Nature of Business and Plan of Operations (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Nature of Business and Plan of Operations
Net loss	$ (78,883)	$ (96,012)	$ (144,817)	$ (60,739)
Accumulated deficit	(932,570)	(1,028,582)
Product revenue		0
Cash and cash equivalents	$ 159,964	$ 267,107	$ 245,026	$ 278,109	$ 142,261