Health Care Costs Payable - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred but not reported (IBNR) claims liability, net	$ 8,900
Health Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Decrease in prior years' healthcare costs payable	$ 679	$ 670