REVENUE RECOGNITION - Adjustments to Operating Results (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Patient Revenues, net	$ 141,082	$ 142,550	$ 282,367	$ 284,050
Operating Expenses	111,440	113,166	223,718	223,833
Total Expenses	140,489	$ 140,494	280,275	$ 279,034
Accounts Receivable	63,591		63,591
Accumulated Deficit	(15,673)		(15,673)		$ (14,534)
Difference Between Revenue Guidance In Effect before And After Topic 606, Adjustment For Implicit Price Concession Of Bad Debt Expense | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Patient Revenues, net	3,789		7,252
Difference Between Revenue Guidance In Effect before And After Topic 606, Adjustment For Implementation | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Patient Revenues, net	(362)		(618)
Accounts Receivable	(618)		(618)
Accumulated Deficit	618		618
Difference Between Revenue Guidance In Effect before And After Topic 606, Allowance For Doubtful Accounts | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable	16,050		16,050
Difference Between Revenue Guidance In Effect before And After Topic 606, Tax Adjustment | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accumulated Deficit	(198)		(198)
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Patient Revenues, net	3,427		6,634
Operating Expenses	3,789		7,252
Total Expenses	3,789		7,252
Accounts Receivable	15,432		15,432
Accumulated Deficit	420		420
Calculated under Revenue Guidance in Effect before Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Patient Revenues, net	144,509		289,001
Operating Expenses	115,229		230,970
Total Expenses	144,278		287,527
Accounts Receivable	79,023		79,023
Accumulated Deficit	$ (15,253)		$ (15,253)