INTANGIBLE ASSETS - Summary of Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 213,434	$ 213,816
Accumulated Amortization	(99,899)	(96,797)
Net Carrying Amount	113,535	117,019
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	174,725	174,940
Accumulated Amortization	(66,555)	(63,727)
Net Carrying Amount	108,170	111,213
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,343	5,466
Accumulated Amortization	(5,263)	(5,306)
Net Carrying Amount	80	160
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	24,691	24,724
Accumulated Amortization	(21,267)	(21,146)
Net Carrying Amount	3,424	3,578
Technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	7,830	7,838
Accumulated Amortization	(6,159)	(5,976)
Net Carrying Amount	1,671	1,862
Licenses
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	845	848
Accumulated Amortization	(655)	(642)
Net Carrying Amount	$ 190	$ 206