RESTRUCTURING CHARGES - Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($) employee	Mar. 31, 2019 USD ($) employee	Mar. 31, 2018 USD ($) employee	Mar. 31, 2017 USD ($) plan employee	Mar. 31, 2016 USD ($) employee
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 18,693	$ 5,209	$ 4,001
Number of restructuring plans | plan				2
FY2017 Plans
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 900
FY2018 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1,700
Number of employees terminated | employee			61
VSP
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 17,200
Number of employees terminated | employee		155
VSP | Scenario, Forecast
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 100
Number of employees terminated | employee	1
Employee-Related
Restructuring Cost and Reserve [Line Items]
Restructuring charges					$ 500
Number of employees terminated | employee					1
Employee-Related | Q1 FY2017 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges				$ 2,000
Number of employees terminated | employee				19
Employee-Related | Q4 FY2017 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges				$ 1,900
Number of employees terminated | employee				41
Employee-Related | FY2018 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 5,100
Facilities Related | Q4 FY2017 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges				$ 400