FAIR VALUE MEASUREMENTS - Schedule of fair value measurement valuation (Details)	Sep. 30, 2020 USD ($)	Oct. 31, 2018 USD ($)	Jun. 11, 2018 USD ($)
Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration		$ 0
Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration		$ 46,800,000	$ 4,400,000
Fair Value | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration	$ 35,175,000
Option pricing model | Minimum | Level 3 | Operating results growth rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration, measurement input	0.244
Option pricing model | Maximum | Level 3 | Operating results growth rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration, measurement input	0.257
Option pricing model | Weighted average | Level 3 | Operating results growth rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration, measurement input	0.251
Option pricing model | Weighted average | Level 3 | Discount rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration, measurement input	0.068