Stock-Based Compensation (Summary of Stock Option Activity) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Stock-Based Compensation [Abstract]
Shares, Balance at December 31, 2017	1,115,865
Shares, Granted	1,500
Shares, Forfeited	(1,322)
Shares, Balance at March 31, 2018	1,116,043	1,115,865
Shares, Vested or expected to vest at March 31, 2018	830,930
Shares, Exercisable at March 31, 2018	146,162
Weighted Average Exercise Price, Outstanding at December 31, 2017	$ 3.17
Weighted Average Exercise Price, Granted	1.23
Weighted Average Exercise Price, Forfeited	17.42
Weighted Average Exercise Price, Outstanding at March 31, 2018	3.15	$ 3.17
Weighted Average Exercise Price, Vested or expected to vest at March 31, 2018	3.92
Weighted Average Exercise Price, Exercisable at March 31, 2018	$ 12.94
Average Remaining Contractual Term (Years), Outstanding at December 31, 2017		8 years 11 months 23 days
Average Remaining Contractual Term (Years), Outstanding at March 31, 2018	8 years 8 months 27 days
Average Remaining Contractual Term (Years), Vested or expected to vest at March 31, 2018	8 years 5 months 19 days
Average Remaining Contractual Term (Years), Exercisable at March 31, 2018	4 years 1 month 10 days
Intrinsic Value, Outstanding at March 31, 2018	$ 196,000
Intrinsic Value, Vested or expected to vest at March 31, 2018	144,000
Intrinsic Value, Exercisable at March 31, 2018	$ 18,000