SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)		1 Months Ended		12 Months Ended			36 Months Ended
	Sep. 14, 2018 USD ($)	Feb. 28, 2021 USD ($)	Apr. 30, 2020 USD ($)	Mar. 31, 2021 USD ($) reporting_unit Segment	Mar. 31, 2020 USD ($) company	Mar. 31, 2019 USD ($)	Mar. 31, 2021 USD ($) company	Feb. 05, 2020 USD ($)	Apr. 03, 2019 USD ($)	Sep. 30, 2018 USD ($)	Jan. 16, 2018 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of reportable segments | Segment				1
Deferred employer payroll taxes				$ 8,900,000			$ 8,900,000
Unrecognized accounts receivable and deferred revenue				$ 7,100,000	$ 11,100,000		$ 7,100,000
Number of reporting units | reporting_unit				1
Number of companies acquired | company					2		2
Number of businesses divested | company							1
Fair value of contingent liability					$ 1,748,000
Amortization included as cost of product				$ 100,000	500,000	$ 1,100,000
Capitalized software development costs				0	0		$ 0
Foreign currency losses				5,500,000	700,000	2,000,000.0
Advertising expense				$ 8,700,000	8,300,000	9,400,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Handheld Network Test Tools Business
Summary Of Significant Accounting Policies [Line Items]
Contingent consideration related to the divestiture	$ 2,300,000					$ 2,300,000				$ 2,300,000
Contingent consideration measurement period	2 years					2 years
Change in fair value of contingent consideration					800,000	$ 1,600,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Handheld Network Test Tools Business | Maximum
Summary Of Significant Accounting Policies [Line Items]
Contingent consideration related to the divestiture	$ 4,000,000.0					$ 4,000,000.0
Computer equipment and internal use software
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life				3 years
Computer equipment and internal use software | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life				5 years
Gigavation
Summary Of Significant Accounting Policies [Line Items]
Fair value of contingent liability					700,000			$ 800,000
Payments of contingent consideration		$ 700,000
Eastwind
Summary Of Significant Accounting Policies [Line Items]
Fair value of contingent liability					$ 1,000,000.0				$ 1,000,000
Payments of contingent consideration			$ 1,000,000.0
Accrued Liabilities
Summary Of Significant Accounting Policies [Line Items]
Deferred employer payroll taxes				$ 4,500,000			4,500,000
Other Noncurrent Liabilities
Summary Of Significant Accounting Policies [Line Items]
Deferred employer payroll taxes				4,400,000			4,400,000
Senior secured revolving credit facility | Line of credit
Summary Of Significant Accounting Policies [Line Items]
Current borrowing capacity				336,000,000			336,000,000
Credit facility				$ 1,000,000,000.0			$ 1,000,000,000.0				$ 1,000,000,000.0