BASIS OF PRESENTATION - Accounts Receivable Aging (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 148,740	$ 156,541
Allowance for doubtful accounts	(45,651)	(44,730)
Net accounts receivable	103,089	111,811
Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	26,226	28,169
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	107,779	117,592
Patient
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	14,735	10,780
Receivables 0 to 180 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	108,099	121,590
Receivables 0 to 180 Days Past Due | Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	18,714	19,891
Receivables 0 to 180 Days Past Due | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	84,190	97,744
Receivables 0 to 180 Days Past Due | Patient
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	5,195	3,955
Receivables Over 180 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	40,641	34,951
Receivables Over 180 Days Past Due | Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	7,512	8,278
Receivables Over 180 Days Past Due | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	23,589	19,848
Receivables Over 180 Days Past Due | Patient
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 9,540	$ 6,825