LONG-TERM DEBT (Details 3) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended	12 Months Ended	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2012	Mar. 31, 2012	Jun. 30, 2012	Mar. 31, 2014	Sep. 30, 2014	Sep. 18, 2006
Long-term debt
Capital lease obligations entered into to finance capital additions			$ 28,860	$ 27,145
Payments of Financing Costs			5,859	3,287
Additional number of shares included in diluted earning per share calculation (in shares)	0	526,000	57,000	983,000
Long-term debt	1,442,680		1,442,680					1,550,383
Revolving credit facility
Long-term debt
Line of Credit Facility, Maximum Borrowing Capacity	1,000,000		1,000,000
Line of Credit Facility, Accordion Feature	250,000		250,000
Payments of Financing Costs		2,795
Long-term debt	212,013		212,013					194,406
Secured Debt [Member]
Long-term debt
Derivative Asset, Fair Value, Gross Liability	141		141					2,426
Long-term debt	360,938		360,938					375,000
Asset-backed Securities [Member]
Long-term debt
Line of Credit Facility, Maximum Borrowing Capacity	225,000		225,000						175,000
Payments of Financing Costs	252
Long-term debt	98,100		98,100					162,400
Equipment leasing facility and other capital leases
Long-term debt
Capital lease obligations entered into to finance capital additions			52	36
Long-term debt	88,651		88,651					74,342
Senior subordinated notes due 2017
Long-term debt
Debt instrument principal amount	175,000		175,000
Debt instrument interest rate stated percentage (as a percent)	8.00%		8.00%
Proceeds from loan, percentage of principal (as a percent)					98.56%
Payments of Financing Costs						4,390
Percentage of principal amount at which the entity may redeem the note before November 15, 2014 (as a percent)	104.00%
Gains (Losses) on Extinguishment of Debt		11,069
Effective interest yield on principal amount (as a percent)	8.25%		8.25%
Senior notes due 2018
Long-term debt
Debt instrument principal amount	350,000		350,000
Debt instrument interest rate stated percentage (as a percent)	8.63%		8.63%
Proceeds from loan, percentage of principal (as a percent)							99.27%
Payments of Financing Costs							7,307
Percentage of principal amount at which the entity may redeem the note before November 15, 2014 (as a percent)	104.79%
Gains (Losses) on Extinguishment of Debt		22,615
Effective interest yield on principal amount (as a percent)	8.75%		8.75%
Long-term debt	0		0					348,423
Senior notes due 2021 [Member]
Long-term debt
Debt instrument principal amount								375,000
Debt instrument interest rate stated percentage (as a percent)								4.875%
Proceeds from loan, percentage of principal (as a percent)	100.00%
Payments of Financing Costs								6,327
Debt Instrument, Redemption with Net Proceeds from Equity Offerings as Percentage of Original Principal	35.00%
Effective interest yield on principal amount (as a percent)								4.875%
Debt Instrument, Repurchase Obligation Due to Change of Control, Percentage of Original Principal	101.00%
Asset sales redemption price, percentage of principal (as a percent)	100.00%
The limit of the principal amount of the debt instrument which the entity may redeem (as a percent)	104.875%
Long-term debt	375,000		375,000					375,000
Senior Notes Due 2022 [Member]
Long-term debt
Debt instrument principal amount								300,000
Debt instrument interest rate stated percentage (as a percent)								5.25%
Proceeds from loan, percentage of principal (as a percent)	100.00%
Payments of Financing Costs								4,990
Debt Instrument, Redemption with Net Proceeds from Equity Offerings as Percentage of Original Principal	35.00%
Effective interest yield on principal amount (as a percent)								5.25%
Debt Instrument, Repurchase Obligation Due to Change of Control, Percentage of Original Principal	101.00%
Asset sales redemption price, percentage of principal (as a percent)	100.00%
The limit of the principal amount of the debt instrument which the entity may redeem (as a percent)	105.25%
Long-term debt	300,000		300,000					0
Convertible senior subordinated notes
Long-term debt
Debt instrument principal amount										201,250
Contingent interest rate per annum calculated on the average trading price for the relevant five day trading period (as a percent)	0.25%
Trading period used to determine payment of contingent interest (in days)			5
Extinguishment of Debt, Amount				95,732
Debt Instrument, Repurchase Option Percentage of Original Principal	100.00%
Percentage of principal amount which triggers payment of contingent interest if it occurs over the specified trading period (as a percent)	120.00%
Percentage of principal amount that the holder of the note may require the entity to repurchase the debt instrument on October 1, 2011, 2016, and 2021 (as a percent)	100.00%
Debt instrument fixed interest rate (as a percent)										2.625%
Number of common stock shares per $1,000 principal amount of the convertible notes (in shares)	36.8679
Principal amount of notes which are convertible into 36.731 shares of common stock	1		1
Conversion price (in dollars per share)	$ 27.12		$ 27.12
Stock Issued During Period, Shares, Conversion of Convertible Securities				2,272,019
Average price of common stock (in dollars per share)			$ 66.71	$ 75.69
Additional number of shares included in diluted earning per share calculation (in shares)			56,692	982,600
Long-term debt	0		0					12,834
Notes Payable, Other Payables [Member]
Long-term debt
Long-term debt	7,978		7,978					7,978
Debt Conversion, Redeemer [Member] | Convertible senior subordinated notes
Long-term debt
Extinguishment of Debt, Amount			12,834
Reported Value Measurement [Member]
Long-term debt
Long-term debt	1,442,680		1,442,680					1,550,383
Estimate of Fair Value Measurement [Member]
Long-term debt
Long-term debt	$ 1,434,621		$ 1,434,621					$ 1,580,447