GOODWILL AND OTHER INTANGIBLE ASSETS, Amortizable Other Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Finite-lived intangible assets, net [Abstract]
Gross carrying amount	$ 169,039	$ 163,149
Accumulated amortization	(93,357)	(84,624)
Carrying amount, net	75,682	78,525
Customer Relationships [Member]
Finite-lived intangible assets, net [Abstract]
Gross carrying amount	168,255	162,200
Accumulated amortization	(92,767)	(83,806)
Carrying amount, net	75,488	78,394
Non-Compete Agreements [Member]
Finite-lived intangible assets, net [Abstract]
Gross carrying amount	784	949
Accumulated amortization	(590)	(818)
Carrying amount, net	$ 194	$ 131