COMPREHENSIVE INCOME (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010
Statement of Income and Comprehensive Income [Abstract]
Net income	$ 30,898	$ 31,552	$ 85,150	$ 82,927
Unrealized gain (loss) on cash flow hedges, net of tax	2,078	1,124	6,112	(2,890)
Foreign currency translation gain (loss), net of tax	(535)	(227)	(942)	495
Unrealized gain (loss) on investments, net of tax	56	(10)	(112)	32
Comprehensive income	$ 32,497	$ 32,439	$ 90,208	$ 80,564