REVENUE RECOGNITION AND ACCOUNTS RECEIVABLE - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
COVID-19, medicaid funds received	$ 6,645		$ 11,709
Disaggregation of Revenue [Line Items]
Total revenues	$ 117,965	$ 118,630	$ 356,195	$ 354,145
Total revenues, as a percent	100.00%	100.00%	100.00%	100.00%
Medicaid
Disaggregation of Revenue [Line Items]
Total revenues	$ 55,844	$ 57,191	$ 164,335	$ 164,815
Total revenues, as a percent	47.30%	48.20%	46.10%	46.50%
Medicare
Disaggregation of Revenue [Line Items]
Total revenues	$ 24,374	$ 19,274	$ 67,470	$ 59,211
Total revenues, as a percent	20.70%	16.20%	18.90%	16.70%
Managed Care
Disaggregation of Revenue [Line Items]
Total revenues	$ 11,967	$ 11,794	$ 36,918	$ 37,911
Total revenues, as a percent	10.10%	9.90%	10.40%	10.70%
Private Pay and other
Disaggregation of Revenue [Line Items]
Total revenues	$ 25,780	$ 30,371	$ 87,472	$ 92,208
Total revenues, as a percent	21.90%	25.70%	24.60%	26.10%