Segmentation Information - Summary of Total Net Product Sale Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net product sales	$ 13,574	$ 0	$ 0
U.S.
Segment Reporting Information [Line Items]
Net product sales	10,819
Italy
Segment Reporting Information [Line Items]
Net product sales	1,209
Other Foreign Countries
Segment Reporting Information [Line Items]
Net product sales	1,546
MYALEPT
Segment Reporting Information [Line Items]
Net product sales	4,953
MYALEPT | U.S.
Segment Reporting Information [Line Items]
Net product sales	4,685
MYALEPT | Italy
Segment Reporting Information [Line Items]
Net product sales	0
MYALEPT | Other Foreign Countries
Segment Reporting Information [Line Items]
Net product sales	268
JUXTAPID
Segment Reporting Information [Line Items]
Net product sales	8,621
JUXTAPID | U.S.
Segment Reporting Information [Line Items]
Net product sales	6,134
JUXTAPID | Italy
Segment Reporting Information [Line Items]
Net product sales	1,209
JUXTAPID | Other Foreign Countries
Segment Reporting Information [Line Items]
Net product sales	$ 1,278