BASIS OF PRESENTATION - Accounts Receivable Aging (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 158,575	$ 157,042
Allowance for doubtful accounts	(56,805)	(59,689)
Net accounts receivable	101,770	97,353
Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	31,900	31,313
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	114,431	114,690
Patient
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	12,244	11,039
Receivables 0 to 180 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	120,458	119,435
Receivables 0 to 180 Days Past Due | Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	21,183	19,944
Receivables 0 to 180 Days Past Due | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	92,194	94,477
Receivables 0 to 180 Days Past Due | Patient
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	7,081	5,014
Receivables Over 180 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	38,117	37,607
Receivables Over 180 Days Past Due | Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	10,717	11,369
Receivables Over 180 Days Past Due | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	22,237	20,213
Receivables Over 180 Days Past Due | Patient
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 5,163	$ 6,025