Derivatives (Schedule of Price Risk Derivatives) (Details)	Sep. 30, 2013
Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	7,552,000
Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	1,869,000
Year One [Member] | Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	2,314,000
Year One [Member] | Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	609,000
Year Two [Member] | Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	4,458,000
Year Two [Member] | Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	1,260,000
Year Three [Member] | Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	780,000
Year Three [Member] | Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held