v2.3.0.11
Debt (Details) (USD $)
 6 Months Ended
Jun. 30, 2011
years
Apr. 05, 2011
Debt    
Credit facility maximum borrowing capacity $ 300,000,000  
Credit facility agreement expiration date September 30, 2012  
Repayment of credit facility borrowings 300,000,000  
Credit facility outstanding balance 0  
Credit facility remaining borrowing capacity 300,000,000  
Term loan payable $ 300,000,000 $ 300,000,000
Term of loan 5  
Repayment terms The term loan is payable in quarterly installments, commencing on June 30, 2012, (with 1.25% of the initial principal amount due on each of the first eight payment dates; 2.50% of the initial principal amount due on each of the next four payment dates; and 5.0% of the initial principal amount due on each of the next three payment dates) with all remaining principal due on April 5, 2016.  
Interest rate on term loan 1.56%