Net Loss Per Common Share - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net loss	$ 9,501	$ 3,470	$ (19,792)	$ (2,844)	$ 5,242	$ (1,069)	$ (4,651)	$ (7,659)	$ (9,665)	$ (8,137)	$ (17,286)
Denominator for basic and diluted EPS:
Weighted-average common shares outstanding (in shares)									44,180	40,242	33,355
Net loss per share attributable to common shareholders (Basic and Diluted) (in dollars per share)									$ (0.22)	$ (0.20)	$ (0.52)
Service-based stock options
Denominator for basic and diluted EPS:
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)									5,100	4,800	4,600
Restricted Stock Units (RSUs)
Denominator for basic and diluted EPS:
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)									200	0	0
Warrants
Denominator for basic and diluted EPS:
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)									0	0	900