STOCK-BASED COMPENSATION Stock Option Activity (Details) - Stock Options [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding at March 31, 2015		1,558,000
Options granted	0	156,000
Options exercised		(197,000)
Options forfeited or expired		(36,000)
Options outstanding at September 30, 2015		1,481,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted average exercise price of options outstanding, March 31, 2015		$ 36.59
Weighted average exercise price of options granted		54.17
Weighted average exercise price of options exercised		30.98
Weighted average exercise price of options forfeited or expired		46.67
Weighted average exercise price of options outstanding, September 30, 2015		$ 38.95
Weighted average remaining contractual life of options outstanding at September 30, 2015		4 years
Aggregate intrinsic value of options outstanding at September 30, 2015		$ 18,645
Vested and expected to vest at September 30, 2015		1,448,000
Weighted average exercise price of options vested and expected to vest at September 30, 2015		$ 38.68
Weighted average remaining contractual life of options vested and expected to vest at September 30, 2015		3 years 329 days
Aggregate intrinsic value of options vested and expected to vest at September 30, 2015		$ 18,580
Exercisable at September 30, 2015		1,032,000
Weighted average exercise price of options exercisable at September 30, 2015		$ 34.39
Weighted average remaining contractual life of options exercisable at September 30, 2015		3 years 37 days
Aggregate intrinsic value of options exercisable at September 30, 2015		$ 17,315
Total intrinsic value of options exercised		5,000	$ 5,900
Total cash received as a result of stock option exercises, net of taxes		6,100
Total unrecognized compensation cost related to unvested stock options		$ 3,800
Weighted average period of recognition for unrecognized compensation cost related to unvested stock options		2 years