Fair value measurement - Certain Items on Recurring Basis (Details) - Measured at fair value on a recurring basis - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Non-agency RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 2,311	$ 2,748
Non-agency RMBS | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	86.00%	81.00%
Non-agency RMBS | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	2.00%	2.00%
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	7.00%	8.00%
Non-agency RMBS | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	5.00%	9.00%
Non-agency RMBS | 2008-2022
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 1,970	$ 2,190
Non-agency RMBS | 2008-2022 | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Non-agency RMBS | 2008-2022 | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency RMBS | 2008-2022 | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency RMBS | 2008-2022 | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency RMBS | 2008-2022 | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 59	$ 114
Non-agency RMBS | 2007 | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency RMBS | 2007 | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	6.00%	4.00%
Non-agency RMBS | 2007 | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency RMBS | 2007 | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	50.00%	39.00%
Non-agency RMBS | 2007 | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	44.00%	57.00%
Non-agency RMBS | 2006
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 100	$ 181
Non-agency RMBS | 2006 | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency RMBS | 2006 | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	34.00%	24.00%
Non-agency RMBS | 2006 | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency RMBS | 2006 | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	50.00%	33.00%
Non-agency RMBS | 2006 | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	16.00%	43.00%
Non-agency RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 102	$ 167
Non-agency RMBS | 2005 | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	5.00%	3.00%
Non-agency RMBS | 2005 | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	4.00%	5.00%
Non-agency RMBS | 2005 | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	1.00%	1.00%
Non-agency RMBS | 2005 | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	41.00%	37.00%
Non-agency RMBS | 2005 | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	49.00%	54.00%
Non-agency RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 80	$ 96
Non-agency RMBS | 2004 and earlier | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	15.00%	16.00%
Non-agency RMBS | 2004 and earlier | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	9.00%	10.00%
Non-agency RMBS | 2004 and earlier | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	5.00%	5.00%
Non-agency RMBS | 2004 and earlier | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	57.00%	57.00%
Non-agency RMBS | 2004 and earlier | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	14.00%	12.00%
Non-agency commercial MBS | 2009-2022 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 3,003	$ 3,125
Non-agency commercial MBS | 2009-2022 | AAA/ AA- | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Non-agency commercial MBS | 2009-2022 | A/ A- | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency commercial MBS | 2009-2022 | BBB/ BBB- | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency commercial MBS | 2009-2022 | BB and lower | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency commercial MBS | 2009-2022 | 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	$ 5,828	$ 6,238
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	$ 2,307	$ 2,332
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	$ 1,168	$ 1,141
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 | Australia
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 648	$ 762
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 | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 593	$ 638
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 | Norway
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 385	$ 457
Foreign covered bonds | Norway | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Foreign covered bonds | Norway | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign covered bonds | Norway | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign covered bonds | Norway | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign covered bonds | Norway | 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	$ 727	$ 908
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%
Sovereign debt/sovereign guaranteed
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 11,092	$ 13,379
Sovereign debt/sovereign guaranteed | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	84.00%	78.00%
Sovereign debt/sovereign guaranteed | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	5.00%	5.00%
Sovereign debt/sovereign guaranteed | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	10.00%	16.00%
Sovereign debt/sovereign guaranteed | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	1.00%	1.00%
Sovereign debt/sovereign guaranteed | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Canada
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 613	$ 630
Sovereign debt/sovereign guaranteed | Canada | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign debt/sovereign guaranteed | Canada | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Canada | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Canada | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Canada | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | UK
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 1,879	$ 1,969
Sovereign debt/sovereign guaranteed | UK | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign debt/sovereign guaranteed | UK | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | UK | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | UK | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | UK | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 3,077	$ 3,585
Sovereign debt/sovereign guaranteed | Germany | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign debt/sovereign guaranteed | Germany | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Germany | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Germany | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Germany | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | France
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 1,532	$ 1,921
Sovereign debt/sovereign guaranteed | France | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign debt/sovereign guaranteed | France | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | France | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | France | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | France | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Singapore
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 1,184	$ 1,018
Sovereign debt/sovereign guaranteed | Singapore | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign debt/sovereign guaranteed | Singapore | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Singapore | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Singapore | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Singapore | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Italy
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 773	$ 1,382
Sovereign debt/sovereign guaranteed | Italy | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Italy | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Italy | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign debt/sovereign guaranteed | Italy | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Italy | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Spain
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 470	$ 782
Sovereign debt/sovereign guaranteed | Spain | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Spain | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	18.00%	8.00%
Sovereign debt/sovereign guaranteed | Spain | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	82.00%	92.00%
Sovereign debt/sovereign guaranteed | Spain | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Spain | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Hong Kong
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 448	$ 531
Sovereign debt/sovereign guaranteed | Hong Kong | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign debt/sovereign guaranteed | Hong Kong | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Hong Kong | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Hong Kong | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Hong Kong | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Japan
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 412	$ 363
Sovereign debt/sovereign guaranteed | Japan | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Japan | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign debt/sovereign guaranteed | Japan | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Japan | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Japan | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 704	$ 1,198
Sovereign debt/sovereign guaranteed | Other | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	78.00%	71.00%
Sovereign debt/sovereign guaranteed | Other | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	5.00%	19.00%
Sovereign debt/sovereign guaranteed | Other | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Other | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	17.00%	10.00%
Sovereign debt/sovereign guaranteed | Other | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 2,536	$ 2,686
Foreign government agencies | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	92.00%	92.00%
Foreign government agencies | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	8.00%	8.00%
Foreign government agencies | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Canada
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 640	$ 566
Foreign government agencies | Canada | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	83.00%	78.00%
Foreign government agencies | Canada | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	17.00%	22.00%
Foreign government agencies | Canada | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Canada | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Canada | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Netherlands
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 406	$ 765
Foreign government agencies | Netherlands | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Foreign government agencies | Netherlands | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Netherlands | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Netherlands | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Netherlands | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Norway
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 478	$ 269
Foreign government agencies | Norway | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Foreign government agencies | Norway | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Norway | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Norway | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Norway | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | France
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 249	$ 301
Foreign government agencies | France | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Foreign government agencies | France | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | France | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | France | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | France | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Sweden
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 280	$ 252
Foreign government agencies | Sweden | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Foreign government agencies | Sweden | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Sweden | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Sweden | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Sweden | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Finland
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 248	$ 267
Foreign government agencies | Finland | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Foreign government agencies | Finland | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Finland | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Finland | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Finland | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 235	$ 266
Foreign government agencies | Other | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	64.00%	64.00%
Foreign government agencies | Other | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	36.00%	36.00%
Foreign government agencies | Other | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Other | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Other | Not Rated
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign debt/sovereign guaranteed | Sovereign debt/sovereign guaranteed | Brazil | Carrying amount
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 120	$ 119