Long-Term Debt (Details) (USD $)
3 Months Ended
Mar. 31, 2012
Dec. 31, 2011
Jul. 26, 2011
Long-term debt      
Less unamortized discount $ (4,305,000) $ (4,517,000)  
Subtotal 457,020,000 483,033,000  
Less current portion (21,638,000) (4,900,000)  
Long-term debt, net of current portion 435,382,000 478,133,000  
Amended Credit Facility
     
Long-term debt      
Increase in effective borrowing rate (as a percent) 0.42%    
Debt issuance costs 12,000,000    
Term Loans
     
Long-term debt      
Subtotal 461,325,000 487,550,000  
Maximum borrowing capacity     490,000,000
Original issue discount (as a percent) 1.00%    
Increase in effective borrowing rate (as a percent) 0.18%    
LIBOR LIBOR    
LIBOR plus interest rate (as a percent) 4.50%    
Interest rate for term loan (as a percent) 5.75%    
Quarterly principal payment 1,225,000    
Annual principal payment 4,900,000    
Maximum percentage of mandatory prepayments of excess cash flow depending on consolidated leverage ratio 50.00%    
Prepayment of principal amount 25,000,000    
Effective interest rate under the Term Loans (as a percent) 6.40%    
Revolving Loans
     
Long-term debt      
Maximum borrowing capacity     120,000,000
Interest rate terms bear interest at the alternative base rate or LIBOR, plus the applicable margin for each rate that fluctuates with the consolidated leverage ratio.    
Funds available under credit facility $ 116,600,000