Stock-Based Compensation (Summary of Stock Option Activity) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Incentive Plan Compensation [Abstract]
Shares, Beginning Balance	74,890	66,964
Shares, Granted	1,070,572	26,419
Shares, Forfeited	(29,597)	(18,493)
Shares, Ending Balance	1,115,865	74,890	66,964
Shares, Vested or expected to vest at December 31, 2017	830,752
Shares, Exercisable at December 30, 2017	136,142
Weighted Average Exercise Price, Outstanding, Beginning Balance	$ 64.50	$ 86.52
Weighted Average Exercise Price, Granted	1.22	26.48
Weighted Average Exercise Price, Forfeited	87.87	89.95
Weighted Average Exercise Price, Outstanding, Ending Balance	3.17	$ 64.50	$ 86.52
Weighted Average Exercise Price, Vested or expected to vest at December 31, 2017	3.94
Weighted Average Exercise Price, Exercisable at December 31, 2017	$ 13.18
Average Remaining Contractual Term (Years), Outstanding	8 years 11 months 23 days	8 years 7 months 24 days	9 years 3 months 15 days
Average Remaining Contractual Term (Years), Vested or expected to vest at December 31, 2017	8 years 8 months 16 days
Average Remaining Contractual Term (Years), Exercisable at December 31, 2017	4 years 7 days
Aggregate Intrinsic Value, Outstanding	$ 118,000
Intrinsic Value, Vested or expected to vest at December 31, 2017	90,000
Intrinsic Value, Exercisable at December 31, 2017	$ 14,000