STOCK-BASED COMPENSATION Stock Option Activity (Details) (Stock Options [Member], USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding at March 31, 2013		2,415
Options granted		176
Options exercised		(667)
Options forfeited or expired		(10)
Options outstanding at September 30, 2013	1,914	1,914
Weighted average exercise price of options outstanding, March 31, 2013		$ 27.96
Weighted average exercise price of options granted		$ 45.98
Weighted average exercise price of options exercised		$ 24.09
Weighted average exercise price of options forfeited or expired		$ 32.74
Weighted average exercise price of options outstanding, September 30, 2013	$ 30.94	$ 30.94
Weighted average remaining contractual life of options outstanding at September 30, 2013	4 years 73 days
Aggregate intrinsic value of options outstanding at September 30, 2013	$ 29,739,000	$ 29,739,000
Vested and expected to vest at September 30, 2013	1,872	1,872
Weighted average exercise price of options vested and expected to vest at September 30, 2013	$ 30.76	$ 30.76
Weighted average remaining contractual life of options vested and expected to vest at September 30, 2013	4 years 73 days
Aggregate intrinsic value of options vested and expected to vest at September 30, 2013	29,419,000	29,419,000
Exercisable at September 30, 2013	1,275	1,275
Weighted average exercise price of options exercisable at September 30, 2013	$ 27.85	$ 27.85
Weighted average remaining contractual life of options exercisable at September 30, 2013	3 years 146 days
Aggregate intrinsic value of options exercisable at September 30, 2013	23,735,000	23,735,000
Total intrinsic value of options exercised		14,500,000	4,500,000
Total cash received as a result of stock option exercises, net of taxes		16,100,000
Total unrecognized compensation cost related to unvested stock options	$ 5,800,000	$ 5,800,000
Weighted average period of recognition for unrecognized compensation cost related to unvested stock options	1 year 329 days