Stock-Based Compensation - Restricted Stock Activity (Details) - Restricted Stock Units - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Number of Shares
Non-vested, beginning balance (in shares)	185,260	408,710
Shares granted (in shares)	576,212	200,000
Shares vested (in shares)	322,760	395,117
Shares forfeited (in shares)	0	28,333
Non-vested, ending balance (in shares)	438,712	185,260
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, beginning balance (in dollars per share)	$ 2.67	$ 2.66
Shares granted (in dollars per share)	1.95	1.20
Shares vested (in dollars per share)	1.92	1.99
Shares forfeited (in dollars per share)	0.00	1.74
Weighted average grant date fair value, ending balance (in dollars per share)	$ 2.28	$ 2.67