Annual report pursuant to Section 13 and 15(d)

Long-Term Debt (Details Textual)

v2.4.0.6
Long-Term Debt (Details Textual) (USD $)
12 Months Ended 1 Months Ended 12 Months Ended 9 Months Ended 12 Months Ended 9 Months Ended 12 Months Ended 1 Months Ended 3 Months Ended 3 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Mar. 31, 2011
New Credit Facility [Member]
Dec. 31, 2011
New Credit Facility [Member]
Mar. 09, 2011
New Credit Facility [Member]
Dec. 31, 2011
New Credit Facility [Member]
Maximum [Member]
Dec. 31, 2011
New Credit Facility [Member]
Maximum [Member]
Dec. 31, 2011
New Credit Facility [Member]
Minimum [Member]
Dec. 31, 2011
New Credit Facility [Member]
Minimum [Member]
Dec. 31, 2011
Prior Credit Facility [Member]
Dec. 31, 2010
Prior Credit Facility [Member]
Jul. 21, 2006
Prior Credit Facility [Member]
Dec. 31, 2011
Secured Debt [Member]
New Credit Facility [Member]
Dec. 31, 2010
Secured Debt [Member]
Prior Credit Facility [Member]
Sep. 30, 2007
Revolving credit facility [Member]
Mar. 31, 2011
Revolving credit facility [Member]
Dec. 31, 2010
Revolving credit facility [Member]
Sep. 12, 2007
Revolving credit facility [Member]
Jul. 21, 2006
Revolving credit facility [Member]
Mar. 31, 2011
Term Loan Portion [Member]
Dec. 31, 2010
Term Loan Portion [Member]
Jul. 21, 2006
Term Loan Portion [Member]
Long-Term Debt (Textual) [Abstract]                                              
New Credit Facility, maturity date         March 9, 2016                                    
Margin portion of interest rate in addition to LIBOR rate       1.75%                         1.25%       1.50%    
Margin portion of interest rate in addition to base rate       0.75%                         0.25%       0.50%    
Margin Portion of Interest Rate in Addition to LIBOR Rate after March 2011             2.50%   1.50%                            
Margin portion of interest rate in addition to base rate after March 2011             1.50%   0.50%                            
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage               0.50%   0.25%                          
Repayment of all amounts outstanding under the Prior Credit Facility by using borrowings under the New Credit Facility       $ 196,000,000                                      
Borrowings under Long-term Lines of Credit   427,000,000 212,000,000   859,700,000           54,000,000                        
Repayments of Long-term Lines of Credit   487,000,000 298,700,000   657,700,000           228,900,000                        
Amount outstanding         202,000,000           0 174,900,000           31,000,000       143,900,000  
Long-term Debt, Weighted Average Interest Rate                           1.89% 1.75%                
Foreign currency borrowings outstanding         0                                    
Credit facility maturity 5 years                                            
Increase in maximum aggregate borrowing capacity                               150,000,000              
Senior secured revolving credit facility           700,000,000             300,000,000           250,000,000 100,000,000     200,000,000
Annual scheduled principal payments, 2012         0                                    
Annual scheduled principal payments, 2013         0                                    
Annual scheduled principal payments, 2014         0                                    
Annual scheduled principal payments, 2015         0                                    
Annual scheduled principal payments, 2016         0                                    
Additional interest rate to federal funds rate         0.50%                                    
Additional interest rate to LIBOR         1.00%                                    
Additional Long Term Debt (Textual) [Abstract]                                              
Debt issuance costs 5,700,000                                            
Interest expense 9,900,000 9,700,000 9,600,000                                        
Write-off of unamortized deferred financing costs resulting from the extinguishment of the prior senior secured facility $ 914,000