GOODWILL AND OTHER INTANGIBLE ASSETS, NET - Activity Related to Other Intangible Assets, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Intangible Assets [Line Items]
Non-cash impairment charge for write-off of intangible assets		$ 1,300
Intangible assets, accumulated amortization	$ 33,050	30,610
Weighted-average amortization period	1 year 8 months 12 days
Intangible Assets [Roll Forward]
Beginning balance	$ 46,061	46,700	$ 44,000
Additions	500	3,400	5,200
Write-off		(1,300)
Amortization	(2,500)	(2,700)	(2,500)
Ending balance	44,132	46,061	46,700
Acquired Names Of Business [Member]
Intangible Assets [Line Items]
Intangible assets, accumulated amortization	500
Noncompete Agreements [Member]
Intangible Assets [Line Items]
Intangible assets, accumulated amortization	21,700
Intangible Assets [Roll Forward]
Beginning balance	2,800	4,900	5,900
Additions	300	600	1,500
Write-off		0
Amortization	(2,500)	(2,700)	(2,500)
Ending balance	600	2,800	4,900
Certificates of Need and Licenses [Member]
Intangible Assets [Roll Forward]
Beginning balance	23,700	24,100	23,900
Additions	200	100	200
Write-off		(500)
Amortization	0	0	0
Ending balance	23,900	23,700	24,100
Acquired Names Of Business [Member]
Intangible Assets [Roll Forward]
Beginning balance	19,600	17,700	14,200
Additions	0	2,700	3,500
Write-off		(800)
Amortization	0	0	0
Ending balance	$ 19,600	$ 19,600	$ 17,700