Goodwill and Intangible Assets Goodwill (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Changes in carrying amounts of goodwill
Beginning Goodwill	$ 130,118	$ 110,327
Accumulated impairment losses	(60,217)	(60,217)
Balance	69,901	50,110
Goodwill, Acquired During Period	0	19,637
Currency valuation	399	154
Ending Goodwill	130,517	130,118
Accumulated impairment losses	(60,217)	(60,217)
Balance	70,300	69,901
Goodwill, Impairment Loss	0
Metals Segment
Changes in carrying amounts of goodwill
Beginning Goodwill	117,145	97,354
Accumulated impairment losses	(60,217)	(60,217)
Balance	56,928	37,137
Goodwill, Acquired During Period	0	19,637
Currency valuation	399	154
Ending Goodwill	117,544	117,145
Accumulated impairment losses	(60,217)	(60,217)
Balance	57,327	56,928
Plastics Segment
Changes in carrying amounts of goodwill
Beginning Goodwill	12,973	12,973
Accumulated impairment losses	0	0
Balance	12,973	12,973
Goodwill, Acquired During Period	0	0
Currency valuation	0	0
Ending Goodwill	12,973	12,973
Accumulated impairment losses	0	0
Balance	$ 12,973	$ 12,973