LONG-TERM DEBT / INTEREST EXPENSE (Details) (USD $)	3 Months Ended		9 Months Ended					9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013 Senior credit facility	Dec. 31, 2012 Senior credit facility	Sep. 30, 2013 Term Loan Facility	Sep. 30, 2012 Term Loan Facility	Dec. 31, 2012 Term Loan Facility	Sep. 30, 2013 Revolving Credit Facility	Dec. 31, 2012 Revolving Credit Facility	Sep. 30, 2013 Letter of credit	Dec. 31, 2012 Letter of credit	Sep. 30, 2013 Mortgage	Dec. 31, 2012 Mortgage	Sep. 30, 2013 Capital leases	Dec. 31, 2012 Capital leases
Long-term Debt
Total Debt	$ 1,096,092,000		$ 1,096,092,000		$ 1,098,562,000	$ 1,094,993,000	$ 1,096,112,000								$ 1,097,000	$ 2,444,000	$ 2,000	$ 6,000
Less: current maturities	(3,099,000)		(3,099,000)		(3,817,000)
Long-term debt	1,092,993,000		1,092,993,000		1,094,745,000
Interest expense, net	11,237,000	12,080,000	33,353,000	32,958,000				33,400,000	33,000,000
Interest rate (as a percent)								3.75%		3.75%
Commitment fee respect of unutilized revolving loan commitments (as a percent)											0.50%	0.50%
Fee for letters of credit to lenders (as a percent)													3.00%	3.00%
Outstanding letters of credit													$ 1,100,000	$ 1,100,000