Derivatives (Schedule of Price Risk Derivatives) (Details)	Dec. 31, 2014
Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	4,802,000
Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	2,134,000
Year One [Member] | Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	4,522,000
Year One [Member] | Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	2,134,000
Year Two [Member] | Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	280,000
Year Two [Member] | Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	0