| Standard label: | Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value |
| Name: | us-gaap:HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue |
| Documentation: | Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for 12 months or longer. |
| 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:HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue |
| Label | Role | Language |
| Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 320 10 50 7 | http://fasb.org/us-gaap/role/ref/legacyRef | 320 |
| Part Of Roll Up: |
| us-gaap:HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue |