Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Total revenue	$ 3,570		$ 4,908	$ 90,000
Operating costs and expenses:
Cost of goods sold	137		181
Research and development	102,108	$ 75,052	277,565	193,302
Selling, general and administrative	88,502	53,693	260,648	125,709
Total operating costs and expenses	190,747	128,745	538,394	319,011
Loss from operations	(187,177)	(128,745)	(533,486)	(229,011)
Interest income, net	7,227	5,817	21,889	14,483
Other income (expense), net	(8)	10	12	34
Net loss	$ (179,958)	$ (122,918)	$ (511,585)	$ (214,494)
Net loss per share—basic and diluted	$ (3.48)	$ (2.63)	$ (10.13)	$ (4.68)
Weighted average number of common shares outstanding—basic and diluted	51,704,687	46,706,770	50,496,489	45,866,676
Comprehensive loss:
Net loss	$ (179,958)	$ (122,918)	$ (511,585)	$ (214,494)
Other comprehensive items:
Unrealized gain (loss) on marketable securities	202	(112)	2,292	(228)
Total other comprehensive gain (loss)	202	(112)	2,292	(228)
Total comprehensive loss	(179,756)	$ (123,030)	(509,293)	(214,722)
Product Revenue [Member]
Total revenue	1,478		1,997
Collaboration Revenue [Member]
Total revenue	$ 2,092		$ 2,911	$ 90,000