SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Receipts (Payments) from Contract Deposits, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Part D subsidy/discount payments	$ (17,762)	$ (17,582)	$ (16,530)
Part D subsidy/discount reimbursements	15,921	18,353	18,498
Net (payments) reimbursements	$ (1,841)	$ 771	$ 1,968