LONG-TERM DEBT LIABILITIES (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
Senior unsecured notes	$ 220,000,000
Financing method lease obligations	0	12,610,000
Other	92,000	121,000
Total	585,202,000	617,731,000
Current amount of long-term debt	(9,808,000)	(3,778,000)
Current amount of finance method lease obligations	(12,610,000)	0
Unamortized original issue discount	(2,651,000)	(2,897,000)
Total long-term debt	560,133,000	598,446,000
Outstanding standby letter of credit	570,000	570,000
Modification Accounting Of Bank Amendment New Deferred Financing Costs	1,100,000		5,200,000
Modification Accounting Of Bank Amendment Existing Deferred Financing Costs	9,000,000
Modification Accounting Of Bank Amendment Third Party Costs	100,000
Previous Credit Facility Financing Costs Deferred Over New Term After Bank Amendment			3,100,000
Revolver, due November 23, 2016
Debt Instrument [Line Items]
Credit Facility	5,000,000	10,000,000
Term B Loan, due November 23, 2018
Debt Instrument [Line Items]
Credit Facility	347,500,000	375,000,000
Revolver, due June 30, 2012
Debt Instrument [Line Items]
Credit Facility		650,000,000
Modification Accounting Of Bank Amendment New Deferred Financing Costs		1,200,000
Previous Credit Facility Financing Costs Written Off After Bank Amendment		800,000
Previous Credit Facility Financing Costs Deferred Over New Term After Bank Amendment		300,000
Term Loan, due June 30, 2012
Debt Instrument [Line Items]
Credit Facility		400,000,000
Modification Accounting Of Bank Amendment New Deferred Financing Costs		12,800,000
Previous Credit Facility Financing Costs Written Off After Bank Amendment		300,000
Unsecured notes due December 1, 2019
Debt Instrument [Line Items]
Senior unsecured notes	$ 220,000,000	$ 220,000,000