Name:	cyn_FinancingReceivableModificationsIncreaseInRecordedInvestment
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the decrease in the amount of outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings due to the removal of loans that are no longer reported as TDRs.

No definition available.

Name:	cyn_FinancingReceivableModificationsNonreportableTDR
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default during the reporting period.

No definition available.

Name:	cyn_FinancingReceivableModificationSubsequentDefaultNumberOfContracts
Namespace Prefix:	cyn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Amount of outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings within the previous 12 months, for which there was a payment default during the reporting period.

No definition available.

Name:	cyn_FinancingReceivableModificationSubsequentDefaultRecordedInvestment
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of specific reserves related to financing receivables that have been modified by troubled debt restructurings within the previous 12 months, for which there was a payment default during the reporting period.

No definition available.

Name:	cyn_FinancingReceivableModificationSubsequentDefaultSpecificReserves
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	cyn_FinancingReceivableTroubledDebtRestructuringsAbstract
Namespace Prefix:	cyn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Represents the number of notes into which an original note is separated.

No definition available.

Name:	cyn_NumberOfNotesIntoWhichOriginalNoteSeparated
Namespace Prefix:	cyn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Reflects the unfunded portion of contractual agreements to lend funds to borrowers for loans whose terms have been modified by troubled debt restructuring.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 40

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6951948&loc=d3e18794-111554

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 15

-Paragraph 40

-Subparagraph b.

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.