STOCK-BASED COMPENSATION: (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018
Stock Option Activity - Number of Shares
Outstanding at beginning of the period (in shares)	2,456,184
Exercised (in shares)	(870,453)
Forfeited or cancelled (in shares)	(25,591)
Outstanding at end of the period (in shares)	1,560,140
Exercisable at the end of the period (in shares)	1,378,721
Weighted-average exercise price per share
Outstanding at the beginning of the period (in dollars per share)	$ 13.30
Exercised (in dollars per share)	11.22
Forfeited or cancelled (in dollars per share)	18.64
Outstanding at the end of the period (in dollars per share)	14.37
Exercisable at the end of the period (in dollars per share)	$ 15.27
Weighted-average remaining contractual term
Weighted average remaining contractual term	4 years 9 months 18 days
Exercisable at the end of the period	4 years 6 months
Aggregate intrinsic value
Exercised	$ 27,517
Outstanding at the end of the period	37,850
Exercisable at the end of the period	$ 32,210
Stock Option and Equity Compensation Plans
Share-based compensation
Total shares reserved for issuance since inception of the stock option and equity compensation plans (in shares)		42,300,000	37,300,000
Shares which remained available for future grants (in shares)	12,300,000
Amended and Restated 2005 Equity Compensation Plan
Share-based compensation
Shares which remained available for future grants (in shares)	37,900,000	32,900,000