Transactions with Affiliated Companies (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	12 Months Ended
	Sep. 30, 2009 year acre sqft	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Transactions with affiliated entities
Accounts receivable		$ 42,893	$ 38,121
Purchase price paid for land, building and equipment		167,007	133,394	330,052
Heidtman Steel Products (Heidtman)
Transactions with affiliated entities
Sales		242,300	202,897	132,272
Percentage of consolidated net sales		3.00%	3.00%	3.00%
Accounts receivable		35,646	31,544	26,983
Purchases		18,998	18,275	11,864
Accounts payable		882	969	468
Area of land (in acres)	32
Area of building (in square foot)	387,000
Lease term (in years)	5
Heidtman Steel Products (Heidtman) | Land and Building
Transactions with affiliated entities
Purchase price paid for land, building and equipment	9,300
Heidtman Steel Products (Heidtman) | Equipment
Transactions with affiliated entities
Purchase price paid for land, building and equipment	18,600
Other smaller affiliated entities
Transactions with affiliated entities
Sales		36,486	37,057	16,156
Accounts receivable		7,247	6,577	3,573
Purchases		239,395	177,166	81,926
Accounts payable		$ 5,702	$ 12,601	$ 6,297