Summary of Significant Accounting Policies - Property (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Property and Equipment
Estimated useful life			P3Y
Gain (loss) from operations	$ (22,515)	$ (15,472)	$ (32,120)	$ (21,749)
Net loss	$ (23,156)	$ (19,681)	$ (31,841)	$ (29,685)
Decrease in net basic and diluted loss per share (in dollars per share)	$ (0.46)	$ (3.58)	$ (0.63)	$ (5.50)
Machinery and equipment | Change to estimated useful life
Property and Equipment
Estimated useful life			P5Y	P3Y
Gain (loss) from operations	$ 400		$ 800
Decrease in net basic and diluted loss per share (in dollars per share)	$ 0.01		$ 0.02