SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Payments of Federal Government’s Claims and Related Reimbursements Under Deposit Accounting (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Health care cost payments	$ (7,477)	$ (7,073)	$ (7,110)
Health care cost reimbursements	7,385	7,130	7,135
Net (payments) reimbursements	$ (92)	$ 57	$ 25

The difference between health care cost payments and reimbursements related to the TRICARE South Region contract.

No definition available.

Name:	hum_HealthCareCostPaymentsAndReimbursementsNet
Namespace Prefix:	hum_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration