Stock Repurchase Programs (Details) (USD $)
1 Months Ended 3 Months Ended 12 Months Ended 0 Months Ended
Dec. 31, 2012
Dec. 31, 2014
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Apr. 30, 2012
Dec. 18, 2013
Nov. 10, 2013
Equity, Class of Treasury Stock [Line Items]                
Shares repurchased 100,000 10,200,000            
Repurchase of common stock $ 600,000 $ 199,900,000 $ 0 $ 201,496,000 $ 602,000      
Share Price             $ 19.50  
2012 Repurchase Program                
Equity, Class of Treasury Stock [Line Items]                
Stock repurchase program, authorized amount           $ 75,000,000    
Stock repurchase program, period in force           12 months    
Tender Offer Repurchase Program 2013 [Member] [Domain]                
Equity, Class of Treasury Stock [Line Items]                
Stock Repurchase Program, Number of Shares Authorized to be Repurchased               10,250,000
Stock Options                
Equity, Class of Treasury Stock [Line Items]                
Shares repurchased   200,000