SEGMENT REPORTING (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Adjustment for [Abstract]
Amortization of intangibles			$ 10,667	$ 11,237
Operating income	$ 13,995	$ 27,392	32,094	48,546
Interest expense	2,592	3,176	5,275	6,573
Other expense (income), net	(145)	141	(394)	(9)
Income before income taxes	11,548	24,075	27,213	41,982
Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	323,688	381,603	665,282	730,107
Operating income for reportable segments	30,767	44,865	65,538	81,964
Operating Segments [Member] | Service Centers [Member]
Segment Reporting Information [Line Items]
Sales	214,116	248,839	439,907	480,063
Operating income for reportable segments	21,119	25,486	43,985	49,911
Operating Segments [Member] | IPS [Member]
Segment Reporting Information [Line Items]
Sales	66,905	90,575	141,169	170,456
Operating income for reportable segments	5,912	15,800	14,539	25,350
Operating Segments [Member] | SCS [Member]
Segment Reporting Information [Line Items]
Sales	42,667	42,189	84,206	79,588
Operating income for reportable segments	3,736	3,579	7,014	6,703
Segment Reconciling Items [Member]
Adjustment for [Abstract]
Amortization of intangibles	5,309	5,660	10,667	11,237
Corporate expense	$ 11,463	$ 11,813	$ 22,777	$ 22,181