SHARE-BASED COMPENSATION: (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares
Stock Option Activity - Number of Shares
Outstanding at beginning of the period (in shares)	3,033,071
Granted (in shares)	299,641
Exercised (in shares)	(130,157)
Forfeited or cancelled (in shares)	(2,052)
Outstanding at end of the period (in shares)	3,200,503
Exercisable at the end of the period (in shares)	2,412,279
Weighted-average exercise price per share
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 13.14
Granted (in dollars per share) | $ / shares	21.32
Exercised (in dollars per share) | $ / shares	14.66
Forfeited or cancelled (in dollars per share) | $ / shares	14.80
Outstanding at the end of the period (in dollars per share) | $ / shares	13.85
Exercisable at the end of the period (in dollars per share) | $ / shares	$ 14.49
Weighted-average remaining contractual term
Weighted average remaining contractual term	5 years 10 months 24 days
Exercisable at the end of the period	5 years 1 month 6 days
Aggregate intrinsic value
Exercised | $	$ 1,532
Outstanding at the end of the period | $	38,971
Exercisable at the end of the period | $	$ 27,826
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)	30,000,000
Shares which remained available for future grants (in shares)	1,200,000
Amended and Restated 2005 Equity Compensation Plan [Member]
Share-based compensation
Shares reserved for issuance	34,500,000
Amended and Restated 2005 Equity Compensation Plan [Member] | Minimum
Share-based compensation
Shares which remained available for future grants (in shares)	28,400,000
Amended and Restated 2005 Equity Compensation Plan [Member] | Maximum
Share-based compensation
Shares which remained available for future grants (in shares)	32,900,000