v3.25.4
Income taxes - Narrative (Details) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Mar. 31, 2025
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Operating Loss Carryforwards [Line Items]          
Swiss federal statutory tax rate   8.50% 8.50% 8.50%  
Operating loss carryforwards   $ 752 $ 227    
Change in valuation allowance   53 1    
Liabilities for unrecognized tax benefits   140 167 $ 161 $ 128
Recorded interest and penalties related to uncertain tax positions   49 42 32  
Unrecognized tax benefits, accrued liabilities   91 125 $ 129  
Foreign earnings to be repatriated   550      
Deferred tax liabilities, undistributed earnings of foreign subsidiaries   23      
Estimated Pillar Two top-up tax expense   12 24    
Pillar Two income tax benefit $ 18        
U.S.          
Operating Loss Carryforwards [Line Items]          
Operating loss carryforwards   $ 599 $ 181