Reinsurance - Rollforward of the reinsurable allowance for credit losses before adoption (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Jan. 01, 2021	Dec. 31, 2020
Fortitude RE
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes	$ 30,612	$ 30,751	$ 42,244	$ 36,801
Excluding Fortitude
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes	$ 36,914	38,971	39,432	36,300
As Previously Reported | Fortitude RE
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes		32,159	34,578	29,135
As Previously Reported | Excluding Fortitude
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes		$ 39,434	$ 38,963
Adjustments for NPR* > 100% | Fortitude RE | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				55
Change due to the current upper-medium grade discount rate | Fortitude RE | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				7,611
General Insurance
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				5,400
Life and Retirement
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				3,176
Life and Retirement | As Previously Reported
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				2,707
Life and Retirement | Reclassification of cost of reinsurance | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				416
Life and Retirement | Reclassification to Market risk benefits | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				(35)
Life and Retirement | Adjustments for NPR* > 100% | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				9
Life and Retirement | Change due to the current upper-medium grade discount rate | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				79
Life and Retirement | Individual Retirement
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				274
Life and Retirement | Individual Retirement | As Previously Reported
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				309
Life and Retirement | Individual Retirement | Reclassification of cost of reinsurance | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				0
Life and Retirement | Individual Retirement | Reclassification to Market risk benefits | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				(35)
Life and Retirement | Individual Retirement | Adjustments for NPR* > 100% | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				0
Life and Retirement | Individual Retirement | Change due to the current upper-medium grade discount rate | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				0
Life and Retirement | Life Insurance
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				2,869
Life and Retirement | Life Insurance | As Previously Reported
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				2,370
Life and Retirement | Life Insurance | Reclassification of cost of reinsurance | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				416
Life and Retirement | Life Insurance | Reclassification to Market risk benefits | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				0
Life and Retirement | Life Insurance | Adjustments for NPR* > 100% | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				9
Life and Retirement | Life Insurance | Change due to the current upper-medium grade discount rate | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				74
Life and Retirement | Institutional Markets
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				33
Life and Retirement | Institutional Markets | As Previously Reported
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				28
Life and Retirement | Institutional Markets | Reclassification of cost of reinsurance | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				0
Life and Retirement | Institutional Markets | Reclassification to Market risk benefits | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				0
Life and Retirement | Institutional Markets | Adjustments for NPR* > 100% | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				0
Life and Retirement | Institutional Markets | Change due to the current upper-medium grade discount rate | ASU 2018-12
Effects of Reinsurance [Line Items]
Reinsurance assets, net of allowance for credit losses and disputes				$ 5