Fair Value of Financial Instruments - Fair Value of Financial Instruments (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021	Nov. 30, 2021
MidCap Credit Facility
Financial liabilities:
Financial liabilities fair value	$ 40.7	$ 40.8
Fair Value, Inputs, Level 3
Financial liabilities:
Financial liabilities fair value			$ 103.2
Carrying Value | MidCap Credit Facility
Financial liabilities:
Financial liabilities fair value	39.2	38.8
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | MidCap Credit Facility
Financial liabilities:
Financial liabilities fair value	40.7	40.8
Senior Convertible Notes
Financial liabilities:
Financial liabilities fair value	206.1	237.5
Senior Convertible Notes | Carrying Value
Financial liabilities:
Financial liabilities fair value	225.0	223.9
Senior Convertible Notes | Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3
Financial liabilities:
Financial liabilities fair value	206.1	237.5
Mann Group Convertible Note
Financial liabilities:
Financial liabilities fair value	13.3	37.8
Mann Group Convertible Note | Carrying Value
Financial liabilities:
Financial liabilities fair value	8.8	18.4
Mann Group Convertible Note | Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3
Financial liabilities:
Financial liabilities fair value	13.3	37.8
Milestone Rights Liability
Financial liabilities:
Financial liabilities fair value	13.0	18.1
Milestone Rights Liability | Carrying Value
Financial liabilities:
Financial liabilities fair value	4.8	5.9
Milestone Rights Liability | Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3
Financial liabilities:
Financial liabilities fair value	13.0	$ 18.1
Contingent Milestone Liability
Financial liabilities:
Financial liabilities fair value	0.8
Contingent Milestone Liability | Carrying Value
Financial liabilities:
Financial liabilities fair value	0.6
Contingent Milestone Liability | Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3
Financial liabilities:
Financial liabilities fair value	$ 0.8