Derivative Instruments and Hedging Activities Notional Contracts by Derivative Type (Details)	3 Months Ended
	Dec. 31, 2016 MMBTU bbl
Crude Oil [Member] | Economic Hedges [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	3,645,000
Produced Gasoline Member | Price Risk Derivative [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	175,000
Commodity Contract [Member] | Economic Hedges [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	310,000
Natural Gas - Short [Member] | Economic Hedges [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	9,600,000
Natural Gas - long [Member] | Price Risk Derivative [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	9,600,000
Natural Gas - long [Member] | Economic Hedges [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	9,600,000
NYMEX WTI Short [Member] | Economic Hedges [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	755,000
Natural Gas [Member] | Economic Hedges [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	10,308,000
Physical Contracts - Long [Member] | Price Risk Derivative [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	150,000
WTI Crude Oil [Member] | Price Risk Derivative [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	519,000
Ultra Low Sulfur Diesel Member | Price Risk Derivative [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	519,000
Forward Contracts [Member] | Economic Hedges [Member]
economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	1,225,000