Net income (loss) per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator:
Net income (loss)	$ 1,378	$ (1,937)	$ 3,269	$ (21,304)
Denominator:
Basic	40,367	32,383	36,303	31,930
Dilutive effect of equity awards	1,850		1,234
Diluted	42,217	32,383	37,537	31,930
Basic net income (loss) per share	$ 0.03	$ (0.06)	$ 0.09	$ (0.67)
Diluted net income (loss) per share	$ 0.03	$ (0.06)	$ 0.09	$ (0.67)