Summary of Significant Accounting Policies (Details 2) (Covered loans)	12 Months Ended
Dec. 31, 2013
Covered loans
FDIC indemnification asset
FDIC reimbursement (as a percent)	80.00%

Represents the percentage of eligible loss that will be reimbursed by Federal Deposit Insurance Corporation ("FDIC") as per loss-sharing agreement between the entity and FDIC.

No definition available.

Name:	cyn_LossSharingAgreementPercentageOfReimbursementFromFDIC
Namespace Prefix:	cyn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration