cm:Level3TextBlock: us-gaap:PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTableTextBlock
| Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Table Text Block] |
| us-gaap:PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTableTextBlock |
| Tabular disclosure of policyholder account balance by range of guaranteed minimum crediting rate and related range of difference between rate being credited to policyholder and respective guaranteed minimum. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTableTextBlock |