Equity Plan - Stock Option Activity (Details) - Options	9 Months Ended
	Sep. 30, 2017 USD ($) $ / shares shares
Number of Shares
Outstanding at the beginning of the period (in shares)	1,719,091
Granted (in shares)	270,000
Exercised (in shares)	(193,863)
Forfeited or expired (in shares)	(151,119)
Outstanding at the end of the period (in shares)	1,644,109
Vested or expected to vest (in shares)	1,545,462
Exercisable at the end of the period (in shares)	1,085,246
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 9.79
Granted (in dollars per share) | $ / shares	14.41
Exercised (in dollars per share) | $ / shares	6.98
Forfeited or expired (in dollars per share) | $ / shares	22.85
Outstanding at the end of the period (in dollars per share) | $ / shares	$ 9.69
Additional Information
Weighted Average Remaining Contractual Life - Outstanding at the end of the period (in years)	6 years 4 months 28 days
Weighted Average Remaining Contractual Life - Vested or expected to vest (in years)	6 years 4 months 28 days
Weighted Average Remaining Contractual Life - Exercisable at the end of the period (in years)	5 years 2 months 16 days
Aggregate Intrinsic Value - Outstanding at the end of the period (in dollars) | $	$ 6,972,963
Aggregate Intrinsic Value - Vested or expected to vest (in dollars) | $	6,554,585
Aggregate Intrinsic Value - Exercisable at the end of the period (in dollars) | $	$ 5,799,239