NetScout Systems (NTCT) 10-Q 6 Feb 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Dec. 31, 2019	Jan. 30, 2020
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Dec. 31, 2019
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 Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		73,855,221
Entity Central Index Key	0001078075
Current Fiscal Year End Date	--03-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Current assets:
Cash and cash equivalents	$ 287,660	$ 409,632
Marketable securities	56,274	76,344
Accounts receivable and unbilled costs, net of allowance for doubtful accounts of $1,728 and $1,583 at December 31, 2019 and March 31, 2019, respectively	244,877	235,318
Inventories and deferred costs	24,977	26,270
Prepaid income taxes	14,454	18,000
Prepaid expenses and other current assets	25,807	35,658
Total current assets	654,049	801,222
Fixed assets, net	58,700	58,951
Operating lease right-of-use assets	65,738
Goodwill	1,718,496	1,715,485
Intangible assets, net	602,856	669,118
Deferred income taxes	7,034	7,218
Long-term marketable securities	2,561	1,012
Other assets	17,905	16,988
Total assets	3,127,339	3,269,994
Current liabilities:
Accounts payable	19,756	24,582
Accrued compensation	70,430	58,501
Accrued other	20,159	23,027
Income taxes payable	1,517	1,318
Deferred revenue and customer deposits	261,151	272,508
Current portion of operating lease liabilities	11,091
Total current liabilities	384,104	379,936
Other long-term liabilities	6,997	19,493
Deferred tax liability	115,470	124,229
Accrued long-term retirement benefits	35,808	36,284
Long-term deferred revenue and customer deposits	104,339	94,619
Operating lease liabilities, net of current portion	67,814
Long-term debt	450,000	550,000
Total liabilities	1,164,532	1,204,561
Commitments and contingencies (Note 14)
Preferred stock, $0.001 par value:
5,000,000 shares authorized; no shares issued or outstanding at December 31, 2019 and March 31, 2019	0	0
Common stock, $0.001 par value:
300,000,000 shares authorized; 121,679,117 and 119,760,132 shares issued and 73,855,221 and 77,610,361 shares outstanding at December 31, 2019 and March 31, 2019, respectively	122	120
Additional paid-in capital	2,873,702	2,828,922
Accumulated other comprehensive loss	(3,345)	(2,639)
Treasury stock at cost, 47,823,896 and 42,149,771 shares at December 31, 2019 and March 31, 2019, respectively	(1,255,675)	(1,119,063)
Retained earnings	348,003	358,093
Total stockholders' equity	1,962,807	2,065,433
Total liabilities and stockholders' equity	$ 3,127,339	$ 3,269,994

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 1,728	$ 1,583
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)	121,679,117	119,760,132
Common stock, shares outstanding (in shares)	73,855,221	77,610,361
Treasury stock, shares (in shares)	47,823,896	42,149,771

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Revenue:
Total revenue	$ 260,024,000	$ 246,008,000	$ 662,469,000	$ 674,916,000
Cost of revenue:
Total cost of revenue	65,585,000	69,584,000	179,460,000	195,591,000
Gross profit	194,439,000	176,424,000	483,009,000	479,325,000
Operating expenses:
Research and development	48,606,000	49,925,000	142,391,000	161,347,000
Sales and marketing	67,653,000	74,024,000	214,245,000	224,207,000
General and administrative	25,048,000	22,788,000	72,436,000	74,141,000
Amortization of acquired intangible assets	16,120,000	16,433,000	48,395,000	57,879,000
Restructuring charges	193,000	13,895,000	466,000	17,514,000
Impairment of intangible assets	0	0	0	35,871,000
Loss on divestiture of business	0	0	0	9,177,000
Total operating expenses	157,620,000	177,065,000	477,933,000	580,136,000
Income (loss) from operations	36,819,000	(641,000)	5,076,000	(100,811,000)
Interest and other expense, net:
Interest income	826,000	1,455,000	3,699,000	3,688,000
Interest expense	(4,629,000)	(7,005,000)	(16,167,000)	(19,320,000)
Other income (expense), net	(112,000)	986,000	538,000	429,000
Total interest and other expense, net	(3,915,000)	(4,564,000)	(11,930,000)	(15,203,000)
Income (loss) before income tax expense (benefit)	32,904,000	(5,205,000)	(6,854,000)	(116,014,000)
Income tax expense (benefit)	(3,821,000)	(1,602,000)	3,236,000	(23,479,000)
Net income (loss)	$ 36,725,000	$ (3,603,000)	$ (10,090,000)	$ (92,535,000)
Basic net income (loss) per share (in dollars per share)	$ 0.49	$ (0.05)	$ (0.13)	$ (1.17)
Diluted net income (loss) per share (in dollars per share)	$ 0.49	$ (0.05)	$ (0.13)	$ (1.17)
Weighted average common shares outstanding used in computing:
Net income (loss) per share - basic (in shares)	74,367	77,774	75,780	78,916
Net income (loss) per share - diluted (in shares)	74,700	77,774	75,780	78,916
Product
Revenue:
Total revenue	$ 143,309,000	$ 134,135,000	$ 321,803,000	$ 341,815,000
Cost of revenue:
Total cost of revenue	34,197,000	40,517,000	90,500,000	107,974,000
Service
Revenue:
Total revenue	116,715,000	111,873,000	340,666,000	333,101,000
Cost of revenue:
Total cost of revenue	$ 31,388,000	$ 29,067,000	$ 88,960,000	$ 87,617,000

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 36,725	$ (3,603)	$ (10,090)	$ (92,535)
Other comprehensive income (loss):
Cumulative translation adjustments	297	(1,170)	(789)	(3,319)
Changes in market value of investments:
Changes in unrealized gains, net of taxes of $1, $12, $12 and $21, respectively	3	12	40	35
Total net change in market value of investments	3	12	40	35
Changes in market value of derivatives:
Changes in market value of derivatives, net of taxes (benefit) of $40, ($53), $6 and ($193), respectively	84		18
Changes in market value of derivatives, net of taxes (benefit) of $40, ($53), $6 and ($193), respectively		(162)		(601)
Reclassification adjustment for net (losses) gains included in net income (loss), net of (benefit) taxes of ($7), $51, $8 and $122, respectively	(30)		25
Reclassification adjustment for net (losses) gains included in net income (loss), net of (benefit) taxes of ($7), $51, $8 and $122, respectively		157		382
Total net change in market value of derivatives	54		43
Total net change in market value of derivatives		(5)		(219)
Other comprehensive income (loss)	354	(1,163)	(706)	(3,503)
Total comprehensive income (loss)	$ 37,079	$ (4,766)	$ (10,796)	$ (96,038)

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Changes in unrealized (losses) gains, (benefit) tax	$ 1	$ 12	$ 12	$ 21
Changes in market value of derivatives, tax (benefit)	40		6
Changes in market value of derivatives, tax (benefit)		(53)		(193)
Reclassification adjustment for net gains included in net income (loss), taxes	$ (7)		$ 8
Reclassification adjustment for net gains included in net income (loss), taxes		$ 51		$ 122

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock Voting	Additional Paid In Capital	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Retained Earnings
Beginning balance (in shares) at Mar. 31, 2018		117,744,913			37,474,890
Beginning balance at Mar. 31, 2018	$ 2,068,782	$ 117	$ 2,665,120	$ 2,895	$ (995,843)	$ 396,493
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(92,535)					(92,535)
Unrealized net investment gains	35			35
Unrealized net losses on derivative financial instruments	(219)			(219)
Cumulative translation adjustments	(3,319)			(3,319)
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		1,369,122
Issuance of common stock pursuant to vesting of restricted stock units	2	$ 2
Stock-based compensation expense for restricted stock units granted to employees	40,423		40,423
Issuance of common stock under employee stock purchase plan (in shares)		302,994
Issuance of common stock under employee stock purchase plan	7,575		7,575
Repurchase of treasury stock (in shares)					4,110,353
Repurchase of treasury stock	(11,416)		96,783		$ (108,199)
Ending balance (in shares) at Dec. 31, 2018		119,417,029			41,585,243
Ending balance at Dec. 31, 2018	2,043,477	$ 119	2,809,901	(608)	$ (1,104,042)	338,107
Beginning balance (in shares) at Sep. 30, 2018		119,231,287			41,526,563
Beginning balance at Sep. 30, 2018	2,036,598	$ 119	2,796,695	555	$ (1,102,481)	341,710
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(3,603)					(3,603)
Unrealized net investment gains	12			12
Unrealized net losses on derivative financial instruments	(5)			(5)
Cumulative translation adjustments	(1,170)			(1,170)
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		185,742
Issuance of common stock pursuant to vesting of restricted stock units	0	$ 0
Stock-based compensation expense for restricted stock units granted to employees	13,206		13,206
Repurchase of treasury stock (in shares)					58,680
Repurchase of treasury stock	(1,561)				$ (1,561)
Ending balance (in shares) at Dec. 31, 2018		119,417,029			41,585,243
Ending balance at Dec. 31, 2018	2,043,477	$ 119	2,809,901	(608)	$ (1,104,042)	338,107
Beginning balance (in shares) at Mar. 31, 2019		119,760,132			42,149,771
Beginning 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)	(10,090)					(10,090)
Unrealized net investment gains	40			40
Unrealized net losses on derivative financial instruments	43			43
Cumulative translation adjustments	(789)			(789)
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		1,621,350
Issuance of common stock pursuant to vesting of restricted stock units	2	$ 2
Stock-based compensation expense for restricted stock units granted to employees	38,187		38,187
Issuance of common stock under employee stock purchase plan (in shares)		297,635
Issuance of common stock under employee stock purchase plan	6,593		6,593
Repurchase of treasury stock (in shares)					5,674,125
Repurchase of treasury stock	(136,612)				$ (136,612)
Ending balance (in shares) at Dec. 31, 2019		121,679,117			47,823,896
Ending balance at Dec. 31, 2019	1,962,807	$ 122	2,873,702	(3,345)	$ (1,255,675)	348,003
Beginning balance (in shares) at Sep. 30, 2019		121,648,747			46,810,700
Beginning balance at Sep. 30, 2019	1,940,264	$ 122	2,863,003	(3,699)	$ (1,230,440)	311,278
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	36,725					36,725
Unrealized net investment gains	3			3
Unrealized net losses on derivative financial instruments	54			54
Cumulative translation adjustments	297			297
Issuance of common stock pursuant to vesting of restricted stock units (in shares)		30,370
Issuance of common stock pursuant to vesting of restricted stock units	0	$ 0
Stock-based compensation expense for restricted stock units granted to employees	10,699		10,699
Repurchase of treasury stock (in shares)					1,013,196
Repurchase of treasury stock	(25,235)				$ (25,235)
Ending balance (in shares) at Dec. 31, 2019		121,679,117			47,823,896
Ending balance at Dec. 31, 2019	$ 1,962,807	$ 122	$ 2,873,702	$ (3,345)	$ (1,255,675)	$ 348,003

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (10,090,000)	$ (92,535,000)
Adjustments to reconcile net loss to cash provided by operating activities, net of the effects of acquisitions:
Depreciation and amortization	87,397,000	106,509,000
Operating lease right-of-use assets	7,872,000
Loss on divestiture of business	0	7,390,000
Loss on disposal of fixed assets	16,000	181,000
Deal-related compensation expense and accretion charges	0	102,000
Share-based compensation expense	39,961,000	44,142,000
Net change in fair value of contingent and contractual liabilities	541,000	0
Accretion of contingent consideration	(24,000)	(64,000)
Impairment of intangible assets	0	35,871,000
Deferred income taxes	(8,480,000)	(27,667,000)
Other losses (gains)	35,000	(206,000)
Changes in assets and liabilities
Accounts receivable and unbilled costs	(9,554,000)	(33,928,000)
Due from related party	0	171,000
Inventories	(1,233,000)	2,683,000
Prepaid expenses and other assets	10,957,000	5,582,000
Accounts payable	(4,647,000)	582,000
Accrued compensation and other expenses	16,009,000	28,385,000
Operating lease liabilities	(9,690,000)
Due to related party	0	232,000
Income taxes payable	24,000	(1,754,000)
Deferred revenue	(1,304,000)	(6,162,000)
Net cash provided by operating activities	117,790,000	69,514,000
Cash flows from investing activities:
Purchase of marketable securities	(89,840,000)	(184,104,000)
Proceeds from sales and maturity of marketable securities	108,413,000	155,346,000
Purchase of fixed assets	(15,207,000)	(19,462,000)
Payments related to the divestiture of business	0	(2,911,000)
Increase in deposits	(29,000)	(97,000)
Acquisition of businesses	(4,154,000)	0
Capitalized software development costs	0	(132,000)
Net cash used in investing activities	(817,000)	(51,360,000)
Cash flows from financing activities:
Issuance of common stock under stock plans	2,000	2,000
Payment of contingent consideration	0	(2,851,000)
Repayment of long-term debt	(100,000,000)	0
Treasury stock repurchases	(125,000,000)	0
Tax withholding on restricted stock units	(11,612,000)	(11,415,000)
Net cash used in financing activities	(236,610,000)	(14,264,000)
Effect of exchange rate changes on cash and cash equivalents	(1,523,000)	(5,380,000)
Net decrease in cash and cash equivalents and restricted cash	(121,160,000)	(1,490,000)
Cash and cash equivalents and restricted cash, beginning of period	409,820,000	370,731,000
Cash and cash equivalents and restricted cash, end of period	288,660,000	369,241,000
Supplemental disclosures:
Cash paid for interest	14,019,000	17,410,000
Cash paid for income taxes	10,494,000	9,150,000
Non-cash transactions:
Transfers of inventory to fixed assets	2,290,000	2,152,000
Additions to property, plant and equipment included in accounts payable	119,000	1,190,000
Tenant improvement allowance	0	10,171,000
Issuance of common stock under employee stock plans	6,593,000	7,575,000
Contingent consideration related to acquisition, included in accrued other	1,000,000	0
Fair value of contingent consideration received as partial consideration for divestiture of business	$ 0	$ 2,257,000

BASIS OF PRESENTATION

BASIS OF PRESENTATION	9 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION The accompanying unaudited interim consolidated financial statements have been prepared by NetScout Systems, Inc. (NetScout or the Company). Certain information and footnote disclosures normally included in financial statements prepared under United States generally accepted accounting principles (GAAP) have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). In the opinion of management, the unaudited interim consolidated financial statements include all adjustments, consisting of normal recurring adjustments, necessary for a fair statement of the Company's financial position and stockholders' equity, results of operations and cash flows. The year-end consolidated balance sheet data and statement of stockholders' equity were derived from the Company's audited financial statements, but do not include all disclosures required by GAAP. The results reported in these unaudited interim consolidated financial statements are not necessarily indicative of results that may be expected for the entire year. All significant intercompany accounts and transactions are eliminated in consolidation. These unaudited interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements, including the notes thereto, included in the Company’s Annual Report on Form 10-K for the fiscal year ended March 31, 2019 filed with the Securities and Exchange Commission on May 28, 2019. Recent Accounting Pronouncements 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, 2021. ASU 2019-12 is effective for NetScout beginning April 1, 2022. 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 Company is currently assessing the effect that ASU 2019-12 will have on its 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. This guidance is effective for fiscal years ending after December 15, 2020. ASU 2018-14 is effective for NetScout beginning April 1, 2021. Early adoption is permitted. The Company is currently assessing the effect that ASU 2018-14 will have on its financial position, results of operations, and disclosures. 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. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year. ASU 2018-13 is effective for NetScout beginning April 1, 2020. Early adoption is permitted. The Company is currently assessing the effect that ASU 2018-13 will have on its financial position, results of operations, and disclosures. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815), Targeted Improvements to Accounting for Hedging Activities (ASU 2017-12). ASU 2017-12 provides guidance to better align an entity's risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The amendments expand and refine hedge accounting for both non-financial and financial risk components and align the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. This standard is effective for financial statements issued for fiscal years beginning after December 15, 2018. The Company adopted ASU 2017-12 effective April 1, 2019. The adoption has had an immaterial 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 and ASU 2019-11 (collectively, Topic 326). Topic 326 requires measurement and recognition of expected credit losses for financial assets held. Topic 326 is effective for annual periods beginning after December 15, 2019, and interim periods therein. Topic 326 is effective for NetScout beginning April 1, 2020, and earlier adoption is permitted. The Company is currently assessing the effect that Topic 326 will have on its financial position, results of operations, and disclosures. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) Section A - Leases: Amendments to the FASB Accounting Standards Codification (ASU 2016-02) and issued subsequent amendments to initial guidance in July 2018 within ASU 2018-10, Codification Improvements to Topic 842, Leases and ASU 2018-11, Leases (Topic 842): Targeted Improvements (collectively, ASC 842). ASC 842 aims 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 as of April 1, 2019 using the modified retrospective method. Please refer to Note 13, "Leases" for further details.

REVENUE RECOGNITION

REVENUE RECOGNITION	9 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
REVENUE RECOGNITION	REVENUE RECOGNITION 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 majority of the Company's product sales consist of hardware products with embedded software that are essential to providing customers the intended functionality of the solutions. The Company also sells software offerings decoupled from the underlying hardware and software solutions to provide customers with enhanced functionality. 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 reseller or distributor as a reduction of revenue to the extent they have recorded revenue from the reseller or distributor. 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 nine months ended December 31, 2019 , the Company recognized revenue of $240.5 million related to the Company's deferred revenue balance reported at March 31, 2019 . 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 or refunds at December 31, 2019 . At December 31, 2019 , the Company had total deferred revenue of $365.5 million , which represents the aggregate total contract price allocated to undelivered performance obligations. The Company expects to recognize $261.2 million, or 71% , of this revenue during the next 12 months, and expects to recognize the remaining $104.3 million, or 29% , of this revenue thereafter. 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, and 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 $4.9 million and $23.3 million at December 31, 2019 and March 31, 2019 , respectively. 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 any significant financing components, or variable consideration or performance obligations satisfied in a prior period recognized during the nine months ended December 31, 2019 . Contract Balances The Company may receive payments from customers based on a billing schedule 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 payments 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 December 31, 2019 , the consolidated balance sheet included $6.8 million in assets related to sales commissions to be expensed in future periods. A balance of $3.8 million was included in prepaid expenses and other current assets, and a balance of $3.0 million was included in other assets in the Company's consolidated balance sheet at December 31, 2019 . At March 31, 2019 , the consolidated balance sheet included $6.4 million in assets related to sales commissions to be expensed in future periods. A balance of $3.8 million was included in prepaid expenses and other current assets, and a balance of $2.6 million was included in other assets in the Company's consolidated balance sheet at March 31, 2019 . During the three and nine months ended December 31, 2019 and 2018 , respectively, the Company recognized $1.6 million , $1.5 million , $4.8 million , and $4.8 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.

CONCENTRATION OF CREDIT RISK AN

CONCENTRATION OF CREDIT RISK AND SIGNIFICANT CUSTOMERS	9 Months Ended
	Dec. 31, 2019
Risks and Uncertainties [Abstract]
CONCENTRATION OF CREDIT RISK AND SIGNIFICANT CUSTOMERS	CONCENTRATION OF CREDIT RISK AND SIGNIFICANT CUSTOMERS Financial instruments that potentially subject the Company to concentration of credit risk consist primarily of investments, trade accounts receivable and accounts payable. The Company's cash, cash equivalents, and marketable securities are placed with financial institutions with high credit standings. At December 31, 2019 and March 31, 2019 , the Company had no direct customers or indirect channel partners which accounted for more than 10% of the accounts receivable balance. During the three and nine months ended December 31, 2019 , no direct customers or indirect channel partners accounted for more than 10% of the Company's total revenue. During the three months ended December 31, 2018 , one direct customer, Verizon, accounted for more than 10% of the Company's total revenue, while no indirect channel partners accounted for more than 10% of total revenue. During the nine months ended December 31, 2018 , no direct customers or indirect channel partners accounted for more than 10% of total revenue. Historically, the Company has not experienced any significant failure of its customers' ability 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.

SHARE-BASED COMPENSATION

SHARE-BASED COMPENSATION	9 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
SHARE-BASED COMPENSATION	SHARE-BASED COMPENSATION The following is a summary of share-based compensation expense including restricted stock units granted pursuant to the Company's 2007 Equity Incentive Plan, as amended (Amended 2007 Plan), and employee stock purchases made under the Company's 2011 Employee Stock Purchase Plan, as amended, (ESPP), based on estimated fair values within the applicable cost and expense lines identified below (in thousands): Three Months Ended Nine Months Ended December 31, December 31, 2019 2018 2019 2018 Cost of product revenue $ 231 $ 375 $ 843 $ 1,188 Cost of service revenue 1,275 1,519 4,584 4,694 Research and development 3,437 3,979 12,076 13,544 Sales and marketing 3,910 4,649 13,333 15,051 General and administrative 2,508 3,237 9,125 9,665 $ 11,361 $ 13,759 $ 39,961 $ 44,142 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. The aggregate number of shares available for issuance under the 2019 Plan will increase by 2.76 shares for each share: (i) subject to an award granted under the Amended 2007 Plan or 2019 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 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 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 Plan. Furthermore, the share reserve under the 2019 Plan is reduced by one share for each share of common stock issued pursuant to a stock option or stock appreciation right and 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 Plan on or after September 12, 2019. At December 31, 2019 , there were 6,902,159 shares of common stock available for grant under the 2019 Plan. The 2019 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). Employee Stock Purchase Plan – The Company maintains the ESPP for all eligible employees as described in the Company's Annual Report on Form 10-K for the year ended March 31, 2019 . 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 value on the last day of such offering period. The offering periods run from March 1st through August 31st and from September 1st through the last day of February each year. During the nine months ended December 31, 2019 , employees purchased 297,635 shares under the ESPP and the value per share was $22.15 .

CASH, CASH EQUIVALENTS, RESTRIC

CASH, CASH EQUIVALENTS, RESTRICTED CASH AND MARKETABLE SECURITIES	9 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
CASH, CASH EQUIVALENTS, RESTRICTED CASH AND MARKETABLE SECURITIES	CASH, CASH EQUIVALENTS, RESTRICTED CASH AND MARKETABLE SECURITIES The Company 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. Cash and cash equivalents consisted of U.S. government and municipal obligations, commercial paper, money market instruments and cash maintained with various financial institutions at December 31, 2019 and March 31, 2019 . 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): December 31, March 31, 2019 December 31, March 31, Cash and cash equivalents $ 287,660 $ 409,632 $ 369,054 $ 369,821 Restricted cash 1,000 188 187 910 Total cash, cash equivalents and restricted cash $ 288,660 $ 409,820 $ 369,241 $ 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 December 31, 2019 , classified as short-term and long-term (in thousands): Amortized Cost Unrealized Gains Fair Value Type of security: U.S. government and municipal obligations $ 27,139 $ 48 $ 27,187 Commercial paper 24,911 — 24,911 Corporate bonds 4,167 9 4,176 Total short-term marketable securities 56,217 57 56,274 U.S. government and municipal obligations 2,549 12 2,561 Total long-term marketable securities 2,549 12 2,561 Total marketable securities $ 58,766 $ 69 $ 58,835 The following is a summary of marketable securities held by NetScout at March 31, 2019 , classified as short-term and long-term (in thousands): Amortized Cost Unrealized Gains Fair Value Type of security: U.S. government and municipal obligations $ 27,610 $ 12 $ 27,622 Commercial paper 48,722 — 48,722 Total short-term marketable securities 76,332 12 76,344 Corporate bonds 1,007 5 1,012 Total long-term marketable securities 1,007 5 1,012 Total marketable securities $ 77,339 $ 17 $ 77,356 Contractual maturities of the Company's marketable securities held at December 31, 2019 and March 31, 2019 were as follows (in thousands): December 31, March 31, Available-for-sale securities: Due in 1 year or less $ 56,274 $ 76,344 Due after 1 year through 5 years 2,561 1,012 $ 58,835 $ 77,356

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Dec. 31, 2019
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 non-observable inputs. The following tables present the Company's financial assets and liabilities measured on a recurring basis using the fair value hierarchy at December 31, 2019 and March 31, 2019 (in thousands): Fair Value Measurements at December 31, 2019 Level 1 Level 2 Level 3 Total ASSETS: Cash and cash equivalents $ 287,660 $ — $ — $ 287,660 U.S. government and municipal obligations 29,748 — — 29,748 Commercial paper — 24,911 — 24,911 Corporate bonds 4,176 — — 4,176 Derivative financial instruments — 93 — 93 Contingent consideration — — 245 245 $ 321,584 $ 25,004 $ 245 $ 346,833 LIABILITIES: Contingent purchase consideration $ — $ — $ (1,000 ) $ (1,000 ) Derivative financial instruments — (11 ) — (11 ) $ — $ (11 ) $ (1,000 ) $ (1,011 ) Fair Value Measurements at March 31, 2019 Level 1 Level 2 Level 3 Total ASSETS: Cash and cash equivalents $ 409,632 $ — $ — $ 409,632 U.S. government and municipal obligations 10,732 16,890 — 27,622 Commercial paper — 48,722 — 48,722 Corporate bonds 1,012 — — 1,012 Derivative financial instruments — 58 — 58 Contingent consideration — — 762 762 $ 421,376 $ 65,670 $ 762 $ 487,808 LIABILITIES: Derivative financial instruments $ — $ (68 ) $ — $ (68 ) $ — $ (68 ) $ — $ (68 ) 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 assets consist of contingent consideration related to the divestiture of the Company's handheld network test (HNT) tools business in September 2018. The contingent consideration represents potential future earnout payments to the Company of up to $4.0 million over two years that are contingent on the HNT tools business achieving certain milestones. The Company recorded a $0.5 million change in the fair value of the contingent consideration for the nine months ended December 31, 2019 , which is included in other income (expense), net within the Company's consolidated statement of operations for the nine months ended December 31, 2019 . The fair value of the contingent consideration was $0.2 million and $0.8 million at December 31, 2019 and March 31, 2019 respectively. The contingent consideration is included in other assets within the Company’s consolidated balance sheet at December 31, 2019 and March 31, 2019 . The Company's Level 3 liability consists of contingent purchase consideration related to the acquisition of certain assets and liabilities of Eastwind Networks, Inc. (Eastwind) in April 2019. The contingent purchase consideration represents amounts deposited into an escrow account, which was established to cover damages NetScout may suffer 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. The contingent purchase consideration is included as accrued other in the Company's consolidated balance sheet at December 31, 2019 . 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 nine months ended December 31, 2019 (in thousands): Contingent Consideration Contingent Purchase Consideration Balance at March 31, 2019 $ 762 $ — Additions to Level 3 — (1,000 ) Change in fair value of contingent consideration (517 ) — Balance at December 31, 2019 $ 245 $ (1,000 ) Accretion income related to the contingent consideration received as partial consideration for the divestiture of the HNT tools business for the nine months ended December 31, 2019 was $24 thousand and was included within interest income.

INVENTORIES

INVENTORIES	9 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
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. Inventories consist of the following (in thousands): December 31, March 31, Raw materials $ 14,980 $ 14,432 Work in process 121 1,181 Finished goods 4,473 7,738 Deferred costs 5,403 2,919 $ 24,977 $ 26,270

ACQUISITIONS & DIVESTITURES

ACQUISITIONS & DIVESTITURES	9 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
ACQUISITIONS & DIVESTITURES	ACQUISITIONS & DIVESTITURES 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. 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 suffer 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. Except to the extent that valid indemnification claims are made prior to such time, the $1.0 million will be 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 will record the liability over the period it is earned as compensation expense for post-combination services. The fair value of intangible assets 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 HNT tools business. As part of the divestiture, the Company recorded contingent consideration which represents potential future earnout payments of up to $4.0 million over two years that are contingent on the HNT tools business achieving certain milestones. The Company recorded a $0.5 million change in the fair value of the contingent consideration, which is included in other income (expense), net within the Company’s consolidated statements of operations for the nine months ended December 31, 2019 . The fair value of the contingent consideration was $0.2 million and $0.8 million at December 31, 2019 and March 31, 2019 , respectively. The contingent consideration is included within other assets within the Company’s consolidated balance sheet. In connection with the divestiture, the Company has entered into a transitional services agreement with the buyer to provide certain services for a period of up to eighteen months . Income (expense) associated with the transitional services agreement for the three and nine months ended December 31, 2019 and 2018 was $(25) thousand , $1.1 million , $1.2 million , and $1.3 million

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	9 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS Goodwill The Company assesses goodwill for impairment at the reporting unit level at least annually, or on an interim basis if an event occurs or circumstances change that would, more likely than not, reduce the fair value of the reporting unit below its carrying value. The Company completed its annual impairment test on January 31, 2019. 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. Through the first half of fiscal year 2020, the Company had two reporting units: (1) Service Assurance and (2) Security. As part of its continued integration efforts, effective during the third quarter of fiscal year 2020, the Company reorganized its business units. As a result of this change, the Company reduced the number of reporting units from two reporting units to one reporting unit. The former Service Assurance and Security reporting units were combined as result of organizational changes made to fully integrate the resources and assets of the Service Assurance and Security business units. The Company completed an assessment of any potential impairment for all reporting units immediately prior to and after the reporting unit change and determined that no impairment existed. As such, no impairment charges were recognized during the nine months ended December 31, 2019 . At December 31, 2019 and March 31, 2019 , the carrying amount of goodwill was $1.7 billion . The change in the carrying amount of goodwill for the nine months ended December 31, 2019 is due to the acquisition of Eastwind and the impact of foreign currency translation adjustments related to asset balances that are recorded in currencies other than the U.S. Dollar. The following table summarizes the changes in the carrying amount of goodwill for the nine months ended December 31, 2019 as follows (in thousands): Balance at March 31, 2019 $ 1,715,485 Goodwill attributed to the Eastwind acquisition 1,003 Foreign currency translation impact 2,008 Balance at December 31, 2019 $ 1,718,496 Intangible Assets The net carrying amounts of intangible assets were $602.9 million and $ 669.1 million at December 31, 2019 and March 31, 2019 , 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. The Company completed its annual impairment test on January 31, 2019. During the three months ended June 30, 2018, 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 nine months ended December 31, 2018 . The impairment charge was recorded within a separate operating expense line item in the Company's consolidated statements of operations during the nine months ended December 31, 2018 . Intangible assets include the indefinite-lived trade name with a carrying value of $18.6 million and the following amortizable intangible assets at December 31, 2019 (in thousands): Cost Accumulated Amortization Net Developed technology $ 245,850 $ (186,356 ) $ 59,494 Customer relationships 770,696 (261,595 ) 509,101 Distributor relationships and technology licenses 6,843 (6,104 ) 739 Definite-lived trademark and trade name 39,205 (24,894 ) 14,311 Core technology 7,192 (7,016 ) 176 Net beneficial leases 336 (336 ) — Non-compete agreements 292 (292 ) — Leasehold interest 500 (500 ) — Backlog 16,327 (16,327 ) — Capitalized software 3,317 (3,152 ) 165 Other 1,208 (938 ) 270 $ 1,091,766 $ (507,510 ) $ 584,256 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, 2019 (in thousands): Cost Accumulated Amortization Net Developed technology $ 242,259 $ (168,289 ) $ 73,970 Customer relationships 772,969 (218,043 ) 554,926 Distributor relationships and technology licenses 6,882 (5,237 ) 1,645 Definite-lived trademark and trade name 39,304 (20,586 ) 18,718 Core technology 7,192 (6,845 ) 347 Net beneficial leases 336 (336 ) — Non-compete agreements 292 (292 ) — Leasehold interest 500 (500 ) — Backlog 16,397 (16,397 ) — Capitalized software 3,317 (2,690 ) 627 Other 1,208 (923 ) 285 $ 1,090,656 $ (440,138 ) $ 650,518 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 for the three and nine months ended December 31, 2019 and 2018, respectively (in thousands): Three Months Ended Nine Months Ended December 31, December 31, 2019 2018 2019 2018 Amortization of intangible assets included as: Cost of product revenue $ 6,564 $ 8,176 20,043 25,858 Operating expense 16,125 16,438 48,410 57,894 $ 22,689 $ 24,614 $ 68,453 $ 83,752 The following is the expected future amortization expense at December 31, 2019 for the fiscal years ending March 31 (in thousands): 2020 (remaining three months) $ 22,682 2021 79,857 2022 69,462 2023 61,758 2024 53,667 Thereafter 296,830 $ 584,256 The weighted-average amortization period of developed technology and core technology is 11.3 years . 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 amortizing all intangible assets is 14.6 years .

DERIVATIVE INSTRUMENTS AND HEDG

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	9 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES NetScout 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. 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 December 31, 2019 and March 31, 2019 were as follows (in thousands): Notional Amounts (a) Prepaid Expenses and Other Current Assets Accrued Other December 31, March 31, December 31, March 31, December 31, March 31, Derivatives Designated as Hedging Instruments: Forward contracts $ 4,883 $ 4,550 $ 93 $ 58 $ 11 $ 68 (a) 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 for the three months ended December 31, 2019 and 2018 (in thousands): Gain (Loss) Recognized in Gain (Loss) Reclassified from December 31, 2019 December 31, 2018 Location December 31, 2019 December 31, 2018 Forward contracts $ 124 $ (215 ) Research and development $ (8 ) $ 60 Sales and marketing (29 ) 148 $ 124 $ (215 ) $ (37 ) $ 208 (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 had on other comprehensive income (loss) (OCI) and results of operations for the nine months ended December 31, 2019 and 2018 (in thousands): (Gain) Loss Recognized in OCI on Derivative (a) Gain (Loss) Reclassified from Accumulated OCI into Income (b) December 31, 2019 December 31, 2018 Location December 31, 2019 December 31, 2018 Forward contracts $ 24 $ (794 ) Research and development $ (16 ) $ 147 Sales and marketing 49 357 $ 24 $ (794 ) $ 33 $ 504 (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.

LONG-TERM DEBT

LONG-TERM DEBT	9 Months Ended
	Dec. 31, 2019
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 nine months ended December 31, 2019 , the Company repaid $100.0 million of borrowings under the Amended Credit Agreement. At December 31, 2019 , $450 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 September 30, 2019, until the Company has delivered financial statements for the quarter ended December 31, 2019 , 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 1.00% per annum for Base Rate loans and 2.00% per annum for LIBOR loans if the Company's consolidated leverage ratio is greater than 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. 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. The Company's Amended Credit Agreement 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 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 September 30, 2019 until the Company has delivered financial statements for the quarter ended December 31, 2019 , 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 December 31, 2019 , 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. The Company has capitalized debt issuance costs totaling $12.2 million at December 31, 2019 , which are being amortized over the life of the revolving credit facility. The unamortized balance was $5.3 million as of December 31, 2019 . The balance of $1.7 million was included as prepaid expenses and other current assets and a balance of $3.6 million

RESTRUCTURING CHARGES

RESTRUCTURING CHARGES	9 Months Ended
	Dec. 31, 2019
Restructuring and Related Activities [Abstract]
RESTRUCTURING CHARGES	RESTRUCTURING CHARGES During the third quarter of 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 twelve months 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. During the nine months ended December 31, 2018 , the Company recorded an additional charge of $1.7 million for one-time termination benefits and facilities-related costs. The one-time termination benefits were paid in full during the fiscal year ended March 31, 2019. During the second quarter of the fiscal year ended March 31, 2019, the Company implemented a voluntary separation program (VSP) for employees who met certain age and service requirements to reduce overall headcount resulting in a total restructuring charge for the program of $17.3 million . As a result of the related workforce reduction, during the nine months ended December 31, 2019 and 2018, the Company recorded restructuring charges totaling $0.1 million and $16.1 million , respectively, related to one-time termination benefits employees who voluntarily terminated their employment with the Company during the period. The one-time termination benefits were paid in full by the end of the first quarter of the fiscal year ending March 31, 2020. During the second quarter of the fiscal year ending March 31, 2020, the Company restructured certain departments to better align functions. As a result of the workforce reduction, during the nine months ended December 31, 2019 , the Company recorded a restructuring charge totaling $0.3 million related to one-time termination benefits for the employees that were notified during the period. Additional one-time termination benefit charges of approximately $0.1 million in the aggregate are anticipated to be recorded in the next three months. The one-time termination benefits are expected to be paid in full by the first quarter of the fiscal year ending March 31, 2021. The following table provides a summary of the activity related to the restructuring plan and the related restructuring liability (in thousands): Q2FY20 Plan VSP Employee-Related Employee-Related Total Balance at March 31, 2019 $ — $ — $ — Restructuring charges to operations 329 123 452 Cash payments (169 ) (123 ) (292 ) Other adjustments 14 — 14 Balance at December 31, 2019 $ 174 $ — $ 174

LEASES

LEASES	9 Months Ended
	Dec. 31, 2019
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. 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 11 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 three and nine months ended December 31, 2019 were as follows (in thousands): Three Months Ended Nine Months Ended December 31, 2019 December 31, 2019 Lease cost under long-term operating leases $ 3,459 $ 9,980 Lease cost under short-term operating leases 1,681 3,430 Variable lease cost under short-term and long-term operating leases 974 3,249 Total operating lease cost $ 6,114 $ 16,659 The table below presents supplemental cash flow information related to leases during the nine months ended December 31, 2019 (in thousands): Cash paid for amounts included in the measurement of lease liabilities $ 9,690 Right-of-use assets obtained in exchange for new operating lease liabilities $ 5,474 Weighted average remaining lease term in years and weighted average discount rate are as follows: Weighted average remaining lease term in years - operating leases 8.80 Weighted average discount rate - operating leases 4.2 % Future minimum payments under non-cancellable leases at December 31, 2019 are as follows (in thousands): Year ending March 31: 2020 (remaining three months) $ 2,990 2021 13,523 2022 12,668 2023 10,475 2024 9,044 Thereafter 45,475 Total lease payments $ 94,175 Less imputed interest (15,270 ) Present value of lease liabilities $ 78,905 As previously disclosed in the Company’s fiscal year Form 10-K and under the previous lease accounting standard, ASC 840, Leases, the following table summarizes the future non-cancelable minimum lease commitments (including office space, copiers, and automobiles) at March 31, 2019 (in thousands): Year ending March 31: 2020 $ 16,102 2021 11,059 2022 9,804 2023 8,807 2024 8,500 Thereafter 43,997 Total $ 98,269

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Acquisition and divestiture related – The Company has a contingent consideration asset related to the divestiture of its HNT tools business in September 2018. The contingent consideration asset represents potential future earnout payments to the Company of up to $4.0 million over two years that are contingent on the HNT tools business achieving certain milestones. The fair value of the contingent consideration asset at December 31, 2019 and March 31, 2019 was $0.2 million and $0.8 million , respectively. The Company had a contingent liability at December 31, 2019 for $1.0 million related to the acquisition of Eastwind in April 2019 for which an escrow account was established to cover damages NetScout may suffer 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 merger agreement. Except to the extent that valid indemnification claims are made prior to such time, the $1.0 million will be paid to the seller in April 2020. 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. The Court denied the Plaintiff's motion for fees. Following additional motions for judgment as a matter of law, the court entered final judgment. On June 12, 2019, NetScout filed its Notice of Appeal of the judgment and all other adverse findings. NetScout has concluded that the risk of loss from this matter is currently neither remote nor probable, and therefore, under GAAP definitions, the risk of loss is termed "reasonably possible." Therefore, accounting rules require NetScout to provide an estimate for the range of potential liability. NetScout currently estimates that the estimated range of liability is between $0

PENSION BENEFIT PLANS

PENSION BENEFIT PLANS	9 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
PENSION BENEFIT PLANS	PENSION BENEFIT PLANS Certain of the Company's non-U.S. employees participate in noncontributory defined benefit pension plans. No ne 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 following sets forth the components of the Company's net periodic pension cost of the noncontributory defined benefit pension plans for the three and nine months ended December 31, 2019 and 2018 (in thousands): Three Months Ended Nine Months Ended December 31, December 31, 2019 2018 2019 2018 Service cost $ 45 $ 61 $ 131 $ 187 Interest cost 105 118 307 362 Net periodic pension cost $ 150 $ 179 $ 438 $ 549 Expected Contributions During the nine months ended December 31, 2019 , the Company made contributions of $0.3 million to its defined benefit pension plans. During the fiscal year ending March 31, 2020 , the Company's cash contribution requirements for its defined benefit pension plans are expected to be less than $1.0 million . As a majority of the participants within the Company's plans are all active employees, the benefit payments are not expected to be material in the foreseeable future.

TREASURY STOCK

TREASURY STOCK	9 Months Ended
	Dec. 31, 2019
Equity [Abstract]
TREASURY STOCK	TREASURY STOCK On May 19, 2015, the Company's board of directors approved a share repurchase program. This program enabled the Company to repurchase up to 20 million shares of its common stock. This plan became effective on July 14, 2015. The Company was not obligated to acquire any specific amount of common stock within any particular timeframe under this program. Through March 31, 2018, the Company had repurchased 20,000,000 shares totaling $607.6 million in the open market under this stock repurchase plan. At March 31, 2018, there were no shares of common stock that remained available to be purchased under the plan. On October 24, 2017, the Company’s Board of Directors approved a new share repurchase program that enables the Company to repurchase up to twenty-five million shares of its common stock. This new program became effective when 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 new share repurchase program. On February 1, 2018, the Company entered into accelerated share repurchase (ASR) agreements with two third-party financial institutions (the Dealers) 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 (until such program was completed) and the twenty-five million share repurchase program. The Company borrowed $300 million against its Amended Credit Facility to finance the payment of the initial purchase price to each of the Dealers. Under the terms of the ASR, the Company made a $150 million payment to each of the Dealers on February 2, 2018 and received an initial delivery of 3,693,931 shares from each of the Dealers, or 7,387,862 shares in the aggregate, which was approximately 70 percent of the total number of shares of the Company's common stock expected to be repurchased under the ASR. As part of this purchase, 970,650 shares for $27.6 million were deducted under the twenty million share repurchase program and 6,417,212 shares for $182.4 million were deducted from the twenty-five million share repurchase program during the fiscal year ended March 31, 2018. Final settlement of the ASR agreements was completed in August 2018. 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 nine months ended December 31, 2018. 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 . Through December 31, 2019 , the Company has repurchased 15,805,003 shares for $418.7 million in the open market under the twenty-five million share repurchase program. At December 31, 2019 , 9,194,997 shares of common stock remained available to be purchased under the current repurchase program. The Company repurchased 5,164,593 shares for $125.0 million during the nine months ended December 31, 2019 under the twenty-five million share repurchase program. In connection with the delivery of shares of the Company's common stock upon vesting of restricted stock units, the Company withheld 509,532 shares and 430,406 shares at a cost of $11.6 million and $11.4 million related to minimum statutory tax withholding requirements on these restricted stock units during the nine months ended December 31, 2019 and 2018 , respectively. These withholding transactions do not fall under the repurchase program described above, and therefore do not reduce the number of shares that are available for repurchase under that program.

NET INCOME (LOSS) PER SHARE

NET INCOME (LOSS) PER SHARE	9 Months Ended
	Dec. 31, 2019
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): Three Months Ended Nine Months Ended December 31, December 31, 2019 2018 2019 2018 Numerator: Net income (loss) $ 36,725 $ (3,603 ) $ (10,090 ) $ (92,535 ) Denominator: Denominator for basic net income (loss) per share - weighted average common shares outstanding 74,367 77,774 75,780 78,916 Dilutive common equivalent shares: Weighted average restricted stock units 333 — — — Denominator for diluted net income (loss) per share - weighted average shares outstanding 74,700 77,774 75,780 78,916 Net (income) loss per share: Basic net income (loss) per share $ 0.49 $ (0.05 ) $ (0.13 ) $ (1.17 ) Diluted net income (loss) per share $ 0.49 $ (0.05 ) $ (0.13 ) $ (1.17 ) The following table sets forth restricted stock units excluded from the calculation of diluted net income (loss) per share, since their inclusion would be anti-dilutive (in thousands): Three Months Ended Nine Months Ended December 31, December 31, 2019 2018 2019 2018 Restricted stock units 2,997 435 694 733 Basic net income (loss) per share is calculated by dividing net income (loss) by the weighted average number of shares outstanding during the period. Unvested restricted shares, although legally issued and outstanding, are not considered outstanding for purposes of calculating basic earnings per share. Diluted net income (loss) per share is calculated by dividing net income (loss) by the weighted average number of shares outstanding plus the dilutive effect, if any, of outstanding stock options, restricted shares and restricted stock units using the treasury stock method. The calculation of the dilutive effect of outstanding equity awards under the treasury stock method includes consideration of proceeds from the assumed exercise of stock options and unrecognized compensation expense as additional proceeds. As we incurred a net loss during the three months ended December 31, 2018 and the nine months ended December 31, 2019 and 2018, all outstanding restricted stock units have an anti-dilutive effect and are therefore excluded from the computation of diluted weighted average shares outstanding.

INCOME TAXES

INCOME TAXES	9 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Generally, the Company's effective tax rate differs from the statutory tax rate due to state income taxes and US taxation on foreign earnings, which are partially offset by research and development tax credits and the Foreign Derived Intangible Income deduction. The Company's effective income tax rates were 11.6% and 30.8% for the three months ended December 31, 2019 and 2018 , respectively. The effective tax rate for the three months ended December 31, 2019 was lower than the effective rate for the three months ended December 31, 2018 , primarily due to a discrete benefit related to the issuance of US regulations in the quarter impacting the Company's estimate of the Base Erosion Anti-Abuse Tax (BEAT). The Company's effective income tax rates were 47.2% and 20.2% for the nine months ended December 31, 2019 and 2018 , respectively. The effective tax rate for the nine months ended December 31, 2019 was higher than the effective rate for the nine months ended December 31, 2018 , primarily due to the establishment of U.S. deferred tax liabilities for certain of the Company's foreign subsidiaries making elections in the first quarter to be treated as U.S. branches for federal income tax purposes, stock-based compensation, and a significant reduction in pre-tax losses as compared to the prior year. These items were partially offset by a discrete benefit related to the issuance of US regulations in the quarter impacting the Company's estimate of BEAT.

SEGMENT AND GEOGRAPHIC INFORMAT

SEGMENT AND GEOGRAPHIC INFORMATION	9 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
SEGMENT AND GEOGRAPHIC INFORMATION	SEGMENT AND GEOGRAPHIC INFORMATION The Company reports revenues and income under one reportable segment. The Company manages its business in the following geographic areas: United States, Europe, Asia and the rest of the world. In accordance with United States export control regulations, the Company does not sell or do business with countries subject to economic sanctions or export controls. Total revenue by geography is as follows (in thousands): Three Months Ended Nine Months Ended December 31, December 31, 2019 2018 2019 2018 United States $ 163,605 $ 148,379 $ 410,252 $ 412,377 Europe 45,049 45,058 110,259 109,529 Asia 15,957 18,187 41,647 54,285 Rest of the world 35,413 34,384 100,311 98,725 $ 260,024 $ 246,008 $ 662,469 $ 674,916

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	9 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On February 5, 2020, the Company acquired 100% of the common stock of Gigavation Incorporated, a cybersecurity company for $8.0 million .

BASIS OF PRESENTATION (Policies

BASIS OF PRESENTATION (Policies)	9 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying unaudited interim consolidated financial statements have been prepared by NetScout Systems, Inc. (NetScout or the Company). Certain information and footnote disclosures normally included in financial statements prepared under United States generally accepted accounting principles (GAAP) have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). In the opinion of management, the unaudited interim consolidated financial statements include all adjustments, consisting of normal recurring adjustments, necessary for a fair statement of the Company's financial position and stockholders' equity, results of operations and cash flows. The year-end consolidated balance sheet data and statement of stockholders' equity were derived from the Company's audited financial statements, but do not include all disclosures required by GAAP. The results reported in these unaudited interim consolidated financial statements are not necessarily indicative of results that may be expected for the entire year. All significant intercompany accounts and transactions are eliminated in consolidation. These unaudited interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements, including the notes thereto, included in the Company’s Annual Report on Form 10-K for the fiscal year ended March 31, 2019 filed with the Securities and Exchange Commission on May 28, 2019.
Recent Accounting Pronouncements	Recent Accounting Pronouncements 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, 2021. ASU 2019-12 is effective for NetScout beginning April 1, 2022. 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 Company is currently assessing the effect that ASU 2019-12 will have on its 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. This guidance is effective for fiscal years ending after December 15, 2020. ASU 2018-14 is effective for NetScout beginning April 1, 2021. Early adoption is permitted. The Company is currently assessing the effect that ASU 2018-14 will have on its financial position, results of operations, and disclosures. 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. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year. ASU 2018-13 is effective for NetScout beginning April 1, 2020. Early adoption is permitted. The Company is currently assessing the effect that ASU 2018-13 will have on its financial position, results of operations, and disclosures. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815), Targeted Improvements to Accounting for Hedging Activities (ASU 2017-12). ASU 2017-12 provides guidance to better align an entity's risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The amendments expand and refine hedge accounting for both non-financial and financial risk components and align the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. This standard is effective for financial statements issued for fiscal years beginning after December 15, 2018. The Company adopted ASU 2017-12 effective April 1, 2019. The adoption has had an immaterial 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 and ASU 2019-11 (collectively, Topic 326). Topic 326 requires measurement and recognition of expected credit losses for financial assets held. Topic 326 is effective for annual periods beginning after December 15, 2019, and interim periods therein. Topic 326 is effective for NetScout beginning April 1, 2020, and earlier adoption is permitted. The Company is currently assessing the effect that Topic 326 will have on its financial position, results of operations, and disclosures. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) Section A - Leases: Amendments to the FASB Accounting Standards Codification (ASU 2016-02) and issued subsequent amendments to initial guidance in July 2018 within ASU 2018-10, Codification Improvements to Topic 842, Leases and ASU 2018-11, Leases (Topic 842): Targeted Improvements (collectively, ASC 842). ASC 842 aims 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 as of April 1, 2019 using the modified retrospective method. Please refer to Note 13, "Leases" for further details.
Revenue Recognition Policy	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 majority of the Company's product sales consist of hardware products with embedded software that are essential to providing customers the intended functionality of the solutions. The Company also sells software offerings decoupled from the underlying hardware and software solutions to provide customers with enhanced functionality. 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 reseller or distributor as a reduction of revenue to the extent they have recorded revenue from the reseller or distributor. 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.

SHARE-BASED COMPENSATION (Table

SHARE-BASED COMPENSATION (Tables)	9 Months Ended
	Dec. 31, 2019
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 granted pursuant to the Company's 2007 Equity Incentive Plan, as amended (Amended 2007 Plan), and employee stock purchases made under the Company's 2011 Employee Stock Purchase Plan, as amended, (ESPP), based on estimated fair values within the applicable cost and expense lines identified below (in thousands): Three Months Ended Nine Months Ended December 31, December 31, 2019 2018 2019 2018 Cost of product revenue $ 231 $ 375 $ 843 $ 1,188 Cost of service revenue 1,275 1,519 4,584 4,694 Research and development 3,437 3,979 12,076 13,544 Sales and marketing 3,910 4,649 13,333 15,051 General and administrative 2,508 3,237 9,125 9,665 $ 11,361 $ 13,759 $ 39,961 $ 44,142

CASH, CASH EQUIVALENTS, RESTR_2

CASH, CASH EQUIVALENTS, RESTRICTED CASH AND MARKETABLE SECURITIES (Tables)	9 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Schedule of Cash, 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): December 31, March 31, 2019 December 31, March 31, Cash and cash equivalents $ 287,660 $ 409,632 $ 369,054 $ 369,821 Restricted cash 1,000 188 187 910 Total cash, cash equivalents and restricted cash $ 288,660 $ 409,820 $ 369,241 $ 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): December 31, March 31, 2019 December 31, March 31, Cash and cash equivalents $ 287,660 $ 409,632 $ 369,054 $ 369,821 Restricted cash 1,000 188 187 910 Total cash, cash equivalents and restricted cash $ 288,660 $ 409,820 $ 369,241 $ 370,731
Summary of Marketable Securities	The following is a summary of marketable securities held by NetScout at December 31, 2019 , classified as short-term and long-term (in thousands): Amortized Cost Unrealized Gains Fair Value Type of security: U.S. government and municipal obligations $ 27,139 $ 48 $ 27,187 Commercial paper 24,911 — 24,911 Corporate bonds 4,167 9 4,176 Total short-term marketable securities 56,217 57 56,274 U.S. government and municipal obligations 2,549 12 2,561 Total long-term marketable securities 2,549 12 2,561 Total marketable securities $ 58,766 $ 69 $ 58,835 The following is a summary of marketable securities held by NetScout at March 31, 2019 , classified as short-term and long-term (in thousands): Amortized Cost Unrealized Gains Fair Value Type of security: U.S. government and municipal obligations $ 27,610 $ 12 $ 27,622 Commercial paper 48,722 — 48,722 Total short-term marketable securities 76,332 12 76,344 Corporate bonds 1,007 5 1,012 Total long-term marketable securities 1,007 5 1,012 Total marketable securities $ 77,339 $ 17 $ 77,356
Summary of Contractual Maturities of Marketable Securities	Contractual maturities of the Company's marketable securities held at December 31, 2019 and March 31, 2019 were as follows (in thousands): December 31, March 31, Available-for-sale securities: Due in 1 year or less $ 56,274 $ 76,344 Due after 1 year through 5 years 2,561 1,012 $ 58,835 $ 77,356

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Dec. 31, 2019
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 December 31, 2019 and March 31, 2019 (in thousands): Fair Value Measurements at December 31, 2019 Level 1 Level 2 Level 3 Total ASSETS: Cash and cash equivalents $ 287,660 $ — $ — $ 287,660 U.S. government and municipal obligations 29,748 — — 29,748 Commercial paper — 24,911 — 24,911 Corporate bonds 4,176 — — 4,176 Derivative financial instruments — 93 — 93 Contingent consideration — — 245 245 $ 321,584 $ 25,004 $ 245 $ 346,833 LIABILITIES: Contingent purchase consideration $ — $ — $ (1,000 ) $ (1,000 ) Derivative financial instruments — (11 ) — (11 ) $ — $ (11 ) $ (1,000 ) $ (1,011 ) Fair Value Measurements at March 31, 2019 Level 1 Level 2 Level 3 Total ASSETS: Cash and cash equivalents $ 409,632 $ — $ — $ 409,632 U.S. government and municipal obligations 10,732 16,890 — 27,622 Commercial paper — 48,722 — 48,722 Corporate bonds 1,012 — — 1,012 Derivative financial instruments — 58 — 58 Contingent consideration — — 762 762 $ 421,376 $ 65,670 $ 762 $ 487,808 LIABILITIES: Derivative financial instruments $ — $ (68 ) $ — $ (68 ) $ — $ (68 ) $ — $ (68 )
Schedule of Reconciliation of Changes in Fair Value of Level III Financial Assets	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 nine months ended December 31, 2019 (in thousands): Contingent Consideration Contingent Purchase Consideration Balance at March 31, 2019 $ 762 $ — Additions to Level 3 — (1,000 ) Change in fair value of contingent consideration (517 ) — Balance at December 31, 2019 $ 245 $ (1,000 )

INVENTORIES (Tables)

INVENTORIES (Tables)	9 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories consist of the following (in thousands): December 31, March 31, Raw materials $ 14,980 $ 14,432 Work in process 121 1,181 Finished goods 4,473 7,738 Deferred costs 5,403 2,919 $ 24,977 $ 26,270

ACQUISITIONS & DIVESTITURES (Ta

ACQUISITIONS & DIVESTITURES (Tables)	9 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Goodwill and Intangible Assets Record for Eastman Acquisition	Initial cash payment $ 4,154 Estimated fair value of contingent purchase consideration 1,000 Estimated purchase price $ 5,154
Estimated Fair Values of Acquired Assets and Liabilities Assumed	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
Fair Value and Estimated Useful Life of the Acquired Identifiable Intangible Asset	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 AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	9 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in Carrying Amount of Goodwill	The following table summarizes the changes in the carrying amount of goodwill for the nine months ended December 31, 2019 as follows (in thousands): Balance at March 31, 2019 $ 1,715,485 Goodwill attributed to the Eastwind acquisition 1,003 Foreign currency translation impact 2,008 Balance at December 31, 2019 $ 1,718,496
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 December 31, 2019 (in thousands): Cost Accumulated Amortization Net Developed technology $ 245,850 $ (186,356 ) $ 59,494 Customer relationships 770,696 (261,595 ) 509,101 Distributor relationships and technology licenses 6,843 (6,104 ) 739 Definite-lived trademark and trade name 39,205 (24,894 ) 14,311 Core technology 7,192 (7,016 ) 176 Net beneficial leases 336 (336 ) — Non-compete agreements 292 (292 ) — Leasehold interest 500 (500 ) — Backlog 16,327 (16,327 ) — Capitalized software 3,317 (3,152 ) 165 Other 1,208 (938 ) 270 $ 1,091,766 $ (507,510 ) $ 584,256 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, 2019 (in thousands): Cost Accumulated Amortization Net Developed technology $ 242,259 $ (168,289 ) $ 73,970 Customer relationships 772,969 (218,043 ) 554,926 Distributor relationships and technology licenses 6,882 (5,237 ) 1,645 Definite-lived trademark and trade name 39,304 (20,586 ) 18,718 Core technology 7,192 (6,845 ) 347 Net beneficial leases 336 (336 ) — Non-compete agreements 292 (292 ) — Leasehold interest 500 (500 ) — Backlog 16,397 (16,397 ) — Capitalized software 3,317 (2,690 ) 627 Other 1,208 (923 ) 285 $ 1,090,656 $ (440,138 ) $ 650,518
Finite-lived Intangible Assets Amortization Expense	The following table provides a summary of amortization expense for the three and nine months ended December 31, 2019 and 2018, respectively (in thousands): Three Months Ended Nine Months Ended December 31, December 31, 2019 2018 2019 2018 Amortization of intangible assets included as: Cost of product revenue $ 6,564 $ 8,176 20,043 25,858 Operating expense 16,125 16,438 48,410 57,894 $ 22,689 $ 24,614 $ 68,453 $ 83,752
Schedule of Expected Future Amortization Expense	The following is the expected future amortization expense at December 31, 2019 for the fiscal years ending March 31 (in thousands): 2020 (remaining three months) $ 22,682 2021 79,857 2022 69,462 2023 61,758 2024 53,667 Thereafter 296,830 $ 584,256

DERIVATIVE INSTRUMENTS AND HE_2

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Tables)	9 Months Ended
	Dec. 31, 2019
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 December 31, 2019 and March 31, 2019 were as follows (in thousands): Notional Amounts (a) Prepaid Expenses and Other Current Assets Accrued Other December 31, March 31, December 31, March 31, December 31, March 31, Derivatives Designated as Hedging Instruments: Forward contracts $ 4,883 $ 4,550 $ 93 $ 58 $ 11 $ 68 (a) 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 for the three months ended December 31, 2019 and 2018 (in thousands): Gain (Loss) Recognized in Gain (Loss) Reclassified from December 31, 2019 December 31, 2018 Location December 31, 2019 December 31, 2018 Forward contracts $ 124 $ (215 ) Research and development $ (8 ) $ 60 Sales and marketing (29 ) 148 $ 124 $ (215 ) $ (37 ) $ 208 (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 had on other comprehensive income (loss) (OCI) and results of operations for the nine months ended December 31, 2019 and 2018 (in thousands): (Gain) Loss Recognized in OCI on Derivative (a) Gain (Loss) Reclassified from Accumulated OCI into Income (b) December 31, 2019 December 31, 2018 Location December 31, 2019 December 31, 2018 Forward contracts $ 24 $ (794 ) Research and development $ (16 ) $ 147 Sales and marketing 49 357 $ 24 $ (794 ) $ 33 $ 504 (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.

RESTRUCTURING CHARGES (Tables)

RESTRUCTURING CHARGES (Tables)	9 Months Ended
	Dec. 31, 2019
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Liability	The following table provides a summary of the activity related to the restructuring plan and the related restructuring liability (in thousands): Q2FY20 Plan VSP Employee-Related Employee-Related Total Balance at March 31, 2019 $ — $ — $ — Restructuring charges to operations 329 123 452 Cash payments (169 ) (123 ) (292 ) Other adjustments 14 — 14 Balance at December 31, 2019 $ 174 $ — $ 174

LEASES (Tables)

LEASES (Tables)	9 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Components of Operating Lease Cost and Supplemental Cash Flow Information	The components of operating lease cost for the three and nine months ended December 31, 2019 were as follows (in thousands): Three Months Ended Nine Months Ended December 31, 2019 December 31, 2019 Lease cost under long-term operating leases $ 3,459 $ 9,980 Lease cost under short-term operating leases 1,681 3,430 Variable lease cost under short-term and long-term operating leases 974 3,249 Total operating lease cost $ 6,114 $ 16,659 The table below presents supplemental cash flow information related to leases during the nine months ended December 31, 2019 (in thousands): Cash paid for amounts included in the measurement of lease liabilities $ 9,690 Right-of-use assets obtained in exchange for new operating lease liabilities $ 5,474 Weighted average remaining lease term in years and weighted average discount rate are as follows: Weighted average remaining lease term in years - operating leases 8.80 Weighted average discount rate - operating leases 4.2 %
ASC 842 Future Minimum Payments Under Non-Cancellable Leases	Future minimum payments under non-cancellable leases at December 31, 2019 are as follows (in thousands): Year ending March 31: 2020 (remaining three months) $ 2,990 2021 13,523 2022 12,668 2023 10,475 2024 9,044 Thereafter 45,475 Total lease payments $ 94,175 Less imputed interest (15,270 ) Present value of lease liabilities $ 78,905
ASC 840 Future Non-Cancelable Minimum Lease Commitments	As previously disclosed in the Company’s fiscal year Form 10-K and under the previous lease accounting standard, ASC 840, Leases, the following table summarizes the future non-cancelable minimum lease commitments (including office space, copiers, and automobiles) at March 31, 2019 (in thousands): Year ending March 31: 2020 $ 16,102 2021 11,059 2022 9,804 2023 8,807 2024 8,500 Thereafter 43,997 Total $ 98,269

PENSION BENEFIT PLANS (Tables)

PENSION BENEFIT PLANS (Tables)	9 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Schedule of Net Periodic Pension Costs of Noncontributory Defined Benefit Pension Plans	The following sets forth the components of the Company's net periodic pension cost of the noncontributory defined benefit pension plans for the three and nine months ended December 31, 2019 and 2018 (in thousands): Three Months Ended Nine Months Ended December 31, December 31, 2019 2018 2019 2018 Service cost $ 45 $ 61 $ 131 $ 187 Interest cost 105 118 307 362 Net periodic pension cost $ 150 $ 179 $ 438 $ 549

NET INCOME (LOSS) PER SHARE (Ta

NET INCOME (LOSS) PER SHARE (Tables)	9 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of Calculations of the Basic and Diluted Net Income (Loss) 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): Three Months Ended Nine Months Ended December 31, December 31, 2019 2018 2019 2018 Numerator: Net income (loss) $ 36,725 $ (3,603 ) $ (10,090 ) $ (92,535 ) Denominator: Denominator for basic net income (loss) per share - weighted average common shares outstanding 74,367 77,774 75,780 78,916 Dilutive common equivalent shares: Weighted average restricted stock units 333 — — — Denominator for diluted net income (loss) per share - weighted average shares outstanding 74,700 77,774 75,780 78,916 Net (income) loss per share: Basic net income (loss) per share $ 0.49 $ (0.05 ) $ (0.13 ) $ (1.17 ) Diluted net income (loss) per share $ 0.49 $ (0.05 ) $ (0.13 ) $ (1.17 )
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 (loss) per share, since their inclusion would be anti-dilutive (in thousands): Three Months Ended Nine Months Ended December 31, December 31, 2019 2018 2019 2018 Restricted stock units 2,997 435 694 733

SEGMENT AND GEOGRAPHIC INFORM_2

SEGMENT AND GEOGRAPHIC INFORMATION (Tables)	9 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Summary of Total Revenue by Geography	Total revenue by geography is as follows (in thousands): Three Months Ended Nine Months Ended December 31, December 31, 2019 2018 2019 2018 United States $ 163,605 $ 148,379 $ 410,252 $ 412,377 Europe 45,049 45,058 110,259 109,529 Asia 15,957 18,187 41,647 54,285 Rest of the world 35,413 34,384 100,311 98,725 $ 260,024 $ 246,008 $ 662,469 $ 674,916

REVENUE RECOGNITION - Additiona

REVENUE RECOGNITION - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue recognized			$ 240.5
Deferred revenue	$ 365.5		365.5
Unrecognized accounts receivable and deferred revenue	4.9		4.9		$ 23.3
Capitalized contract cost	6.8		6.8		6.4
Amortization of capitalized costs to obtain contracts	1.6	$ 1.5	$ 4.8	$ 4.8
Minimum
Disaggregation of Revenue [Line Items]
Payment terms			30 days
Maximum
Disaggregation of Revenue [Line Items]
Payment terms			90 days
Prepaid expenses and other current assets
Disaggregation of Revenue [Line Items]
Capitalized contract cost	3.8		$ 3.8		3.8
Other assets
Disaggregation of Revenue [Line Items]
Capitalized contract cost	$ 3		$ 3		$ 2.6

REVENUE RECOGNITION - Performan

REVENUE RECOGNITION - Performance Obligations (Details) $ in Millions	Dec. 31, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue from Contract with Customer [Abstract]
Revenue, remaining performance obligation, amount	$ 261.2
Revenue, remaining performance obligation, percentage	71.00%
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]: 2021-01-01
Revenue from Contract with Customer [Abstract]
Revenue, remaining performance obligation, amount	$ 104.3
Revenue, remaining performance obligation, percentage	29.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period

SHARE-BASED COMPENSATION (Detai

SHARE-BASED COMPENSATION (Details) $ / shares in Units, $ in Thousands	Sep. 12, 2019shares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		$ 11,361	$ 13,759	$ 39,961	$ 44,142
ESPP
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Percentage of common stock price for employees				85.00%
Additional shares (in shares) | shares				297,635
Share price (in USD per share) | $ / shares		$ 22.15		$ 22.15
Maximum | Incentive Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Term of options granted, years				5 years
2019 Equity Incentive Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Number of shares reserved for issuance (in shares) | shares	6,794,651
Number of new shares (in shares) | shares	5,500,000
Reduction for each share of common stock pursuant to option	1
Reduction for each share of common stock pursuant to other than option	2.76
Number of shares available for grant (in shares) | shares		6,902,159		6,902,159
Share-based awards generally vest, years				4 years
Percentage of incentive stock options granted				110.00%
2019 Equity Incentive Plan | Minimum
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Percentage of fair market value of common stock				100.00%
Percentage of voting stock				10.00%
2019 Equity Incentive Plan | Maximum
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Term of options granted, years				7 years
Amended 2007 Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Number of shares reserved for issuance (in shares) | shares	1,294,651
Cost of product revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		$ 231	375	$ 843	1,188
Cost of service revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		1,275	1,519	4,584	4,694
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		3,437	3,979	12,076	13,544
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		3,910	4,649	13,333	15,051
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense		$ 2,508	$ 3,237	$ 9,125	$ 9,665

CASH, CASH EQUIVALENTS, RESTR_3

CASH, CASH EQUIVALENTS, RESTRICTED CASH AND MARKETABLE SECURITIES - Summary of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Cash and cash equivalents	$ 287,660	$ 409,632	$ 369,054	$ 369,821
Restricted cash	1,000	188	187	910
Total cash, cash equivalents and restricted cash	$ 288,660	$ 409,820	$ 369,241	$ 370,731

CASH, CASH EQUIVALENTS, RESTR_4

CASH, CASH EQUIVALENTS, RESTRICTED CASH AND MARKETABLE SECURITIES - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 58,766	$ 77,339
Unrealized Gains	69	17
Fair Value	58,835	77,356
Short-term marketable securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	56,217	76,332
Unrealized Gains	57	12
Fair Value	56,274	76,344
Short-term marketable securities | U.S. government and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	27,139	27,610
Unrealized Gains	48	12
Fair Value	27,187	27,622
Short-term marketable securities | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	24,911	48,722
Unrealized Gains	0	0
Fair Value	24,911	48,722
Short-term marketable securities | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,167
Unrealized Gains	9
Fair Value	4,176
Long-term marketable securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,549	1,007
Unrealized Gains	12	5
Fair Value	2,561	1,012
Long-term marketable securities | U.S. government and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,549
Unrealized Gains	12
Fair Value	$ 2,561
Long-term marketable securities | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		1,007
Unrealized Gains		5
Fair Value		$ 1,012

CASH, CASH EQUIVALENTS, RESTR_5

CASH, CASH EQUIVALENTS, RESTRICTED CASH AND MARKETABLE SECURITIES - Summary of Contractual Maturities of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Available-for-sale securities:
Due in 1 year or less	$ 56,274	$ 76,344
Due after 1 year through 5 years	2,561	1,012
Available-for-sale Securities	$ 58,835	$ 77,356

FAIR VALUE MEASUREMENTS - Sched

FAIR VALUE MEASUREMENTS - Schedule of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
ASSETS:
Cash and cash equivalents	$ 287,660	$ 409,632
Available-for-sale securities	58,835	77,356
Derivative financial instruments	93	58
Contingent consideration	245	762
Total assets	346,833	487,808
LIABILITIES:
Contingent purchase consideration	(1,000)
Derivative financial instruments	(11)	(68)
Total liabilities	(1,011)	(68)
U.S. government and municipal obligations
ASSETS:
Available-for-sale securities	29,748	27,622
Commercial paper
ASSETS:
Available-for-sale securities	24,911	48,722
Corporate bonds
ASSETS:
Available-for-sale securities	4,176	1,012
Level 1
ASSETS:
Cash and cash equivalents	287,660	409,632
Derivative financial instruments	0	0
Contingent consideration	0	0
Total assets	321,584	421,376
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	29,748	10,732
Level 1 | Commercial paper
ASSETS:
Available-for-sale securities	0	0
Level 1 | Corporate bonds
ASSETS:
Available-for-sale securities	4,176	1,012
Level 2
ASSETS:
Cash and cash equivalents	0	0
Derivative financial instruments	93	58
Contingent consideration	0	0
Total assets	25,004	65,670
LIABILITIES:
Contingent purchase consideration	0
Derivative financial instruments	(11)	(68)
Total liabilities	(11)	(68)
Level 2 | U.S. government and municipal obligations
ASSETS:
Available-for-sale securities	0	16,890
Level 2 | Commercial paper
ASSETS:
Available-for-sale securities	24,911	48,722
Level 2 | Corporate bonds
ASSETS:
Available-for-sale securities	0	0
Level 3
ASSETS:
Cash and cash equivalents	0	0
Derivative financial instruments	0	0
Contingent consideration	245	762
Total assets	245	762
LIABILITIES:
Contingent purchase consideration	(1,000)
Derivative financial instruments	0	0
Total liabilities	(1,000)	0
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	$ 0

FAIR VALUE MEASUREMENTS - Narra

FAIR VALUE MEASUREMENTS - Narrative (Details) - USD ($)	Sep. 14, 2018	Dec. 31, 2019	Mar. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Change in fair value contingent consideration in other expense		$ 500,000
HNT tools business | Disposed of by Sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent consideration related to the divestiture, measurement period	2 years
Change in fair value contingent consideration in other expense		500,000
Disposal group, not discontinued operation, change in amount of contingent consideration, asset		200,000	$ 800,000
Contingent consideration, change in fair value of contingent consideration		$ 24,000
HNT tools business | Disposed of by Sale | Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent consideration related to the divestiture	$ 4,000,000

FAIR VALUE MEASUREMENTS - Recon

FAIR VALUE MEASUREMENTS - Reconciliation of Changes in Level 3 Assets and Liabilities (Details) - Fair value, measurements, recurring $ in Thousands	9 Months Ended
	Dec. 31, 2019USD ($)
Contingent Consideration
Balance at March 31, 2019	$ 762
Change in fair value of contingent consideration	(517)
Balance at December 31, 2019	245
Contingent Purchase Consideration
Balance at March 31, 2019	0
Additions to Level 3	(1,000)
Balance at December 31, 2019	$ (1,000)

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Inventory Disclosure [Abstract]
Raw materials	$ 14,980	$ 14,432
Work in process	121	1,181
Finished goods	4,473	7,738
Deferred costs	5,403	2,919
Total inventories	$ 24,977	$ 26,270

ACQUISITIONS & DIVESTITURES - E

ACQUISITIONS & DIVESTITURES - Eastwind Acquisition Narrative (Details) - USD ($) $ in Thousands	Apr. 03, 2019	Dec. 31, 2019
Business Acquisition [Line Items]
Estimated fair value of contingent purchase consideration		$ 1,000
Useful Life (Years)		14 years 7 months 6 days
Eastwind
Business Acquisition [Line Items]
Estimated purchase price	$ 5,154
Estimated fair value of contingent purchase consideration	1,000	$ 1,000
Cash retention payments	$ 300
Developed technology | Eastwind
Business Acquisition [Line Items]
Useful Life (Years)	10 years

ACQUISITIONS & DIVESTITURES -_2

ACQUISITIONS & DIVESTITURES - Eastwind Acquisition (Details) - USD ($) $ in Thousands	Apr. 03, 2019	Dec. 31, 2019
Business Acquisition [Line Items]
Estimated fair value of contingent purchase consideration		$ 1,000
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

ACQUISITIONS & DIVESTITURES -_3

ACQUISITIONS & DIVESTITURES - Eastwind Estimated Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Apr. 03, 2019	Mar. 31, 2019
Business Acquisition [Line Items]
Goodwill	$ 1,718,496		$ 1,715,485
Eastwind
Business Acquisition [Line Items]
Property, plant and equipment		$ 17
Intangible assets		4,230
Accrued other liabilities		(96)
Goodwill		$ 1,003

ACQUISITIONS & DIVESTITURES -_4

ACQUISITIONS & DIVESTITURES - Eastwind Acquired Indentifiable Intangible Asset (Details) - USD ($) $ in Thousands	Apr. 03, 2019	Dec. 31, 2019
Business Acquisition [Line Items]
Useful Life (Years)		14 years 7 months 6 days
Developed technology | Eastwind
Business Acquisition [Line Items]
Fair Value	$ 4,230
Useful Life (Years)	10 years

ACQUISITIONS & DIVESTITURES - H

ACQUISITIONS & DIVESTITURES - HNT Tools Business Divestiture (Details) - USD ($)	Sep. 14, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
Business Acquisition [Line Items]
Change in fair value contingent consideration in other expense				$ 500,000
Transitional services, period (up to)				18 months
Income from divestiture		$ (25,000)	$ 1,200,000	$ 1,100,000	$ 1,300,000
HNT tools business | Disposed of by Sale
Business Acquisition [Line Items]
Contingent consideration related to the divestiture, measurement period	2 years
Change in fair value contingent consideration in other expense				500,000
Disposal group, not discontinued operation, change in amount of contingent consideration, asset		$ 200,000		$ 200,000		$ 800,000
HNT tools business | Disposed of by Sale | Maximum
Business Acquisition [Line Items]
Contingent consideration related to the divestiture	$ 4,000,000

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS - Narrative (Details)	3 Months Ended			6 Months Ended	9 Months Ended
	Dec. 31, 2019USD ($)reporting_unit	Sep. 30, 2019reporting_unit	Dec. 31, 2018USD ($)	Sep. 30, 2019reporting_unit	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Mar. 31, 2019USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Number of reporting units | reporting_unit	1	2		2
Impairment of intangible assets	$ 0		$ 0		$ 0	$ 35,871,000
Goodwill	1,718,496,000				1,718,496,000		$ 1,715,485,000
Carrying value of intangible assets	602,856,000				$ 602,856,000		669,118,000
Weighted average useful life of acquired intangible assets					14 years 7 months 6 days
Developed and core technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets					11 years 3 months 18 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
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 18,600,000				$ 18,600,000		$ 18,600,000

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS - Schedule of Changes in Carrying Amount of Goodwill (Details) $ in Thousands	9 Months Ended
	Dec. 31, 2019USD ($)
Goodwill [Roll Forward]
Balance at March 31, 2019	$ 1,715,485
Goodwill attributed to the Eastwind acquisition	1,003
Foreign currency translation impact	2,008
Balance at December 31, 2019	$ 1,718,496

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Cost	$ 1,091,766	$ 1,090,656
Accumulated Amortization	(507,510)	(440,138)
Net	584,256	650,518
Developed technology
Finite-Lived Intangible Assets [Line Items]
Cost	245,850	242,259
Accumulated Amortization	(186,356)	(168,289)
Net	59,494	73,970
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Cost	770,696	772,969
Accumulated Amortization	(261,595)	(218,043)
Net	509,101	554,926
Distributor relationships and technology licenses
Finite-Lived Intangible Assets [Line Items]
Cost	6,843	6,882
Accumulated Amortization	(6,104)	(5,237)
Net	739	1,645
Definite-lived trademark and trade name
Finite-Lived Intangible Assets [Line Items]
Cost	39,205	39,304
Accumulated Amortization	(24,894)	(20,586)
Net	14,311	18,718
Core technology
Finite-Lived Intangible Assets [Line Items]
Cost	7,192	7,192
Accumulated Amortization	(7,016)	(6,845)
Net	176	347
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	500
Accumulated Amortization	(500)	(500)
Net	0	0
Backlog
Finite-Lived Intangible Assets [Line Items]
Cost	16,327	16,397
Accumulated Amortization	(16,327)	(16,397)
Net	0	0
Capitalized software
Finite-Lived Intangible Assets [Line Items]
Cost	3,317	3,317
Accumulated Amortization	(3,152)	(2,690)
Net	165	627
Other
Finite-Lived Intangible Assets [Line Items]
Cost	1,208	1,208
Accumulated Amortization	(938)	(923)
Net	$ 270	$ 285

GOODWILL AND INTANGIBLE ASSET_5

GOODWILL AND INTANGIBLE ASSETS - Schedule of Amortization Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	$ 22,689	$ 24,614	$ 68,453	$ 83,752
Cost of product revenue
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	6,564	8,176	20,043	25,858
Operating expense
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	$ 16,125	$ 16,438	$ 48,410	$ 57,894

GOODWILL AND INTANGIBLE ASSET_6

GOODWILL AND INTANGIBLE ASSETS - Schedule of Expected Future Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020 (remaining three months)	$ 22,682
2021	79,857
2022	69,462
2023	61,758
2024	53,667
Thereafter	296,830
Net	$ 584,256	$ 650,518

DERIVATIVE INSTRUMENTS AND HE_3

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Narrative (Details)	9 Months Ended
	Dec. 31, 2019
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 - Cash flow hedges - Designated as hedging instrument - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Derivatives, Fair Value [Line Items]
Notional Amounts	$ 4,883	$ 4,550
Prepaid Expenses and Other Current Assets
Derivatives, Fair Value [Line Items]
Prepaid Expenses and Other Current Assets	93	58
Accrued Other
Derivatives, Fair Value [Line Items]
Accrued Other	$ 11	$ 68

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	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative	$ 124		$ 24
Gain (Loss) Recognized in OCI on Derivative		$ (215)		$ (794)
Gain (Loss) Reclassified from Accumulated OCI into Income	(37)		33
Research and development
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative	124		24
Gain (Loss) Recognized in OCI on Derivative		(215)		(794)
Gain (Loss) Reclassified from Accumulated OCI into Income	(8)		(16)
Sales and marketing
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income	$ (29)		$ 49
Cash flow hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income		208		504
Cash flow hedges | Research and development
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income		60		147
Cash flow hedges | Sales and marketing
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income		$ 148		$ 357

LONG-TERM DEBT (Details)

LONG-TERM DEBT (Details)	Jan. 16, 2018USD ($)shares	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Feb. 01, 2018USD ($)
Debt Instrument [Line Items]
Stock authorized to repurchase under stock repurchase program (in shares) | shares	25,000,000
Repaid borrowings			$ 100,000,000
Senior secured revolving credit facility | Line of credit
Debt Instrument [Line Items]
Debt term	5 years
Credit facility	$ 1,000,000,000
Amount outstanding under credit facility		$ 450,000,000	450,000,000	$ 300,000,000
Commitment fee percentage		0.25%
Debt default, acceleration clause, required consent percentage	50.00%
Debt issuance cost, gross		$ 12,200,000	12,200,000
Unamortized debt issuance costs		5,300,000	5,300,000
Senior secured revolving credit facility | Line of credit | Prepaid expenses and other current assets
Debt Instrument [Line Items]
Unamortized debt issuance costs		1,700,000	1,700,000
Senior secured revolving credit facility | Line of credit | Other assets
Debt Instrument [Line Items]
Unamortized debt issuance costs		$ 3,600,000	$ 3,600,000
Senior secured revolving credit facility | Line of credit | Maximum
Debt Instrument [Line Items]
Commitment fee percentage		0.30%
Senior secured revolving credit facility | Line of credit | Maximum | Foreign Subsidiaries
Debt Instrument [Line Items]
Voting stock pledge limit for any foreign subsidiary	65.00%
Senior secured revolving credit facility | Line of credit | Minimum
Debt Instrument [Line Items]
Commitment fee percentage		0.15%
Senior secured revolving credit facility | Line of credit | Federal funds effective rate
Debt Instrument [Line Items]
Interest rate in excess of effective rate	0.50%
Senior secured revolving credit facility | Line of credit | LIBOR
Debt Instrument [Line Items]
Interest rate in excess of effective rate	1.00%
Senior secured revolving credit facility | Line of credit | LIBOR | LIBOR loans
Debt Instrument [Line Items]
Interest rate in excess of effective rate		1.50%
Senior secured revolving credit facility | Line of credit | LIBOR | LIBOR loans | Maximum
Debt Instrument [Line Items]
Interest rate in excess of effective rate		2.00%
Senior secured revolving credit facility | Line of credit | LIBOR | LIBOR loans | Minimum
Debt Instrument [Line Items]
Interest rate in excess of effective rate		1.00%
Senior secured revolving credit facility | Line of credit | Base rate | Base rate loans
Debt Instrument [Line Items]
Interest rate in excess of effective rate		0.50%
Senior secured revolving credit facility | Line of credit | Base rate | Base rate loans | Maximum
Debt Instrument [Line Items]
Interest rate in excess of effective rate		1.00%
Senior secured revolving credit facility | Line of credit | Base rate | Base rate loans | Minimum
Debt Instrument [Line Items]
Interest rate in excess of effective rate		0.00%
Letter of credit sub-facility | Line of credit
Debt Instrument [Line Items]
Credit facility	$ 75,000,000
Senior secured revolving credit facility leverage ratio terms one | Line of credit | Maximum
Debt Instrument [Line Items]
Leverage ratio		3.50	3.50
Senior secured revolving credit facility leverage ratio terms one | Line of credit | Minimum
Debt Instrument [Line Items]
Leverage ratio		1.50	1.50
Senior secured revolving credit facility leverage ratio terms two | Line of credit | Maximum
Debt Instrument [Line Items]
Leverage ratio		2.75	2.75
Senior secured revolving credit facility leverage ratio terms two | Line of credit | Minimum
Debt Instrument [Line Items]
Leverage ratio		1.50	1.50

RESTRUCTURING CHARGES - Narrati

RESTRUCTURING CHARGES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 193	$ 13,895		$ 466	$ 17,514
Employee-Related
Restructuring Cost and Reserve [Line Items]
Restructuring charges						1,700	$ 5,100
One-time Termination Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges					300
VSP
Restructuring Cost and Reserve [Line Items]
Restructuring charges				$ 17,300	$ 100	$ 16,100
Forecast | One-time Termination Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 100

RESTRUCTURING CHARGES - Schedul

RESTRUCTURING CHARGES - Schedule of Restructuring Liability (Details) $ in Thousands	9 Months Ended
	Dec. 31, 2019USD ($)
Restructuring Reserve [Roll Forward]
Balance at March 31, 2019	$ 0
Restructuring charges to operations	452
Cash payments	(292)
Other adjustments	14
Balance at December 31, 2019	174
Q2FY20 Plan | Employee Related Restructuring Plan 2019
Restructuring Reserve [Roll Forward]
Balance at March 31, 2019	0
Restructuring charges to operations	329
Cash payments	(169)
Other adjustments	14
Balance at December 31, 2019	174
VSP | Employee Related Restructuring Plan 2019
Restructuring Reserve [Roll Forward]
Balance at March 31, 2019	0
Restructuring charges to operations	123
Cash payments	(123)
Other adjustments	0
Balance at December 31, 2019	$ 0

LEASES - Narrative (Details)

LEASES - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2019	Apr. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 65,738
Operating lease liabilities	$ 78,905
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		$ 68,200
Operating lease liabilities		83,200
Elimination of deferred rent		$ 15,000
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Remaining lease terms	1 year
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Remaining lease terms	11 years

LEASES - Operating Lease Cost (

LEASES - Operating Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Dec. 31, 2019	Dec. 31, 2019
Leases [Abstract]
Lease cost under long-term operating leases	$ 3,459	$ 9,980
Lease cost under short-term operating leases	1,681	3,430
Variable lease cost under short-term and long-term operating leases	974	3,249
Total operating lease cost	$ 6,114	$ 16,659

LEASES - Supplemental Cash Flow

LEASES - Supplemental Cash Flow Information (Details) $ in Thousands	9 Months Ended
	Dec. 31, 2019USD ($)
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities	$ 9,690
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 5,474
Weighted average remaining lease term in years - operating leases	8 years 9 months 18 days
Weighted average discount rate - operating leases	4.20%

LEASES - Future Minimum Payment

LEASES - Future Minimum Payments Under Non-Cancellable Leases (Details) $ in Thousands	Dec. 31, 2019USD ($)
Leases [Abstract]
2020 (remaining three months)	$ 2,990
2021	13,523
2022	12,668
2023	10,475
2024	9,044
Thereafter	45,475
Total lease payments	94,175
Less imputed interest	(15,270)
Present value of lease liabilities	$ 78,905

LEASES - ASC 840 Future Non-Can

LEASES - ASC 840 Future Non-Cancelable Minimum Lease Commitments (Details) $ in Thousands	Mar. 31, 2019USD ($)
Leases [Abstract]
2020	$ 16,102
2021	11,059
2022	9,804
2023	8,807
2024	8,500
Thereafter	43,997
Total	$ 98,269

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Details)	Sep. 14, 2018USD ($)	Oct. 13, 2017USD ($)	Sep. 30, 2018USD ($)	Oct. 31, 2017patent	Mar. 31, 2016patentsubsidiary	Dec. 31, 2019USD ($)	Apr. 03, 2019USD ($)	Mar. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Line Items]
Estimated fair value of contingent purchase consideration						$ 1,000,000
Number of subsidiary entities | subsidiary					2
Number of patents allegedly infringed | patent				3	5
Damages sought			$ 2,800,000
Minimum
Commitments and Contingencies Disclosure [Line Items]
Estimated litigation liability						0
Pre-suit damages
Commitments and Contingencies Disclosure [Line Items]
Damages sought		$ 3,500,000
Post-suit damages
Commitments and Contingencies Disclosure [Line Items]
Damages sought		$ 2,250,000
Eastwind
Commitments and Contingencies Disclosure [Line Items]
Estimated fair value of contingent purchase consideration						1,000,000	$ 1,000,000
Disposed of by Sale | HNT tools business
Commitments and Contingencies Disclosure [Line Items]
Contingent consideration related to the divestiture, measurement period	2 years
Disposal group, not discontinued operation, change in amount of contingent consideration, asset						$ 200,000		$ 800,000
Disposed of by Sale | HNT tools business | Maximum
Commitments and Contingencies Disclosure [Line Items]
Contingent consideration related to the divestiture	$ 4,000,000

PENSION BENEFIT PLANS - Narrati

PENSION BENEFIT PLANS - Narrative (Details) $ in Millions	9 Months Ended
	Dec. 31, 2019USD ($)employee
Defined Benefit Plan Disclosure [Line Items]
Contributions to defined benefit pension plans	$ 0.3
Expected cash contribution requirements for defined benefit pension plans, less than	$ 1
United States
Defined Benefit Plan Disclosure [Line Items]
Number of employees participating in noncontributory defined benefit pension plans | employee	0

PENSION BENEFIT PLANS - Net Per

PENSION BENEFIT PLANS - Net Periodic Pension Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Service cost	$ 45	$ 61	$ 131	$ 187
Interest cost	105	118	307	362
Net periodic pension cost	$ 150	$ 179	$ 438	$ 549

TREASURY STOCK (Details)

TREASURY STOCK (Details) $ / shares in Units, $ in Thousands	Feb. 02, 2018USD ($)shares	Feb. 01, 2018USD ($)dealer	Aug. 31, 2018$ / sharesshares	Dec. 31, 2019USD ($)shares	Dec. 31, 2018USD ($)shares	Mar. 31, 2018USD ($)shares	Dec. 31, 2019USD ($)shares	Mar. 31, 2018USD ($)shares	Jan. 16, 2018shares	Oct. 24, 2017shares	May 19, 2015shares
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 | $				$ 125,000	$ 0
Restricted stock units
Equity, Class of Treasury Stock [Line Items]
Shares paid for tax withholding (in shares)				509,532	430,406
Cost related to tax withholding | $				$ 11,600	$ 11,400
Senior secured revolving credit facility | Line of credit
Equity, Class of Treasury Stock [Line Items]
Amount borrowed for repurchase | $		$ 300,000		$ 450,000			$ 450,000
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
Shares repurchased during the period (in shares)						970,650		20,000,000
Shares repurchased during the period, value | $						$ 27,600		$ 607,600
Stock remaining to be purchased (in shares)						0		0
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
Shares repurchased during the period (in shares)				5,164,593		6,417,212	15,805,003
Shares repurchased during the period, value | $				$ 125,000		$ 182,400	$ 418,700
ASR Agreements
Equity, Class of Treasury Stock [Line Items]
Shares repurchased during the period (in shares)	7,387,862		11,067,809		3,679,947
Shares repurchased during the period, value | $		$ 300,000			$ 96,800
Stock remaining to be purchased (in shares)				9,194,997			9,194,997
Stock repurchase program, number of dealers | dealer		2
Number of shares acquired from each of dealers (in shares)	3,693,931
Percentage of total number of shares expected to be repurchased	70.00%
Shares repurchased during the period, average cost per share (in dollars per share) | $ / shares			$ 27.11
ASR Agreements | Dealer one
Equity, Class of Treasury Stock [Line Items]
Shares repurchased during the period, value | $	$ 150,000
ASR Agreements | Dealer two
Equity, Class of Treasury Stock [Line Items]
Shares repurchased during the period, value | $	$ 150,000

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	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net income (loss)	$ 36,725	$ (3,603)	$ (10,090)	$ (92,535)
Denominator:
Denominator for basic net income (loss) per share - weighted average common shares outstanding (in shares)	74,367	77,774	75,780	78,916
Dilutive common equivalent shares:
Weighted average restricted stock units (in shares)	333	0	0	0
Denominator for diluted net income (loss) per share - weighted average shares outstanding (in shares)	74,700	77,774	75,780	78,916
Net (income) loss per share:
Basic net income (loss) per share (in dollars per share)	$ 0.49	$ (0.05)	$ (0.13)	$ (1.17)
Diluted net income (loss) per share (in dollars per share)	$ 0.49	$ (0.05)	$ (0.13)	$ (1.17)

NET INCOME (LOSS) PER SHARE - A

NET INCOME (LOSS) PER SHARE - Antidilutive Securities Excluded from Computation (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	2,997	435	694	733

INCOME TAXES (Details)

INCOME TAXES (Details)	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Effective income tax rate	11.60%	30.80%	47.20%	20.20%

SEGMENT AND GEOGRAPHIC INFORM_3

SEGMENT AND GEOGRAPHIC INFORMATION (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			1
Total revenue	$ 260,024	$ 246,008	$ 662,469	$ 674,916
United States
Segment Reporting Information [Line Items]
Total revenue	163,605	148,379	410,252	412,377
Europe
Segment Reporting Information [Line Items]
Total revenue	45,049	45,058	110,259	109,529
Asia
Segment Reporting Information [Line Items]
Total revenue	15,957	18,187	41,647	54,285
Rest of the world
Segment Reporting Information [Line Items]
Total revenue	$ 35,413	$ 34,384	$ 100,311	$ 98,725

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - Gigavation Incorporated - Subsequent Event $ in Millions	Feb. 05, 2020USD ($)
Subsequent Event [Line Items]
Percentage of common stock acquired	100.00%
Payments to acquire businesses	$ 8

Uncategorized Items - ntct-2019

Label	Element	Value
Accounting Standards Update 2014-09 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 34,149,000
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 34,149,000