Segment Information - Additional Information (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2018 customer segment product	Mar. 31, 2017 customer	Dec. 31, 2017
Segment Reporting Information [Line Items]
Number of operating segments | segment	1
Number of commercial products | product	2
Customer Concentration Risk | Sales Revenue, Net
Segment Reporting Information [Line Items]
Number of major customers		2
Customer concentration risk, percentage	67.00%	49.00%
Customer Concentration Risk | Accounts Receivable
Segment Reporting Information [Line Items]
Number of major customers	1
Customer concentration risk, percentage	57.00%	29.00%
Geographic Concentration Risk | Intangible Assets | Aegerion
Segment Reporting Information [Line Items]
Customer concentration risk, percentage	100.00%		100.00%
U.S. | Geographic Concentration Risk | Intangible Assets | Aegerion
Segment Reporting Information [Line Items]
Customer concentration risk, percentage	65.00%		65.00%
U.S. | Geographic Concentration Risk | Property and Equipment
Segment Reporting Information [Line Items]
Customer concentration risk, percentage	76.00%		75.00%
Europe | Geographic Concentration Risk | Intangible Assets | Aegerion
Segment Reporting Information [Line Items]
Customer concentration risk, percentage	35.00%		35.00%