GOODWILL AND OTHER INTANGIBLE ASSETS - Finite-lived Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 156,567	$ 169,039
Accumulated Amortization	(103,985)	(101,832)
Carrying Amount, net	52,582	67,207	$ 78,525
Amortization of intangible assets	15,074	16,586	$ 17,266
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	156,282	168,255
Accumulated Amortization	(103,796)	(101,200)
Carrying Amount, net	52,486	67,055
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	285	784
Accumulated Amortization	(189)	(632)
Carrying Amount, net	$ 96	$ 152