Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property and Equipment
Total Property and Equipment	$ 33,984	$ 33,158
Less Accumulated Depreciation and Amortization	(23,612)	(19,966)
Property and Equipment, Net	10,372	13,192
Depreciation and amortization expense	4,414	3,095	$ 2,998
Laboratory Equipment
Property and Equipment
Total Property and Equipment	7,770	6,771
Manufacturing Equipment
Property and Equipment
Total Property and Equipment	4,354	4,312
Office Furniture and Equipment
Property and Equipment
Total Property and Equipment	3,764	3,677
Leasehold Improvements
Property and Equipment
Total Property and Equipment	17,164	17,115
Construction in Progress
Property and Equipment
Total Property and Equipment	$ 932	$ 1,283