Significant Accounting Policies (Property Plant and Equipment & Intangible Assets) (Details)	12 Months Ended
	Dec. 31, 2012
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	40 years
Machinery and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	3 years
Machinery and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	15 years
Building Improvements | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	4 years
Building Improvements | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	40 years
NACoal | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful life	30 years