Shareholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended			3 Months Ended
	Jun. 04, 2019	Apr. 30, 2019	Apr. 30, 2018	Oct. 31, 2017	Jun. 30, 2018	Jun. 30, 2019
Public Offering
Subsidiary, Sale of Stock [Line Items]
Number of shares issued (in shares)	17,424,243
Price of shares (in USD per share)	$ 8.25
Net proceeds from sale of shares	$ 134.5
Underwriter's Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Number of shares issued (in shares)	2,272,727
Private Placement
Subsidiary, Sale of Stock [Line Items]
Number of shares issued (in shares)				138,361
Net proceeds from sale of shares				$ 2.0
Roivant Sciences, Ltd. | Private Placement
Subsidiary, Sale of Stock [Line Items]
Number of shares issued (in shares)			1,110,015
Price of shares (in USD per share)			$ 20.27
Gross proceeds from sale of shares			$ 22.5
Cowen and Company, LLC | Private Placement
Subsidiary, Sale of Stock [Line Items]
Number of shares issued (in shares)		106,494			2,767,129
Price of shares (in USD per share)					$ 21.47	$ 24.65
Net proceeds from sale of shares		$ 2.5			$ 57.3
Aggregate offering price			$ 100.0
Remaining capacity in offering program						$ 10.4