Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating expenses
Research and development	$ 42,673	$ 20,664	$ 93,295	$ 55,253
General and administrative	7,073	6,752	22,301	18,575
Total operating expenses	49,746	27,416	115,596	73,828
Loss from operations	(49,746)	(27,416)	(115,596)	(73,828)
Interest income	220	120	661	354
Other income (expense), net	(262)	(39)	(1,044)	(210)
Net loss before provision for income taxes	(49,788)	(27,335)	(115,979)	(73,684)
Provision for income taxes			128
Net Loss	$ (49,788)	$ (27,335)	$ (116,107)	$ (73,684)
Net loss per share - basic and diluted	$ (1.40)	$ (0.92)	$ (3.29)	$ (2.50)
Weighted-average common shares used to compute basic and diluted net loss per share	35,680	29,574	35,336	29,495