Lending Activities - Credit quality performance indicators for commercial mortgages (Details) $ in Millions	Jun. 30, 2022 USD ($) loan	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) loan	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 49,917		$ 46,677
Allowance for credit losses	$ 603	$ 617	$ 629	$ 701	$ 787	$ 814
Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	644		649
Total	$ 37,205		$ 35,665
Allowance for credit losses	$ 525	$ 533	$ 545	$ 587	$ 662	$ 685
Percent of Total	100.00%		100.00%
Percentage of total, allowance for credit losses	1.00%		2.00%
Commercial mortgage loans | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	631		636
Total	$ 36,462		$ 35,015
Percent of Total	98.00%		98.00%
Commercial mortgage loans | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	10		8
Total	$ 630		$ 515
Percent of Total	2.00%		2.00%
Commercial mortgage loans | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	0		0
Total	$ 0		$ 0
Percent of Total	0.00%		0.00%
Commercial mortgage loans | >90 days delinquent or in process of foreclosure
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	3		5
Total	$ 113		$ 135
Percent of Total	0.00%		0.00%
Commercial mortgage loans | Apartments
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 13,706		$ 14,267
Allowance for credit losses	88		109
Commercial mortgage loans | Apartments | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	13,706		14,267
Commercial mortgage loans | Apartments | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Apartments | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Apartments | >90 days delinquent or in process of foreclosure
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Offices
Financing Receivable, Credit Quality Indicator [Line Items]
Total	10,931		10,130
Allowance for credit losses	230		247
Commercial mortgage loans | Offices | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	10,513		9,695
Commercial mortgage loans | Offices | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Total	353		354
Commercial mortgage loans | Offices | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Offices | >90 days delinquent or in process of foreclosure
Financing Receivable, Credit Quality Indicator [Line Items]
Total	65		81
Commercial mortgage loans | Retail
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,478		4,857
Allowance for credit losses	98		103
Commercial mortgage loans | Retail | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,290		4,778
Commercial mortgage loans | Retail | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Total	140		25
Commercial mortgage loans | Retail | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Retail | >90 days delinquent or in process of foreclosure
Financing Receivable, Credit Quality Indicator [Line Items]
Total	48		54
Commercial mortgage loans | Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	5,505		3,858
Allowance for credit losses	67		47
Commercial mortgage loans | Industrial | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	5,505		3,858
Commercial mortgage loans | Industrial | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Industrial | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Industrial | >90 days delinquent or in process of foreclosure
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Hotel
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,192		2,121
Allowance for credit losses	33		31
Commercial mortgage loans | Hotel | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,055		1,985
Commercial mortgage loans | Hotel | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Total	137		136
Commercial mortgage loans | Hotel | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Hotel | >90 days delinquent or in process of foreclosure
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Others
Financing Receivable, Credit Quality Indicator [Line Items]
Total	393		432
Allowance for credit losses	9		8
Commercial mortgage loans | Others | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	393		432
Commercial mortgage loans | Others | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Others | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Others | >90 days delinquent or in process of foreclosure
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 0		$ 0