Stock-Based Compensation - Stock Options (Details) - Stock options - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Shares Underlying Options
Outstanding at the beginning of the period (in shares)	6,906,001
Forfeited (in shares)	(100,000)
Outstanding at the end of the period (in shares)	6,806,001	6,906,001
Exercisable at June 30, 2018	6,578,161
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 7.92
Forfeited (in dollars per share)	6.93
Outstanding at the end of the period (in dollars per share)	7.93	$ 7.92
Exercise price (in dollars per share)	$ 7.93
Weighted Average Remaining Contractual Term
Begining Balance	4 years 7 months 6 days	5 years
Exercisable at June 30, 2018	4 years 6 months
Aggregate intrinsic Value
Outstanding (in dollars)	$ 629,680
Intrinsic Value (in dollars)	$ 629,680