Net Income (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net income (loss)	$ (4,931)	$ (3,786)	$ (3,289)	$ 3,618	$ (8,269)	$ (4,705)	$ (12,006)	$ (9,356)
Weighted average common shares outstanding (Basic) (in shares)	46,669			45,272			46,355	45,112
Weighted average common shares outstanding (Diluted) (in shares)	46,669			47,314			46,355	45,112
Net income (loss) per common share (Basic) (in USD per share)	$ (0.11)			$ 0.08			$ (0.26)	$ (0.21)
Net income (loss) per common share (Diluted) (in USD per share)	$ (0.11)			$ 0.08			$ (0.26)	$ (0.21)
Stock options
Anti-dilutive shares excluded from the calculation of diluted earnings per share(a):
Aggregate number of common equivalent shares (related to options, warrants and preferred stock) that have been excluded from computations of diluted net loss per common share (in shares)	5,852			2,390			5,852	5,692
Restricted stock units
Anti-dilutive shares excluded from the calculation of diluted earnings per share(a):
Aggregate number of common equivalent shares (related to options, warrants and preferred stock) that have been excluded from computations of diluted net loss per common share (in shares)	412			0			412	273