SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Intangible Assets (Details)	12 Months Ended
	Dec. 31, 2018
Managed care contracts
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives	4 years
Minimum | Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives	1 year
Maximum | Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives	5 years