ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES AND OTHER LIABILITIES - Accrued expenses and other current liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES AND OTHER LIABILITIES
Patient prepayments, deposits and refunds payable	$ 25,242		$ 30,194
Accrued professional fees	4,260		11,612
Insurance and self-insurance accruals	8,894		8,901
Accrued sales taxes and other taxes	6,055		6,335
Derivative liability	1,222
Accrued interest payable	400		845
Other current liabilities	8,185		8,421
Total accrued expenses and other current liabilities	$ 54,258	$ 67,335	$ 66,308