Fair value measurement - Certain Items on Recurring Basis (Details) - Assets measured at fair value on a recurring basis - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Non-agency RMBS | Origination in 2004 and Earlier, 2005, 2006 and 2007 through 2020
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 512	$ 640
Non-agency RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 1,941	$ 1,233
Non-agency RMBS | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	61.00%	25.00%
Non-agency RMBS | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	4.00%	9.00%
Non-agency RMBS | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	2.00%	3.00%
Non-agency RMBS | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	33.00%	63.00%
Non-agency RMBS | 2007-2020
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 1,311	$ 464
Non-agency RMBS | 2007-2020 | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	88.00%	55.00%
Non-agency RMBS | 2007-2020 | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	1.00%
Non-agency RMBS | 2007-2020 | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency RMBS | 2007-2020 | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	12.00%	44.00%
Non-agency RMBS | 2006
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 244	$ 291
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	23.00%	21.00%
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	77.00%	79.00%
Non-agency RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 243	$ 305
Non-agency RMBS | 2005 | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	4.00%	5.00%
Non-agency RMBS | 2005 | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	2.00%
Non-agency RMBS | 2005 | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	7.00%	8.00%
Non-agency RMBS | 2005 | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	89.00%	85.00%
Non-agency RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 143	$ 173
Non-agency RMBS | 2004 and earlier | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	20.00%	22.00%
Non-agency RMBS | 2004 and earlier | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	9.00%	24.00%
Non-agency RMBS | 2004 and earlier | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	12.00%	4.00%
Non-agency RMBS | 2004 and earlier | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	59.00%	50.00%
Non-agency commercial MBS | 2009-2020 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 2,711	$ 2,178
Non-agency commercial MBS | 2009-2020 | AAA/ AA- | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	98.00%
Non-agency commercial MBS | 2009-2020 | A/ A- | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	2.00%
Non-agency commercial MBS | 2009-2020 | BBB/ BBB- | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Non-agency commercial MBS | 2009-2020 | BB and lower | 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	$ 5,841	$ 4,197
Foreign covered bonds | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	99.00%	100.00%
Foreign covered bonds | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	1.00%	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 | Canada
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 2,368	$ 1,798
Foreign covered bonds | Canada | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	98.00%	100.00%
Foreign covered bonds | Canada | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	2.00%	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 | UK
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 1,130	$ 984
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 | Australia
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 775	$ 431
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 | Norway
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 609	$ 287
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 | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 479	$ 357
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 | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 480	$ 340
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%
Sovereign Debt
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 14,093	$ 12,646
Sovereign Debt | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	65.00%	73.00%
Sovereign Debt | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	7.00%	5.00%
Sovereign Debt | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	27.00%	21.00%
Sovereign Debt | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	1.00%	1.00%
Sovereign Debt | Canada
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 732	$ 271
Sovereign Debt | Canada | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign Debt | Canada | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Canada | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Canada | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | UK
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 2,037	$ 3,318
Sovereign Debt | UK | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign Debt | UK | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | UK | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | UK | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 2,155	$ 1,997
Sovereign Debt | Germany | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign Debt | Germany | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Germany | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Germany | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | France
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 1,846	$ 1,272
Sovereign Debt | France | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign Debt | France | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | France | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | France | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Spain
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 1,835	$ 1,453
Sovereign Debt | Spain | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Spain | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	5.00%	6.00%
Sovereign Debt | Spain | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	95.00%	94.00%
Sovereign Debt | Spain | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Italy
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 1,974	$ 1,260
Sovereign Debt | Italy | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Italy | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Italy | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign Debt | Italy | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Singapore
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 949	$ 742
Sovereign Debt | Singapore | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign Debt | Singapore | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Singapore | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Singapore | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Ireland
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 522	$ 301
Sovereign Debt | Ireland | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Ireland | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign Debt | Ireland | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Ireland | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Netherlands
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 471	$ 791
Sovereign Debt | Netherlands | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign Debt | Netherlands | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Netherlands | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Netherlands | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Japan
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 437	$ 274
Sovereign Debt | Japan | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Japan | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign Debt | Japan | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Japan | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Belgium
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 253	$ 79
Sovereign Debt | Belgium | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign Debt | Belgium | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Belgium | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Belgium | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Austria
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 294	$ 240
Sovereign Debt | Austria | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign Debt | Austria | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Austria | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Austria | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Hong Kong
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 206	$ 411
Sovereign Debt | Hong Kong | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Sovereign Debt | Hong Kong | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Hong Kong | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Hong Kong | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Sovereign Debt | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 382	$ 237
Sovereign Debt | Other | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	51.00%	39.00%
Sovereign Debt | Other | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	4.00%
Sovereign Debt | Other | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	18.00%	0.00%
Sovereign Debt | Other | BB and lower
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	31.00%	57.00%
Foreign government agencies
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 3,970	$ 2,643
Foreign government agencies | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	94.00%	95.00%
Foreign government agencies | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	6.00%	5.00%
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 | Canada
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 442	$ 71
Foreign government agencies | Canada | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	72.00%	0.00%
Foreign government agencies | Canada | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	28.00%	100.00%
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 | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 1,483	$ 1,131
Foreign government agencies | Germany | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	100.00%	100.00%
Foreign government agencies | Germany | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Germany | BBB/ BBB-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	0.00%	0.00%
Foreign government agencies | Germany | BB and lower
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	$ 293	$ 42
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 | Netherlands
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 800	$ 678
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 | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 430	$ 274
Foreign government agencies | Other | AAA/ AA-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	77.00%	79.00%
Foreign government agencies | Other | A/ A-
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Ratings	23.00%	21.00%
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 | Sweden
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 276	$ 202
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 | Finland
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 246	$ 245
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%
Carrying amount | Sovereign debt/sovereign guaranteed | Sovereign debt/sovereign guaranteed | Brazil
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total carrying value	$ 119	$ 134