v3.26.1
Income Taxes - Schedule of Reconciliation between Effective Tax Rates and Statutory Rates (Detail) - USD ($)
8 Months Ended 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Apr. 30, 2025
Apr. 30, 2024
Effective Income Tax Rate Reconciliation [Line Items]        
Loss before income tax expense $ (110,557,000) $ (110,454,000) $ (180,052,000) $ (126,644,000)
Income tax benefit at U.S. federal statutory rate, Amount $ (23,217,000)      
Income tax benefit at U.S. federal statutory rate 21.00%   21.00% 21.00%
Foreign rate differential     1.80% 2.30%
Nondeductible expenses - UK R&D credit     (0.40%) (8.30%)
UK income from royalty financing     (15.30%)  
Other     (0.20%) (0.40%)
Valuation allowance, Amount $ 13,968,000      
Valuation allowance (12.60%)   (1.30%) (12.70%)
Tax credits, Amount $ (41,000)      
Tax credits 0.00%      
162(m) permanent adjustment, Amount $ 758,000      
162(m) permanent adjustment (0.70%)   (0.40%) (1.90%)
Stock-based compensation, Amount $ 486,000      
Stock-based compensation (0.40%)      
GILTI, Amount $ 9,104,000      
GILTI (8.20%)   (7.20%)  
Other nontaxable or nondeductible, Amount $ 92,000      
Other nontaxable or nondeductible (0.10%)      
Other items, Amount $ 165,000      
Other items (0.10%)      
Income Tax Expense (Benefit), Total $ (1,033,000)   $ 3,392,000 $ 0
Total effective rate 1.00%   (2.00%)  
Switzerland [Member]        
Effective Income Tax Rate Reconciliation [Line Items]        
Foreign rate differential, Amount $ 830,000      
Foreign rate differential (0.80%)      
Other, Amount $ 15,000      
Other 0.00%      
Valuation allowance, Amount $ 1,462,000      
Valuation allowance (1.30%)      
United Kingdom [Member]        
Effective Income Tax Rate Reconciliation [Line Items]        
Other, Amount $ (369,000)      
Other 0.30%      
Valuation allowance, Amount $ 568,000      
Valuation allowance (0.50%)      
Tax credits, Amount $ (5,122,000)      
Tax credits 4.60%      
Other Foreign Countries [Member]        
Effective Income Tax Rate Reconciliation [Line Items]        
Foreign rate differential, Amount $ 268,000      
Foreign rate differential (0.20%)