Fair Value of Financial Instruments - Fair Value of Financial Instruments (Parenthetical) (Detail) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
MidCap Credit Facility
Fair Value Of Financial Instruments [Line Items]
Note payable, percentage of hypothetical yield	12	12
Note payable, percentage of interest rate increases (decreases)	2.00%	2.00%
MidCap Credit Facility | Minimum
Fair Value Of Financial Instruments [Line Items]
Financial liabilities fair value	$ 29.7	$ 35.0
MidCap Credit Facility | Maximum
Fair Value Of Financial Instruments [Line Items]
Financial liabilities fair value	$ 30.4	$ 36.0
Mann Group Convertible Notes
Fair Value Of Financial Instruments [Line Items]
Note payable, percentage of hypothetical yield	13	13
Note payable, percentage of interest rate increases (decreases)	2.00%	2.00%
Mann Group Convertible Notes | Volatility
Fair Value Of Financial Instruments [Line Items]
Note payable, fair value key inputs	55.6	62.7
Mann Group Convertible Notes | Minimum
Fair Value Of Financial Instruments [Line Items]
Financial liabilities fair value	$ 16.9	$ 14.2
Mann Group Convertible Notes | Maximum
Fair Value Of Financial Instruments [Line Items]
Financial liabilities fair value	$ 17.4	$ 14.7
Senior Convertible Notes
Fair Value Of Financial Instruments [Line Items]
Note payable, percentage of hypothetical yield	11	11
Note payable, percentage of interest rate increases (decreases)	2.00%	2.00%
Senior Convertible Notes | Volatility
Fair Value Of Financial Instruments [Line Items]
Note payable, fair value key inputs	59.9	62.7
Senior Convertible Notes | Minimum
Fair Value Of Financial Instruments [Line Items]
Financial liabilities fair value	$ 239.8	$ 224.1
Senior Convertible Notes | Maximum
Fair Value Of Financial Instruments [Line Items]
Financial liabilities fair value	$ 253.3	$ 238.9
Financing Liability
Fair Value Of Financial Instruments [Line Items]
Note payable, percentage of hypothetical yield	9.5	9.5
Note payable, percentage of interest rate increases (decreases)	2.00%
Financing Liability | Minimum
Fair Value Of Financial Instruments [Line Items]
Financial liabilities fair value	$ 94.0
Financing Liability | Maximum
Fair Value Of Financial Instruments [Line Items]
Financial liabilities fair value	$ 122.4
Milestone Rights | Risk-Free Rate
Fair Value Of Financial Instruments [Line Items]
Note payable, fair value key inputs	4.2	3.88
Milestone Rights | Dividend Yield
Fair Value Of Financial Instruments [Line Items]
Note payable, fair value key inputs	0	0
Milestone Rights | Volatility
Fair Value Of Financial Instruments [Line Items]
Note payable, fair value key inputs	50	50
Milestone Rights | Period
Fair Value Of Financial Instruments [Line Items]
Note payable, fair value key inputs	7.75	8
Milestone Rights | Credit Risk
Fair Value Of Financial Instruments [Line Items]
Note payable, fair value key inputs	17	17
Contingent Milestone Liability | Risk-Free Rate
Fair Value Of Financial Instruments [Line Items]
Note payable, fair value key inputs	4.29	4.01
Contingent Milestone Liability | Dividend Yield
Fair Value Of Financial Instruments [Line Items]
Note payable, fair value key inputs	0	0
Contingent Milestone Liability | Volatility
Fair Value Of Financial Instruments [Line Items]
Note payable, fair value key inputs	43	43
Contingent Milestone Liability | Period
Fair Value Of Financial Instruments [Line Items]
Note payable, fair value key inputs	13.75	15
Contingent Milestone Liability | Credit Risk
Fair Value Of Financial Instruments [Line Items]
Note payable, fair value key inputs	17	17
Liability for Sale of Future Royalties
Fair Value Of Financial Instruments [Line Items]
Note payable, percentage of hypothetical yield	11
Note payable, percentage of interest rate increases (decreases)	2.00%
Liability for Sale of Future Royalties | Minimum
Fair Value Of Financial Instruments [Line Items]
Financial liabilities fair value	$ 139.6
Liability for Sale of Future Royalties | Maximum
Fair Value Of Financial Instruments [Line Items]
Financial liabilities fair value	$ 184.4