SHARE-BASED COMPENSATION: (Details 2)	6 Months Ended
	Sep. 30, 2015 $ / shares shares
Stock options outstanding and exercisable by exercise price range
Options outstanding (in shares) | shares	4,183,216
Options outstanding - Weighted-average remaining contractual life	5 years 2 months 16 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 14.15
Options exercisable (in shares) | shares	2,858,695
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 14.72
Range of exercise price per share from $0.63 to $8.90
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	0.63
Exercise price per share, high end of range (in dollars per share)	$ 8.90
Options outstanding (in shares) | shares	953,132
Options outstanding - Weighted-average remaining contractual life	6 years 4 months 6 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 1.69
Options exercisable (in shares) | shares	502,923
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 1.71
Range of exercise price per share from $11.08 to $14.42
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	11.08
Exercise price per share, high end of range (in dollars per share)	$ 14.42
Options outstanding (in shares) | shares	1,229,467
Options outstanding - Weighted-average remaining contractual life	4 years 6 months 22 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 13.17
Options exercisable (in shares) | shares	1,116,140
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 13.16
Range of exercise price per share from $15.10 to $19.76
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	15.10
Exercise price per share, high end of range (in dollars per share)	$ 19.76
Options outstanding (in shares) | shares	866,027
Options outstanding - Weighted-average remaining contractual life	5 years 9 months 7 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 17.14
Options exercisable (in shares) | shares	442,448
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 16.52
Range of exercise price per share from $20.44 to $25.00
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	20.44
Exercise price per share, high end of range (in dollars per share)	$ 25.00
Options outstanding (in shares) | shares	1,039,737
Options outstanding - Weighted-average remaining contractual life	4 years 9 months 7 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 21.88
Options exercisable (in shares) | shares	716,996
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 22.18
Range of exercise price per share from $26.33 to $62.06
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	26.33
Exercise price per share, high end of range (in dollars per share)	$ 62.06
Options outstanding (in shares) | shares	94,853
Options outstanding - Weighted-average remaining contractual life	1 year 8 months 23 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 40.00
Options exercisable (in shares) | shares	80,188
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 41.31