Health Care Costs Payable - Components of Change in Health Care Costs Payable (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Health care costs payable, beginning of the period	$ 10,142
Less: Claims paid
Health care costs payable, end of the period	10,895
Health Care Benefits
Less: Claims paid
Benefit costs recorded in other insurance liabilities	22	$ 21
Corporate / Other
Less: Claims paid
Benefit costs recorded in other insurance liabilities	51	61
Health Insurance Product Line
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Health care costs payable, beginning of the period	10,142	8,678
Less: Reinsurance recoverables	5	8
Less: Impact of discount rate on long-duration insurance reserves	8	0
Health care costs payable, beginning of the period, net	10,129	8,670
Add: Components of incurred health care costs
Current year	21,068	18,504
Prior years	(693)	(676)
Total incurred health care costs	20,375	17,828
Less: Claims paid
Current year	11,957	10,225
Prior years	7,645	6,183
Total claims paid	19,602	16,408
Add: Premium deficiency reserve	0	13
Health care costs payable, end of the period, net	10,902	10,090
Add: Reinsurance recoverables	5	8
Add: Impact of discount rate on long-duration insurance reserves	(12)	7
Health care costs payable, end of the period	10,895	10,105
Premium deficiency reserve	0	13
Health Insurance Product Line | Thailand Business
Less: Claims paid
Other	$ 0	$ (13)