v2.4.0.8
Stockholders' Equity (Details) (USD $)
 3 Months Ended 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Class of Stock [Line Items]        
Allocated Share-based Compensation Expense $ 2,810,000 $ 2,361,000 $ 8,423,000 $ 6,781,000
Treasury Stock, Shares, Acquired 505,137 393,031   898,168
Treasury Stock Acquired, Average Cost Per Share $ 13.98 $ 13.49 $ 15.37 $ 13.76
Shares Repurchased to date     5,853,975  
2008 Repurchase Program [Member]
        
Class of Stock [Line Items]        
Stock Repurchase Program, Authorized Amount     90,000,000  
2012 Repurchase Program [Member]
        
Class of Stock [Line Items]        
Stock Repurchase Program, Authorized Amount     50,000,000  
Performance Shares [Member]
        
Class of Stock [Line Items]        
Allocated Share-based Compensation Expense $ 400,000 $ 200,000 $ 1,200,000 $ 800,000