Document And Entity Information	9 Months Ended
	Jul. 31, 2014	Sep. 02, 2014
Document And Entity Information [Abstract]
Entity Registrant Name	PIEDMONT NATURAL GAS CO INC
Entity Central Index Key	0000078460
Document Type	10-Q
Document Period End Date	Jul. 31, 2014
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2014
Amendment Flag	false
Current Fiscal Year End Date	--10-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock Shares Outstanding		78,339,849