SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Patient Accounts Receivable Narrative (Details) - day	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Concentration Risk [Line Items]
Percentage of patient receivables outstanding	10.00%
Accounts receivable derived from Medicare	57.00%	56.00%
Historical collection rate from Medicare	99.00%
Rate of request for anticipated payment submitted for the initial episode of care	60.00%
Rate of request for anticipated payment submitted for subsequent episodes of care	50.00%
Maximum days to submit final bill from the start of episode	120
Maximum days to submit final bill from the date the request for anticipated payment was paid	60