Asset Acquisition - Additional Information (Details) - Axis Therapeutics - USD ($) $ in Millions		9 Months Ended
	Jun. 29, 2018	Sep. 30, 2018
Asset Acquisition [Line Items]
Capital contributions to joint venture	$ 30.0	$ 30.0
Percentage of ownership in joint venture	55.00%
Research and Development Expenses
Asset Acquisition [Line Items]
Non-cash expense		$ 24.5
Licensing Agreements
Asset Acquisition [Line Items]
Upfront payment in the form of issuance of common stock, shares	267,952
Upfront payment in the form of issuance of common stock	$ 5.0
XLifeSc | IPR & D
Asset Acquisition [Line Items]
Percentage of ownership in joint venture	45.00%
Percentage of nonmonetary exchange of shares		45.00%
Fair value of equity shares issued		$ 24.5