LONG-TERM DEBT AND LEASE FINANCING OBLIGATION (Details 2) (USD $)	12 Months Ended			1 Months Ended			12 Months Ended		12 Months Ended	1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Apr. 30, 2011 7.125% senior notes due 2013 and 9.5% senior notes due 2014	Apr. 04, 2011 7.125% senior notes due 2013	Apr. 04, 2011 9.5% senior notes due 2014	Dec. 31, 2012 Lease financing obligation Y	Dec. 31, 2011 Lease financing obligation	Dec. 31, 2011 Other	Oct. 31, 2011 10.75% senior subordinated notes due 2016	Oct. 20, 2011 10.75% senior subordinated notes due 2016	Oct. 11, 2011 10.75% senior subordinated notes due 2016
Long-term debt
Interest rate (as a percent)					7.125%	9.50%						10.75%
Principal debt extinguished, net of original issuance discounts				$ 22,200,000
Redemption price per 100 face value											105.375
Debt redemption. principal amount, basis for redemption											100
Payments made for debt extinguishment									18,000,000	44,100,000
Scheduled maturities of long-term debt outstanding
Thereafter	450,000,000
Cash payments for interest	55,800,000	63,400,000	45,300,000
Lease financing obligation	112,269,000	109,899,000					112,300,000	109,900,000
Lease financing obligation term (in years)							10
Amount of collateralized letter of credit	11,500,000	15,800,000					5,900,000	8,000,000
Future minimum lease payments
2013							7,800,000
2014							7,800,000
2015							8,100,000
2016							8,200,000
2017							2,000,000
Thereafter