cm:Level2TextBlock: us-gaap:CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy
| Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] |
| us-gaap:CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy |
| Entity's cash and cash equivalents accounting policy with respect to restricted balances. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy |