Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued clinical costs	$ 3,565	$ 2,495
Accrued employee compensation and related costs	5,898	7,755
Accrued professional fees	4,735	4,118
Accrued sales allowances	12,912	13,471
Accrued royalties	4,281	3,588
Other accrued liabilities	14,227	10,411
Total	$ 45,618	$ 41,838