Stock-based Compensation (Schedule of Option Activity) (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2018 USD ($) $ / shares shares
Stock-based Compensation [Abstract]
Number of Shares, Outstanding at December 31, 2017 | shares		4,768,838
Number of Shares, Options granted | shares		318,600
Number of Shares, Options exercised | shares	0	(49,937)
Number of Shares, Options forfeited | shares
Number of Shares, Options cancelled or expired | shares		(220,131)
Number of Shares, Outstanding at June 30, 2018 | shares	4,817,370	4,817,370
Number of Shares, Vested or expected to vest at June 30, 2018 | shares	4,804,494	4,804,494
Number of Shares, Exercisable at June 30, 2018 | shares	4,173,641	4,173,641
Weighted Average Exercise Price, Outstanding at December 31, 2017 | $ / shares		$ 3.02
Weighted Average Exercise Price, Options granted | $ / shares		1.62
Weighted Average Exercise Price, Options exercised | $ / shares		1.26
Weighted Average Exercise Price, Options forfeited | $ / shares
Weighted Average Exercise Price, Options cancelled or expired | $ / shares		4.47
Weighted Average Exercise Price, Outstanding at June 30, 2018 | $ / shares	$ 2.88	2.88
Weighted Average Exercise Price, Vested or expected to vest at June 30, 2018 | $ / shares	2.86	2.86
Weighted Average Exercise Price, Exercisable at June 30, 2018 | $ / shares	$ 3.87	$ 3.87
Weighted Average Remaining Contractual Life (In Years), Outstanding at June 30, 2018		4 years 22 days
Weighted Average Remaining Contractual Life (In Years), Vested or expected to vest at June 30, 2018		4 years 22 days
Weighted Average Remaining Contractual Life (In Years), Exercisable at June 30, 2018		3 years 10 months 13 days
Aggregate Intrinsic Value, Outstanding at June 30, 2018 | $	$ 399,766	$ 399,766
Aggregate Intrinsic Value, Vested or expected to vest at June 30, 2018 | $	399,480	399,480
Aggregate Intrinsic Value, Exercisable at June 30, 2018 | $	$ 385,433	$ 385,433