Stock-Based Compensation - Restricted Stock Units (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Weighted Average Exercise Price Per Share
Unrecognized stock-based compensation expense | $	$ 5,900
Unrecognized compensation expense, weighted-average period expected to be recognized	2 years 10 months 24 days
RSU
Number of Restricted Stock Units
Balance, beginning of period | shares	30,680
Granted | shares	60,450
Cancelled/forfeited | shares	(1,900)
Balance, end of period | shares	89,230
Weighted Average Exercise Price Per Share
Balance, beginning of period (price per share) | $ / shares	$ 10.55
Granted (price per share) | $ / shares	8.66
Cancelled/forfeited | $ / shares	8.39
Balance, end of period (price per share) | $ / shares	$ 9.32
2016 Employee Incentive Plan | RSU
Weighted Average Exercise Price Per Share
Unrecognized stock-based compensation expense | $	$ 625,000
Unrecognized compensation expense, weighted-average period expected to be recognized	2 years 10 months 24 days