INTANGIBLE ASSETS, NET - Intangible Assets, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets, Net [Abstract]
Total	$ 48,125	$ 48,828
Tradenames [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Total	30,256	30,256
Referral Relationships [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Total	16,361	16,895
Accumulated amortization	$ 9,903	9,370
Referral Relationships [Member] | Minimum [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Estimated useful life	6 years
Referral Relationships [Member] | Maximum [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Estimated useful life	16 years
Non-compete Agreements [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Total	$ 1,508	1,677
Accumulated amortization	$ 4,885	$ 4,716
Non-compete Agreements [Member] | Minimum [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Estimated useful life	5 years
Non-compete Agreements [Member] | Maximum [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Estimated useful life	6 years