Derivatives (Schedule of Price Risk Derivatives) (Details)	Sep. 30, 2014 T
Coal sales [Member]
Derivative [Line Items]
Derivatives Held	3,656,000
Coal purchases [Member]
Derivative [Line Items]
Derivatives Held	1,576,000
Year One, Remainder [Member] | Coal sales [Member]
Derivative [Line Items]
Derivatives Held	1,156,000
Year One, Remainder [Member] | Coal purchases [Member]
Derivative [Line Items]
Derivatives Held	751,000
Year Two [Member] | Coal sales [Member]
Derivative [Line Items]
Derivatives Held	2,340,000
Year Two [Member] | Coal purchases [Member]
Derivative [Line Items]
Derivatives Held	825,000
Year Three [Member] | Coal sales [Member]
Derivative [Line Items]
Derivatives Held	160,000
Year Three [Member] | Coal purchases [Member]
Derivative [Line Items]
Derivatives Held	0