Lending Activities - Credit quality of commercial mortgages (Details) $ in Millions	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 49,917	$ 46,677
Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	3,861	2,820
2021	3,001	2,708
2020	2,686	5,897
2019	5,656	5,989
2018	5,752	3,734
Prior	16,249	14,517
Total	$ 37,205	$ 35,665
Weighted average debt service coverage ratio	1.9
Weighted average loan-to-value ratio (as a percent)	57.00%	57.00%
Less than 65% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	$ 3,330	$ 2,286
2021	2,408	2,272
2020	2,227	4,149
2019	3,960	4,815
2018	4,560	2,892
Prior	11,210	9,902
Total	27,695	26,316
65% to 75% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	531	372
2021	447	410
2020	398	1,748
2019	1,659	1,174
2018	1,162	406
Prior	3,455	3,490
Total	7,652	7,600
76% to 80% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	114	0
2020	0	0
2019	0	0
2018	30	188
Prior	468	274
Total	612	462
Greater than 80% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	162
2021	32	26
2020	61	0
2019	37	0
2018	0	248
Prior	1,116	851
Total	1,246	1,287
Greater than 1.2X | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	3,687	2,245
2021	2,347	1,662
2020	1,671	5,126
2019	5,032	3,926
2018	4,002	3,557
Prior	13,827	10,796
Total	30,566	27,312
1.00 - 1.20X | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	174	574
2021	654	1,019
2020	992	700
2019	553	1,138
2018	1,137	136
Prior	1,214	1,929
Total	4,724	5,496
Less than 1.00X | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	1
2021	0	27
2020	23	71
2019	71	925
2018	613	41
Prior	1,208	1,792
Total	$ 1,915	$ 2,857