REVENUE RECOGNITION AND ALLOWANCE FOR CREDIT LOSSES (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Percentage of net revenues	100.00%	100.00%	100.00%	100.00%
Net accounts receivable	100.00%		100.00%		100.00%
DIS business
Segment Reporting Information [Line Items]
Percentage of net revenues	97.00%	96.00%	96.00%	96.00%
Net accounts receivable	96.00%		96.00%		95.00%
DIS business \| Healthcare Insurers
Segment Reporting Information [Line Items]
Percentage of net revenues	35.00%	35.00%	35.00%	36.00%
Net accounts receivable	31.00%		31.00%		22.00%
DIS business \| Healthcare Insurers \| Fee-for-service
Segment Reporting Information [Line Items]
Percentage of net revenues	32.00%	32.00%	32.00%	33.00%
DIS business \| Healthcare Insurers \| Capitated
Segment Reporting Information [Line Items]
Percentage of net revenues	3.00%	3.00%	3.00%	3.00%
DIS business \| Government Payers
Segment Reporting Information [Line Items]
Percentage of net revenues	12.00%	15.00%	13.00%	15.00%
Net accounts receivable	8.00%		8.00%		11.00%
DIS business \| Client Payers
Segment Reporting Information [Line Items]
Percentage of net revenues	39.00%	32.00%	36.00%	32.00%
Net accounts receivable	42.00%		42.00%		42.00%
DIS business \| Patients
Segment Reporting Information [Line Items]
Percentage of net revenues	11.00%	14.00%	12.00%	13.00%
Net accounts receivable	15.00%		15.00%		20.00%
DIS business \| Minimum
Segment Reporting Information [Line Items]
Percentage of net revenues	95.00%	95.00%	95.00%	95.00%
All other operating segments \| DS Businesses
Segment Reporting Information [Line Items]
Percentage of net revenues	3.00%	4.00%	4.00%	4.00%
Net accounts receivable	4.00%		4.00%		5.00%