SHARE-BASED COMPENSATION: Stock options outstanding and exercisable (Details)	3 Months Ended
	Jun. 30, 2016 $ / shares shares
Stock options outstanding and exercisable by exercise price range
Options outstanding (in shares) | shares	3,417,029
Options outstanding - Weighted-average remaining contractual life	5 years 1 month 6 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 14.78
Options exercisable (in shares) | shares	2,645,523
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 15.03
Range of exercise price per share from $0.85 to $9.99
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	0.85
Exercise price per share, high end of range (in dollars per share)	$ 9.99
Options outstanding (in shares) | shares	626,572
Options outstanding - Weighted-average remaining contractual life	6 years 9 months 18 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 1.85
Options exercisable (in shares) | shares	387,045
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 1.85
Range of exercise price per share from $10.00 to $19.99
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	10.00
Exercise price per share, high end of range (in dollars per share)	$ 19.99
Options outstanding (in shares) | shares	1,756,862
Options outstanding - Weighted-average remaining contractual life	5 years 1 month 6 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 15.10
Options exercisable (in shares) | shares	1,439,173
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 14.51
Range of exercise price per share from $20.00 to $24.99
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	20.00
Exercise price per share, high end of range (in dollars per share)	$ 24.99
Options outstanding (in shares) | shares	1,014,043
Options outstanding - Weighted-average remaining contractual life	4 years 1 month 6 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 21.88
Options exercisable (in shares) | shares	809,531
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 22.06
Range of exercise price per share from $25.00 to $32.85
Stock options outstanding and exercisable by exercise price range
Exercise price per share, low end of range (in dollars per share)	25.00
Exercise price per share, high end of range (in dollars per share)	$ 32.85
Options outstanding (in shares) | shares	19,552
Options outstanding - Weighted-average remaining contractual life	7 years 4 months 24 days
Options outstanding - Weighted-average exercise price per share (in dollars per share)	$ 32.85
Options exercisable (in shares) | shares	9,774
Options exercisable - Weighted-average exercise price per share (in dollars per share)	$ 32.85