Nature of Business and Plan of Operations (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 26, 2019 employee	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Net loss			$ (87,197)	$ (80,237)
Accumulated deficit	$ (1,270,532)		(1,270,532)			$ (1,183,335)
Total revenues	15,542	$ 9,287	24,126	29,102
Cash and cash equivalents	$ 239,825	$ 345,058	$ 239,825	$ 345,058		$ 262,252	$ 267,107
Workforce reduction, number of positions | employee					220
Number of months Capital resources meets capital expenditures			12 months
Product
Total revenues			$ 0