Equity Plan - Stock Option Activity (Details) - Options	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Number of Shares
Outstanding at the beginning of the period (in shares)	1,602,732
Granted (in shares)	305,500
Exercised (in shares)	(207,838)
Forfeited or expired (in shares)	(36,969)
Outstanding at the end of the period (in shares)	1,663,425
Vested or expected to vest (in shares)	1,563,620
Exercisable at the end of the period (in shares)	998,257
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 9.54
Granted (in dollars per share) | $ / shares	16.82
Exercised (in dollars per share) | $ / shares	9.63
Forfeited or expired (in dollars per share) | $ / shares	15.41
Outstanding at the end of the period (in dollars per share) | $ / shares	$ 10.73
Additional Information
Weighted Average Remaining Contractual Life - Outstanding at the end of the period (in years)	6 years 11 months 5 days
Weighted Average Remaining Contractual Life - Vested or expected to vest (in years)	6 years 11 months 5 days
Weighted Average Remaining Contractual Life - Exercisable at the end of the period (in years)	5 years 7 months 2 days
Aggregate Intrinsic Value - Outstanding at the end of the period (in dollars) | $	$ 10,414,939
Aggregate Intrinsic Value - Vested or expected to vest (in dollars) | $	9,790,043
Aggregate Intrinsic Value - Exercisable at the end of the period (in dollars) | $	$ 8,644,366