Stockholder's Equity - Stock Option Activity (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Number of Stock Options
Exercised (in shares)	(2,070,964)	(4,693,918)
2012 Omnibus Incentive Plan
Number of Stock Options
Outstanding (in shares)	2,822,855
Options granted (in shares)	1,140,351
Exercised (in shares)	(90,332)
Forfeited or expired (in shares)	(47,466)
Outstanding (in shares)	3,825,408	2,822,855
Exercisable (in shares)	2,094,706
Weighted-Average Exercise Price
Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 2.42
Granted, Weighted-Average Exercise Price (in dollars per share)	4.93
Exercised, Weighted-Average Exercise Price (in dollars per share)	2.11
Forfeited or expired, Weighted-Average Exercise Price (in dollars per share)	3.53
Outstanding, Weighted-Average Exercise Price (in dollars per share)	3.16	$ 2.42
Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 2.34
Outstanding, Weighted-Average Remaining Contractual Life	7 years 10 months 24 days
Exercisable, Weighted-Average Remaining Contractual Life	7 years 2 months 12 days
Outstanding, Aggregate Intrinsic Value	$ 3,329,666
Exercisable, Aggregate Intrinsic Value	$ 2,749,687
2006 Stock Plan
Number of Stock Options
Outstanding (in shares)	3,041,686
Options granted (in shares)	0
Exercised (in shares)	(1,664,176)
Forfeited or expired (in shares)	(183,428)
Outstanding (in shares)	1,194,082	3,041,686
Exercisable (in shares)	1,149,902
Weighted-Average Exercise Price
Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 2.62
Granted, Weighted-Average Exercise Price (in dollars per share)	0.00
Exercised, Weighted-Average Exercise Price (in dollars per share)	1.31
Forfeited or expired, Weighted-Average Exercise Price (in dollars per share)	4.94
Outstanding, Weighted-Average Exercise Price (in dollars per share)	4.08	$ 2.62
Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 4.09
Outstanding, Weighted-Average Remaining Contractual Life	4 years
Exercisable, Weighted-Average Remaining Contractual Life	4 years 1 month 6 days
Outstanding, Aggregate Intrinsic Value	$ 54,747
Exercisable, Aggregate Intrinsic Value	$ 54,747
The 2016 Inducement Omnibus Incentive Plan
Number of Stock Options
Outstanding (in shares)	310,000
Options granted (in shares)	575,000
Exercised (in shares)	0
Forfeited or expired (in shares)	(67,500)
Outstanding (in shares)	817,500	310,000
Exercisable (in shares)	0
Weighted-Average Exercise Price
Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 6.02
Granted, Weighted-Average Exercise Price (in dollars per share)	4.95
Exercised, Weighted-Average Exercise Price (in dollars per share)	0.00
Forfeited or expired, Weighted-Average Exercise Price (in dollars per share)	5.92
Outstanding, Weighted-Average Exercise Price (in dollars per share)	5.27	$ 6.02
Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 0.00
Outstanding, Weighted-Average Remaining Contractual Life	9 years 3 months 18 days
Outstanding, Aggregate Intrinsic Value	$ 0
Non-Plan Option Activity
Number of Stock Options
Outstanding (in shares)	316,456
Options granted (in shares)	0
Exercised (in shares)	(316,456)
Forfeited or expired (in shares)	0
Outstanding (in shares)	0	316,456
Weighted-Average Exercise Price
Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 1.34
Granted, Weighted-Average Exercise Price (in dollars per share)	0.00
Exercised, Weighted-Average Exercise Price (in dollars per share)	1.34
Forfeited or expired, Weighted-Average Exercise Price (in dollars per share)	0.00
Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 0.00	$ 1.34