospective basis, while certain amendments must be applied on a retrospective or modified retrospective basis. The adoption is not expected to have a material impact on the Company's financial position, results of operations, and disclosures. In August 2018, the FASB issued ASU 2018-14, Compensation – Retirement Benefits – Defined Benefit Plans – General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans. This ASU adds, modifies and clarifies several disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The Company adopted the guidance as of April 1, 2020. The adoption did not have a material impact on the Company's consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. ASU 2018-13 adds, modifies and removes several disclosure requirements relative to the three levels of inputs used to measure fair value in accordance with Topic 820, Fair Value Measurement. The Company adopted the guidance as of April 1, 2020. The adoption did not have a material impact on the Company's consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13) and also issued subsequent amendments to the initial guidance: ASU 2018-19, ASU 2019-04, ASU 2019-05, ASU 2019-11 and ASU 2020-02 (collectively, Topic 326). Topic 326 requires measurement and recognition of expected credit losses for financial assets held. Topic 326 replaces the existing incurred loss impairment model with an expected loss methodology, which will result in more timely recognition of credit losses. The Company adopted the guidance prospectively as of April 1, 2020. The adoption did not result in a cumulative adjustment to retained earnings and did not have an impact on the Company's consolidated financial statements other than with respect to the updated disclosure requirements.

REVENUE RECOGNITION (Tables)

REVENUE RECOGNITION (Tables)	12 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Summary of Allowance for Doubtful Accounts	The following table summarizes the activity in the allowance for credit losses (in thousands): Balance at March 31, 2020 $ 1,350 Provision for allowance for credit losses 48 Recoveries and other adjustments (733) Write off charged against the allowance for credit losses (249) Balance at March 31, 2021 $ 416

CASH, CASH EQUIVALENTS AND MA_2

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES (Tables)	12 Months Ended
	Mar. 31, 2021
Cash and Cash Equivalents [Abstract]
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the consolidated statements of cash flows (in thousands): March 31, 2021 March 31, 2020 March 31, 2019 March 31, 2018 Cash and cash equivalents $ 467,176 $ 338,489 $ 409,632 $ 369,821 Restricted cash $ — 1,748 188 910 Total cash, cash equivalents and restricted cash $ 467,176 $ 340,237 $ 409,820 $ 370,731
Schedule of Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the consolidated statements of cash flows (in thousands): March 31, 2021 March 31, 2020 March 31, 2019 March 31, 2018 Cash and cash equivalents $ 467,176 $ 338,489 $ 409,632 $ 369,821 Restricted cash $ — 1,748 188 910 Total cash, cash equivalents and restricted cash $ 467,176 $ 340,237 $ 409,820 $ 370,731
Summary of Marketable Securities Classified as Short-term and Long-term	The following is a summary of marketable securities held by NetScout at March 31, 2021 classified as short-term and long-term (in thousands): Amortized Unrealized Fair Type of security: U.S. government and municipal obligations $ 3,571 $ 7 $ 3,578 Commercial paper 5,699 — 5,699 Total short-term marketable securities 9,270 7 9,277 Total long-term marketable securities — — — Total marketable securities $ 9,270 $ 7 $ 9,277 The following is a summary of marketable securities held by NetScout at March 31, 2020, classified as short-term and long-term (in thousands): Amortized Unrealized Fair Type of security: U.S. government and municipal obligations $ 28,621 $ 107 $ 28,728 Commercial paper 14,644 — 14,644 Corporate bonds 4,587 10 4,597 Total short-term marketable securities 47,852 117 47,969 U.S. government and municipal obligations 2,562 51 2,613 Total long-term marketable securities 2,562 51 2,613 Total marketable securities $ 50,414 $ 168 $ 50,582
Summary of Contractual Maturities of Marketable Securities	Contractual maturities of the Company's marketable securities held at March 31, 2021 and 2020 (in thousands) were as follows: March 31, March 31, Available-for-sale securities: Due in 1 year or less $ 9,277 $ 47,969 Due after 1 year through 5 years — 2,613 $ 9,277 $ 50,582

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities	The following tables present the Company's financial assets and liabilities measured on a recurring basis using the fair value hierarchy at March 31, 2021 and 2020 (in thousands): Fair Value Measurements at March 31, 2021 Level 1 Level 2 Level 3 Total ASSETS: Cash and cash equivalents $ 467,176 $ — $ — $ 467,176 U.S. government and municipal obligations 2,539 1,039 — 3,578 Commercial paper — 5,699 — 5,699 Derivative financial instruments — 57 — 57 $ 469,715 $ 6,795 $ — $ 476,510 LIABILITIES: Derivative financial instruments — (191) — (191) $ — $ (191) $ — $ (191) Fair Value Measurements at March 31, 2020 Level 1 Level 2 Level 3 Total ASSETS: Cash and cash equivalents $ 338,489 $ — $ — $ 338,489 U.S. government and municipal obligations 31,341 — — 31,341 Commercial paper — 14,644 — 14,644 Corporate bonds 4,597 — — 4,597 $ 374,427 $ 14,644 $ — $ 389,071 LIABILITIES: Contingent purchase consideration $ — $ — $ (1,748) $ (1,748) Derivative financial instruments — (49) — (49) $ — $ (49) $ (1,748) $ (1,797)
Schedule of Reconciliation of Changes in Fair Value of Level Three Financial Liabilities	The following table sets forth a reconciliation of changes in the fair value of the Company’s Level 3 financial liabilities for the fiscal year ended March 31, 2021 (in thousands): Contingent Balance at March 31, 2020 $ (1,748) Additions to Level 3 — Payments made 1,748 Balance at March 31, 2021 $ — The following table sets forth a reconciliation of changes in the fair value of the Company’s Level 3 financial assets and liabilities for the fiscal year ended March 31, 2020 (in thousands): Contingent Contingent Balance at March 31, 2019 $ — $ 762 Additions to Level 3 (1,800) — Change in fair value of contingent consideration — (762) Payments received 52 — Balance at March 31, 2020 $ (1,748) $ —

INVENTORIES (Tables)

INVENTORIES (Tables)	12 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories are stated at the lower of actual cost or net realizable value. Cost is determined by using the FIFO method. Inventories consisted of the following (in thousands): March 31, 2021 2020 Raw materials $ 13,189 $ 15,311 Work in process 16 819 Finished goods 6,168 5,376 Deferred costs 3,440 721 $ 22,813 $ 22,227

FIXED ASSETS (Tables)

FIXED ASSETS (Tables)	12 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Schedule of Fixed Assets	Fixed assets consisted of the following (in thousands): Estimated Useful Life in Years March 31, 2021 2020 Furniture and fixtures 3-7 $ 9,742 $ 9,561 Computer equipment and internal use software 3-5 177,098 170,518 Leasehold improvements (1) up to 12 53,980 51,910 Demonstration and spare part units 2-5 17,968 19,626 258,788 251,615 Less – accumulated depreciation (210,314) (193,900) $ 48,474 $ 57,715 (1) Leasehold improvements are depreciated over the shorter of the lease term or anticipated useful life of the improvement.

ACQUISITIONS & DIVESTITURES (Ta

ACQUISITIONS & DIVESTITURES (Tables)	12 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
Summary of Purchase Price Allocation	The following table summarizes the allocation of the purchase price (in thousands): Initial cash payment $ 7,200 Estimated fair value of contingent purchase consideration 800 Estimated purchase price $ 8,000 Initial cash payment $ 4,154 Estimated fair value of contingent purchase consideration 1,000 Estimated purchase price $ 5,154
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table reflects the estimated fair value of assets acquired and liabilities assumed (in thousands): Cash $ 7 Accounts receivable 209 Prepaid and other current assets 5 Intangible assets 4,760 Deferred tax liability (693) Accounts payable (50) Accrued other liabilities (54) Goodwill $ 3,816 The following table reflects the estimated fair value of assets acquired and liabilities assumed (in thousands): Property, plant and equipment $ 17 Intangible assets 4,230 Accrued other liabilities (96) Goodwill $ 1,003
Schedule of Fair Value of Acquired Identifiable Intangible Asset and Related Useful Life	The following table reflects the fair value of the acquired identifiable intangible asset and related estimated useful life (in thousands): Fair Value Useful Life (Years) Developed technology $ 4,760 10 The following table reflects the fair value of the acquired identifiable intangible asset and related estimated useful life (in thousands): Fair Value Useful Life (Years) Developed technology $ 4,230 10

GOODWILL & INTANGIBLE ASSETS (T

GOODWILL & INTANGIBLE ASSETS (Tables)	12 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in Carrying Amount of Goodwill	The changes in the carrying amount of goodwill for the fiscal years ended March 31, 2021 and 2020 are as follows (in thousands): Balance at March 31, 2019 $ 1,715,485 Goodwill attributed to the Eastwind acquisition 1,003 Goodwill attributed to the Gigavation acquisition 3,816 Foreign currency translation impact 5,376 Balance at March 31, 2020 $ 1,725,680 Foreign currency translation impact (8,126) Balance at March 31, 2021 $ 1,717,554
Schedule of Intangible Assets	Intangible assets include the indefinite lived trade name with a carrying value of $18.6 million and the following amortizable intangible assets at March 31, 2021 (in thousands): Cost Accumulated Net Developed technology $ 252,071 $ (212,688) $ 39,383 Customer relationships 775,898 (333,903) 441,995 Distributor relationships and technology licenses 11,469 (7,829) 3,640 Definite-lived trademark and trade name 39,434 (31,467) 7,967 Core technology 7,192 (7,192) — Net beneficial leases 336 (336) — Non-compete agreements 292 (292) — Capitalized software 3,317 (3,281) 36 Other 1,208 (963) 245 $ 1,091,217 $ (597,951) $ 493,266 Intangible assets include the indefinite lived trade name with a carrying value of $18.6 million and the following amortizable intangible assets at March 31, 2020 (in thousands): Cost Accumulated Net Developed technology $ 249,675 $ (191,876) $ 57,799 Customer relationships 767,366 (275,361) 492,005 Distributor relationships and technology licenses 6,785 (6,321) 464 Definite-lived trademark and trade name 39,059 (26,246) 12,813 Core technology 7,192 (7,074) 118 Net beneficial leases 336 (336) — Non-compete agreements 292 (292) — Leasehold interest 500 (500) — Backlog 16,223 (16,223) — Capitalized software 3,317 (3,202) 115 Other 1,208 (943) 265 $ 1,091,953 $ (528,374) $ 563,579
Summary of Amortization Expense	The following table provides a summary of amortization expense during the fiscal years ended March 31, 2021, 2020, and 2019 (in thousands). Years Ended March 31, 2021 2020 2019 Amortization of intangible assets included as: Cost of product revenue 20,457 26,664 34,039 Operating expense 61,151 64,525 74,325 $ 81,608 $ 91,189 $ 108,364
Schedule of Expected Future Amortization Expense	The following is the expected future amortization expense at March 31, 2021 for the fiscal years ended March 31 (in thousands): 2022 $ 71,540 2023 63,799 2024 55,547 2025 48,476 2026 44,386 Thereafter 209,518 Total $ 493,266

DERIVATIVE INSTRUMENTS AND HE_2

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Tables)	12 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Notional Amounts and Fair Values of Derivative Instruments on Consolidated Balance Sheet	The notional amounts and fair values of derivative instruments in the consolidated balance sheets at March 31, 2021 and 2020 were as follows (in thousands): Notional Amounts (a) Prepaid Expenses and Other Current Assets Accrued Other March 31, 2021 March 31, 2020 March 31, 2021 March 31, 2020 March 31, 2021 March 31, 2020 Derivatives Designated as Hedging Instruments: Forward contracts $ 11,037 $ 1,722 $ 57 $ — $ 152 $ 49 Derivatives Not Designated as Hedging Instruments: Forward contracts 6,373 — — — 39 — $ 57 $ — $ 191 $ 49 Notional amounts represent the gross contract/notional amount of the derivatives outstanding.
Summary of Effect of Foreign Exchange Forward Contracts on OCI and Results of Operations	The following table provides the effect foreign exchange forward contracts had on other comprehensive income (loss), (OCI) and results of operations during the fiscal years ended March 31, 2021 and 2020 (in thousands): Gain (Loss) Recognized Gain (Loss) Reclassified from March 31, March 31, March 31, March 31, 2021 2020 Location 2021 2020 Forward contracts $ 274 $ (103) Research and development $ (57) $ (19) Sales and marketing (252) 47 $ 274 $ (103) $ (309) $ 28 (a) The amount represents the change in fair value of derivative contracts due to changes in spot rates. (b) The amount represents reclassification from other comprehensive income to earnings that occurs when the hedged item affects earnings. The following table provides the effect foreign exchange forward contracts not designated as hedging instruments had on the Company's results of operations during the fiscal years ended March 31, 2021 and 2020 (in thousands): Gain Recognized in Income March 31, March 31, Location 2021 2020 Forward contracts General and administrative $ 115 $ — $ 115 $ — (a) The amount represents the change in fair value of derivative contracts due to changes in spot rates.

RESTRUCTURING CHARGES (Tables)

RESTRUCTURING CHARGES (Tables)	12 Months Ended
	Mar. 31, 2021
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Activities	The following table provides a summary of the activity related to the restructuring plans and the related restructuring liability (in thousands): FY2018 Plan VSP Q2 FY20 Plan Q4 FY20 Plan Employee-Related Facilities Related Employee-Related Employee-Related Employee-Related Total Balance at March 31, 2018 $ 3,696 $ — $ — $ — $ — $ 3,696 Restructuring charges to operations 1,017 643 17,248 — — 18,908 Cash payments (4,240) (458) (17,329) — — (22,027) Other adjustments (473) (185) 81 — — (577) Balance at March 31, 2019 $ — $ — $ — $ — $ — $ — Restructuring charges to operations — — 123 465 2,069 2,657 Cash payments — — (123) (434) (339) (896) Other adjustments — — — (28) (13) (41) Balance at March 31, 2020 $ — $ — $ — $ 3 $ 1,717 $ 1,720 Restructuring charges to operations — — — — 62 62 Cash payments — — — (3) (1,860) (1,863) Other adjustments — — — — 81 81 Balance at March 31, 2021 $ — $ — $ — $ — $ — $ —

NET INCOME (LOSS) PER SHARE (Ta

NET INCOME (LOSS) PER SHARE (Tables)	12 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of Calculations of Basic and Diluted Net Income per Share and Potential Common Shares	Calculations of the basic and diluted net income (loss) per share and potential common shares are as follows (in thousands, except for per share data): Fiscal Year Ended March 31, 2021 2020 2019 Numerator: Net income (loss) $ 19,352 $ (2,754) $ (73,324) Denominator: Denominator for basic net income (loss) per share - weighted average common shares outstanding 73,103 75,162 78,617 Dilutive common equivalent shares: Weighted average restricted stock units 719 — — Denominator for diluted net income (loss) per share - weighted average shares outstanding 73,822 75,162 78,617 Net income (loss) per share: Basic net income (loss) per share $ 0.26 $ (0.04) $ (0.93) Diluted net income (loss) per share $ 0.26 $ (0.04) $ (0.93)
Summary of Antidilutive Securities Excluded from Computation of Diluted EPS	The following table sets forth restricted stock units excluded from the calculation of diluted net income per share, since their inclusion would be antidilutive (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Restricted stock units 2,864 675 706

STOCK PLANS (Tables)

STOCK PLANS (Tables)	12 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Summary of Share-Based Compensation Expense	The following is a summary of share-based compensation expense including restricted stock units and employee stock purchases made under the Company's employee stock purchase plan (ESPP) based on estimated fair values within the applicable cost and expense lines identified below (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Cost of product revenue $ 1,038 $ 1,069 $ 1,463 Cost of service revenue 5,823 5,774 5,959 Research and development 16,138 15,511 17,321 Sales and marketing 17,328 17,085 18,923 General and administrative 11,565 11,422 12,662 $ 51,892 $ 50,861 $ 56,328
Summary of Transactions under Amended 2007 and 2019 Equity Incentive Plan	Transactions under the Amended 2007, 2019 Plan and 2019 Amended Plan during the fiscal years ended March 31, 2021, 2020 and 2019 are summarized in the table below. Restricted Stock Units Number of Weighted Outstanding – March 31, 2018 4,078,780 $ 31.77 Granted 2,178,339 30.10 Vested (1,438,219) 32.49 Canceled (608,245) 30.52 Outstanding – March 31, 2019 4,210,655 $ 30.84 Granted 2,062,110 26.32 Vested (1,651,284) 31.03 Canceled (347,008) 29.74 Outstanding – March 31, 2020 4,274,473 $ 28.68 Granted 2,038,681 27.42 Vested (1,630,228) 28.63 Canceled (187,313) 28.28 Outstanding – March 31, 2021 4,495,613 $ 28.14
Schedule of Aggregate Intrinsic Values of Stock Options and Restricted Stock Units	The aggregate intrinsic value of stock options exercised and the fair value of restricted stock units vested at March 31, 2021, 2020 and 2019 were as follows (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Total fair value of restricted stock unit awards vested $ 42,510 $ 37,783 $ 38,070

PENSION BENEFIT PLANS (Tables)

PENSION BENEFIT PLANS (Tables)	12 Months Ended
	Mar. 31, 2021
Retirement Benefits [Abstract]
Schedule of Changes in Benefit Obligation	The components of the change in benefit obligation of the pension plan is as follows (in thousands): March 31, March 31, 2021 2020 Benefit obligation, at beginning of year $ 32,805 $ 34,895 Service cost 333 341 Interest cost 667 603 Benefits paid and other (400) (359) Actuarial loss (gain) 2,205 (1,644) Foreign exchange rate impact 1,976 (1,031) Benefit obligation, at end of year $ 37,586 $ 32,805
Schedule of Changes in Fair Value of Plan Assets	The reconciliation of the beginning and ending balances of the fair value of the assets of the pension plan is as follows (in thousands): March 31, March 31, 2021 2020 Fair value of plan assets, at beginning of year $ — $ — Employer direct benefit payments 400 359 Benefits paid and other (400) (359) Fair value of plan assets, at end of year $ — $ —
Schedule of Net Benefit Costs	The following sets forth the components of the Company's net periodic pension cost of the noncontributory defined benefit pension plans for the fiscal years ended March 31, 2021, 2020, and 2019 (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Service cost $ 333 $ 341 $ 304 Interest cost 667 603 704 Net periodic pension cost $ 1,000 $ 944 $ 1,008
Schedule of Assumptions Used	Weighted average assumptions used to determine net periodic pension cost at date of measurement: March 31, March 31, March 31, 2021 2020 2019 Discount rate 1.60 % 1.90 % 1.80 % Rate of compensation increase 3.00 % 3.00 % 3.00 %
Schedule of Expected Benefit Payments	The following sets forth benefit payments, which reflect expected future service, as appropriate, expected to be paid by the plan in the periods indicated (in thousands): 2022 $ 485 2023 $ 553 2024 $ 605 2025 $ 716 2026 $ 932 2027 - 2031 $ 5,656

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax Expense	Income (loss) before income tax expense (benefit) consisted of the following (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Domestic $ 4,985 $ (1,502) $ (107,088) Foreign 17,319 3,426 14,176 $ 22,304 $ 1,924 $ (92,912)
Summary of Components of Income Tax Expense	The components of the income tax expense (benefit) are as follows (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Current income tax expense: Federal $ 14,701 $ 2,817 $ 3,902 State 2,426 1,850 (136) Foreign 9,902 9,712 10,618 27,029 14,379 14,384 Deferred income tax benefit: Federal (18,190) (5,287) (25,347) State (3,404) (2,897) (3,845) Foreign (2,483) (1,517) (4,780) (24,077) (9,701) (33,972) $ 2,952 $ 4,678 $ (19,588)
Schedule of Federal Statutory Income Tax Rate to Effective Tax Rate	The income tax expense (benefit) computed using the federal statutory income tax rate differs from NetScout's effective tax rate primarily due to the following: Fiscal Year Ended March 31, 2021 2020 2019 Statutory U.S. federal tax rate 21.0 % 21.0 % 21.0 % State taxes, net of federal tax effect 2.1 (47.8) 3.4 U.S. research and development tax credits (23.7) (245.9) 7.1 Effect of foreign operations (5.3) (66.9) (0.1) Meals and entertainment 0.7 43.7 (1.0) Change in valuation allowance 24.0 250.0 2.2 Internal restructuring charges — 196.5 — Stock compensation 5.2 172.1 (2.6) Divestiture — — (1.0) GILTI/FDII (20.2) (174.3) 2.9 BEAT — — (7.0) 2017 Tax Act (transition tax and re-measurement of deferreds) — — 0.4 Foreign withholding 13.8 220.6 (3.1) Provision to return (2.3) (152.8) (1.0) Other permanent differences (2.1) 26.9 (0.1) 13.2 % 243.1 % 21.1 %
Summary of Components of Net Deferred Tax Assets	The components of net deferred tax assets and liabilities are as follows (in thousands): Fiscal Year Ended March 31, 2021 2020 Deferred tax assets: Accrued expenses $ 8,480 $ 5,060 Deferred revenue 17,648 14,420 Reserves 2,898 3,216 Pension and other retiree benefits 6,160 5,078 Net operating loss carryforwards 11,526 12,443 Tax credit carryforwards 19,432 14,138 Share-based compensation 5,397 4,534 Operating lease liability 17,333 18,213 Other deferred tax assets 2,116 20 Total gross deferred tax assets 90,990 77,122 Valuation allowance (11,406) (5,641) Net deferred tax assets 79,584 71,481 Deferred tax liabilities: Intangible assets (132,635) (146,950) Other deferred tax liabilities (8,848) (8,061) Operating lease right-of-use asset (14,474) (15,152) Depreciation (7,818) (9,492) Total deferred tax liability $ (84,191) $ (108,174)
Schedule of Reconciliation of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of gross unrecognized tax benefits, excluding interest and penalties, for the fiscal years ended March 31, 2021, 2020 and 2019 is as follows (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 Balance at April 1, $ 1,151 $ 1,314 $ 2,215 Additions based on tax positions related to the current year 48 49 28 Release of tax positions of prior years (286) (212) (194) Decrease relating to settlements with taxing authorities — — (735) Balance at March 31, $ 913 $ 1,151 $ 1,314

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Components of Operating Lease Cost and Supplemental Cash Flow Information	The components of operating lease cost for the fiscal years ended March 31, 2021 and 2020 were as follows (in thousands): Fiscal Year Ended March 31, 2021 2020 Lease cost under long-term operating leases $ 13,092 $ 13,318 Lease cost under short-term operating leases 3,678 4,172 Variable lease cost under short-term and long-term operating leases 3,800 4,259 Total operating lease cost $ 20,570 $ 21,749 The table below presents supplemental cash flow information related to leases during the fiscal years ended March 31, 2021 and 2020 (in thousands): Fiscal Year Ended March 31, 2021 2020 Right-of-use assets obtained in exchange for new operating lease liabilities $ 2,492 $ 11,127 At March 31, 2021 and 2020, the weighted average remaining lease term in years and weighted average discount rate were as follows: March 31, 2021 March 31, 2020 Weighted average remaining lease term in years - operating leases 7.70 8.59 Weighted average discount rate - operating leases 4.1 % 4.1 %
Future Minimum Payments Under Non-Cancellable Leases	Future minimum payments under non-cancellable leases at March 31, 2021 are as follows (in thousands): Year Ending March 31, 2022 $ 14,085 2023 12,890 2024 10,299 2025 10,098 2026 9,087 Thereafter 29,286 Total lease payments $ 85,745 Less imputed interest (12,124) Present value of lease liabilities $ 73,621

SEGMENT AND GEOGRAPHIC INFORM_2

SEGMENT AND GEOGRAPHIC INFORMATION (Tables)	12 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Summary of Total Revenue by Geography	Total revenue by geography is as follows (in thousands): Fiscal Year Ended March 31, 2021 2020 2019 United States $ 484,129 $ 545,620 $ 553,267 Europe 160,372 154,510 148,036 Asia 56,562 59,939 72,355 Rest of the world 130,219 131,751 136,260 $ 831,282 $ 891,820 $ 909,918

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	Sep. 14, 2018USD ($)	Feb. 28, 2021USD ($)	Apr. 30, 2020USD ($)	Mar. 31, 2021USD ($)reporting_unitSegment	Mar. 31, 2020USD ($)company	Mar. 31, 2019USD ($)	Mar. 31, 2021USD ($)company	Feb. 05, 2020USD ($)	Apr. 03, 2019USD ($)	Sep. 30, 2018USD ($)	Jan. 16, 2018USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of reportable segments | Segment				1
Deferred employer payroll taxes				$ 8,900,000			$ 8,900,000
Unrecognized accounts receivable and deferred revenue				$ 7,100,000	$ 11,100,000		$ 7,100,000
Number of reporting units | reporting_unit				1
Number of companies acquired | company					2		2
Number of businesses divested | company							1
Fair value of contingent liability					$ 1,748,000
Amortization included as cost of product				$ 100,000	500,000	$ 1,100,000
Capitalized software development costs				0	0		$ 0
Foreign currency losses				5,500,000	700,000	2,000,000
Advertising expense				$ 8,700,000	8,300,000	9,400,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Handheld Network Test Tools Business
Summary Of Significant Accounting Policies [Line Items]
Contingent consideration related to the divestiture	$ 2,300,000					$ 2,300,000				$ 2,300,000
Contingent consideration measurement period	2 years					2 years
Change in fair value of contingent consideration					800,000	$ 1,600,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Handheld Network Test Tools Business | Maximum
Summary Of Significant Accounting Policies [Line Items]
Contingent consideration related to the divestiture	$ 4,000,000					$ 4,000,000
Computer equipment and internal use software
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life				3 years
Computer equipment and internal use software | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life				5 years
Gigavation
Summary Of Significant Accounting Policies [Line Items]
Fair value of contingent liability					700,000			$ 800,000
Payments of contingent consideration		$ 700,000
Eastwind
Summary Of Significant Accounting Policies [Line Items]
Fair value of contingent liability					$ 1,000,000				$ 1,000,000
Payments of contingent consideration			$ 1,000,000
Accrued Liabilities
Summary Of Significant Accounting Policies [Line Items]
Deferred employer payroll taxes				$ 4,500,000			4,500,000
Other Noncurrent Liabilities
Summary Of Significant Accounting Policies [Line Items]
Deferred employer payroll taxes				4,400,000			4,400,000
Senior secured revolving credit facility | Line of credit
Summary Of Significant Accounting Policies [Line Items]
Current borrowing capacity				336,000,000			336,000,000
Credit facility				$ 1,000,000,000			$ 1,000,000,000				$ 1,000,000,000

REVENUE RECOGNITION - Additiona

REVENUE RECOGNITION - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue recognized	$ 262.5
Deferred revenue	373.1
Capitalized contract cost	7.4	$ 7.2
Capitalized contract cost, amortization	6.3	6.5
Prepaid Expenses and Other Current Assets
Disaggregation of Revenue [Line Items]
Capitalized contract cost	4.1	3.9
Other assets
Disaggregation of Revenue [Line Items]
Capitalized contract cost	$ 3.3	$ 3.3
Minimum
Disaggregation of Revenue [Line Items]
Payment terms	30 days
Maximum
Disaggregation of Revenue [Line Items]
Payment terms	90 days

REVENUE RECOGNITION - Performan

REVENUE RECOGNITION - Performance Obligations (Details) $ in Millions	Mar. 31, 2021USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-04-01
Revenue from Contract with Customer [Abstract]
Revenue, remaining performance obligation, amount	$ 269.8
Revenue, remaining performance obligation, percentage	72.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-04-01
Revenue from Contract with Customer [Abstract]
Revenue, remaining performance obligation, amount	$ 103.3
Revenue, remaining performance obligation, percentage	28.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period

REVENUE RECOGNITION - Allowance

REVENUE RECOGNITION - Allowance for Credit Losses (Details) $ in Thousands	12 Months Ended
	Mar. 31, 2021USD ($)
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Accounts receivable beginning balance	$ 1,350
Provision for allowance for credit losses	48
Recoveries and other adjustments	(733)
Write off charged against the allowance for credit losses	(249)
Accounts receivable ending balance	$ 416

CASH, CASH EQUIVALENTS AND MA_3

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES - Summary of Cash, Cash Equivalent and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 467,176	$ 338,489	$ 409,632	$ 369,821
Restricted cash	0	1,748	188	910
Total cash, cash equivalents and restricted cash	$ 467,176	$ 340,237	$ 409,820	$ 370,731

CASH, CASH EQUIVALENTS AND MA_4

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES - Summary of Marketable Securities Classified as Short-term and Long-term (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Cash, Cash Equivalents and Marketable Securities [Line Items]
Amortized Cost	$ 9,270	$ 50,414
Unrealized Gains	7	168
Fair Value	9,277	50,582
Short-term marketable securities
Cash, Cash Equivalents and Marketable Securities [Line Items]
Amortized Cost	9,270	47,852
Unrealized Gains	7	117
Fair Value	9,277	47,969
Short-term marketable securities | U.S. government and municipal obligations
Cash, Cash Equivalents and Marketable Securities [Line Items]
Amortized Cost	3,571	28,621
Unrealized Gains	7	107
Fair Value	3,578	28,728
Short-term marketable securities | Commercial paper
Cash, Cash Equivalents and Marketable Securities [Line Items]
Amortized Cost	5,699	14,644
Unrealized Gains	0	0
Fair Value	5,699	14,644
Short-term marketable securities | Corporate bonds
Cash, Cash Equivalents and Marketable Securities [Line Items]
Amortized Cost		4,587
Unrealized Gains		10
Fair Value		4,597
Long-term marketable securities
Cash, Cash Equivalents and Marketable Securities [Line Items]
Amortized Cost	0	2,562
Unrealized Gains	0	51
Fair Value	$ 0	2,613
Long-term marketable securities | U.S. government and municipal obligations
Cash, Cash Equivalents and Marketable Securities [Line Items]
Amortized Cost		2,562
Unrealized Gains		51
Fair Value		$ 2,613

CASH, CASH EQUIVALENTS AND MA_5

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES - Summary of Contractual Maturities of Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Available-for-sale securities:
Due in 1 year or less	$ 9,277	$ 47,969
Due after 1 year through 5 years	0	2,613
Fair Value	$ 9,277	$ 50,582

FAIR VALUE MEASUREMENTS - Sched

FAIR VALUE MEASUREMENTS - Schedule of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
ASSETS:
Cash and cash equivalents	$ 467,176	$ 338,489
Available for sale securities	9,277	50,582
Derivative financial instruments	57
Total assets	476,510	389,071
LIABILITIES:
Contingent purchase consideration		(1,748)
Derivative financial instruments	(191)	(49)
Total liabilities	(191)	(1,797)
U.S. government and municipal obligations
ASSETS:
Available for sale securities	3,578	31,341
Commercial paper
ASSETS:
Available for sale securities	5,699	14,644
Corporate bonds
ASSETS:
Available for sale securities		4,597
Level 1
ASSETS:
Cash and cash equivalents	467,176	338,489
Derivative financial instruments	0
Total assets	469,715	374,427
LIABILITIES:
Contingent purchase consideration		0
Derivative financial instruments	0	0
Total liabilities	0	0
Level 1 | U.S. government and municipal obligations
ASSETS:
Available for sale securities	2,539	31,341
Level 1 | Commercial paper
ASSETS:
Available for sale securities	0	0
Level 1 | Corporate bonds
ASSETS:
Available for sale securities		4,597
Level 2
ASSETS:
Cash and cash equivalents	0	0
Derivative financial instruments	57
Total assets	6,795	14,644
LIABILITIES:
Contingent purchase consideration		0
Derivative financial instruments	(191)	(49)
Total liabilities	(191)	(49)
Level 2 | U.S. government and municipal obligations
ASSETS:
Available for sale securities	1,039	0
Level 2 | Commercial paper
ASSETS:
Available for sale securities	5,699	14,644
Level 2 | Corporate bonds
ASSETS:
Available for sale securities		0
Level 3
ASSETS:
Cash and cash equivalents	0	0
Derivative financial instruments	0
Total assets	0	0
LIABILITIES:
Contingent purchase consideration		(1,748)
Derivative financial instruments	0	0
Total liabilities	0	(1,748)
Level 3 | U.S. government and municipal obligations
ASSETS:
Available for sale securities	0	0
Level 3 | Commercial paper
ASSETS:
Available for sale securities	$ 0	0
Level 3 | Corporate bonds
ASSETS:
Available for sale securities		$ 0

FAIR VALUE MEASUREMENTS - Narra

FAIR VALUE MEASUREMENTS - Narrative (Details)	Sep. 14, 2018USD ($)	Feb. 28, 2021USD ($)	Apr. 30, 2020USD ($)	Mar. 31, 2020USD ($)company	Mar. 31, 2019USD ($)	Mar. 31, 2021company	Feb. 05, 2020USD ($)	Apr. 03, 2019USD ($)	Sep. 30, 2018USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of companies acquired | company				2		2
Fair value of contingent liability				$ 1,748,000
Fair value, measurements, recurring | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability adjustment included in earnings				36,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Handheld Network Test Tools Business
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration related to the divestiture	$ 2,300,000				$ 2,300,000				$ 2,300,000
Contingent consideration measurement period	2 years				2 years
Change in fair value of contingent consideration				800,000	$ 1,600,000
Maximum | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Handheld Network Test Tools Business
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration related to the divestiture	$ 4,000,000				$ 4,000,000
Gigavation
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of contingent liability				700,000			$ 800,000
Payments of contingent consideration		$ 700,000
Eastwind
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of contingent liability				$ 1,000,000				$ 1,000,000
Payments of contingent consideration			$ 1,000,000

FAIR VALUE MEASUREMENTS - Recon

FAIR VALUE MEASUREMENTS - Reconciliation of Changes in Level 3 Liabilities (Details) - Fair value, measurements, recurring - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Contingent Purchase Consideration
Beginning balance	$ (1,748)	$ 0
Additions to Level 3		(1,800)
Payments made	1,748	52
Ending balance	0	(1,748)
Contingent Consideration
Beginning balance	$ 0	762
Change in fair value of contingent consideration		(762)
Ending balance		$ 0

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Inventory Disclosure [Abstract]
Raw materials	$ 13,189	$ 15,311
Work in process	16	819
Finished goods	6,168	5,376
Deferred costs	3,440	721
Total inventories	$ 22,813	$ 22,227

FIXED ASSETS - Schedule of Fixe

FIXED ASSETS - Schedule of Fixed Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 258,788	$ 251,615
Less – accumulated depreciation	(210,314)	(193,900)
Fixed assets, net	48,474	57,715
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 9,742	9,561
Furniture and fixtures | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Furniture and fixtures | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Computer equipment and internal use software
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Fixed assets, gross	$ 177,098	170,518
Computer equipment and internal use software | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Computer equipment and internal use software | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 53,980	51,910
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	12 years
Demonstration and spare part units
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 17,968	$ 19,626
Demonstration and spare part units | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	2 years
Demonstration and spare part units | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years

FIXED ASSETS - Narrative (Detai

FIXED ASSETS - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 22.4	$ 23.4	$ 27.4

ACQUISITIONS & DIVESTITURES - N

ACQUISITIONS & DIVESTITURES - Narrative (Details) - USD ($)	Feb. 05, 2020	Apr. 03, 2019	Sep. 14, 2018	Feb. 28, 2021	Apr. 30, 2020	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2018
Business Acquisition [Line Items]
Estimated fair value of contingent purchase consideration							$ 1,748,000
Weighted average useful life of acquired intangible assets						14 years 7 months 6 days
Loss on divestiture of business						$ 0	0	$ 9,472,000
Handheld Network Test Tools Business | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Business Acquisition [Line Items]
Cash proceeds from divestiture			$ 1,300,000
Contingent consideration related to the divestiture			$ 2,300,000					$ 2,300,000	$ 2,300,000
Contingent consideration measurement period			2 years					2 years
Net liabilities transferred								$ 4,600,000
Loss on divestiture of business								9,500,000
Transaction costs								1,300,000
Incentive compensation payable								500,000
Transitional services agreement			18 months
Transitional services within other expense						$ 200,000	1,200,000
Handheld Network Test Tools Business | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Maximum
Business Acquisition [Line Items]
Contingent consideration related to the divestiture			$ 4,000,000					$ 4,000,000
Gigavation
Business Acquisition [Line Items]
Percentage of voting interests acquired	100.00%
Estimated purchase price	$ 8,000,000
Estimated fair value of contingent purchase consideration	$ 800,000						700,000
Withdraw from escrow account							100,000
Payments of contingent consideration				$ 700,000
Gigavation | Developed technology
Business Acquisition [Line Items]
Weighted average useful life of acquired intangible assets	10 years
Eastwind
Business Acquisition [Line Items]
Estimated purchase price		$ 5,154,000
Estimated fair value of contingent purchase consideration		1,000,000					$ 1,000,000
Payments of contingent consideration					$ 1,000,000
Cash retention payments received		$ 300,000
Eastwind | Developed technology
Business Acquisition [Line Items]
Weighted average useful life of acquired intangible assets		10 years

ACQUISITIONS & DIVESTITURES - S

ACQUISITIONS & DIVESTITURES - Summary of Purchase Price Allocation (Details) - USD ($) $ in Thousands	Feb. 05, 2020	Apr. 03, 2019	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Business Acquisition [Line Items]
Estimated fair value of contingent purchase consideration				$ 1,748
Estimated fair value of assets acquired and liabilities assumed:
Goodwill			$ 1,717,554	1,725,680	$ 1,715,485
Gigavation
Business Acquisition [Line Items]
Initial cash payment	$ 7,200
Estimated fair value of contingent purchase consideration	800			700
Estimated purchase price	8,000
Estimated fair value of assets acquired and liabilities assumed:
Cash	7
Accounts receivable	209
Prepaid and other current assets	5
Intangible assets	4,760
Deferred tax liability	(693)
Accounts payable	(50)
Accrued other liabilities	(54)
Goodwill	$ 3,816
Eastwind
Business Acquisition [Line Items]
Initial cash payment		$ 4,154
Estimated fair value of contingent purchase consideration		1,000		$ 1,000
Estimated purchase price		5,154
Estimated fair value of assets acquired and liabilities assumed:
Property, plant and equipment		17
Intangible assets		4,230
Accrued other liabilities		(96)
Goodwill		$ 1,003

ACQUISITIONS & DIVESTITURES -_2

ACQUISITIONS & DIVESTITURES - Schedule of Fair value of Acquired Identifiable Intangible Assets and Related Estimates of Useful Lives (Details) - USD ($) $ in Thousands	Feb. 05, 2020	Apr. 03, 2019	Mar. 31, 2021
Acquired Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)			14 years 7 months 6 days
Gigavation | Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value	$ 4,760
Useful Life (Years)	10 years
Eastwind | Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value		$ 4,230
Useful Life (Years)		10 years

GOODWILL & INTANGIBLE ASSETS -

GOODWILL & INTANGIBLE ASSETS - Narrative (Details) $ in Thousands	12 Months Ended
	Mar. 31, 2021USD ($)reporting_unit	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Number of reporting units | reporting_unit	1
Goodwill	$ 1,717,554	$ 1,725,680	$ 1,715,485
Carrying value of intangible assets	511,866	582,179
Impairment of intangible assets	$ 0	0	$ 35,871
Weighted average useful life of acquired intangible assets	14 years 7 months 6 days
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 18,600	18,600
Distributor relationships and technology licenses
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 4,500	$ 0
Distributor relationships and technology licenses | Minimum
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	3 years
Distributor relationships and technology licenses | Maximum
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	4 years
Developed and core technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	11 years 2 months 12 days
Customer and distributor relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	15 years 10 months 24 days
Trademarks and trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	8 years 7 months 6 days
Capitalized software
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	3 years

GOODWILL & INTANGIBLE ASSETS _2

GOODWILL & INTANGIBLE ASSETS - Schedule of Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Goodwill [Roll Forward]
Beginning balance	$ 1,725,680	$ 1,715,485
Foreign currency translation impact	(8,126)	5,376
Ending balance	$ 1,717,554	1,725,680
Eastwind
Goodwill [Roll Forward]
Goodwill attributed to acquisition		1,003
Gigavation
Goodwill [Roll Forward]
Goodwill attributed to acquisition		$ 3,816

GOODWILL & INTANGIBLE ASSETS _3

GOODWILL & INTANGIBLE ASSETS - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Cost	$ 1,091,217	$ 1,091,953
Accumulated Amortization	(597,951)	(528,374)
Net	493,266	563,579
Developed technology
Finite-Lived Intangible Assets [Line Items]
Cost	252,071	249,675
Accumulated Amortization	(212,688)	(191,876)
Net	39,383	57,799
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Cost	775,898	767,366
Accumulated Amortization	(333,903)	(275,361)
Net	441,995	492,005
Distributor relationships and technology licenses
Finite-Lived Intangible Assets [Line Items]
Cost	11,469	6,785
Accumulated Amortization	(7,829)	(6,321)
Net	3,640	464
Definite-lived trademark and trade name
Finite-Lived Intangible Assets [Line Items]
Cost	39,434	39,059
Accumulated Amortization	(31,467)	(26,246)
Net	7,967	12,813
Core technology
Finite-Lived Intangible Assets [Line Items]
Cost	7,192	7,192
Accumulated Amortization	(7,192)	(7,074)
Net	0	118
Net beneficial leases
Finite-Lived Intangible Assets [Line Items]
Cost	336	336
Accumulated Amortization	(336)	(336)
Net	0	0
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Cost	292	292
Accumulated Amortization	(292)	(292)
Net	0	0
Leasehold interest
Finite-Lived Intangible Assets [Line Items]
Cost		500
Accumulated Amortization		(500)
Net		0
Backlog
Finite-Lived Intangible Assets [Line Items]
Cost		16,223
Accumulated Amortization		(16,223)
Net		0
Capitalized software
Finite-Lived Intangible Assets [Line Items]
Cost	3,317	3,317
Accumulated Amortization	(3,281)	(3,202)
Net	36	115
Other
Finite-Lived Intangible Assets [Line Items]
Cost	1,208	1,208
Accumulated Amortization	(963)	(943)
Net	$ 245	$ 265

GOODWILL & INTANGIBLE ASSETS _4

GOODWILL & INTANGIBLE ASSETS - Schedule of Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Amortization expenses	$ 81,608	$ 91,189	$ 108,364
Cost of product revenue
Finite-Lived Intangible Assets [Line Items]
Amortization expenses	20,457	26,664	34,039
Operating expense
Finite-Lived Intangible Assets [Line Items]
Amortization expenses	$ 61,151	$ 64,525	$ 74,325

GOODWILL & INTANGIBLE ASSETS _5

GOODWILL & INTANGIBLE ASSETS - Schedule of Expected Future Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2022	$ 71,540
2023	63,799
2024	55,547
2025	48,476
2026	44,386
Thereafter	209,518
Net	$ 493,266	$ 563,579

DERIVATIVE INSTRUMENTS AND HE_3

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Narrative (Details)	12 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Managing period of hedging forecasted cash flows for operating expenses denominated in foreign currencies	12 months
Contract maturity period	12 months

DERIVATIVE INSTRUMENTS AND HE_4

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Summary of Notional Amounts and Fair Values of Derivative Instruments on Consolidated Balance Sheet (Details) - Forward contracts - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Prepaid Expenses and Other Current Assets
Derivatives, Fair Value [Line Items]
Prepaid Expenses and Other Current Assets	$ 57	$ 0
Accrued Other
Derivatives, Fair Value [Line Items]
Accrued Other	191	49
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional amounts	11,037	1,722
Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets
Derivatives, Fair Value [Line Items]
Prepaid Expenses and Other Current Assets	57	0
Designated as Hedging Instrument | Accrued Other
Derivatives, Fair Value [Line Items]
Accrued Other	152	49
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional amounts	6,373	0
Not Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets
Derivatives, Fair Value [Line Items]
Prepaid Expenses and Other Current Assets	0	0
Not Designated as Hedging Instrument | Accrued Other
Derivatives, Fair Value [Line Items]
Accrued Other	$ 39	$ 0

DERIVATIVE INSTRUMENTS AND HE_5

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Summary of Effect of Foreign Exchange Forward Contracts on Other Comprehensive Income And Results Of Operations (Details) - Forward contracts - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative	$ 274	$ (103)
Gain (Loss) Reclassified from Accumulated OCI into Income	(309)	28
Gain Recognized in Income	115	0
Research and development
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative	274	(103)
Gain (Loss) Reclassified from Accumulated OCI into Income	(57)	(19)
Sales and marketing
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income	(252)	47
General and administrative
Derivative Instruments, Gain (Loss) [Line Items]
Gain Recognized in Income	$ 115	$ 0

RESTRUCTURING CHARGES - Narrati

RESTRUCTURING CHARGES - Narrative (Details) $ in Thousands	12 Months Ended
	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)plan	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 62	$ 2,674	$ 18,693
Number of restructuring plans | plan		2
Restructuring costs addition	$ 100
FY2018 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges			1,700
VSP
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 100	$ 17,200
Employee-Related | FY2018 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges				$ 5,100
Employee-Related | Q2 FY20 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges		500
Employee-Related | Q4 FY20 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 2,100

RESTRUCTURING CHARGES - Schedul

RESTRUCTURING CHARGES - Schedule of Restructuring Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Restructuring Reserve [Roll Forward]
Beginning Balance	$ 1,720	$ 0	$ 3,696
Restructuring charges to operations	62	2,657	18,908
Cash payments	(1,863)	(896)	(22,027)
Other adjustments	81	(41)	(577)
Ending Balance	0	1,720	0
Employee-Related | FY2018 Plan
Restructuring Reserve [Roll Forward]
Beginning Balance	0	0	3,696
Restructuring charges to operations	0	0	1,017
Cash payments	0	0	(4,240)
Other adjustments	0	0	(473)
Ending Balance	0	0	0
Employee-Related | VSP
Restructuring Reserve [Roll Forward]
Beginning Balance	0	0	0
Restructuring charges to operations	0	123	17,248
Cash payments	0	(123)	(17,329)
Other adjustments	0	0	81
Ending Balance	0	0	0
Employee-Related | Q2 FY20 Plan
Restructuring Reserve [Roll Forward]
Beginning Balance	3	0	0
Restructuring charges to operations	0	465	0
Cash payments	(3)	(434)	0
Other adjustments	0	(28)	0
Ending Balance	0	3	0
Employee-Related | Q4 FY20 Plan
Restructuring Reserve [Roll Forward]
Beginning Balance	1,717	0	0
Restructuring charges to operations	62	2,069	0
Cash payments	(1,860)	(339)	0
Other adjustments	81	(13)	0
Ending Balance	0	1,717	0
Facilities Related | FY2018 Plan
Restructuring Reserve [Roll Forward]
Beginning Balance	0	0	0
Restructuring charges to operations	0	0	643
Cash payments	0	0	(458)
Other adjustments	0	0	(185)
Ending Balance	$ 0	$ 0	$ 0

LONG-TERM DEBT (Details)

LONG-TERM DEBT (Details)	Jan. 16, 2018USD ($)shares	Mar. 31, 2021USD ($)	Mar. 31, 2021USD ($)
Debt Instrument [Line Items]
Stock authorized to repurchase under stock repurchase program (in shares) | shares	25,000,000
Repaid borrowings			$ 100,000,000
Line of credit | Senior secured revolving credit facility
Debt Instrument [Line Items]
Debt term	5 years
Credit facility	$ 1,000,000,000	$ 1,000,000,000	1,000,000,000
Amount outstanding under credit facility		$ 350,000,000	350,000,000
Commitment fee percentage		0.25%
Debt default, acceleration clause, required consent percentage	50.00%
Debt issuance costs		$ 12,200,000	12,200,000
Unamortized debt issuance costs		3,100,000	3,100,000
Line of credit | Senior secured revolving credit facility | Prepaid Expenses and Other Current Assets
Debt Instrument [Line Items]
Unamortized debt issuance costs		1,700,000	1,700,000
Line of credit | Senior secured revolving credit facility | Other assets
Debt Instrument [Line Items]
Unamortized debt issuance costs		$ 1,400,000	$ 1,400,000
Line of credit | Senior secured revolving credit facility | Maximum
Debt Instrument [Line Items]
Commitment fee percentage		0.30%
Line of credit | Senior secured revolving credit facility | Maximum | Foreign Subsidiaries
Debt Instrument [Line Items]
Voting stock pledge limit for any foreign subsidiary	65.00%
Line of credit | Senior secured revolving credit facility | Minimum
Debt Instrument [Line Items]
Commitment fee percentage		0.15%
Line of credit | Senior secured revolving credit facility | Federal funds effective rate
Debt Instrument [Line Items]
Interest rate in excess of effective rate	0.50%
Line of credit | Senior secured revolving credit facility | LIBOR
Debt Instrument [Line Items]
Interest rate in excess of effective rate	1.00%
Line of credit | Senior secured revolving credit facility | LIBOR | LIBOR loans
Debt Instrument [Line Items]
Interest rate in excess of effective rate		1.50%
Line of credit | Senior secured revolving credit facility | LIBOR | LIBOR loans | Maximum
Debt Instrument [Line Items]
Interest rate in excess of effective rate		1.75%
Line of credit | Senior secured revolving credit facility | LIBOR | LIBOR loans | Minimum
Debt Instrument [Line Items]
Interest rate in excess of effective rate		1.00%
Line of credit | Senior secured revolving credit facility | Base rate | Base rate loans
Debt Instrument [Line Items]
Interest rate in excess of effective rate		0.50%
Line of credit | Senior secured revolving credit facility | Base rate | Base rate loans | Maximum
Debt Instrument [Line Items]
Interest rate in excess of effective rate		0.75%
Line of credit | Senior secured revolving credit facility | Base rate | Base rate loans | Minimum
Debt Instrument [Line Items]
Interest rate in excess of effective rate		0.00%
Line of credit | Letter of credit sub-facility
Debt Instrument [Line Items]
Credit facility	$ 75,000,000
Line of credit | Revolving Credit Facility Leverage Ratio Terms 1 | Maximum
Debt Instrument [Line Items]
Leverage ratio		3.50	3.50
Line of credit | Revolving Credit Facility Leverage Ratio Terms 1 | Minimum
Debt Instrument [Line Items]
Leverage ratio		1.50	1.50
Line of credit | Revolving Credit Facility Leverage Ratio Terms 2 | Maximum
Debt Instrument [Line Items]
Leverage ratio		2.75	2.75
Line of credit | Revolving Credit Facility Leverage Ratio Terms 2 | Minimum
Debt Instrument [Line Items]
Leverage ratio		1.50	1.50

NET INCOME (LOSS) PER SHARE - S

NET INCOME (LOSS) PER SHARE - Schedule of Calculations of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net income (loss)	$ 19,352	$ (2,754)	$ (73,324)
Denominator:
Denominator for basic net income (loss) per share - weighted average common shares outstanding (in shares)	73,103	75,162	78,617
Dilutive common equivalent shares:
Weighted average restricted stock units (in shares)	719	0	0
Denominator for diluted net income (loss) per share - weighted average shares outstanding (in shares)	73,822	75,162	78,617
Net income (loss) per share:
Basic net income (loss) per share (in dollars per share)	$ 0.26	$ (0.04)	$ (0.93)
Diluted net income (loss) per share (in dollars per share)	$ 0.26	$ (0.04)	$ (0.93)

NET INCOME (LOSS) PER SHARE - A

NET INCOME (LOSS) PER SHARE - Antidilutive Securities Excluded from Computation (Details) - shares shares in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	2,864	675	706

TREASURY STOCK (Details)

TREASURY STOCK (Details)	Feb. 01, 2018USD ($)dealershares	Mar. 31, 2021USD ($)shares	Mar. 31, 2020USD ($)shares	Mar. 31, 2019USD ($)shares	Mar. 31, 2018USD ($)shares	Mar. 31, 2019$ / sharesshares	Jan. 16, 2018shares	Oct. 24, 2017shares	Oct. 23, 2017shares
Equity, Class of Treasury Stock [Line Items]
Stock authorized to repurchase under stock repurchase program (in shares)							25,000,000
Shares repurchased during the period, value | $		$ 3,275,000	$ 175,000,000	$ 14,468,000
Stock remaining to be purchased (in shares)		7,089,160
Restricted stock units
Equity, Class of Treasury Stock [Line Items]
Shares paid for tax withholding (in shares)		506,917	519,241	451,683
Cost related to tax withholding | $		$ 13,300,000	$ 11,900,000	$ 11,900,000
Share repurchase program, October 2017
Equity, Class of Treasury Stock [Line Items]
Stock authorized to repurchase under stock repurchase program (in shares)	25,000,000			25,000,000	25,000,000	25,000,000		25,000,000
Shares repurchased during the period, value | $		$ 3,300,000	$ 175,000,000	$ 14,500,000
Shares repurchased during the period (in shares)		154,271	7,116,159	543,251	6,417,212
Share repurchase program, May 2015
Equity, Class of Treasury Stock [Line Items]
Stock authorized to repurchase under stock repurchase program (in shares)	20,000,000				20,000,000				20,000,000
Shares repurchased during the period (in shares)					970,650
ASR Agreements
Equity, Class of Treasury Stock [Line Items]
Number of third-party financial institutions (the Dealers) | dealer	2
Shares repurchased during the period, value | $	$ 300,000,000			$ 96,800,000
Shares repurchased during the period (in shares)				3,679,947	7,387,862	11,067,809
Treasury stock acquired value | $					$ 210,000,000
Average cost per share (in dollars per share) | $ / shares						$ 27.11

STOCK PLANS - Narrative (Detail

STOCK PLANS - Narrative (Details)	Sep. 10, 2020shares	Sep. 12, 2019shares	Nov. 08, 2018shares	Mar. 01, 2012USD ($)shares	Mar. 31, 2021USD ($)$ / sharesshares	Sep. 09, 2020	Mar. 31, 2020	Mar. 31, 2019	Sep. 07, 2011shares
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost | $					$ 94,800,000
Unrecognized cost, period for recognition, years					1 year 3 months 18 days
Employee stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares purchased by employees (in shares)					561,669
Shares issued under ESPP plan, weighted average purchase price per share (in dollars per share) | $ / shares					$ 25.69
Shares available for future issuance under the ESPP (in shares)					1,751,813
Maximum | Incentive options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of options granted, years					5 years
2011 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, equity awards reserved for issuance (in shares)									2,500,000
Number of additional shares available (in shares)			3,000,000
Maximum payroll deductions for purchase of shares by participants				20.00%
Maximum number of shares available for purchased by participants (in shares)				2,000
Cap on fair value of shares available for purchase by participants | $				$ 25,000
Percentage of common stock price for employees				85.00%
2011 Employee Stock Purchase Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cap on fair value of shares available for purchase by participants | $				$ 50,000
2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, equity awards reserved for issuance (in shares)		6,794,651
Number of additional shares available (in shares)	2,967,262	5,500,000
Minimum vesting requirement					4 years
Reduction for each share of common stock pursuant to other than option		1
Shares available for grant (in shares)					4,495,613
Percentage of incentive stock option granted					110.00%
2019 Equity Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of options granted, years					7 years
2019 Equity Incentive Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of fair market value of common stock					100.00%
Percentage of voting stock					10.00%
2007 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares available (in shares)		1,294,651
2007 Equity Incentive Plan | Independent Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of annualized forfeiture rate for awards granted					0.00%		0.00%	0.00%
2007 Equity Incentive Plan | Senior Executives
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of annualized forfeiture rate for awards granted					2.00%		2.00%	2.00%
2007 Equity Incentive Plan | Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of annualized forfeiture rate for awards granted					5.00%		5.00%	5.00%
2019 Amended, Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, equity awards reserved for issuance (in shares)	7,667,262
Number of additional shares available (in shares)	4,700,000
Minimum vesting requirement	1 year
Reduction for each share of common stock pursuant to other than option	2.32	2.76
Addition in reserve equity	2.32					2.76
Reduction for each share of common stock pursuant to option		1
Shares available for grant (in shares)					7,868,290

STOCK PLANS - Summary of Share-

STOCK PLANS - Summary of Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 51,892	$ 50,861	$ 56,328
Cost of product revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	1,038	1,069	1,463
Cost of service revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	5,823	5,774	5,959
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	16,138	15,511	17,321
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	17,328	17,085	18,923
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 11,565	$ 11,422	$ 12,662

STOCK PLANS - Summary of Transa

STOCK PLANS - Summary of Transactions under Amended 2007 and 2019 Plan (Details) - $ / shares	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Restricted Stock Units, Number of Awards
Beginning outstanding balance (in shares)	4,274,473	4,210,655	4,078,780
Granted (in shares)	2,038,681	2,062,110	2,178,339
Vested (in shares)	(1,630,228)	(1,651,284)	(1,438,219)
Canceled (in shares)	(187,313)	(347,008)	(608,245)
Ending outstanding balance (in shares)	4,495,613	4,274,473	4,210,655
Restricted Stock Units, Weighted Average Fair Value
Beginning outstanding balance (in dollars per share)	$ 28.68	$ 30.84	$ 31.77
Granted (in dollars per share)	27.42	26.32	30.10
Vested (in dollars per share)	28.63	31.03	32.49
Canceled (in dollars per share)	28.28	29.74	30.52
Ending outstanding balance (in dollars per share)	$ 28.14	$ 28.68	$ 30.84

STOCK PLANS - Schedule of Aggre

STOCK PLANS - Schedule of Aggregate Intrinsic Values of Stock Options and Restricted Stock Units (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of restricted stock unit awards vested	$ 42,510	$ 37,783	$ 38,070

PENSION BENEFIT PLANS - Narrati

PENSION BENEFIT PLANS - Narrative (Details)	12 Months Ended
	Mar. 31, 2021USD ($)employee	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Retirement plan employee's contribution, percentage matched	50.00%
Retirement plan employee's contribution, percentage of match	6.00%
Retirement plan employer contributions vest at rate per year of service, percentage	25.00%
Retirement plan employer contributions	$ 6,700,000	$ 6,700,000	$ 6,600,000
Unrecognized actuarial loss, before tax	2,200,000
Unrecognized actuarial loss, net of tax	1,500,000
Amount expected to be recognized in net periodic pension costs in next fiscal year	0
Plan assets expected to be returned to the Company	0
Employer direct benefit payments	$ 400,000	$ 359,000
United States
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of employees in the U.S. participating in noncontributory defined benefit pension plants | employee	0

PENSION BENEFIT PLANS - Defined

PENSION BENEFIT PLANS - Defined Benefit Pension Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, at beginning of year	$ 32,805	$ 34,895
Service cost	333	341	$ 304
Interest cost	667	603	704
Benefits paid and other	(400)	(359)
Actuarial loss (gain)	2,205	(1,644)
Foreign exchange rate impact	1,976	(1,031)
Benefit obligation, at end of year	$ 37,586	$ 32,805	$ 34,895

PENSION BENEFIT PLANS - Fair Va

PENSION BENEFIT PLANS - Fair Value of the Assets Pension Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, at beginning of year	$ 0	$ 0
Employer direct benefit payments	400	359
Benefits paid and other	(400)	(359)
Fair value of plan assets, at end of year	$ 0	$ 0

PENSION BENEFIT PLANS - Net Per

PENSION BENEFIT PLANS - Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Retirement Benefits [Abstract]
Service cost	$ 333	$ 341	$ 304
Interest cost	667	603	704
Net periodic pension cost	$ 1,000	$ 944	$ 1,008

PENSION BENEFIT PLANS - Weighte

PENSION BENEFIT PLANS - Weighted Average Net Periodic Pension Cost (Details)	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Retirement Benefits [Abstract]
Discount rate	1.60%	1.90%	1.80%
Rate of compensation increase	3.00%	3.00%	3.00%

PENSION BENEFIT PLANS - Expecte

PENSION BENEFIT PLANS - Expected Contributions (Details) $ in Thousands	Mar. 31, 2021USD ($)
Retirement Benefits [Abstract]
2022	$ 485
2023	553
2024	605
2025	716
2026	932
2027 - 2031	$ 5,656

INCOME TAXES - Income Before In

INCOME TAXES - Income Before Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Domestic	$ 4,985	$ (1,502)	$ (107,088)
Foreign	17,319	3,426	14,176
Income before income tax expense	$ 22,304	$ 1,924	$ (92,912)

INCOME TAXES - Summary of Compo

INCOME TAXES - Summary of Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Current income tax expense:
Federal	$ 14,701	$ 2,817	$ 3,902
State	2,426	1,850	(136)
Foreign	9,902	9,712	10,618
Current income tax expense, Total	27,029	14,379	14,384
Deferred income tax benefit:
Federal	(18,190)	(5,287)	(25,347)
State	(3,404)	(2,897)	(3,845)
Foreign	(2,483)	(1,517)	(4,780)
Deferred income tax expense (benefit), Total	(24,077)	(9,701)	(33,972)
Income tax expense (benefit), Total	$ 2,952	$ 4,678	$ (19,588)

INCOME TAXES - Schedule of Fede

INCOME TAXES - Schedule of Federal Statutory Income Tax Rate to Effective Tax Rate (Details)	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Statutory U.S. federal tax rate	21.00%	21.00%	21.00%
State taxes, net of federal tax effect	2.10%	(47.80%)	3.40%
U.S. research and development tax credits	(23.70%)	(245.90%)	7.10%
Effect of foreign operations	(5.30%)	(66.90%)	(0.10%)
Meals and entertainment	0.70%	43.70%	(1.00%)
Change in valuation allowance	24.00%	250.00%	2.20%
Internal restructuring charges	0.00%	196.50%	0.00%
Stock compensation	5.20%	172.10%	(2.60%)
Divestiture	0.00%	0.00%	(1.00%)
GILTI/FDII	(20.20%)	(174.30%)	2.90%
BEAT	0.00%	0.00%	(7.00%)
2017 Tax Act (transition tax and re-measurement of deferreds)	0.00%	0.00%	0.40%
Foreign withholding	13.80%	220.60%	(3.10%)
Provision to return	(2.30%)	(152.80%)	(1.00%)
Other permanent differences	(2.10%)	26.90%	(0.10%)
Total effective income tax rate	13.20%	243.10%	21.10%

INCOME TAXES - Summary of Com_2

INCOME TAXES - Summary of Components of Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Deferred tax assets:
Accrued expenses	$ 8,480	$ 5,060
Deferred revenue	17,648	14,420
Reserves	2,898	3,216
Pension and other retiree benefits	6,160	5,078
Net operating loss carryforwards	11,526	12,443
Tax credit carryforwards	19,432	14,138
Share-based compensation	5,397	4,534
Operating lease liability	17,333	18,213
Other deferred tax assets	2,116	20
Total gross deferred tax assets	90,990	77,122
Valuation allowance	(11,406)	(5,641)
Net deferred tax assets	79,584	71,481
Deferred tax liabilities:
Intangible assets	(132,635)	(146,950)
Other deferred tax liabilities	(8,848)	(8,061)
Operating lease right-of-use asset	(14,474)	(15,152)
Depreciation	(7,818)	(9,492)
Total deferred tax liability	$ (84,191)	$ (108,174)

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Provisional income tax expense related to transition tax associated with deemed repatriation of foreign earnings	$ 11.4	$ 5.6
Provisional income tax benefit related to re-measurement of deferred tax assets and liabilities	5.8		$ 87
State net operating loss carryforwards	11
Federal net operating loss carryforwards	44
Tax credit carryforwards	15
Foreign net operating loss carryforwards	45
Foreign tax credit carryforwards	$ 7
One-time transition charge			$ 2

INCOME TAXES - Schedule of Reco

INCOME TAXES - Schedule of Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance at April 1,	$ 1,151	$ 1,314	$ 2,215
Additions based on tax positions related to the current year	48	49	28
Release of tax positions of prior years	(286)	(212)	(194)
Decrease relating to settlements with taxing authorities	0	0	(735)
Balance at March 31,	$ 913	$ 1,151	$ 1,314

LEASES - Additional Information

LEASES - Additional Information (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020	Apr. 01, 2019
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	$ 61,512	$ 68,583
Present value of lease liabilities	$ 73,621
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease terms	1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease terms	10 years
ASU 2016-02
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets			$ 68,200
Present value of lease liabilities			83,200
Elimination of deferred rent			$ 15,000

LEASES - Operating Lease Cost (

LEASES - Operating Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Lease cost under long-term operating leases	$ 13,092	$ 13,318
Lease cost under short-term operating leases	3,678	4,172
Variable lease cost under short-term and long-term operating leases	3,800	4,259
Total operating lease cost	$ 20,570	$ 21,749

LEASES - Supplemental Cash Flow

LEASES - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 2,492	$ 11,127
Weighted average remaining lease term in years - operating leases	7 years 8 months 12 days	8 years 7 months 2 days
Weighted average discount rate - operating leases	4.10%	4.10%

LEASES - Future Minimum Payment

LEASES - Future Minimum Payments Under Non-Cancellable Leases (Details) $ in Thousands	Mar. 31, 2021USD ($)
Leases [Abstract]
2022	$ 14,085
2023	12,890
2024	10,299
2025	10,098
2026	9,087
Thereafter	29,286
Total lease payments	85,745
Less imputed interest	(12,124)
Present value of lease liabilities	$ 73,621

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Details)

Jul. 14, 2020USD ($)

Oct. 13, 2017USD ($)

Feb. 28, 2021USD ($)

Apr. 30, 2020USD ($)

Sep. 30, 2018USD ($)

Oct. 31, 2017patent

Mar. 31, 2016subsidiarypatent

Mar. 31, 2021USD ($)

Mar. 31, 2020USD ($)company

Mar. 31, 2019USD ($)

Mar. 31, 2021USD ($)company

Feb. 05, 2020USD ($)

Apr. 03, 2019USD ($)

Commitments and Contingencies Disclosure [Line Items]

Number of companies acquired | company

2

2

Fair value of contingent liability

$ 1,748,000

Payment of contingent consideration

$ 1,748,000

0

$ 2,851,000

Number of subsidiary entities | subsidiary

2

Number of patents allegedly infringed | patent

3

5

Loss contingency, damages awarded, value

$ 2,800,000

Unconditional purchase obligation

55,300,000

$ 55,300,000

Pre-Suit Damages

Commitments and Contingencies Disclosure [Line Items]

Loss contingency, damages awarded, value

$ 3,500,000

$ 3,500,000

Post-Suit Damages

Commitments and Contingencies Disclosure [Line Items]

Loss contingency, damages awarded, value

$ 2,250,000

$ 2,250,000

Minimum

Commitments and Contingencies Disclosure [Line Items]

Estimate of potential enhancement

0

0

Maximum

Commitments and Contingencies Disclosure [Line Items]

Estimate of potential enhancement

$ 2,800,000

$ 2,800,000

Gigavation

Commitments and Contingencies Disclosure [Line Items]

Fair value of contingent liability

700,000

$ 800,000

Payment of contingent consideration

$ 700,000

Eastwind

Commitments and Contingencies Disclosure [Line Items]

Fair value of contingent liability

$ 1,000,000

$ 1,000,000

Payment of contingent consideration

$ 1,000,000

Efflux Systems, Inc.

Commitments and Contingencies Disclosure [Line Items]

Payment of contingent consideration

500,000

Simena LLC

Commitments and Contingencies Disclosure [Line Items]

Payment of contingent consideration

$ 5,000,000

SEGMENT AND GEOGRAPHIC INFORM_3

SEGMENT AND GEOGRAPHIC INFORMATION (Details) $ in Thousands	12 Months Ended
	Mar. 31, 2021USD ($)Segment	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)
Segment Reporting [Abstract]
Number of segments | Segment	1
Segment Reporting Information [Line Items]
Total revenue	$ 831,282	$ 891,820	$ 909,918
United States
Segment Reporting Information [Line Items]
Total revenue	484,129	545,620	553,267
Europe
Segment Reporting Information [Line Items]
Total revenue	160,372	154,510	148,036
Asia
Segment Reporting Information [Line Items]
Total revenue	56,562	59,939	72,355
Rest of the world
Segment Reporting Information [Line Items]
Total revenue	$ 130,219	$ 131,751	$ 136,260

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Allowance for credit losses
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Fiscal Year	$ 1,350	$ 1,583	$ 1,991
Additions Resulting in Charges to Operations	48	1,450	826
Charges to Other Accounts	(733)	(1,202)	(464)
Deductions Due to Write-Offs	(249)	(481)	(770)
Balance at End of Fiscal Year	416	1,350	1,583
Deferred tax asset valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Fiscal Year	5,641	835	3,108
Additions Resulting in Charges to Operations	5,765	4,806	905
Charges to Other Accounts	0	0	0
Deductions Due to Write-Offs	0	0	(3,178)
Balance at End of Fiscal Year	$ 11,406	$ 5,641	$ 835

Uncategorized Items - ntct-2021

Label	Element	Value
Accounting Standards Update [Extensible List]	us-gaap_AccountingStandardsUpdateExtensibleList	us-gaap:AccountingStandardsUpdate201409Member