STOCK-BASED COMPENSATION: Stock options outstanding and exercisable (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Stock options outstanding and exercisable by exercise price range
Options outstanding (in shares)	1,560,140
Options outstanding - Weighted-average remaining contractual life	4 years 9 months 18 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 14.37
Options exercisable (in shares)	1,378,388
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 15.27
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)	304,455
Options outstanding - Weighted-average remaining contractual life	5 years 3 months 18 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 1.45
Options exercisable (in shares)	192,111
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 1.46
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)	732,241
Options outstanding - Weighted-average remaining contractual life	3 years 10 months 24 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 14.78
Options exercisable (in shares)	662,833
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 14.50
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)	523,444
Options outstanding - Weighted-average remaining contractual life	5 years 9 months 18 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 21.31
Options exercisable (in shares)	523,444
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 21.31
Stock options
Stock options outstanding and exercisable by exercise price range
Share-based compensation expense	$ 2.6	$ 4.0
Share-based compensation not yet recognized	$ 3.4
Period for recognition of unrecognized stock-based compensation expense	3 years