Property, Plant And Equipment (Depreciation, Depletion And Amortization) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	$ 8,248	$ 9,627	$ 25,695	$ 27,789
Asset Retirement Costs [Member]
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	(140)	32	(315)	146
Intangible Assets [Member]
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	20	20	60	61
Mining And Other Equipment And Related Facilities [Member]
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	7,202	7,931	22,171	22,652
Coal Properties And Oil And Natural Gas Properties [Member]
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	701	1,173	2,234	3,672
Mine Development Costs [Member]
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	$ 465	$ 471	$ 1,545	$ 1,258