SEGMENT REPORTING (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Reporting Information [Line Items]
Sales	$ 289,923	$ 207,855	$ 804,104	$ 588,617
Operating income for reportable segments	36,418	22,702	99,369	64,816
Adjustment for [Abstract]
Amortization of intangibles	3,474	1,595	8,264	4,805
Corporate and other expense, net	8,430	6,671	25,839	20,402
Total operating income	24,514	14,436	65,266	39,609
Interest expense, net	2,287	760	3,878	2,805
Other expense (income), net	(21)	(4)	(33)	(40)
Income before income taxes	22,248	13,680	61,421	36,844
Service Centers [Member]
Segment Reporting Information [Line Items]
Sales	212,497	141,817	571,675	412,871
Operating income for reportable segments	26,410	15,866	67,455	47,987
IPS [Member]
Segment Reporting Information [Line Items]
Sales	38,854	31,342	113,466	69,841
Operating income for reportable segments	7,227	4,812	22,414	10,755
SCS [Member]
Segment Reporting Information [Line Items]
Sales	38,572	34,696	118,963	105,905
Operating income for reportable segments	$ 2,781	$ 2,024	$ 9,500	$ 6,074