SEGMENT REPORTING (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Sales	$ 256,215	$ 323,688	$ 509,776	$ 665,282
Operating income	8,849	13,995	6,847	32,094
Adjustment for [Abstract]
Amortization of intangibles			9,038	10,667
Total operating income	8,849	13,995	6,847	32,094
Interest expense	3,951	2,592	7,360	5,275
Other expense (income), net	9	(145)	(146)	(394)
Income (loss) before income taxes	4,889	11,548	(367)	27,213
Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	256,215	323,688	509,776	665,282
Amortization	4,510	5,309	9,038	10,667
Operating income	17,776	25,458	26,571	54,871
Operating income, excluding amortization	22,286	30,767	35,609	65,538
Operating income for reportable segments, excluding amortization	22,286	30,767	35,609	65,538
Adjustment for [Abstract]
Total operating income	17,776	25,458	26,571	54,871
Operating Segments [Member] | Service Centers [Member]
Segment Reporting Information [Line Items]
Sales	161,832	214,116	329,334	439,907
Amortization	2,284	2,928	4,579	5,904
Operating income	10,313	18,191	17,555	38,081
Operating income, excluding amortization	12,597	21,119	22,134	43,985
Adjustment for [Abstract]
Total operating income	10,313	18,191	17,555	38,081
Operating Segments [Member] | IPS [Member]
Segment Reporting Information [Line Items]
Sales	54,353	66,905	101,784	141,169
Amortization	1,955	2,107	3,917	4,215
Operating income	3,532	3,805	1,876	10,324
Operating income, excluding amortization	5,487	5,912	5,793	14,539
Adjustment for [Abstract]
Total operating income	3,532	3,805	1,876	10,324
Operating Segments [Member] | SCS [Member]
Segment Reporting Information [Line Items]
Sales	40,030	42,667	78,658	84,206
Amortization	271	274	542	548
Operating income	3,931	3,462	7,140	6,466
Operating income, excluding amortization	4,202	3,736	7,682	7,014
Adjustment for [Abstract]
Total operating income	3,931	3,462	7,140	6,466
Segment Reconciling Items [Member]
Adjustment for [Abstract]
Amortization of intangibles	4,510	5,309	9,038	10,667
Corporate expense	$ 8,927	$ 11,463	$ 19,724	$ 22,777