BASIS OF PRESENTATION - Accounts Receivable Aging (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 149,948	$ 157,042
Allowance for doubtful accounts	(51,314)	(59,689)
Net accounts receivable	98,634	97,353
Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	30,805	31,313
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	105,732	114,690
Patient
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	13,411	11,039
Receivables 0 to 180 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	114,591	119,435
Receivables 0 to 180 Days Past Due | Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	20,860	19,944
Receivables 0 to 180 Days Past Due | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	86,977	94,477
Receivables 0 to 180 Days Past Due | Patient
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	6,754	5,014
Receivables Over 180 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	35,357	37,607
Receivables Over 180 Days Past Due | Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	9,945	11,369
Receivables Over 180 Days Past Due | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	18,755	20,213
Receivables Over 180 Days Past Due | Patient
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 6,657	$ 6,025