v3.26.1
Fair value measurement - Certain Items on Recurring Basis (Details) - Measured at fair value on a recurring basis - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Non-agency RMBS    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 1,524 $ 1,515
Non-agency RMBS | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Non-agency RMBS | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency RMBS | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency RMBS | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency RMBS | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency RMBS | 2008-2026    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 1,519 $ 1,509
Non-agency RMBS | 2008-2026 | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Non-agency RMBS | 2008-2026 | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency RMBS | 2008-2026 | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency RMBS | 2008-2026 | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency RMBS | 2008-2026 | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency RMBS | 2007 and earlier    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 5 $ 6
Non-agency RMBS | 2007 and earlier | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency RMBS | 2007 and earlier | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Non-agency RMBS | 2007 and earlier | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency RMBS | 2007 and earlier | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency RMBS | 2007 and earlier | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency commercial MBS | 2009-2026 | Domestic    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 1,967 $ 2,196
Non-agency commercial MBS | 2009-2026 | AAA/ AA- | Domestic    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Non-agency commercial MBS | 2009-2026 | A+/ A- | Domestic    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency commercial MBS | 2009-2026 | BBB+/ BBB- | Domestic    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency commercial MBS | 2009-2026 | BB+ and lower | Domestic    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-agency commercial MBS | 2009-2026 | Not rated | Domestic    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 7,885 $ 8,068
Foreign covered bonds | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Foreign covered bonds | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Canada    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 1,727 $ 1,923
Foreign covered bonds | Canada | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Foreign covered bonds | Canada | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Canada | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Canada | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Canada | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | UK    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 1,113 $ 1,057
Foreign covered bonds | UK | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Foreign covered bonds | UK | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | UK | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | UK | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | UK | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Germany    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 714 $ 793
Foreign covered bonds | Germany | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Foreign covered bonds | Germany | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Germany | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Germany | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Germany | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Australia    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 783 $ 882
Foreign covered bonds | Australia | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Foreign covered bonds | Australia | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Australia | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Australia | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Australia | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Singapore    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 529 $ 607
Foreign covered bonds | Singapore | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Foreign covered bonds | Singapore | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Singapore | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Singapore | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Singapore | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Netherlands    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 485 $ 531
Foreign covered bonds | Netherlands | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Foreign covered bonds | Netherlands | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Netherlands | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Netherlands | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Netherlands | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Other    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 1,440 $ 1,333
Foreign covered bonds | Other | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Foreign covered bonds | Other | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Other | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Other | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Other | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Austria    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 516 $ 451
Foreign covered bonds | Austria | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Foreign covered bonds | Austria | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Austria | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Austria | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Austria | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Belgium    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 578 $ 491
Foreign covered bonds | Belgium | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Foreign covered bonds | Belgium | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Belgium | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Belgium | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Foreign covered bonds | Belgium | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Canada    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 1,879 $ 1,835
Non-U.S. government | Canada | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 87.00% 90.00%
Non-U.S. government | Canada | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 13.00% 10.00%
Non-U.S. government | Canada | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Canada | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Canada | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | UK    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 4,437 $ 4,702
Non-U.S. government | UK | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Non-U.S. government | UK | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | UK | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | UK | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | UK | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Germany    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 2,156 $ 2,045
Non-U.S. government | Germany | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Non-U.S. government | Germany | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Germany | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Germany | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Germany | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Netherlands    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 1,588 $ 1,825
Non-U.S. government | Netherlands | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Non-U.S. government | Netherlands | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Netherlands | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Netherlands | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Netherlands | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Other    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 1,380 $ 1,490
Non-U.S. government | Other | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 52.00% 56.00%
Non-U.S. government | Other | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 38.00% 33.00%
Non-U.S. government | Other | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 4.00% 3.00%
Non-U.S. government | Other | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 6.00% 8.00%
Non-U.S. government | Other | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | France    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 1,808 $ 2,037
Non-U.S. government | France | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 28.00% 31.00%
Non-U.S. government | France | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 72.00% 69.00%
Non-U.S. government | France | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | France | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | France | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Austria    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 925 $ 742
Non-U.S. government | Austria | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Non-U.S. government | Austria | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Austria | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Austria | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Austria | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Finland    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 819 $ 688
Non-U.S. government | Finland | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Non-U.S. government | Finland | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Finland | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Finland | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Finland | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Spain    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 626 $ 628
Non-U.S. government | Spain | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Spain | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Non-U.S. government | Spain | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Spain | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Spain | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Japan    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 377 $ 470
Non-U.S. government | Japan | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Japan | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 100.00% 100.00%
Non-U.S. government | Japan | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Japan | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Japan | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Belgium    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 418 $ 371
Non-U.S. government | Belgium | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 42.00% 100.00%
Non-U.S. government | Belgium | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 58.00% 0.00%
Non-U.S. government | Belgium | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Belgium | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Belgium | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Non-U.S. government | Sovereign debt/sovereign guaranteed | Brazil | Carrying amount    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 86 $ 112
Supranational    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 11,251 $ 11,735
Supranational | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 86.00% 87.00%
Supranational | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 14.00% 13.00%
Supranational | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Supranational | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Supranational | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Total non-U.S. government    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Total carrying value $ 27,664 $ 28,568
Total non-U.S. government | AAA/ AA-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 82.00% 83.00%
Total non-U.S. government | A+/ A-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 18.00% 17.00%
Total non-U.S. government | BBB+/ BBB-    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Total non-U.S. government | BB+ and lower    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%
Total non-U.S. government | Not rated    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Ratings 0.00% 0.00%