Medical Claims and Benefits Payable - Components of Change in Medical Claims and Benefits Payable (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Insurance Claims
Medical claims and benefits payable, beginning balance	$ 3,528	$ 3,363
Components of medical care costs related to:
Current year	21,573	20,521
Prior years	(358)	(338)
Total medical care costs	21,215	20,183
Payments for medical care costs related to:
Current year	18,228	17,538
Prior years	2,707	2,481
Total paid	20,935	20,019
Acquired balances, net of post-acquisition adjustments	96	8
Change in non-risk and other provider payables	331	87
Medical claims and benefits payable, ending balance	4,235	3,622
Medicaid
Insurance Claims
Medical claims and benefits payable, beginning balance	2,815	2,580
Components of medical care costs related to:
Current year	17,630	16,520
Prior years	(327)	(282)
Total medical care costs	17,303	16,238
Payments for medical care costs related to:
Current year	14,961	14,133
Prior years	2,074	1,861
Total paid	17,035	15,994
Acquired balances, net of post-acquisition adjustments	83	8
Change in non-risk and other provider payables	335	91
Medical claims and benefits payable, ending balance	3,501	2,923
Medicare
Insurance Claims
Medical claims and benefits payable, beginning balance	452	404
Components of medical care costs related to:
Current year	2,811	2,525
Prior years	(6)	(38)
Total medical care costs	2,805	2,487
Payments for medical care costs related to:
Current year	2,340	2,103
Prior years	424	337
Total paid	2,764	2,440
Acquired balances, net of post-acquisition adjustments	13	0
Change in non-risk and other provider payables	(4)	(4)
Medical claims and benefits payable, ending balance	502	447
Marketplace
Insurance Claims
Medical claims and benefits payable, beginning balance	261	379
Components of medical care costs related to:
Current year	1,132	1,476
Prior years	(25)	(18)
Total medical care costs	1,107	1,458
Payments for medical care costs related to:
Current year	927	1,302
Prior years	209	283
Total paid	1,136	1,585
Acquired balances, net of post-acquisition adjustments	0	0
Change in non-risk and other provider payables	0	0
Medical claims and benefits payable, ending balance	$ 232	$ 252