Stockholders' Equity - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) $ / shares shares
Number of Stock Options
Outstanding (in shares) | shares	3,680,146
Exercised (in shares) | shares	(162,841)
Forfeited or expired (in shares) | shares	(85,000)
Outstanding (in shares) | shares	3,432,305
Exercisable (in shares) | shares	3,333,817
Weighted- average Exercise Price
Outstanding (in dollars per share) | $ / shares	$ 3.60
Exercised (in dollars per share) | $ / shares	3.47
Forfeited or expired (in dollars per share) | $ / shares	3.65
Outstanding (in dollars per share) | $ / shares	3.61
Exercisable, Weighted-Average Exercise Price (in dollars per share) | $ / shares	$ 3.60
Outstanding, Weighted-Average Remaining Contractual Life	4 years 9 months 18 days
Exercisable, Weighted-Average Remaining Contractual Life	4 years 8 months 12 days
Outstanding, Aggregate Intrinsic Value | $	$ 7,791
Exercisable, Aggregate Intrinsic Value | $	$ 7,607