STOCK-BASED COMPENSATION: Stock-based compensation activity, by award type (Details) - USD ($) $ in Millions	9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based compensation
Other non-employee stock-based compensation	$ 0.9	$ 0.9
Total non-cash stock-based compensation	72.3	61.6
Stock-based compensation of discontinued operations	0.0	62.9
Total non-cash stock-based compensation included in the condensed consolidated statement of equity	49.0	113.7
Cost of revenue
Share-based compensation
Total non-cash stock-based compensation	2.8	2.6
Research and development
Share-based compensation
Total non-cash stock-based compensation	17.3	14.0
Sales and marketing
Share-based compensation
Total non-cash stock-based compensation	34.4	29.2
General and administrative
Share-based compensation
Total non-cash stock-based compensation	17.8	15.8
Stock options
Share-based compensation
Share-based compensation expense	2.8	2.6
Restricted stock units
Share-based compensation
Share-based compensation expense	40.5	34.6
Arbor Holdback Agreement | Arbor
Share-based compensation
Share-based compensation expense	2.6	11.5
Consideration Holdback | Data Plus Math Corporation
Share-based compensation
Share-based compensation expense	4.1	0.0
Pacific Data Partners, LLC Agreement Plan | Pacific Data Partners LLC
Share-based compensation
Share-based compensation expense	21.4	11.8
Liability-based equity awards
Share-based compensation
Total non-cash stock-based compensation	$ (23.3)	$ (10.8)