Lending Activities - Credit quality of residential mortgages (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 48,779	$ 46,677
Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
2022	437	2,956
2021	3,055	964
2020	865	408
2019	332	167
2018	123	274
Prior	828	723
Total	5,640	5,492
780 and greater | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
2022	205	1,601
2021	2,233	691
2020	663	297
2019	237	107
2018	80	192
Prior	574	501
Total	3,992	3,389
720 - 779 | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
2022	219	1,306
2021	737	230
2020	171	86
2019	76	44
2018	32	58
Prior	171	154
Total	1,406	1,878
660 - 719 | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
2022	13	48
2021	81	42
2020	29	22
2019	16	12
2018	9	20
Prior	62	49
Total	210	193
600 - 659 | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	1
2021	4	1
2020	2	2
2019	2	3
2018	2	2
Prior	14	12
Total	24	21
Less than 600 | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	1
2019	1	1
2018	0	2
Prior	7	7
Total	$ 8	$ 11