Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Schedule of Changes in Number of Outstanding Stock Options Under Director Plan, Stock Plan and 2011 Incentive Plan) (Details)

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Stock-Based Compensation (Schedule of Changes in Number of Outstanding Stock Options Under Director Plan, Stock Plan and 2011 Incentive Plan) (Details) - $ / shares
3 Months Ended 12 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Stock-Based Compensation [Abstract]    
Options, Outstanding - December 31, 2017 1,172,659  
Options, Awarded 178,665  
Options, Exercised  
Options, Forfeited (19,052)  
Options, Outstanding - March 31, 2018 1,332,272 1,172,659
Options, Exercisable at March 31, 2018 783,430  
Options, Expected to vest March 31, 2018 1,332,272  
Weighted average exercise price per share, Outstanding - December 31, 2017 $ 8.63  
Weighted average exercise price per share, Awarded 3.61  
Weighted average exercise price per share, Exercised  
Weighted average exercise price per share, Forfeited 13.07  
Weighted average exercise price per share, Outstanding - March 31, 2018 7.90 $ 8.63
Weighted average exercise price per share, Exercisable at March 31, 2018 9.88  
Weighted average exercise price per share, Expected to vest March 31, 2018 $ 7.90  
Options, Outstanding - Weighted average remaining contractual term (in years) 4 years 8 months 16 days 4 years 6 months 18 days
Options, Exercisable - Weighted average remaining contractual term (in years) 3 years 9 months 22 days  
Options, Expected to vest - Weighted average remaining contractual term (in years) 4 years 8 months 16 days