Description of Business and Basis of Presentation (Details) $ in Thousands		3 Months Ended		6 Months Ended
	Mar. 15, 2018 USD ($)	Jun. 30, 2018 USD ($) drug product	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) drug product	Jun. 30, 2017 USD ($)	Aug. 31, 2014 USD ($)
Debt Instrument [Line Items]
Number of commercial products | product		2		2
Number of orphan drugs | drug		1		1
Net income (loss)		$ 31,262	$ 21,436	$ 64,090	$ 52,398
Cash used to fund operating activities				$ 34,197	$ 26,697
Net proceeds from new loan, net of debt discount	$ 20,000
Convertible Notes
Debt Instrument [Line Items]
Aggregate principal amount of convertible notes issued						$ 325,000