cm:Member: us-gaap:FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember
| Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member] |
| us-gaap:FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember |
| Investments in debentures, bonds and other debt securities issued by the Federal Home Loan Mortgage Corporation (FHLMC or Freddie Mac). |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember |