Stockholders' Equity - Stock Options and a Summary of Activity (Details) - $ / shares	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Stockholders' Equity Note [Abstract]
Fair value of options issued	$ 4.11	$ 3.34
Exercise price	$ 5.54	$ 4.34
Expected life of option (in years)	5 years 9 months 18 days	5 years 7 months 6 days
Risk-free interest rate	1.70%	1.80%
Expected volatility	88.30%	98.10%
Dividend yield	0.00%	0.00%
Number of Option
Outstanding at beginning of period (in options)	459,271
Granted (in options)	223,500
Exercised (in options)	(10,393)
Canceled/forfeited (in options)	(78,008)
Expired (in options)	(5,900)
Outstanding at end of period (in options)	588,470
Vested and expected to vest at period end (in options)	531,671
Exercisable at period end (in options)	303,011
Weighted Average Exercise Price Per Share
Outstanding at beginning of period (in dollars per share)	$ 8.95
Granted (in dollars per share)	5.54
Exercised (in dollars per share)	3.71
Canceled/forfeited (in dollars per share)	6.02
Expired (in dollars per share)	96.00
Outstanding at end of period (in dollars per share)	7.26
Vested and expected to vest at period end (in dollars per share)	7.45
Exercisable at period end (in dollars per share)	$ 9.00
Weighted Average Remaining Contractual Life (in years)
Outstanding at end of period	8 years 3 months 18 days
Vested and expected to vest at period end	8 years 2 months 12 days
Exercisable at period end	7 years 4 months 24 days