DEBT (Details) (USD $)	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Mar. 31, 2013
Debt Instrument [Line Items]
Total debt	$ 831,083,000		$ 831,083,000		$ 787,269,000
Less short-term borrowings and current maturities of long-term debt	(6,989,000)		(6,989,000)		(22,323,000)
Long-term debt, less current maturities	824,094,000		824,094,000		764,946,000
Proceeds from borrowings			160,146,000	0
Letters of Credit Outstanding, Amount	500,000		500,000
Long Term Convertible Debt Current And Noncurrent [Abstract]
Debt Instrument, Convertible, Effective Interest Rate	6.90%	6.90%	6.90%	6.90%
Amortization of debt discount			1,722,000	1,772,000
Term Loan [Member]
Debt Instrument [Line Items]
Total debt	228,107,000		228,107,000		230,625,000
Repayment of debt			2,300,000
Term Loan [Member] | Third Amendment [Member]
Balances Of Debt And Equity Components [Abstract]
Debt Instrument, Face Amount	250,000,000		250,000,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Total debt	45,000,000		45,000,000		0
Repayment of debt			112,500,000
Proceeds from borrowings			157,500,000
Revolving Credit Facility [Member] | Second Amendment [Member]
Balances Of Debt And Equity Components [Abstract]
Debt Instrument, Face Amount					200,000,000
Revolving Credit Facility [Member] | Third Amendment [Member]
Balances Of Debt And Equity Components [Abstract]
Debt Instrument, Face Amount	350,000,000		350,000,000
Convertible Senior Notes Due 2038 [Member]
Debt Instrument [Line Items]
Total debt	107,906,000		107,906,000		106,196,000
Debt Instrument, Interest Rate, Stated Percentage	3.00%		3.00%
Balances Of Debt And Equity Components [Abstract]
Equity component- net carrying value	14,905,000		14,905,000		14,905,000
Debt Instrument, Face Amount	115,000,000		115,000,000		115,000,000
Debt component- unamortized discount	(7,094,000)		(7,094,000)		(8,804,000)
Long Term Convertible Debt Current And Noncurrent [Abstract]
Contractual coupon interest	863,000	863,000	1,726,000	1,726,000
Amortization of debt discount	789,000	903,000	1,710,000	1,772,000
Total interest expense	1,652,000	1,766,000	3,436,000	3,498,000
Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Total debt	450,000,000		450,000,000		450,000,000
Debt Instrument, Interest Rate, Stated Percentage	6.25%		6.25%
Other debt [Member]
Debt Instrument [Line Items]
Total debt	$ 70,000		$ 70,000		$ 448,000