BENEFITS PAYABLE - Activity in Benefits Payable (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balances, beginning of period	$ 8,289	$ 8,143
Acquisitions	0	42
Incurred related to:
Current year	39,121	35,164
Prior years	(397)	(719)
Total incurred	38,724	34,445
Paid related to:
Current year	(30,356)	(27,556)
Prior years	(7,007)	(6,589)
Total paid	(37,363)	(34,145)
Balances, end of period	9,650	8,485
Retail
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balances, beginning of period	7,675	7,428
Acquisitions	0	42
Incurred related to:
Current year	37,299	32,986
Prior years	(367)	(619)
Total incurred	36,932	32,367
Paid related to:
Current year	(29,061)	(25,953)
Prior years	(6,459)	(5,990)
Total paid	(35,520)	(31,943)
Balances, end of period	9,087	7,894
Total IBNR included in benefits payable	5,500
Group and Specialty
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balances, beginning of period	614	715
Incurred related to:
Current year	2,121	2,492
Prior years	(30)	(100)
Total incurred	2,091	2,392
Paid related to:
Current year	(1,594)	(1,917)
Prior years	(548)	(599)
Total paid	(2,142)	(2,516)
Balances, end of period	563	$ 591
Total IBNR included in benefits payable	$ 488