COMMITMENTS, GUARANTEES AND CONTINGENCIES (Details) beneficiary in Millions, $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019 beneficiary	Dec. 31, 2020	Dec. 31, 2018 State	Nov. 02, 2017 USD ($)
Loss Contingencies [Line Items]
Percentage of risk score calculated from claims submitted through EDS	25.00%		15.00%
Number of states comprising TRICARE beneficiaries | State			32
Number of TRICARE beneficiaries | beneficiary	6
Litigation recoveries sought | $				$ 611
Tricare East Region Contract
Loss Contingencies [Line Items]
Contract term years	5 years
Forecast
Loss Contingencies [Line Items]
Percentage of risk score calculated from claims submitted through EDS		50.00%
Medicare
Loss Contingencies [Line Items]
Percentage of premiums and services revenue	82.00%
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	4.00%