Health Care Costs Payable - Reconciliation of Health Care Costs Payable (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Health care costs payable, beginning of period, net	$ 7,936
Less: Claims paid
Health care costs payable, end of period, net	8,808	$ 7,936
Health Care Benefits
Less: Claims paid
Benefit costs recorded in other insurance liabilities	59	41	$ 41
Corporate/ Other
Less: Claims paid
Benefit costs recorded in other insurance liabilities	212	221	285
Health Insurance Product Line
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Health care costs payable, beginning of period	7,936	6,879	6,147
Less: Reinsurance recoverables	10	5	4
Health care costs payable, beginning of period, net	7,926	6,874	6,143
Acquisitions, net	0	414	0
Add: Components of incurred health care costs
Current year	64,761	55,835	52,723
Decrease in prior years' healthcare costs payable	(788)	(429)	(524)
Total incurred health care costs	63,973	55,406	52,199
Less: Claims paid
Current year	56,323	48,770	46,158
Prior years	6,792	6,009	5,314
Total claims paid	63,115	54,779	51,472
Add: Premium deficiency reserve	16	11	4
Health care costs payable, end of period, net	8,800	7,926	6,874
Add: Reinsurance recoverables	8	10	5
Health care costs payable, end of period	$ 8,808	$ 7,936	$ 6,879