Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

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, 2017 and 2016. 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,
2017
Operating expenses	$	60,314		$	32,182		$	27,768		$	25,429
Net loss	$	(58,513	)	$	(32,372	)	$	(28,433	)	$	(25,787	)
Net loss per common share—basic and diluted	$	(1.60	)	$	(0.89	)	$	(0.82	)	$	(0.76	)
	DECEMBER 31,			SEPTEMBER 30,			JUNE 30,			MARCH 31,
2016
Operating expenses	$	28,757		$	23,315		$	22,690		$	22,110
Net loss	$	(29,322	)	$	(23,814	)	$	(23,219	)	$	(22,704	)
Net loss per common share—basic and diluted	$	(0.87	)	$	(0.81	)	$	(0.87	)	$	(0.85	)