| Standard label: | Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Postretirement Benefits |
| Name: | us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits |
| Documentation: | Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from postretirement benefits. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | As Of (instant) |
| Balance type: | Debit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits |
| Label | Role | Language |
| Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Postretirement Benefits | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 740 10 50 6 | http://fasb.org/us-gaap/role/ref/legacyRef | 740 |
| Part Of Roll Up: |
| us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits |