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Shareholders' Equity (Initial Public Offering, Preferred Stock and Common Stock, Narrative) (Details)
 1 Months Ended 12 Months Ended
Aug. 10, 2009
USD ($)
$ / shares
shares
Jan. 31, 2018
USD ($)
Dec. 31, 2018
USD ($)
shares
Dec. 31, 2017
USD ($)
shares
Dec. 31, 2016
USD ($)
shares
Initial Public Offering [Abstract]          
Initial public offering, issuance costs     $ 383,310 $ 27,950 $ 0
Preferred Stock [Abstract]          
Preferred stock, shares authorized | shares     20,000,000    
Common Stock [Abstract]          
Shelf Registration, sale of corporate securities (up to)   $ 100,000,000      
Common stock          
Initial Public Offering [Abstract]          
Initial public offering, effective date Aug. 10, 2009        
Initial public offering, shares issued | shares 5,000,000        
Initial public offering, price per share | $ / shares $ 17.00        
Initial public offering, gross proceeds $ 85,000,000.0        
Initial public offering, underwriting discounts 6,000,000.0        
Initial public offering, issuance costs 4,200,000        
Initial public offering, net proceeds $ 74,800,000        
Initial public offering, number of shares common stock received in exchange for preferred stock 2,000,000        
Common stock          
Initial Public Offering [Abstract]          
Initial public offering, shares issued | shares     30,704    
Common Stock [Abstract]          
Share-based compensation, shares | shares     170,759 146,275 223,987
Exercise of options and related tax benefit, shares | shares         3,409