The cumulative amount of revenue increase relating to the joint proposal.

No definition available.

Name:	CNIG_JointProposalCumulativeRevenueIncrease
Namespace Prefix:	CNIG_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Prior amount of revenue allowed to be earned from local production before sharing.

No definition available.

Name:	CNIG_JointProposalOpportunityToEarnFromLocalProductionBeforeSharingCurrent
Namespace Prefix:	CNIG_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The percent increase for the opportunity to earn from local production before sharing for the joint proposal.

No definition available.

Name:	CNIG_JointProposalOpportunityToEarnFromLocalProductionBeforeSharingPercentIncrease
Namespace Prefix:	CNIG_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Current amount of revenue allowed to be earned from local production before sharing.

No definition available.

Name:	CNIG_JointProposalOpportunityToEarnFromLocalProductionBeforeSharingPrior
Namespace Prefix:	CNIG_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The amount of revenue increase relating to the joint proposal.

No definition available.

Name:	CNIG_JointProposalRevenueIncrease
Namespace Prefix:	CNIG_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Name:	CNIG_RateCasesDetailsNarrativeAbstract
Namespace Prefix:	CNIG_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The percentage amount of return on equity.

No definition available.

Rate Cases (Details Narrative) (USD $)	12 Months Ended			36 Months Ended
Rate Cases (Details Narrative) (USD $)	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2015
Rate Cases Details Narrative
Joint proposal, revenue increase	$ 323,591	$ 899,674	$ 944,310
Joint proposal, cumulative revenue increase				4,955,869
Joint proposal, opportunity to earn from local production before sharing, current			545,284
Joint proposal, opportunity to earn from local production before sharing, percent increase			118.00%
Joint proposal, opportunity to earn from local production before sharing, prior			$ 250,000
Return on equity			9.50%