FINANCING ARRANGEMENTS (Details) (USD $)					0 Months Ended				0 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Senior secured notes	Dec. 31, 2011 Senior secured notes	Jul. 30, 2012 Senior secured notes Repayment of Debt [Member]	Jul. 13, 2012 Senior secured notes Repayment of Debt [Member]	Aug. 15, 2012 Senior secured notes Repayment of Debt [Member]	Jul. 16, 2012 Senior secured notes Repayment of Debt [Member]	Jul. 30, 2012 Senior secured notes Issuance of Debt [Member]	Jul. 30, 2012 Senior secured notes Issuance of Debt [Member] Redemption Period, Twelve Month Period Commencing on August 1, 2016 [Member]	Jul. 30, 2012 Senior secured notes Issuance of Debt [Member] Redemption Period, Twelve Month Period Commencing on August 1, 2017 [Member]	Jul. 30, 2012 Senior secured notes Issuance of Debt [Member] Redemption Period, Commencing on August 1, 2018 [Member]	Jul. 30, 2012 Senior secured notes Issuance of Debt [Member] Redemption Period, Prior to August 1, 2015 [Member]	Jul. 30, 2012 Senior secured notes Issuance of Debt [Member] Redemption Period, Prior to August 1, 2015 [Member] Maximum [Member]
Financing arrangements
Senior secured notes, at 7.625%, due on August 15, 2016			$ 520,000,000	$ 520,000,000			$ 150,900,000	$ 490,000,000
Revolving credit facility, due May 31, 2016	0	0
Unamortized notes premium and discount, net			3,481,000	4,203,000
Long-term obligations	523,481,000	524,203,000
Debt Instrument, Interest Rate, Stated Percentage			7.625%						5.25%
Revolving credit facility, maximum borrowing capacity	163,500,000
Letters of Credit Outstanding, Amount	86,500,000
Extinguishment of Debt, Amount					339,100,000	30,000,000
Debt Instrument, Face Amount									800,000,000
Proceeds from Issuance of Long-term Debt									262,800,000
Gains (Losses) on Extinguishment of Debt					(26,500,000)
Gains (Losses) on Extinguishment of Debt, before Write off of Deferred Debt Issuance Cost					(21,200,000)
Write off of Deferred Debt Issuance Cost					(5,300,000)
Unamortized Debt Issuance Expense					(8,800,000)
Debt Instrument, Unamortized Premium					$ 3,500,000
Interest Rate Computed On The Basis of a 360 Day Year									360 days
Interest at a Rate Computed on the Basis of Twelve 30-Day Month									30 days
Debt Instrument, Redemption Payment Term, Percentage of Principal Amount														35.00%
Long-term Debt Redemption Price with Net Proceeds from Equity offerings as Percentage of Principal Amount													105.25%
Long-term Debt Redemption, Price as Percentage of Principal Amount										102.625%	101.313%	100.00%	100.00%
Long-term Debt Redemption Price Due to Change of Control as Percentage of Principal Amount													101.00%