v3.6.0.2
Shareholders' Equity (Details) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
Feb. 28, 2014
Dec. 31, 2013
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Class of Stock [Line Items]            
Treasury Shares     19,303,578 18,151,560    
Additional authorized shares purchased     9,123,721      
Common stock repurchased (in shares) 1,000,952 3,502,627        
Preferred stock, authorized (in shares)     1,000,000      
Preferred stock, issued (in shares)     0      
Stock repurchased during period   $ 125,000        
Percent of shares authorized for repurchase   80.00%        
Repurchased shares     $ 34,525   $ 0  
Share repurchases, effective average price per share (in dollars per share) $ 27.76          
Treasury Stock            
Class of Stock [Line Items]            
Repurchased shares   $ 100,000 34,525   25,000  
Share repurchases, price paid per share (in dollars per share)   $ 28.55        
Additional Paid-in Capital            
Class of Stock [Line Items]            
Repurchased shares     $ 0   $ (25,000) $ 25,000
Nonvoting Common Stock            
Class of Stock [Line Items]            
Common stock repurchased (in shares)     1,372,700 0 1,000,952