Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Valuation Allowance [Line Items]
Increase in valuation allowance	$ 29,300,000
U.S. federal net operating loss carryforwards	0
Non-US Net operating loss carryforwards	$ 2,223,300,000
Operating loss carryforwards expiration period	2027
Unrecognized tax benefits, gross	$ 44,148,000	$ 34,536,000	$ 21,395,000	$ 11,967,000
Unrecognized tax benefits would favorably impact the effective tax rate if recognized	40,100,000
Accrued interest or penalties related to uncertain tax positions	0	0	0
Uncertain tax positions recognized	0	$ 0	$ 0
U.S. Domestic Federal [Member] | Research and Development [Member]
Valuation Allowance [Line Items]
Tax credit carryforward amount	$ 28,200,000
Tax credit carryforward, expiration year	2040
Uncertain tax positions	$ 18,100,000
U.S. Domestic Federal [Member] | Orphan Drug Credit Carryforwards [Member]
Valuation Allowance [Line Items]
Tax credit carryforward amount	$ 27,000,000
Tax credit carryforward, expiration year	2040
Uncertain tax positions	$ 11,500,000
U.S. Domestic State [Member] | Research and Development [Member]
Valuation Allowance [Line Items]
Tax credit carryforward amount	$ 19,300,000
Tax credit carryforward, expiration year	2035
Uncertain tax positions	$ 12,800,000
Switzerland [Member]
Valuation Allowance [Line Items]
Non-US Net operating loss carryforwards	1,115,600,000
Canton of Zug [Member]
Valuation Allowance [Line Items]
Non-US Net operating loss carryforwards	1,115,600,000
United Kingdom [Member]
Valuation Allowance [Line Items]
Non-US Net operating loss carryforwards	$ 2,100,000