INTANGIBLE ASSETS - Summary of Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 214,488	$ 214,345
Accumulated Amortization	(61,358)	(54,184)
Net Carrying Amount	153,130	160,161
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	175,305	175,226
Accumulated Amortization	(41,811)	(38,712)
Net Carrying Amount	133,494	136,514
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,560	5,563
Accumulated Amortization	(4,625)	(4,509)
Net Carrying Amount	935	1,054
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	24,879	24,830
Accumulated Amortization	(9,896)	(6,211)
Net Carrying Amount	14,983	18,619
Technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	7,880	7,867
Accumulated Amortization	(4,529)	(4,292)
Net Carrying Amount	3,351	3,575
Licenses
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	864	859
Accumulated Amortization	(497)	(460)
Net Carrying Amount	$ 367	$ 399