| Standard label: | Accumulated Deferred Investment Tax Credit |
| Name: | us-gaap:AccumulatedDeferredInvestmentTaxCredit |
| Documentation: | The noncurrent portion of the reserve for accumulated deferred investment tax credits as of the balance sheet date. This is the remaining investment credit, which will reduce the cost of services collected from ratepayers by a ratable portion over the investment's regulatory life. |
| 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:AccumulatedDeferredInvestmentTaxCredit |
| Label | Role | Language |
| Accumulated Deferred Investment Tax Credit | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 210 10 S99 1 (SX 210.5-02.26(b)) | http://fasb.org/us-gaap/role/ref/legacyRef | 210 |
| FASB Accounting Standards Codification 255 10 55 8 | http://fasb.org/us-gaap/role/ref/legacyRef | 255 |
| FASB Accounting Standards Codification 740 10 45 27 | http://fasb.org/us-gaap/role/ref/legacyRef | 740 |
| Part Of Roll Up: |
| us-gaap:LiabilitiesOtherThanLongtermDebtNoncurrent |