Regulatory Matters (Details)	Jun. 30, 2016
Regulated Operations [Abstract]
Number of cities where current franchises are held	7
Number of cities where we continue to operate under expired franchises	15

The number of cities where the entity continues to operate under the conditions of expired franchises.

No definition available.

Name:	dgas_NumberOfCitiesWhereWeContinueToOperateUnderExpiredFranchises
Namespace Prefix:	dgas_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant