Debt - Non-Recourse Debt (Details)				3 Months Ended
	Jan. 08, 2018 USD ($) $ / shares	Jan. 07, 2018 USD ($) item $ / shares shares	Oct. 11, 2016 USD ($)	Mar. 31, 2018 USD ($)
Debt Instrument [Line Items]
Gross proceeds from sale of common stock			$ 30,000,000
Non-Recourse Debt				$ 182,216,000
RPI | Funding and Purchase Agreements [Member]
Debt Instrument [Line Items]
Collaborative agreement purchase price	$ 175,000,000	$ 175,000,000
Collaborative arrangement royalty rate		4.15%
Percentage of revenue participation rights to repurchase		50.00%
Discount rate to calculate net present value of projected royalty payments		5.00%
RPI | Maximum | Funding and Purchase Agreements [Member]
Debt Instrument [Line Items]
Collaborative arrangement maximum royalty		$ 2,000,000,000
Percentage of excess of global annual sales threshold limit		1.75%
RPI | Minimum | Funding and Purchase Agreements [Member]
Debt Instrument [Line Items]
Collaborative arrangement excess of global annual sales threshold limit		$ 6,000,000,000
Private placement | RPI
Debt Instrument [Line Items]
Number of units of value to account for in the transaction | item		2
Allocation of transaction price to common stock and additional paid-in capital		$ 67,800,000
Non-Recourse Debt		$ 182,200,000
Effective interest rate recognition period		20 years
Effective interest rate (as a percent)		25.646%
Non-cash interest expenses				$ 10,600,000
Private placement | RPI | Common stock purchase agreement
Debt Instrument [Line Items]
Agreement purchase shares of common stock | shares		4,373,178
Share Price | $ / shares	$ 17.15	$ 17.15
Gross proceeds from sale of common stock	$ 75,000,000	$ 75,000,000