Document and Entity Information - USD ($)	3 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Entity Information [Line Items]
Entity Registrant Name	Delta Natural Gas Co Inc
Entity Central Index Key	0000277375
Current Fiscal Year End Date	--06-30
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float		$ 148,491,236
Entity Common Stock, Shares Outstanding	7,116,381
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q1
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016