Net income (loss) per share - Computation of Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net income (loss)	$ 6,307	$ (14,091)
Weighted average shares used to compute per share amount:
Basic (in shares)	48,615	46,414
Diluted (in shares)	50,617	46,414
Basic net income (loss) per share (in dollars per share)	$ 0.13	$ (0.30)
Diluted net income (loss) per share (in dollars per share)	$ 0.12	$ (0.30)