REVENUE RECOGNITION - Summary of Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 62,036	$ 66,257
Medicaid
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	25,366	27,532
Medicare
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	10,686	15,706
Managed Care
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	8,376	8,126
Private Pay and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 17,608	$ 14,893