SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Patient Accounts Receivable Narrative (Details) - day	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Percentage of patient receivables outstanding	10.00%
Historical collection rate from Medicare	99.00%
Portion of accounts receivable derived from Medicare	64.00%	58.00%
Rate of request for anticipated payment submitted for the initial period of care	20.00%
Maximum days to submit final bill from the start of period of care	90
Maximum days to submit final bill from the date the request for anticipated payment was paid	60