Derivative Instruments and Hedging Activities Notional Contracts by Derivative Type (Details)	3 Months Ended
	Dec. 31, 2014 MMBTU
Natural Gas - long [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	28,800,000
WTI Crude Oil [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	4,380,000
Ultra Low Sulfur Diesel Member
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	4,380,000
Commodity WTI Spread [Member] [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	4,015,000
Commodity WTI Long [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	1,095,000
Commodity Price Swap Natural Gas Long [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	28,800,000
Commodity Price Swap Natural Gas Short [Member] [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	28,800,000
NYMEX WTI Short [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	2,058,000
Maturing in Next Twelve Months [Member] | Natural Gas - long [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,600,000
Maturing in Next Twelve Months [Member] | WTI Crude Oil [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	4,380,000
Maturing in Next Twelve Months [Member] | Ultra Low Sulfur Diesel Member
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	4,380,000
Maturing in Next Twelve Months [Member] | Commodity WTI Spread [Member] [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	4,015,000
Maturing in Next Twelve Months [Member] | Commodity WTI Long [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	1,095,000
Maturing in Next Twelve Months [Member] | Commodity Price Swap Natural Gas Long [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,600,000
Maturing in Next Twelve Months [Member] | Commodity Price Swap Natural Gas Short [Member] [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,600,000
Maturing in Next Twelve Months [Member] | NYMEX WTI Short [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	2,058,000
Maturing in Year Two [Member] | Natural Gas - long [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,600,000
Maturing in Year Two [Member] | WTI Crude Oil [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	0
Maturing in Year Two [Member] | Ultra Low Sulfur Diesel Member
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	0
Maturing in Year Two [Member] | Commodity Price Swap Natural Gas Long [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,600,000
Maturing in Year Two [Member] | Commodity Price Swap Natural Gas Short [Member] [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,600,000
Maturing in Year Two [Member] | NYMEX WTI Short [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	0
Maturing in Year Three [Member] | Natural Gas - long [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,600,000
Maturing in Year Three [Member] | WTI Crude Oil [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	0
Maturing in Year Three [Member] | Ultra Low Sulfur Diesel Member
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	0
Maturing in Year Three [Member] | Commodity Price Swap Natural Gas Long [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,600,000
Maturing in Year Three [Member] | Commodity Price Swap Natural Gas Short [Member] [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,600,000
Maturing in Year Three [Member] | NYMEX WTI Short [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	0