Reserve for Unpaid Losses and Loss Adjustment Expenses - GB Liabilities for Unpaid Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Beginning liabilities for unpaid losses and loss adjustment expenses, gross	$ 41,243
Less: payments
Ending liabilities for unpaid losses and loss adjustment expenses, gross	41,219
Group Insurance Policy [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Beginning liabilities for unpaid losses and loss adjustment expenses, gross	8,160	$ 8,210
Reinsurance recoverables	243	254	$ 245	$ 245
Beginning liabilities for unpaid losses and loss adjustment expenses, net	7,915	7,965
Provision for unpaid losses and loss adjustment expense
Current incurral year	2,622	2,497
Prior year's discount accretion	103	107
Prior incurral year development [1]	(265)	(242)
Total provision for unpaid losses and loss adjustment expenses	2,460	2,362
Less: payments
Current incurral year	(1,012)	(984)
Prior incurral years	(1,416)	(1,500)
Total payments	(2,428)	(2,484)
Beginning liabilities for unpaid losses and loss adjustment expenses, net	7,947	7,843	$ 7,915	$ 7,965
Ending liabilities for unpaid losses and loss adjustment expenses, gross	8,190	8,097
Group Insurance Policy [Member] | Disability Insurance Policy [Member]
Provision for unpaid losses and loss adjustment expense
Prior incurral year development [1]	236	195
Group Insurance Policy [Member] | group life term, disability and accident [Member]
Provision for unpaid losses and loss adjustment expense
Prior incurral year development [1]	19	40
Group Insurance Policy [Member] | Supplemental Health
Provision for unpaid losses and loss adjustment expense
Prior incurral year development [1]	10	10
Group Insurance Policy [Member] | Other Operating Income (Expense) [Member]
Provision for unpaid losses and loss adjustment expense
Total provision for unpaid losses and loss adjustment expenses	$ 91	$ 92