- Attributable to common stockholders (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect
Common stock equivalents (in shares)	6,006	5,899
Stock options
Common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect
Common stock equivalents (in shares)	1,370	1,299
Warrants
Common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect
Common stock equivalents (in shares)	4,591	4,600
Restricted Stock Units (RSUs)
Common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect
Common stock equivalents (in shares)	45	0