Net Loss Per Share - Computation of basic and diluted net loss per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net loss	$ (7,283)	$ (8,418)	$ (11,242)	$ (10,669)	$ (15,701)	$ (21,911)
Net loss from continuing operations	(7,115)		(11,374)		(15,533)	(21,764)
(Loss) income from discontinued operations, net of taxes	$ (168)		$ 132		$ (168)	$ (147)
Weighted average common shares outstanding, basic (in shares)	98,810		107,535		98,696	107,279
Weighted average common shares outstanding, diluted (in shares)	98,810		107,535		98,696	107,279
Continuing operations, basic (in dollars per share)	$ (0.07)		$ (0.11)		$ (0.16)	$ (0.20)
Continuing operations, diluted (in dollars per share)	(0.07)		(0.11)		(0.16)	(0.20)
Discontinuing operations, basic (in dollars per share)	0.00		0.00		(0.00)	0.00
Discontinuing operations, diluted (in dollars per share)	$ 0.00		$ 0.00		$ (0.00)	$ 0.00