v3.26.1
Investment securities - Debt Securities, Held-to-maturity, Credit Quality Indicator (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Available-for-sale, amount $ 48,256 $ 48,094
Unrealized gain (loss) $ (2,939) $ (2,717)
Ratings (percent) 0.00% 0.00%
Agency residential mortgage-backed securities (“RMBS”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Available-for-sale, amount $ 29,099 $ 26,432
Unrealized gain (loss) $ (2,459) $ (2,269)
Ratings (percent) 0.00% 0.00%
U.S. Treasury    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Available-for-sale, amount $ 6,123 $ 7,830
Unrealized gain (loss) $ (164) $ (155)
Ratings (percent) 0.00% 0.00%
Non-U.S. government    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Available-for-sale, amount $ 5,273 $ 5,654
Unrealized gain (loss) $ (26) $ 2
Ratings (percent) 0.00% 0.00%
U.S. government agencies    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Available-for-sale, amount $ 2,513 $ 2,653
Unrealized gain (loss) $ (176) $ (178)
Ratings (percent) 0.00% 0.00%
Agency commercial mortgage-backed securities (“MBS”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Available-for-sale, amount $ 2,707 $ 2,937
Unrealized gain (loss) $ (113) $ (117)
Ratings (percent) 0.00% 0.00%
Collateralized loan obligations (“CLOs”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Available-for-sale, amount $ 1,842 $ 1,841
Unrealized gain (loss) $ 1 $ (1)
Ratings (percent) 0.00% 0.00%
Foreign covered bonds    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Available-for-sale, amount $ 688 $ 736
Unrealized gain (loss) $ (2) $ 2
Ratings (percent) 0.00% 0.00%
Other debt securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Available-for-sale, amount $ 11 $ 11
Unrealized gain (loss) $ 0 $ (1)
Ratings (percent) 100.00% 100.00%
AAA/ AA-    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 98.00% 98.00%
AAA/ AA- | Agency residential mortgage-backed securities (“RMBS”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 100.00% 100.00%
AAA/ AA- | U.S. Treasury    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 100.00% 100.00%
AAA/ AA- | Non-U.S. government    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 83.00% 86.00%
AAA/ AA- | U.S. government agencies    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 100.00% 100.00%
AAA/ AA- | Agency commercial mortgage-backed securities (“MBS”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 100.00% 100.00%
AAA/ AA- | Collateralized loan obligations (“CLOs”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 100.00% 100.00%
AAA/ AA- | Foreign covered bonds    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 100.00% 100.00%
AAA/ AA- | Other debt securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
A+/ A-    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 2.00% 2.00%
A+/ A- | Agency residential mortgage-backed securities (“RMBS”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
A+/ A- | U.S. Treasury    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
A+/ A- | Non-U.S. government    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 17.00% 14.00%
A+/ A- | U.S. government agencies    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
A+/ A- | Agency commercial mortgage-backed securities (“MBS”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
A+/ A- | Collateralized loan obligations (“CLOs”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
A+/ A- | Foreign covered bonds    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
A+/ A- | Other debt securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BBB+/ BBB-    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BBB+/ BBB- | Agency residential mortgage-backed securities (“RMBS”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BBB+/ BBB- | U.S. Treasury    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BBB+/ BBB- | Non-U.S. government    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BBB+/ BBB- | U.S. government agencies    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BBB+/ BBB- | Agency commercial mortgage-backed securities (“MBS”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BBB+/ BBB- | Collateralized loan obligations (“CLOs”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BBB+/ BBB- | Foreign covered bonds    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BBB+/ BBB- | Other debt securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BB+ and lower    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BB+ and lower | Agency residential mortgage-backed securities (“RMBS”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BB+ and lower | U.S. Treasury    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BB+ and lower | Non-U.S. government    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BB+ and lower | U.S. government agencies    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BB+ and lower | Agency commercial mortgage-backed securities (“MBS”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BB+ and lower | Collateralized loan obligations (“CLOs”)    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BB+ and lower | Foreign covered bonds    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%
BB+ and lower | Other debt securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Ratings (percent) 0.00% 0.00%