v3.26.1
Shareholders' equity - Issued and Outstanding Preferred Stock (Detail) - USD ($)
$ / shares in Units, $ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Class of Stock [Line Items]      
Preferred stock, shares issued (in shares) 10,220,000   10,260,000
Preferred stock, shares outstanding (in shares) 10,220,000   10,260,000
Carrying Amount $ 2,434   $ 2,834
Preferred Series F      
Class of Stock [Line Items]      
Preferred stock, shares issued (in shares) 50,000   50,000
Preferred stock, shares outstanding (in shares) 50,000   50,000
Preferred stock, liquidation preference per share (in USD per share) $ 10,000    
Preferred stock dividend rate (as a percent) 5.125%    
Carrying Amount $ 500   $ 500
Preferred stock per share dividend amount (in USD per share) $ 128.13 $ 128.13  
Preferred stock. dividend rate spread (as a percent) 3.78%    
Preferred Series G      
Class of Stock [Line Items]      
Preferred stock, shares issued (in shares) 0   40,000
Preferred stock, shares outstanding (in shares) 0   40,000
Preferred stock, liquidation preference per share (in USD per share) $ 10,000    
Preferred stock dividend rate (as a percent) 0.00%    
Carrying Amount $ 0   $ 400
Preferred stock per share dividend amount (in USD per share) $ 182.60 182.60  
Preferred Series H      
Class of Stock [Line Items]      
Preferred stock, shares issued (in shares) 10,000,000   10,000,000
Preferred stock, shares outstanding (in shares) 10,000,000   10,000,000
Preferred stock, liquidation preference per share (in USD per share) $ 25    
Preferred stock dividend rate (as a percent) 5.625%    
Carrying Amount $ 261   $ 261
Preferred stock per share dividend amount (in USD per share) $ 0.35 0.35  
Preferred stock. dividend rate spread (as a percent) 4.28%    
Preferred Series I      
Class of Stock [Line Items]      
Preferred stock, shares issued (in shares) 50,000   50,000
Preferred stock, shares outstanding (in shares) 50,000   50,000
Preferred stock, liquidation preference per share (in USD per share) $ 10,000    
Preferred stock dividend rate (as a percent) 3.50%    
Carrying Amount $ 500   $ 500
Preferred stock per share dividend amount (in USD per share) $ 87.50 87.50  
Preferred stock. dividend rate spread (as a percent) 2.679%    
Preferred Series J      
Class of Stock [Line Items]      
Preferred stock, shares issued (in shares) 75,000   75,000
Preferred stock, shares outstanding (in shares) 75,000   75,000
Preferred stock, liquidation preference per share (in USD per share) $ 10,000    
Preferred stock dividend rate (as a percent) 7.50%    
Carrying Amount $ 733   $ 733
Preferred stock per share dividend amount (in USD per share) $ 187.50 187.50  
Preferred Series K      
Class of Stock [Line Items]      
Preferred stock, shares issued (in shares) 45,000   45,000
Preferred stock, shares outstanding (in shares) 45,000   45,000
Preferred stock, liquidation preference per share (in USD per share) $ 10,000    
Preferred stock dividend rate (as a percent) 6.35%    
Carrying Amount $ 440   $ 440
Preferred stock per share dividend amount (in USD per share) $ 158.75 $ 0