| Standard label: | Gas Purchase Payable, Current |
| Name: | us-gaap:GasPurchasePayableCurrent |
| Documentation: | Carrying value as of the balance sheet date of obligations incurred and payable for purchases of natural gas. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | As Of (instant) |
| Balance type: | Credit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:GasPurchasePayableCurrent |
| Label | Role | Language |
| Gas Purchase Payable, Current | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 210 10 S99 1 (SX 210.5-02.19(a)) | http://fasb.org/us-gaap/role/ref/legacyRef | 210 |
| Part Of Roll Up: |
| us-gaap:AccountsPayableCurrent |