COMMITMENTS, GUARANTEES AND CONTINGENCIES (Details) beneficiary in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021 beneficiary state	Dec. 31, 2020
Loss Contingencies [Line Items]
Percentage of risk score calculated from claims submitted through EDS	75.00%	50.00%
Number of states comprising TRICARE beneficiaries | state	32
Number of TRICARE beneficiaries | beneficiary	6
Tricare East Region Contract
Loss Contingencies [Line Items]
Contract term years	5 years
Medicare
Loss Contingencies [Line Items]
Percentage of premiums and services revenue	84.00%
Military services
Loss Contingencies [Line Items]
Percentage of premiums and services revenue	1.00%
Medicaid
Loss Contingencies [Line Items]
Percentage of premiums and services revenue	6.00%