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Stock-Based Compensation (Restricted Stock Activity) (Details) - $ / shares
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Shares, Nonvested, beginning of period 14,901    
Shares, Nonvested, end of period 14,401 14,901  
Restricted Stock [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Shares, Nonvested, beginning of period 14,901 14,401 15,151
Shares, Granted 14,650 14,650 14,650
Shares, Vested (14,493) (13,196) (14,363)
Shares, Forfeited (657) (954) (1,037)
Shares, Nonvested, end of period 14,401 14,901 14,401
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]      
Weighted Average Grant Date Fair Value, Nonvested, beginning of period (in USD per share) $ 23.05 $ 22.98 $ 22.27
Weighted Average Grant Date Fair Value, Granted (in USD per share) 27.46 23.07 23.85
Weighted Average Grant Date Fair Value, Vested (in USD per share) 25.90 23.00 23.09
Weighted Average Grant Date Fair Value, Forfeited (in USD per share) 23.00 23.00 23.50
Weighted Average Grant Date Fair Value, Nonvested, end of period (in USD per share) $ 24.68 $ 23.05 $ 22.98