Stock-Based Compensation (Summary of Stock Option Activity) (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Stock-Based Compensation [Abstract]
Shares, Balance at December 31, 2017	1,115,865
Shares, Granted	36,500
Shares, Forfeited	(1,450)
Shares, Balance at June 30, 2018	1,150,915	1,115,865
Shares, Vested or expected to vest at June 30, 2018	865,802
Shares, Exercisable at June 30, 2018	174,578
Weighted Average Exercise Price, Outstanding at December 31, 2017	$ 3.17
Weighted Average Exercise Price, Granted	1.20
Weighted Average Exercise Price, Forfeited	17.46
Weighted Average Exercise Price, Outstanding at June 30, 2018	3.09	$ 3.17
Weighted Average Exercise Price, Vested or expected to vest at June 30, 2018	3.80
Weighted Average Exercise Price, Exercisable at June 30, 2018	$ 11.43
Average Remaining Contractual Term (Years), Outstanding at December 31, 2017		8 years 11 months 23 days
Average Remaining Contractual Term (Years), Outstanding at June 30, 2018	8 years 6 months 11 days
Average Remaining Contractual Term (Years), Vested or expected to vest at June 30, 2018	8 years 3 months 15 days
Average Remaining Contractual Term (Years), Exercisable at June 30, 2018	4 years 8 months 1 day
Intrinsic Value, Outstanding at June 30, 2018	$ 234,000
Intrinsic Value, Vested or expected to vest at June 30, 2018	172,000
Intrinsic Value, Exercisable at June 30, 2018	$ 29,000