INTANGIBLE ASSETS, NET - Amortization Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Amortization of Deferred Charges [Abstract]
Total amortization expenses	$ 822	$ 790
Referral Relationships [Member]
Amortization of Deferred Charges [Abstract]
Total amortization expenses	783	613
Non-compete Agreements [Member]
Amortization of Deferred Charges [Abstract]
Total amortization expenses	$ 39	$ 177

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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