| Standard label: | Increase (Decrease) in Frequent Flyer Liability |
| Name: | us-gaap:IncreaseDecreaseInFrequentFlyerLiability |
| Documentation: | The increase (decrease) during the reporting period in the amount of unearned revenue related to the estimated incremental cost for points or miles outstanding and awards that expect to be redeemed through customer loyalty programs. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | For Period (duration) |
| Balance type: | Debit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:IncreaseDecreaseInFrequentFlyerLiability |
| Label | Role | Language |
| Increase (Decrease) in Frequent Flyer Liability | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 230 10 45 28 (a) | http://fasb.org/us-gaap/role/ref/otherTransitionRef | 230 |