Nature of Business and Plan of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Net loss			$ (53,386)	$ (87,197)
Accumulated deficit	$ (1,340,854)		(1,340,854)		$ (1,287,468)
Total revenues	15,025	$ 15,542	28,312	24,126
Cash and cash equivalents	$ 219,506	$ 239,825	219,506	$ 239,825	$ 176,225	$ 262,252
Net proceeds generated from public offering			$ 97,743
Number of months Capital resources meets capital expenditures			12 months
Product
Total revenues			$ 0