LONG TERM DEBT (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Long-Term Debt
Total Debt	$ 518,486,000	$ 520,646,000
Less current portion	(11,528,000)	(11,082,000)
Long Term Debt	506,958,000	509,564,000
On or prior to November 15, 2013
Long-Term Debt
Maximum percentage of the aggregate principal amount up to which the notes may be redeemed	35.00%
Percentage of the aggregate principal amount at which the notes may be redeemed	107.125%
Revolving Credit Facility
Long-Term Debt
Interest, base rate	LIBOR
Interest rate margin (as a percent)	3.25%
Maximum borrowing capacity	100,000,000
Balance available under the credit facility	99,500,000
Funds drawn under the credit facility	0
Revolving Credit Facility | Minimum
Long-Term Debt
Consolidated interest coverage ratio	3.50
Revolving Credit Facility | Maximum
Long-Term Debt
Total leverage ratio	4.00
Standby letters of credit
Long-Term Debt
Balance available under the credit facility	500,000
Term Loan
Long-Term Debt
Total Debt	292,550,000	293,300,000
Interest, base rate	LIBOR
Interest rate margin (as a percent)	3.00%
LIBOR floor applicable to term loans under Credit Agreement (as a percent)	1.00%
Issuance of debt	300,000,000
Mandatory prepayment	750,000
Interest rate (as a percent)	4.00%
7.125% Senior Notes due 2018
Long-Term Debt
Total Debt	200,000,000	200,000,000
Interest rate stated percentage	7.125%
Subordinated seller notes, non-collateralized, net of unamortized discount with principal and interest payable in either monthly, quarterly or annual installments at effective interest rates ranging from 2.00% to 4.00%, maturing through November 2018
Long-Term Debt
Total Debt	$ 25,936,000	$ 27,346,000
Interest rate, minimum (as a percent)	2.00%
Interest rate, maximum (as a percent)	4.00%