Summary of Significant Accounting Policies - Cash and Cash Equivalents and Foreign Currency (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Cash and Cash Equivalents and Restricted Cash [Abstract]      
Restricted cash $ 20,000   $ 33,860
Foreign Currency      
Foreign currency transaction gains (loss) $ 22,266 $ 6,438  
The 7 1/4% Notes      
Foreign Currency      
Stated interest rate (as a percent) 7.25%   7.25%
6 3/4% Notes      
Foreign Currency      
Stated interest rate (as a percent) 6.75%   6.75%