BASIS OF PRESENTATION - Accounts Receivable Aging (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 153,538	$ 156,541
Allowance for doubtful accounts	(44,061)	(44,730)
Net accounts receivable	109,477	111,811
Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	25,154	28,169
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	114,295	117,592
Patient
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	14,089	10,780
Receivables 0 to 180 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	115,829	121,590
Receivables 0 to 180 Days Past Due | Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	17,963	19,891
Receivables 0 to 180 Days Past Due | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	91,676	97,744
Receivables 0 to 180 Days Past Due | Patient
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	6,190	3,955
Receivables Over 180 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	37,709	34,951
Receivables Over 180 Days Past Due | Government
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	7,191	8,278
Receivables Over 180 Days Past Due | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	22,619	19,848
Receivables Over 180 Days Past Due | Patient
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 7,899	$ 6,825