GOODWILL AND INTANGIBLE ASSETS - Other Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets	$ 94,660		$ 94,660		$ 94,660
Accumulated Amortization	(25,892)		(25,892)		(23,007)
Intangible Assets, net	68,768		68,768		71,653
Amortization of intangible assets	1,442	$ 1,518	2,884	$ 3,047
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2017	5,800		5,800
2018	5,800		5,800
2019	5,600		5,600
2020	4,800		4,800
2021	4,400		4,400
Trade names
Indefinite-Lived Intangible Assets (Excluding Goodwill) [Abstract]
Indefinite lived intangible assets	30,100		30,100		30,100
Non-competition agreements
Finite-Lived Intangible Assets, Net [Abstract]
Finite lived, Intangible Assets	8,350		8,350		8,350
Finite lived, Intangible Assets, net	3,731		3,731		4,421
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated Amortization	(4,619)		$ (4,619)		(3,929)
Weighted average remaining useful lives			2 years 2 months 23 days
Customer relationships
Finite-Lived Intangible Assets, Net [Abstract]
Finite lived, Intangible Assets	56,210		$ 56,210		56,210
Finite lived, Intangible Assets, net	34,937		34,937		37,132
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated Amortization	(21,273)		$ (21,273)		$ (19,078)
Weighted average remaining useful lives			8 years 7 days
Flatbed
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Amortization of intangible assets	437	489	$ 874	979
Specialized
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Amortization of intangible assets	$ 1,005	$ 1,029	$ 2,010	$ 2,068