EMPLOYEE BENEFIT PLANS - Changes in Benefit Obligation and Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Projected benefit obligation:
Beginning of year	$ 89,206	$ 0
Acquisition of Furmanite	0	80,410
Service cost	90	79
Interest cost	2,438	2,504
Actuarial loss	890	18,233
Benefits paid	(4,187)	(2,804)
Foreign currency translation adjustment and other	8,438	(9,216)
End of year	96,875	89,206
Fair value of plan assets:
Beginning of year	67,967	0
Acquisition of Furmanite	0	66,901
Actual gain on plan assets	7,383	10,222
Employer contributions	4,350	1,182
Benefits paid	(4,187)	(2,804)
Foreign currency translation adjustment and other	6,386	(7,534)
End of year	81,899	67,967
Excess projected obligation under (over) fair value of plan assets at end of year	(14,976)	(21,239)
Amounts recognized in accumulated other comprehensive loss:
Net actuarial loss	$ (7,221)	$ (10,518)