Intangible Assets - Carrying Value and Accumulated Amortization (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 252,458	$ 252,458
Accumulated Amortization	(39,734)	(27,186)
Net Carrying Value	212,724	225,272
Developed Technology Rights | JUXTAPID
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	42,300	42,300
Accumulated Amortization	(6,230)	(4,262)
Net Carrying Value	36,070	38,038
Developed Technology Rights | MYALEPT
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	210,158	210,158
Accumulated Amortization	(33,504)	(22,924)
Net Carrying Value	$ 176,654	$ 187,234