Lending Activities - Credit quality performance indicators for commercial mortgages (Details) $ in Millions	Sep. 30, 2023 USD ($) loan	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($) loan	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Allowance for credit losses	$ 38,521		$ 38,351
Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	638		629
Total	$ 37,996		$ 37,128
Allowance for credit losses	$ 812	$ 737	$ 640	$ 564	$ 525	$ 545
Percent of Total	100.00%		100.00%
Percentage of total, allowance for credit losses	2.00%		2.00%
Commercial mortgage loans | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	635		625
Total	$ 37,765		$ 36,913
Percent of Total	99.00%		99.00%
Commercial mortgage loans | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	1		0
Total	$ 34		$ 0
Percent of Total	0.00%		0.00%
Commercial mortgage loans | >90 days delinquent or in process of foreclosure(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	2		4
Total	$ 197		$ 215
Percent of Total	1.00%		1.00%
Commercial mortgage loans | Apartments
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 15,175		$ 14,597
Allowance for credit losses	93		100
Commercial mortgage loans | Apartments | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	15,175		14,597
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(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Offices
Financing Receivable, Credit Quality Indicator [Line Items]
Total	9,952		10,275
Allowance for credit losses	507		351
Commercial mortgage loans | Offices | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	9,761		10,102
Commercial mortgage loans | Offices | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	34		0
Commercial mortgage loans | Offices | >90 days delinquent or in process of foreclosure(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	157		173
Commercial mortgage loans | Retail
Financing Receivable, Credit Quality Indicator [Line Items]
Total	3,976		3,816
Allowance for credit losses	83		81
Commercial mortgage loans | Retail | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	3,936		3,774
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(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	40		42
Commercial mortgage loans | Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	6,414		6,006
Allowance for credit losses	86		71
Commercial mortgage loans | Industrial | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	6,414		6,006
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(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Hotel
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,047		2,027
Allowance for credit losses	37		29
Commercial mortgage loans | Hotel | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,047		2,027
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(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0
Commercial mortgage loans | Others
Financing Receivable, Credit Quality Indicator [Line Items]
Total	432		407
Allowance for credit losses	6		8
Commercial mortgage loans | Others | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	432		407
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(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 0		$ 0