SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Patient Accounts Receivable Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) day	Jun. 30, 2017 USD ($)	Dec. 31, 2017
Concentration Risk [Line Items]
Percentage of patient receivables outstanding			10.00%
Accounts receivable derived from Medicare	56.00%		56.00%		59.00%
Historical collection rate from Medicare			99.00%
Revenue adjustment to Medicare revenue | $	$ 2.5	$ 5.0	$ 4.2	$ 8.4
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
Customer Concentration Risk | Accounts Receivable | Single Payor
Concentration Risk [Line Items]
Concentration risk (percent)			11.80%