Commitment & Contingencies (Details) (USD $)	12 Months Ended
	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2009	Oct. 31, 1997
Commitment & Contingencies Details [Abstract]
Operating Lease Payments	$ 4,496,000	$ 5,303,000	$ 6,173,000
Operating Leases Future Minimum Payments Due Current	3,560,000
Operating Leases Future Minimum Payments Due In Two Years	4,068,000
Operating Leases Future Minimum Payments Due In Three Years	3,941,000
Operating Leases Future Minimum Payments Due In Four Years	3,766,000
Operating Leases Future Minimum Payments Due In Five Years	3,720,000
Operating Leases Future Minimum Payments Due Thereafter	35,424,000
Operating Leases Future Minimum Payments Due	54,479,000
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation Balance On First Anniversary	175,397,000
Unrecorded Unconditional Purchase Obligation Balance On Second Anniversary	107,503,000
Unrecorded Unconditional Purchase Obligation Balance On Third Anniversary	86,711,000
Unrecorded Unconditional Purchase Obligation Balance On Fourth Anniversary	75,017,000
Unrecorded Unconditional Purchase Obligation Balance On Fifth Anniversary	57,154,000
UnRecorded Unconditional Purchase Obligation Due After Fifth Year	336,767,000
UnRecorded Unconditional Purchase Obligation	838,549,000
Letters Of Credit Issued And Outstanding	3,500,000
Number Of Regulatory Commissions	3
MGP Sites Under Settlement				9
MGP Sites Not Under Settlement	4
Site Contingency [Line Items]
Accrual For Environmental Loss Contingencies	2,800,000
MGP Facility Enviromental Liability	1,500,000
LNG Facility Liability	1,000,000
Under Ground Storage Tank Liability	300,000
Estimated Enviromental Costs On Which Piedmont Does Not Earn Return	9,600,000
Site Contingency, Unasserted Claims	0
Tennessee Regulatory Authority [Member]
Schedule Of Regulatory Matters Line Items [Abstract]
Proposed Recovery Unamortized Environmental Costs	2,000,000
Hickory North Carolina Site [Member]
Site Contingency [Line Items]
Site Contingency Environmental Remediation Costs Recognized	1,400,000
Nashville MGP [Member]
Site Contingency [Line Items]
Site Contingency Environmental Remediation Costs Recognized	1,500,000
Huntersville LNG Facility [Member]
Site Contingency [Line Items]
Site Contingency Environmental Remediation Costs Recognized	3,200,000
Administrative Consent Order Expected Maximum Fine	100,000
Clemmons North Carolina Site [Member]
Site Contingency [Line Items]
Environmental Remediation Costs Estimated	144,540
Accrued Environmental Loss Contingencies Noncurrent	36,135
Nashville LNG Facility [Member]
Site Contingency [Line Items]
Site Contingency Environmental Remediation Costs Recognized	400,000
Environmental Remediation Costs Estimated	500,000
Pipeline And Storage Capacity Contacts [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation Balance On First Anniversary	151,456,000
Unrecorded Unconditional Purchase Obligation Balance On Second Anniversary	100,637,000
Unrecorded Unconditional Purchase Obligation Balance On Third Anniversary	80,603,000
Unrecorded Unconditional Purchase Obligation Balance On Fourth Anniversary	73,059,000
Unrecorded Unconditional Purchase Obligation Balance On Fifth Anniversary	57,154,000
UnRecorded Unconditional Purchase Obligation Due After Fifth Year	336,767,000
UnRecorded Unconditional Purchase Obligation	799,676,000
Gas Supply Contracts [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation Balance On First Anniversary	6,974,000
Unrecorded Unconditional Purchase Obligation Balance On Second Anniversary	11,000
Unrecorded Unconditional Purchase Obligation Balance On Third Anniversary	0
Unrecorded Unconditional Purchase Obligation Balance On Fourth Anniversary	0
Unrecorded Unconditional Purchase Obligation Balance On Fifth Anniversary	0
UnRecorded Unconditional Purchase Obligation Due After Fifth Year	0
UnRecorded Unconditional Purchase Obligation	6,985,000
Telecommunications And Technology Outsourcing Contracts [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation Balance On First Anniversary	11,055,000
Unrecorded Unconditional Purchase Obligation Balance On Second Anniversary	6,855,000
Unrecorded Unconditional Purchase Obligation Balance On Third Anniversary	6,108,000
Unrecorded Unconditional Purchase Obligation Balance On Fourth Anniversary	1,958,000
Unrecorded Unconditional Purchase Obligation Balance On Fifth Anniversary	0
UnRecorded Unconditional Purchase Obligation Due After Fifth Year	0
UnRecorded Unconditional Purchase Obligation	25,976,000
Other [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation Balance On First Anniversary	5,912,000
Unrecorded Unconditional Purchase Obligation Balance On Second Anniversary	0
Unrecorded Unconditional Purchase Obligation Balance On Third Anniversary	0
Unrecorded Unconditional Purchase Obligation Balance On Fourth Anniversary	0
Unrecorded Unconditional Purchase Obligation Balance On Fifth Anniversary	0
UnRecorded Unconditional Purchase Obligation Due After Fifth Year	0
UnRecorded Unconditional Purchase Obligation	$ 5,912,000