GOODWILL AND OTHER INTANGIBLE ASSETS - Estimated Future Annual Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2019	$ 15,479
2020	12,674
2021	10,792
2022	10,091
2023	8,665
Thereafter	9,506
Carrying Amount, net	67,207	$ 78,525	$ 94,831
Customer relationships
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Carrying Amount, net	$ 67,055	78,394
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years 6 months 7 days
Non-compete agreements
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Carrying Amount, net	$ 152	$ 131
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years 2 months 27 days