Stock-Based Compensation (Summary of Stock Option Activity) (Details) - Stock Options [Member]	3 Months Ended
	Mar. 31, 2017 USD ($) $ / shares shares
Number of Shares
Outstanding | shares	4,512,550
Granted | shares	27,900
Exercised | shares	0
Forfeited | shares	(15,543)
Expired | shares	(2,234)
Outstanding | shares	4,522,673
Vested (exercisable) | shares	2,208,494
Expected to vest after (unexercisable) | shares	2,314,179
Weighted-Average Exercise Price/Share
Outstanding | $ / shares	$ 4.01
Granted | $ / shares	3.18
Exercised | $ / shares	0
Forfeited | $ / shares	1.93
Expired | $ / shares	11.05
Outstanding | $ / shares	4
Vested (exercisable) | $ / shares	4.21
Expected to vest after (unexercisable) | $ / shares	$ 3.81
Weighted-Average Remaining Contractual Term (Years)
Outstanding	7 years 10 months 24 days
Vested (exercisable)	7 years 3 months 18 days
Expected to vest after (unexercisable)	2 years 3 months 18 days
Aggregated Intrinsic Value
Outstanding | $	$ 531,800	[1]
Vested (exercisable) | $	122,300	[1]
Expected to vest after (unexercisable) | $	$ 409,500	[1]

[1] Aggregate intrinsic value represents the difference between the exercise price of the option and the closing market price of our common stock on March 31, 2017, which was $2.36 per share.