Health Care Costs Payable - Components of Change in Health Care Costs Payable (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Health care costs payable, beginning of the period	$ 12,049
Less: Reinsurance recoverables	5
Less: Impact of discount rate on long-duration insurance reserves	(23)
Health care costs payable, beginning of the period, net	12,067
Add: Components of incurred health care costs
Current year	28,212
Prior years	(479)
Total incurred health care costs	27,733
Less: Claims paid
Current year	16,263
Prior years	9,150
Total claims paid	25,413
Health care costs payable, end of the period, net	14,387
Add: Reinsurance recoverables	4
Add: Impact of discount rate on long-duration insurance reserves	(23)
Health care costs payable, end of the period	14,368
Health Care Benefits
Less: Claims paid
Benefit costs recorded in other insurance liabilities	23	$ 22
Corporate/ Other
Less: Claims paid
Benefit costs recorded in other insurance liabilities	$ 47	51
Health Insurance Product Line
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Health care costs payable, beginning of the period		10,142
Less: Reinsurance recoverables		5
Less: Impact of discount rate on long-duration insurance reserves		8
Health care costs payable, beginning of the period, net		10,129
Add: Components of incurred health care costs
Current year		21,068
Prior years		(693)
Total incurred health care costs		20,375
Less: Claims paid
Current year		11,957
Prior years		7,645
Total claims paid		19,602
Health care costs payable, end of the period, net		10,902
Add: Reinsurance recoverables		5
Add: Impact of discount rate on long-duration insurance reserves		(12)
Health care costs payable, end of the period		$ 10,895