Long-Term Debt (Details) (USD $)
Share data in Thousands, unless otherwise specified
 12 Months Ended 12 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Dec. 31, 2011
Amended Credit Facility
Dec. 31, 2011
Amended Credit Facility
Scheduled Principal Payment
Dec. 31, 2011
Amended Credit Facility
Estimated Excess Cash Flow Principal Payment
Dec. 31, 2011
Term Loans
Jul. 26, 2011
Term Loans
Dec. 31, 2011
Revolving Loans
Jul. 26, 2011
Revolving Loans
Apr. 30, 2010
Prior Credit Facilities
Dec. 31, 2010
Prior Credit Facilities
Dec. 31, 2009
Prior Credit Facilities
May 31, 2011
Revolving Credit Facility
year
Dec. 31, 2011
Revolving Credit Facility
Long-term debt                              
Less unamortized discount             $ (4,517,000)                
Subtotal 483,033,000           487,550,000                
Less current portion (4,900,000)                            
Long-term portion 478,133,000                            
Maximum borrowing capacity                   120,000,000     185,000,000 150,000,000  
Maximum borrowing capacity before amendment               490,000,000              
Original issue discount (as a percent)             1.00%                
Increase in effective interest rate due to original issue discount (as a percent)             0.18%   0.42%            
LIBOR             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%                
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                 119,600,000            
Debt issuance costs 12,019,000   2,236,000 12,000,000                      
Effective interest rate under the Term Loans (as a percent)             6.40%                
Maturity period (in years)                           5  
Termination of interest rate swap                     2,700,000        
Principal payments required for the next five years                              
Total 2012       4,900,000 4,900,000                    
Total 2013       55,062,000 4,900,000 50,162,000                  
Total 2014       36,346,000 4,900,000 31,446,000                  
Total 2015       39,959,000 4,900,000 35,059,000                  
Total 2016       42,159,000 4,900,000 37,259,000                  
Common stock, shares issued                     3,700        
Proceeds from issuance of shares   107,917,000 52,487,000               108,000,000        
Retirement of outstanding debt                     97,000,000        
Write-off of deferred loan fees to interest expense                       2,900,000      
Reclassification of accumulated interest rate swap losses from accumulated other comprehensive loss to interest expense                       $ 2,100,000