Derivatives (Schedule of Price Risk Derivatives) (Details)	Jun. 30, 2014 T
Coal sales [Member]
Derivative [Line Items]
Derivatives Held	4,884,000
Coal purchases [Member]
Derivative [Line Items]
Derivatives Held	1,668,000
Year One [Member] | Coal sales [Member]
Derivative [Line Items]
Derivatives Held	2,504,000
Year One [Member] | Coal purchases [Member]
Derivative [Line Items]
Derivatives Held	1,308,000
Year Two [Member] | Coal sales [Member]
Derivative [Line Items]
Derivatives Held	2,380,000
Year Two [Member] | Coal purchases [Member]
Derivative [Line Items]
Derivatives Held	360,000