ASSETS HELD FOR SALE - Schedule of assets and liabilities held for sale (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating lease right-of-use assets	$ 138,640	$ 133,899
Operating lease liabilities	4,291	5,767
Current liabilities held for sale	4,291	5,767
Certain Clinics In Pennsylvania, Ohio, and New Jersey and Other Property and Equipment | Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Inventories	269	265
Prepaid expenses and other current assets	20	20
Property and equipment, net	11,036	11,245
Operating lease right-of-use assets	3,970	5,408
Goodwill	34,184	34,184
Valuation allowance on disposal group	(282)	(1,023)
Total assets held for sale	49,197	50,099
Operating lease liabilities	4,291	5,767
Current liabilities held for sale	$ 4,291	$ 5,767