Quarterly Results (unaudited)

12 Months Ended

Dec. 31, 2015

Quarterly Financial Information Disclosure [Abstract]

Quarterly Results (unaudited)

11. Quarterly Results (unaudited)

	Three Months Ended
	March 31,			June 30,			September 30,			December 31,
	2015			2015			2015			2015
	(in thousands, except per share data)
	(unaudited)
Operating expenses	$	10,896		$	10,889		$	19,678		$	20,050
Loss from operations	$	(10,896	)	$	(10,889	)	$	(19,678	)	$	(20,050	)
Other income (expense), net	$	201		$	200		$	203		$	193
Net loss	$	(10,695	)	$	(10,689	)	$	(19,475	)	$	(19,857	)
Net loss per share applicable to common    stockholders—basic and diluted	$	(0.53	)	$	(0.40	)	$	(0.68	)	$	(0.66	)
	Three Months Ended
	March 31,			June 30,			September 30,			December 31,
	2014			2014			2014			2014
	(in thousands, except per share data)
	(unaudited)
Operating expenses	$	9,909		$	7,840		$	9,584		$	10,607
Loss from operations	$	(9,909	)	$	(7,840	)	$	(9,584	)	$	(10,607	)
Other income (expense), net	$	212		$	222		$	236		$	237
Net loss	$	(9,697	)	$	(7,618	)	$	(9,348	)	$	(10,370	)
Net loss per share applicable to common    stockholders—basic and diluted	$	(43.37	)	$	(0.39	)	$	(0.47	)	$	(0.52	)