Shareholders' Equity (Details) (USD $)
12 Months Ended 1 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Mar. 26, 2014
Feb. 18, 2016
May 30, 2014
Class of Stock [Line Items]            
Common stock, par value $ 2.50 $ 2.50        
Aggregate purchase price of preferred stock sold to treasury $ 12,000,000 $ 25,000,000        
Stock Issued During Period, Value, New Issues 12,510,000          
Number of shares of common stock that may be issued 15,000,000 15,000,000        
Common stock dividend, shares percentage   5.00%        
Common stock dividend payable date Dec. 09, 2014 Dec. 10, 2013        
Common stock dividend, shares 275,900 225,937 211,564      
Private Placement [Member]            
Class of Stock [Line Items]            
Shares issued through private placement 650,000          
Common stock, par value       $ 2.50    
Net proceeds from common stock private placement       12,500,000    
Gross amount of private placement       13,000,000    
Issuance costs       500,000    
Series B Preferred Stock [Member]            
Class of Stock [Line Items]            
Shares of Preferred Stock Sold to US Treasury 12,000 25,000        
Liquidation value $ 1,000 $ 1,000        
Par value of preferred stock $ 2.50 $ 2.50        
Annual dividend rate 1.00% 1.00% 1.54%      
Preferred Stock, Redemption Amount           $ 13,000,000
Scenario, Forecast [Member] | Series B Preferred Stock [Member]            
Class of Stock [Line Items]            
Preferred stock, dividend rate, percentage         9.00%  
Quarterly lending incentive fee         0.50%