Stock-Based Compensation - Restricted Stock Units (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Weighted Average Exercise Price Per Share
Unrecognized stock-based compensation expense | $	$ 6,200
Unrecognized compensation expense, weighted-average period expected to be recognized	3 years 3 months 18 days
RSU
Number of Restricted Stock Units
Balance, beginning of period | shares	30,680
Granted | shares	36,350
Cancelled/forfeited | shares	(400)
Balance, end of period | shares	66,630
Weighted Average Exercise Price Per Share
Balance, beginning of period (price per share) | $ / shares	$ 10.55
Granted (price per share) | $ / shares	9.12
Cancelled/forfeited | $ / shares	7.80
Balance, end of period (price per share) | $ / shares	$ 9.79
2016 Employee Incentive Plan | RSU
Weighted Average Exercise Price Per Share
Unrecognized stock-based compensation expense | $	$ 535,000
Unrecognized compensation expense, weighted-average period expected to be recognized	3 years 4 months 24 days