SHARE-BASED COMPENSATION: (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Stock Option Activity - Number of Shares
Outstanding at beginning of the period (in shares)	2,565,287
Exercised (in shares)	(125,437)
Forfeited or cancelled (in shares)	(25,831)
Outstanding at end of the period (in shares)	2,414,019
Exercisable at the end of the period (in shares)	2,169,170
Weighted-average exercise price per share
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 13.61
Exercised (in dollars per share) | $ / shares	8.80
Forfeited or cancelled (in dollars per share) | $ / shares	14.25
Outstanding at the end of the period (in dollars per share) | $ / shares	13.86
Exercisable at the end of the period (in dollars per share) | $ / shares	$ 14.58
Weighted-average remaining contractual term
Weighted average remaining contractual term	5 years 1 month 6 days
Exercisable at the end of the period	4 years 9 months 18 days
Aggregate intrinsic value
Exercised | $	$ 2,426
Outstanding at the end of the period | $	38,910
Exercisable at the end of the period | $	$ 33,397
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)	34,500,000
Shares which remained available for future grants (in shares)	5,100,000