Nature of Business and Plan of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Net loss			$ (127,044)	$ (82,894)
Accumulated deficit	$ (1,141,536)		(1,141,536)		$ (1,028,582)
Revenue	10,928	$ 8,480	40,030	75,999
Cash and cash equivalents	$ 303,205	$ 194,851	$ 303,205	$ 194,851	$ 267,107	$ 159,964
Number of months Capital resources meets capital expenditures			12 months
Product
Revenue			$ 0