STOCK-BASED COMPENSATION (Narrative) (Details) (USD $)	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
2003 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved under plan (shares)	13,900,000
Percent of estimated fair market value at the date of grant (percentage)	100.00%
Options to purchase shares of common stock (shares)	1,933,775
Unvested restricted stock (shares)	1,115,786
Shares available for future grant (shares)	3,324,264
2002 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved under plan (shares)	307,607
Percentage of fair market value at date of grant (percentage)	85.00%
Shares issued under the ESPP	151,607	158,596	182,209
Offering period	6 months
Total cash received from employees as a result of stock issuances under the ESPP	$ 5,400,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock (shares)	1,172,000	1,025,000
Restricted stock granted (shares)	582,000
Weighted average grant date fair value (in dollars per share)	$ 46.02	$ 32.22	$ 36.37
Period for recognition for unrecognized compensation cost	2 years 0 days
Total unrecognized compensation cost	28,600,000
Total grant date fair value	12,800,000	7,900,000	5,500,000
Restricted Stock | 2003 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ratio for grants of restricted stock, numerator (shares)	2.5
Initial value of restricted stock received (maximum)	2,000,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase shares of common stock (shares)	1,934,000	2,415,000
Period for recognition for unrecognized compensation cost	1 year 328 days
Total intrinsic value	16,300,000	15,600,000	27,600,000
Total cash received from employees as a result of exercises, net of taxes	18,700,000
Total net tax benefit attributable to stock options exercised	5,400,000
Total unrecognized compensation cost	4,800,000
Restricted Stock Units (RSUs) | 2003 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Initial value of restricted stock received (maximum)	$ 2,000,000
Minimum | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting period (years)	3 years
Maximum | 2003 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of award (years)	7 years
Maximum | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting period (years)	4 years
Options Granted Subsequent to September 2007
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting period (years)	3 years
Options granted from September 2004 to September 2007
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting period (years)	4 years