SHARE-BASED COMPENSATION: (Details 2) (USD $)	6 Months Ended
	Sep. 30, 2014
Stock options outstanding and exercisable by exercise price range
Options outstanding (in shares)	5,796,746
Options outstanding - Weighted-average remaining contractual life	5 years 3 months 29 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 14.42
Options exercisable (in shares)	3,373,001
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 18.18
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)	1,464,856
Options outstanding - Weighted-average remaining contractual life	7 years 9 months 15 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 1.56
Options exercisable (in shares)	183,530
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 2.64
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)	1,719,118
Options outstanding - Weighted-average remaining contractual life	5 years 9 months 4 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 13.21
Options exercisable (in shares)	1,195,887
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 13.10
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)	686,167
Options outstanding - Weighted-average remaining contractual life	1 year 11 months 12 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 16.38
Options exercisable (in shares)	686,167
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 16.38
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)	1,588,894
Options outstanding - Weighted-average remaining contractual life	4 years 10 months 24 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 22.32
Options exercisable (in shares)	989,258
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 22.95
Range of exercise price per share from $26.33 to $29.30
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)	$ 29.30
Options outstanding (in shares)	114,530
Options outstanding - Weighted-average remaining contractual life	9 months 15 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 27.94
Options exercisable (in shares)	114,530
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 27.94
Range of exercise price per share from $32.85 to $35.16
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	$ 32.85
Exercise price per share, high end of range (in dollars per share)	$ 35.16
Options outstanding (in shares)	91,259
Options outstanding - Weighted-average remaining contractual life	2 years 6 months 11 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 34.45
Options exercisable (in shares)	71,707
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 34.88
Range of exercise price per share from $41.38 to $62.06
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	$ 41.38
Exercise price per share, high end of range (in dollars per share)	$ 62.06
Options outstanding (in shares)	131,922
Options outstanding - Weighted-average remaining contractual life	10 months 17 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 41.83
Options exercisable (in shares)	131,922
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 41.83