Lending Activities - Credit Quality Performance Indicators for Commercial Mortgages (Details) $ in Millions	Mar. 31, 2024 USD ($) loan	Dec. 31, 2023 USD ($) loan	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Allowance for credit losses	$ 38,501	$ 38,473
Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	614	612
Total	$ 38,478	$ 38,009
Allowance for credit losses	$ 784	$ 752	$ 706	$ 640
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	610	610
Total	$ 38,147	$ 37,937
Percent of Total	99.00%	100.00%
Commercial mortgage loans | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	2	1
Total	$ 261	$ 29
Percent of Total	1.00%	0.00%
Commercial mortgage loans | >90 days delinquent or in process of foreclosure
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	2	1
Total	$ 70	$ 43
Percent of Total	0.00%	0.00%
Commercial mortgage loans | Apartments
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 15,268	$ 15,129
Allowance for credit losses	82	94
Commercial mortgage loans | Apartments | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	15,268	15,129
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	9,663	9,708
Allowance for credit losses	441	415
Commercial mortgage loans | Offices | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	9,573	9,679
Commercial mortgage loans | Offices | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	61	29
Commercial mortgage loans | Offices | 90 days or less delinquent | Fortitude RE Funds Withheld Assets
Financing Receivable, Credit Quality Indicator [Line Items]
Total	61
Commercial mortgage loans | Offices | >90 days delinquent or in process of foreclosure
Financing Receivable, Credit Quality Indicator [Line Items]
Total	29	0
Commercial mortgage loans | Retail
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,413	4,306
Allowance for credit losses	113	109
Commercial mortgage loans | Retail | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,172	4,263
Commercial mortgage loans | Retail | 90 days or less delinquent
Financing Receivable, Credit Quality Indicator [Line Items]
Total	200	0
Commercial mortgage loans | Retail | 90 days or less delinquent | Fortitude RE Funds Withheld Assets
Financing Receivable, Credit Quality Indicator [Line Items]
Total	20
Commercial mortgage loans | Retail | >90 days delinquent or in process of foreclosure
Financing Receivable, Credit Quality Indicator [Line Items]
Total	41	43
Commercial mortgage loans | Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	6,572	6,367
Allowance for credit losses	98	90
Commercial mortgage loans | Industrial | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	6,572	6,367
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	2,039	2,053
Allowance for credit losses	43	38
Commercial mortgage loans | Hotel | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,039	2,053
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	523	446
Allowance for credit losses	7	6
Commercial mortgage loans | Others | In good standing
Financing Receivable, Credit Quality Indicator [Line Items]
Total	523	446
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