v2.4.0.6
Long-term Debt and Derivatives (Details 2) (USD $)
Mar. 31, 2012
Dec. 31, 2011
Future minimum repayments of long-term debt    
Within one year $ 44,581,000  
1-3 years 128,942,000  
3-5 years 825,223,000  
Over 5 years 1,033,543,000  
Total minimum payments 2,032,289,000 2,044,914,000
Letters of credit outstanding 24,500,000  
Available borrowing capacity 390,500,000  
Senior secured credit facility
   
Future minimum repayments of long-term debt    
Total minimum payments 1,703,125,000 1,715,750,000
Long-term Debt    
Term loan amount outstanding 1,703,100,000  
Revolving credit facility
   
Long-term Debt    
Revolving credit facility amount outstanding 285,000,000  
Variable rate Term Loan A
   
Long-term Debt    
Term loan amount outstanding 673,700,000  
Variable rate Term Loan B
   
Long-term Debt    
Term loan amount outstanding $ 744,400,000