ACQUISITIONS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended				12 Months Ended		12 Months Ended		12 Months Ended		1 Months Ended	12 Months Ended		12 Months Ended		1 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Jul. 29, 2009 Kuang Tai Metal Industry Co., Ltd.	Jun. 30, 2011 Techalloy	Jul. 29, 2011 Techalloy	Jun. 30, 2011 Torchmate	Jul. 29, 2011 Torchmate	Dec. 31, 2010 OOO Severstal-metiz	Mar. 11, 2011 OOO Severstal-metiz	Jan. 31, 2011 SSCO Manufacturing, Inc. (d/b/a Arc Products) Y	Dec. 31, 2010 SSCO Manufacturing, Inc. (d/b/a Arc Products)	Dec. 31, 2011 SSCO Manufacturing, Inc. (d/b/a Arc Products)	Oct. 31, 2010 MGM	Oct. 29, 2010 MGM	Jul. 31, 2009 Jinzhou Jin Tai Welding and Metal Co. Y	Jul. 31, 2009 Jinzhou Jin Tai Welding and Metal Co.	Dec. 31, 2009 Jinzhou Jin Tai Welding and Metal Co.	Dec. 31, 2008 Jinzhou Jin Tai Welding and Metal Co.	Jul. 29, 2009 Jinzhou Jin Tai Welding and Metal Co.
Acquisitions
Consideration paid in cash and assumed debt														$ 36,900				$ 16,861					$ 28,500
Fair value of assets acquired														32,814		2,361		8,049	3,613
Goodwill from acquisition														4,086		5,919		8,812	3,473
Annual sales at the date of acquisition	694,513	701,624	699,293	599,179	564,292	519,338	515,584	470,958	2,694,609	2,070,172	1,729,285		70,000		13,000							30,000
Sales from acquisition date through year end																										53,956
Consideration paid in cash																8,280			3,280									35,531
Sales for last annual period																	40,000										186,774
Sales for period immediately preceding acquisition																									74,834
Fair value of contingent consideration liability																			3,806		4,297
Period of estimated sales as basis for contingent consideration (in years)																			5
Sales for prior annual period																				Not Significant
Acquisition percentage																												100.00%
Percentage of direct interest in equity method investment												35.00%																21.00%
Percentage of indirect interest in equity method investment																												27.00%
Estimated fair value of ownership interest exchanged																												22,723
Estimated fair value of interest in equity method investments																												8,675
Additional amount of cash committed to be paid																												4,181
Period over which the additional amount of cash is committed to be paid (in years)																								3
Carrying values of interest in equity method investments	24,618				22,909				24,618	22,909	22,899	29,368																9,973
Excess carrying value over fair value of interests resulting in a loss																										$ 7,943