Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for losses
Allowance for losses	$ 5,367,000	$ 6,718,000
Inventories
Lower of cost or market charges included in cost of sales, exclusive of depreciation and depletion	218,800,000	20,100,000	4,700,000
Lower of cost or market charges included in depreciation and depletion	$ 17,400,000	$ 1,000,000
Revenues | Customer Concentration Risk | Foreign steel and coke producers
Concentrations of Credit Risk and Major Customers
Concentration risk percentage	78.00%	76.00%
Revenues | Customer Concentration Risk | Single customer one
Concentrations of Credit Risk and Major Customers
Concentration risk percentage			13.00%
Revenues | Customer Concentration Risk | Single customer two
Concentrations of Credit Risk and Major Customers
Concentration risk percentage			10.30%
Net receivables | Credit Concentration Risk | Foreign steel and coke producers
Concentrations of Credit Risk and Major Customers
Concentration risk percentage	50.00%	63.00%