BENEFITS PAYABLE - Activity in Benefits Payable (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 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	57,512	52,529
Prior years	(404)	(768)
Total incurred	57,108	51,761
Paid related to:
Current year	(48,835)	(44,370)
Prior years	(7,325)	(6,818)
Total paid	(56,160)	(51,188)
Balances, end of period	9,237	8,758
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	54,731	49,247
Prior years	(379)	(673)
Total incurred	54,352	48,574
Paid related to:
Current year	(46,608)	(41,721)
Prior years	(6,757)	(6,216)
Total paid	(53,365)	(47,937)
Balances, end of period	8,662	8,107
Total IBNR included in benefits payable	5,200
Group and Specialty
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balances, beginning of period	614	715
Acquisitions	0	0
Incurred related to:
Current year	3,168	3,769
Prior years	(25)	(95)
Total incurred	3,143	3,674
Paid related to:
Current year	(2,614)	(3,136)
Prior years	(568)	(602)
Total paid	(3,182)	(3,738)
Balances, end of period	575	$ 651
Total IBNR included in benefits payable	$ 484