Net loss per share attributable to common stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jul. 31, 2019
Numerator:
Net loss attributable to common stockholders, basic and diluted	$ (4,633)	$ (5,153)
Denominator:
Weighted average common stock, basic and diluted (in shares)	44,272	43,527
Net loss per share attributable to common stockholders:
Basic and diluted (in dollars per share)	$ (0.10)	$ (0.12)
Stock repurchase program
Remaining approved repurchase amount	$ 19,255
Maximum
Stock repurchase program
Stock repurchase amount			$ 20,000