Net loss per share attributable to common stockholders (Tables)

12 Months Ended

Dec. 31, 2015

Net loss per share attributable to common stockholders

Schedule of computation of basic and diluted net loss per share attributable to common stockholders

	Years ended December 31,
	2015			2014			2013
	(in thousands)
Numerator:
Net loss attributable to common stockholders, basic and diluted	$	(22,292	)	$	(19,521	)	$	(3,968	)
Denominator:
Weighted average number of common stock, basic and diluted		36,849			35,753			35,578
Net loss per share attributable to common stockholders:
Basic and diluted	$	(0.60	)	$	(0.55	)	$	(0.11	)