GOODWILL AND INTANGIBLE ASSETS - Narrative (Details) $ in Thousands	9 Months Ended
	Dec. 31, 2017 USD ($) reporting_unit	Mar. 31, 2017 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Number of reporting units | reporting_unit	2
Goodwill	$ 1,716,371	$ 1,718,162
Carrying value of intangible assets	$ 859,160	931,269
Weighted average useful life of acquired intangible assets	14 years 7 months
Developed and core technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	11 years 5 months 15 days
Customer and distributor relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	16 years 1 month
Trademarks and trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	8 years 6 months
Leasehold interest
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	5 years 7 months 6 days
Backlog
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	2 years
Capitalized software
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	4 years
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 18,600	18,600
Service Assurance
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	1,200,000	1,200,000
Security
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 555,300	$ 548,500