cm:Concept: us-gaap:PaymentsToAcquireShortTermInvestments
| Payments to Acquire Short-term Investments |
| us-gaap:PaymentsToAcquireShortTermInvestments |
| The cash outflow for securities or other assets acquired, which qualify for treatment as an investing activity and are to be liquidated, if necessary, within the current operating cycle. Includes cash flows from securities classified as trading securities that were acquired for reasons other than sale in the short-term. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:PaymentsToAcquireShortTermInvestments |