STOCK-BASED COMPENSATION: Performance Stock Option Unit Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercised (in dollars per share)	$ 5.73
Future expense for performance stock option units	$ 180,500
Number of shares
Outstanding at beginning of the period (in shares)	1,374,430
Forfeited or cancelled (in shares)	(8,138)
Outstanding at end of the period (in shares)	1,394,264
Exercisable at the end of the period (in shares)	1,281,248
Weighted-average exercise price per share
Outstanding at the beginning of the period (in dollars per share)	$ 14.81
Forfeited or cancelled (in dollars per share)	5.13
Outstanding at the end of the period (in dollars per share)	14.21
Exercisable at the end of the period (in dollars per share)	$ 15.31
Weighted-average remaining contractual term
Weighted average remaining contractual term	3 years 10 months 24 days
Exercisable at the end of the period	3 years 7 months 6 days
Aggregate intrinsic value
Outstanding at the end of the period	$ 47,212
Exercisable at the end of the period	41,973
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 40,500	$ 34,600
Performance stock
Number of shares
Outstanding at beginning of the period (in shares)	130,154
Forfeited or cancelled (in shares)	(130,154)
Outstanding at end of the period (in shares)	0
Exercisable at the end of the period (in shares)	0
Weighted-average exercise price per share
Outstanding at the beginning of the period (in dollars per share)	$ 21.44
Forfeited or cancelled (in dollars per share)	21.44
Outstanding at the end of the period (in dollars per share)	0
Exercisable at the end of the period (in dollars per share)	$ 0
Weighted-average remaining contractual term
Weighted average remaining contractual term
Aggregate intrinsic value
Outstanding at the end of the period	$ 0
Exercisable at the end of the period	$ 0