Medical Claims Liability - Schedule of Change in Medical Claims Liability (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance, January 1	$ 16,745	$ 14,243
Less: Reinsurance recoverable	26	23
Balance, January 1, net	16,719	14,220
Acquisitions and divestitures		249
Incurred related to:
Current year	90,148	84,457
Prior years	(1,888)	(1,196)
Total incurred	88,260	83,261
Paid related to:
Current year	75,402	70,305
Prior years	12,481	10,968
Total paid	87,883	81,273
Balance, June 30, net	17,096	16,457
Plus: Reinsurance recoverable	45	8
Balance, June 30	17,141	16,465
Medicaid
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance, January 1	11,253	9,845
Less: Reinsurance recoverable	7	23
Balance, January 1, net	11,246	9,822
Acquisitions and divestitures		0
Incurred related to:
Current year	60,379	57,074
Prior years	(1,303)	(966)
Total incurred	59,076	56,108
Paid related to:
Current year	50,774	47,481
Prior years	8,517	7,343
Total paid	59,291	54,824
Balance, June 30, net	11,031	11,106
Plus: Reinsurance recoverable	4	8
Balance, June 30	11,035	11,114
Medicare
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance, January 1	3,431	2,286
Less: Reinsurance recoverable	0	0
Balance, January 1, net	3,431	2,286
Acquisitions and divestitures		0
Incurred related to:
Current year	14,680	14,624
Prior years	(326)	(22)
Total incurred	14,354	14,602
Paid related to:
Current year	12,069	11,603
Prior years	2,452	1,963
Total paid	14,521	13,566
Balance, June 30, net	3,264	3,322
Plus: Reinsurance recoverable	0	0
Balance, June 30	3,264	3,322
Commercial
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance, January 1	1,921	2,014
Less: Reinsurance recoverable	19	0
Balance, January 1, net	1,902	2,014
Acquisitions and divestitures		0
Incurred related to:
Current year	13,994	10,609
Prior years	(256)	(193)
Total incurred	13,738	10,416
Paid related to:
Current year	11,575	9,046
Prior years	1,376	1,580
Total paid	12,951	10,626
Balance, June 30, net	2,689	1,804
Plus: Reinsurance recoverable	41	0
Balance, June 30	2,730	1,804
Other
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance, January 1	140	98
Less: Reinsurance recoverable	0	0
Balance, January 1, net	140	98
Acquisitions and divestitures		249
Incurred related to:
Current year	1,095	2,150
Prior years	(3)	(15)
Total incurred	1,092	2,135
Paid related to:
Current year	984	2,175
Prior years	136	82
Total paid	1,120	2,257
Balance, June 30, net	112	225
Plus: Reinsurance recoverable	0	0
Balance, June 30	$ 112	$ 225