Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Summary of Quarterly Financial Information

The following table presents selected unaudited quarterly financial information for the years ended December 31, 2016 and 2015. The results for any quarter are not necessarily indicative of future quarterly results and, accordingly, period to period comparisons should not be relied upon as an indication of future performance.

	FOR THE QUARTER ENDED
(in thousands, except per share amounts)	DECEMBER 31,			SEPTEMBER 30,			JUNE 30,			MARCH 31,
Year Ended December 31, 2016
Operating expenses	$	(28,757	)	$	(23,315	)	$	(22,690	)	$	(22,110	)
Net loss attributable to common stockholders	$	(29,322	)	$	(23,814	)	$	(23,219	)	$	(22,704	)
Net loss per share attributable to common stockholders—basic and diluted	$	(0.87	)	$	(0.81	)	$	(0.87	)	$	(0.85	)
	DECEMBER 31,			SEPTEMBER 30,			JUNE 30,			MARCH 31,
Year Ended December 31, 2015
Operating expenses	$	(19,950	)	$	(17,366	)	$	(18,129	)	$	(19,641	)
Net loss attributable to common stockholders	$	(20,377	)	$	(17,961	)	$	(18,786	)	$	(17,239	)
Net loss per share attributable to common stockholders—basic and diluted	$	(0.76	)	$	(0.69	)	$	(0.73	)	$	(0.70	)