v3.26.1
Preferred stock - Summary (Details) - USD ($)
$ / shares in Units, $ in Millions
 6 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Class of Stock [Line Items]    
Total shares issued and outstanding (shares) 48,001 48,826
Carrying value $ 4,754 $ 4,836
Series A Preferred Stock    
Class of Stock [Line Items]    
Preferred stock, basis spread on variable rate 0.565%  
Per annum dividend rate 4.00%  
Total shares issued and outstanding (shares) 5,001 5,001
Carrying value $ 500 $ 500
Liquidation preference per share (usd per share) $ 100,000  
Series F Preferred Stock    
Class of Stock [Line Items]    
Preferred stock, basis spread on variable rate 3.131%  
Per annum dividend rate 4.625%  
Total shares issued and outstanding (shares) 10,000 10,000
Carrying value $ 990 $ 990
Liquidation preference per share (usd per share) $ 100,000  
Series H Preferred Stock    
Class of Stock [Line Items]    
Preferred stock, basis spread on variable rate 3.352%  
Per annum dividend rate 3.70%  
Total shares issued and outstanding (shares) 0 5,825
Carrying value $ 0 $ 576
Liquidation preference per share (usd per share) $ 100,000  
Series I Preferred Stock    
Class of Stock [Line Items]    
Preferred stock, basis spread on variable rate 2.63%  
Per annum dividend rate 3.75%  
Total shares issued and outstanding (shares) 13,000 13,000
Carrying value $ 1,287 $ 1,287
Liquidation preference per share (usd per share) $ 100,000  
Series J Preferred Stock    
Class of Stock [Line Items]    
Preferred stock, basis spread on variable rate 2.297%  
Per annum dividend rate 6.30%  
Total shares issued and outstanding (shares) 5,000 5,000
Carrying value $ 494 $ 494
Liquidation preference per share (usd per share) $ 100,000  
Series K Preferred Stock    
Class of Stock [Line Items]    
Preferred stock, basis spread on variable rate 2.161%  
Per annum dividend rate 6.15%  
Total shares issued and outstanding (shares) 5,000 5,000
Carrying value $ 494 $ 494
Liquidation preference per share (usd per share) $ 100,000  
Series L Preferred Stock    
Class of Stock [Line Items]    
Preferred stock, basis spread on variable rate 2.271%  
Per annum dividend rate 5.95%  
Total shares issued and outstanding (shares) 5,000 5,000
Carrying value $ 495 $ 495
Liquidation preference per share (usd per share) $ 100,000  
Series M Preferred Stock    
Class of Stock [Line Items]    
Preferred stock, basis spread on variable rate 2.034%  
Per annum dividend rate 5.625%  
Total shares issued and outstanding (shares) 5,000 0
Carrying value $ 494 $ 0
Liquidation preference per share (usd per share) $ 100,000