STOCKHOLDERS' EQUITY: - Stock-based Compensation Expense Related to Discontinued Operations (Details) $ in Millions	12 Months Ended
	Mar. 31, 2020 USD ($) numberOfExerciseMultiple	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)
Share-based compensation
Stock-based compensation of discontinued operations	$ 0.0	$ 62.8	$ 10.3
Holdback expenses	$ 38.3
Consideration Holdback
Share-based compensation
Contingent consideration arrangements, number of annual increments | numberOfExerciseMultiple	3
Data Plus Math Corporation
Share-based compensation
Holdback consideration transferred	$ 24.7
Holdback expenses	$ 6.2
Data Plus Math Corporation | Consideration Holdback
Share-based compensation
Contingent consideration arrangements, number of annual increments | numberOfExerciseMultiple	3
Arbor
Share-based compensation
Holdback consideration transferred	$ 38.3