Inventory (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Inventory Disclosure [Abstract]
Excess of Replacement or Current Costs over Stated LIFO Value	$ 150,912	$ 148,513
Inventory Valuation Reserves	3,500	3,800
Reserves for Obsolete Inventories, Period Increase (Decrease)	$ (300)	$ (700)	$ 600