Health Care Costs Payable - Components of Change in Health Care Costs Payable (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 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	11,998
Health Care Benefits
Less: Claims paid
Benefit costs recorded in other insurance liabilities	42	$ 41
Corporate / Other
Less: Claims paid
Benefit costs recorded in other insurance liabilities	102	149
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
Acquisitions, net	1,102	0
Add: Components of incurred health care costs
Current year	42,705	35,884
Prior years	(619)	(666)
Total incurred health care costs	42,086	35,218
Less: Claims paid
Current year	32,502	26,971
Prior years	8,800	6,732
Total claims paid	41,302	33,703
Add: Premium deficiency reserve	0	5
Health care costs payable, end of the period, net	12,015	10,190
Add: Reinsurance recoverables	5	4
Add: Impact of discount rate on long-duration insurance reserves	(22)	8
Health care costs payable, end of the period	11,998	10,202
Premium deficiency reserve	$ 0	$ 5