SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Receipts (Payments) from Contract Deposits, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Part D subsidy/discount payments	$ (12,121)	$ (17,762)	$ (17,582)
Part D subsidy/discount reimbursements	11,119	15,921	18,353
Net (payments) reimbursements	$ (1,002)	$ (1,841)	$ 771