REVENUE RECOGNITION AND ACCOUNTS RECEIVABLE - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
COVID-19, Medicaid funds received	$ 4,203		$ 5,064
Total revenues	$ 118,243	$ 117,967	$ 238,230	$ 235,517
Total revenues, as a percent	100.00%	100.00%	100.00%	100.00%
Medicaid
Disaggregation of Revenue [Line Items]
Total revenues	$ 54,161	$ 53,812	$ 108,491	$ 107,623
Total revenues, as a percent	45.80%	45.60%	45.50%	45.70%
Medicare
Disaggregation of Revenue [Line Items]
Total revenues	$ 22,424	$ 19,545	$ 43,096	$ 39,936
Total revenues, as a percent	19.00%	16.60%	18.10%	17.00%
Managed Care
Disaggregation of Revenue [Line Items]
Total revenues	$ 12,355	$ 13,120	$ 24,951	$ 26,118
Total revenues, as a percent	10.40%	11.10%	10.50%	11.10%
Private Pay and other
Disaggregation of Revenue [Line Items]
Total revenues	$ 29,303	$ 31,490	$ 61,692	$ 61,840
Total revenues, as a percent	24.80%	26.70%	25.90%	26.20%