STOCKHOLDERS' EQUITY: - Summary of Options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Stock options outstanding and exercisable by exercise price range
Options outstanding (in shares)	2,565,287
Options outstanding - Weighted-average remaining contractual life	5 years 6 months 14 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 13.61
Options exercisable (in shares)	1,995,309
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 13.60
Stock options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Share-based compensation expense	$ 5.0	$ 6.9	$ 9.8
Future share-based compensation expense	$ 6.2
Period for recognition of unrecognized stock-based compensation expense	3 years
Stock options | Arbor and Circulate
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Share-based compensation expense	$ 2.7
Range of exercise price per share from $0.61 to $9.99
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	$ 0.61
Exercise price per share, high end of range (in dollars per share)	$ 9.99
Options outstanding (in shares)	619,749
Options outstanding - Weighted-average remaining contractual life	6 years 29 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 1.68
Options exercisable (in shares)	434,021
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 1.79
Range of exercise price per share from $10.00 to $19.99
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	10.00
Exercise price per share, high end of range (in dollars per share)	$ 19.99
Options outstanding (in shares)	1,229,616
Options outstanding - Weighted-average remaining contractual life	4 years 8 months 1 day
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 14.96
Options exercisable (in shares)	1,043,930
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 14.47
Range of exercise price per share from $20.00 to $24.99
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	20.00
Exercise price per share, high end of range (in dollars per share)	$ 24.99
Options outstanding (in shares)	696,370
Options outstanding - Weighted-average remaining contractual life	6 years 7 months 6 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 21.31
Options exercisable (in shares)	497,806
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 21.32
Range of exercise price per share from $25.00 to $32.85
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	25.00
Exercise price per share, high end of range (in dollars per share)	$ 32.85
Options outstanding (in shares)	19,552
Options outstanding - Weighted-average remaining contractual life	5 years 7 months 13 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 32.85
Options exercisable (in shares)	19,552
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 32.85
LiveRamp Employees | Stock options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Share-based compensation expense	$ 1.1	$ 4.3	$ 6.7