SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Health Care Cost Payments, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Health care cost payments	$ (7,110)	$ (6,943)	$ (6,253)
Health care cost reimbursements	7,135	6,898	6,252
Net reimbursements (payments)	$ 25	$ (45)	$ (1)