Accrued Expenses and Other Current Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Accrued Expenses and Other Current Liabilities [Abstract]
Payroll and employee benefits	$ 80,782	$ 65,323
Taxes other than income taxes	123,100	133,331
Interest	70,619	55,266
Coal supply agreement liability	16,327	38,441
Workers’ compensation	10,155	11,666
Asset retirement obligations	44,178	27,119
Other	10,287	17,061
Accrued Liabilities, Current	$ 355,448	$ 348,207