Financial Instruments Commodity Contract Volumes (Details)	Sep. 30, 2014 MMcf
Regulated Distribution Segment [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	31,812
Regulated Distribution Segment [Member] | Not Designated as Hedging Instrument [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	31,812
Regulated Distribution Segment [Member] | Fair Value Hedging [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	0
Regulated Distribution Segment [Member] | Cash Flow Hedging [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	0
Nonregulated Segment [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	135,703
Nonregulated Segment [Member] | Not Designated as Hedging Instrument [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	96,711
Nonregulated Segment [Member] | Fair Value Hedging [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	(10,298)
Nonregulated Segment [Member] | Cash Flow Hedging [Member]
Commodity Contract Outstanding Volumes [Line Items]
Investment Contract Volume	49,290