INTANGIBLE ASSETS, NET - Amortization Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Finite Lived Intangible Assets [Line Items]
Total amortization expenses	$ 758	$ 520	$ 2,098	$ 1,518
Tradenames [Member]
Finite Lived Intangible Assets [Line Items]
Total amortization expenses	0	20	0	62
Referral Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Total amortization expenses	527	352	1,466	1,027
Non-compete Agreements [Member]
Finite Lived Intangible Assets [Line Items]
Total amortization expenses	$ 231	$ 148	$ 632	$ 429