Stock Options - Composition of Options Outstanding and Exercisable (Details) shares in Thousands	9 Months Ended
	Sep. 30, 2020 $ / shares shares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding, Number | shares	2,670
Option Outstanding, Price	$ 2.05
Options Outstanding, Life (years)	7 years 8 months 12 days
Options Exercisable, Number | shares	1,267
Options Exercisable, Price	$ 2.79
$0.42 - $0.83
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Range Limit	0.42
Exercise Prices, Upper Range Limit	$ 0.83
Options Outstanding, Number | shares	1,922
Option Outstanding, Price	$ 0.65
Options Outstanding, Life (years)	7 years 10 months 24 days
Options Exercisable, Number | shares	711
Options Exercisable, Price	$ 0.65
$2.61 - $3.74
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Range Limit	2.61
Exercise Prices, Upper Range Limit	$ 3.74
Options Outstanding, Number | shares	157
Option Outstanding, Price	$ 3.15
Options Outstanding, Life (years)	2 years 8 months 12 days
Options Exercisable, Number | shares	136
Options Exercisable, Price	$ 3.38
$4.39 - $4.45
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices, Lower Range Limit	4.39
Exercise Prices, Upper Range Limit	$ 4.45
Options Outstanding, Number | shares	113
Option Outstanding, Price	$ 4.39
Options Outstanding, Life (years)	4 years
Options Exercisable, Number | shares	113
Options Exercisable, Price	$ 4.39
$6.83
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices	$ 6.83
Options Outstanding, Number | shares	478
Option Outstanding, Price	$ 6.83
Options Outstanding, Life (years)	9 years 2 months 12 days
Options Exercisable, Number | shares	307
Options Exercisable, Price	$ 6.83