Stock-Based Compensation - Outstanding Options and Exercisable Options Information by Range of Exercise Prices (Details)	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options outstanding, number of shares (in shares) | shares	2,718,971
Options outstanding, average remaining contractual life (years)	6 years 9 months 29 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 8.02
Options vested and exercisable, number of shares (in shares) | shares	2,126,781
Options vested and exercisable, weighted-average exercise price (in dollars per share)	$ 5.32
$0.84-$2.11
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share)	0.84
Exercise price, upper limit (in dollars per share)	$ 2.11
Options outstanding, number of shares (in shares) | shares	87,394
Options outstanding, average remaining contractual life (years)	1 year 6 months 7 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 1.56
Options vested and exercisable, number of shares (in shares) | shares	87,394
Options vested and exercisable, weighted-average exercise price (in dollars per share)	$ 1.52
$3.24-$3.98
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share)	3.24
Exercise price, upper limit (in dollars per share)	$ 3.98
Options outstanding, number of shares (in shares) | shares	564,938
Options outstanding, average remaining contractual life (years)	4 years 4 months 6 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 3.47
Options vested and exercisable, number of shares (in shares) | shares	564,938
Options vested and exercisable, weighted-average exercise price (in dollars per share)	$ 3.50
$4.32-$5.94
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share)	4.32
Exercise price, upper limit (in dollars per share)	$ 5.94
Options outstanding, number of shares (in shares) | shares	1,409,650
Options outstanding, average remaining contractual life (years)	7 years 1 month 9 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 4.63
Options vested and exercisable, number of shares (in shares) | shares	1,306,033
Options vested and exercisable, weighted-average exercise price (in dollars per share)	$ 4.61
$6.84-$7.92
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share)	6.84
Exercise price, upper limit (in dollars per share)	$ 7.92
Options outstanding, number of shares (in shares) | shares	39,844
Options outstanding, average remaining contractual life (years)	7 years 11 months 15 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 7.32
Options vested and exercisable, number of shares (in shares) | shares	20,298
Options vested and exercisable, weighted-average exercise price (in dollars per share)	$ 7.20
$17.72-$18.96
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share)	17.72
Exercise price, upper limit (in dollars per share)	$ 18.96
Options outstanding, number of shares (in shares) | shares	154,189
Options outstanding, average remaining contractual life (years)	9 years 4 months 13 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 17.85
Options vested and exercisable, number of shares (in shares) | shares	51,110
Options vested and exercisable, weighted-average exercise price (in dollars per share)	$ 17.82
$19.02-$22.00
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price, lower limit (in dollars per share)	19.02
Exercise price, upper limit (in dollars per share)	$ 22.00
Options outstanding, number of shares (in shares) | shares	462,956
Options outstanding, average remaining contractual life (years)	9 years 18 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 21.91
Options vested and exercisable, number of shares (in shares) | shares	97,008
Options vested and exercisable, weighted-average exercise price (in dollars per share)	$ 21.94