Lending Activities - Credit quality of residential mortgages (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 49,917	$ 46,677
Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
2022	407	2,956
2021	3,104	964
2020	879	408
2019	340	167
2018	128	274
Prior	862	723
Total	5,720	5,492
780 and greater | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
2022	199	1,601
2021	2,266	691
2020	674	297
2019	243	107
2018	83	192
Prior	596	501
Total	4,061	3,389
720 - 779 | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
2022	200	1,306
2021	752	230
2020	174	86
2019	78	44
2018	33	58
Prior	177	154
Total	1,414	1,878
660 - 719 | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
2022	8	48
2021	82	42
2020	29	22
2019	16	12
2018	10	20
Prior	66	49
Total	211	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	16	12
Total	26	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