Property, Plant And Equipment (Depreciation, Depletion And Amortization) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	$ 10,212	$ 11,092
Mining And Other Equipment And Related Facilities [Member]
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	8,136	8,764
Coal Properties [Member]
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	1,379	1,546
Mine Development Costs [Member]
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	671	612
Intangible Assets [Member]
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	21	21
Asset Retirement Costs [Member]
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	$ 5	$ 149