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
	Jun. 30, 2013	Jun. 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	151
Options exercised	(549)
Options forfeited or expired	(8)
Options outstanding at June 30, 2013	2,009
Weighted average exercise price of options outstanding, March 31, 2013	$ 27.96
Weighted average exercise price of options granted	$ 45.68
Weighted average exercise price of options exercised	$ 23.97
Weighted average exercise price of options forfeited or expired	$ 31.63
Weighted average exercise price of options outstanding, June 30, 2013	$ 30.36
Weighted average remaining contractual life of options outstanding at June 30, 2013	4 years 73 days
Aggregate intrinsic value of options outstanding at June 30, 2013	$ 27,517,000
Vested and expected to vest at June 30, 2013	1,960
Weighted average exercise price of options vested and expected to vest at June 30, 2013	$ 30.17
Weighted average remaining contractual life of options vested and expected to vest at June 30, 2013	4 years 73 days
Aggregate intrinsic value of options vested and expected to vest at June 30, 2013	27,178,000
Exercisable at June 30, 2013	1,298
Weighted average exercise price of options exercisable at June 30, 2013	$ 27.09
Weighted average remaining contractual life of options exercisable at June 30, 2013	3 years 110 days
Aggregate intrinsic value of options exercisable at June 30, 2013	21,844,000
Total intrinsic value of options exercised	12,200,000	800,000
Total cash received as a result of stock option exercises, net of taxes	13,200,000
Total unrecognized compensation cost related to unvested stock options	$ 6,600,000
Weighted average period of recognition for unrecognized compensation cost related to unvested stock options	2 years 0 days