Nature of Business and Plan of Operations (Details) - USD ($) $ in Thousands		3 Months Ended												12 Months Ended
	Jan. 27, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net loss														$ (104,133)	$ (168,843)	$ (96,012)
Accumulated deficit		$ (1,287,468)				$ (1,183,335)								(1,287,468)	(1,183,335)
Total revenues		44,864	$ 13,281	$ 15,542	$ 8,584	13,416	$ 10,928	$ 9,287	$ 19,815	$ 39,448	$ 8,480	$ 39,020	$ 28,499	82,271	53,446	115,447
Cash and cash equivalents		$ 176,225				$ 262,252				$ 267,107				$ 176,225	262,252	267,107	$ 159,964
Net proceeds generated from public offering															$ 162,512	$ 101,663
Number of months Capital resources meets capital expenditures														12 months
Product
Total revenues														$ 0
Subsequent event
Net proceeds generated from public offering	$ 97,700