Net (loss) income per share attributable to common stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jul. 31, 2019
Numerator:
Net (loss) income attributable to common stockholders, basic and diluted	$ (5,840)	$ 216	$ (10,473)	$ (4,937)
Denominator:
Weighted average common stock, basic (in shares)	44,391,000	44,041,000	44,331,000	43,786,000
Weighted average common stock, diluted (in shares)	44,391,000	44,378,000	44,331,000	43,786,000
Net (loss) income per share attributable to common stockholders:
Basic (in dollars per share)	$ (0.13)	$ 0.00	$ (0.24)	$ (0.11)
Diluted (in dollars per share)	$ (0.13)	$ 0.00	$ (0.24)	$ (0.11)
Stock repurchase program
Remaining approved repurchase amount	$ 19,255		$ 19,255
RSUs
Net (loss) income per share attributable to common stockholders:
Shares of common stock excluded from the computation of diluted net income per share that were anti-dilutive		435,000
Stok options
Denominator:
Effect of dilutive	0	191,000	0	0
RSUs
Denominator:
Effect of dilutive	0	146,000	0	0
Maximum
Stock repurchase program
Stock repurchase amount					$ 20,000