Lending Activities - Credit quality performance indicators for commercial mortgages (Details) $ in Millions	Dec. 31, 2023 USD ($) loan	Dec. 31, 2022 USD ($) loan	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 47,565	$ 45,166
Allowance for credit losses	$ 698	$ 600	$ 496	$ 657
Commercial Mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	601	611
Total	$ 34,172	$ 32,993
Allowance for credit losses	$ 614	$ 531	$ 423	$ 546
Percent of Total	100.00%	100.00%
Percentage of total, allowance for credit losses	2.00%	2.00%
Commercial Mortgages | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	600	599
Total	$ 34,154	$ 32,344
Percent of Total	100.00%	98.00%
Commercial Mortgages | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan		9
Total		$ 482
Percent of Total		1.00%
Commercial Mortgages | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	1	0
Total	$ 18	$ 0
Percent of Total	0.00%	0.00%
Commercial Mortgages | >90 days delinquent or in process of foreclosure(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	0	3
Total	$ 0	$ 167
Percent of Total	0.00%	1.00%
Commercial Mortgages | Apartments
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 13,861	$ 13,226
Allowance for credit losses	85	89
Commercial Mortgages | Apartments | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	13,861	13,226
Commercial Mortgages | Apartments | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Total		0
Commercial Mortgages | Apartments | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0	0
Commercial Mortgages | Apartments | >90 days delinquent or in process of foreclosure(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0	0
Commercial Mortgages | Offices
Financing Receivable, Credit Quality Indicator [Line Items]
Total	8,486	8,966
Allowance for credit losses	340	294
Commercial Mortgages | Offices | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	8,468	8,470
Commercial Mortgages | Offices | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Total		329
Commercial Mortgages | Offices | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	18	0
Commercial Mortgages | Offices | >90 days delinquent or in process of foreclosure(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0	167
Commercial Mortgages | Retail
Financing Receivable, Credit Quality Indicator [Line Items]
Total	3,787	3,286
Allowance for credit losses	74	54
Commercial Mortgages | Retail | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	3,787	3,192
Commercial Mortgages | Retail | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Total		94
Commercial Mortgages | Retail | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0	0
Commercial Mortgages | Retail | >90 days delinquent or in process of foreclosure(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0	0
Commercial Mortgages | Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	5,908	5,417
Allowance for credit losses	83	65
Commercial Mortgages | Industrial | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	5,908	5,417
Commercial Mortgages | Industrial | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Total		0
Commercial Mortgages | Industrial | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0	0
Commercial Mortgages | Industrial | >90 days delinquent or in process of foreclosure(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0	0
Commercial Mortgages | Hotel
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,805	1,808
Allowance for credit losses	27	23
Commercial Mortgages | Hotel | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,805	1,749
Commercial Mortgages | Hotel | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Total		59
Commercial Mortgages | Hotel | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0	0
Commercial Mortgages | Hotel | >90 days delinquent or in process of foreclosure(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0	0
Commercial Mortgages | Others
Financing Receivable, Credit Quality Indicator [Line Items]
Total	325	290
Allowance for credit losses	5	6
Commercial Mortgages | Others | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	325	290
Commercial Mortgages | Others | Restructured
Financing Receivable, Credit Quality Indicator [Line Items]
Total		0
Commercial Mortgages | Others | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0	0
Commercial Mortgages | Others | >90 days delinquent or in process of foreclosure(a)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 0	$ 0