COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Credit Facility [Abstract]
2018	$ 0
2019	0
2020	53,400
2021	0
2022	0
Thereafter	0
Long term debt	53,400
Less amount representing interest	0
Credit agreement net of interest	53,400
Operating Leases [Abstract]
2017	19,347
2018	16,608
2019	12,386
2020	8,185
2021	6,022
Thereafter	15,860
Operating Leases, Total	78,408
Less amount representing interest	0
Operating leases net of interest	78,408
Lease rent expense	17,400	$ 20,700	$ 18,700
Outstanding net loan commitment	38,500
Future employment contract commitments	3,400
Surety bonds	$ 12,700