Equity Plan - Stock Option Activity (Details) - Options	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Number of Shares
Outstanding at the beginning of the period (in shares)	1,602,732
Granted (in shares)	330,500
Exercised (in shares)	(276,844)
Forfeited or expired (in shares)	(85,785)
Outstanding at the end of the period (in shares)	1,570,603
Vested or expected to vest (in shares)	1,476,367
Exercisable at the end of the period (in shares)	1,058,010
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 9.54
Granted (in dollars per share) | $ / shares	16.66
Exercised (in dollars per share) | $ / shares	9.63
Forfeited or expired (in dollars per share) | $ / shares	14.22
Outstanding at the end of the period (in dollars per share) | $ / shares	$ 10.76
Additional Information
Weighted Average Remaining Contractual Life - Outstanding at the end of the period (in years)	6 years 5 months 9 days
Weighted Average Remaining Contractual Life - Vested or expected to vest (in years)	6 years 5 months 9 days
Weighted Average Remaining Contractual Life - Exercisable at the end of the period (in years)	5 years 4 months 6 days
Aggregate Intrinsic Value - Outstanding at the end of the period (in dollars) | $	$ 3,311,870
Aggregate Intrinsic Value - Vested or expected to vest (in dollars) | $	3,113,157
Aggregate Intrinsic Value - Exercisable at the end of the period (in dollars) | $	$ 3,203,117