Name:	cyn_AcquisitionCoveredLoans
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

This element represents the fair value of covered other real estate owned that an entity acquired in an acquisition. Covered other real estate owned are other real estate owned subject to loss share agreements with the Federal Deposit Insurance Corporation.

No definition available.

Name:	cyn_AcquisitionCoveredOtherRealEstateOwned
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

This element represents the fair value of deposits that an entity acquired in an acquisition.

No definition available.

Name:	cyn_AcquisitionDeposits
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Fair value of borrowings and nonrecourse debt assumed in the business acquisition.

No definition available.

Name:	cyn_BusinessAcquisitionBorrowingsAndNonrecourseDebtAssumed
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Carrying value of assets acquired in the business acquisition.

No definition available.

Name:	cyn_BusinessAcquisitionCarryingValueOfAssetsAcquired
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Carrying value of liabilities assumed in the business acquisition.

No definition available.

Name:	cyn_BusinessAcquisitionCarryingValueOfLiabilitiesAssumed
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Represents the fair value of lease receivables acquired in the business acquisition.

No definition available.

Name:	cyn_BusinessAcquisitionFairValueOfLeaseReceivablesAcquired
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Fair value of goodwill acquired in the business acquisition.

No definition available.

Name:	cyn_BusinessAcquisitionGoodwillAcquired
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Represents cash received from the FDIC for the net settlement of a business combination.

No definition available.

Name:	cyn_CashReceivedFromFDIC
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Represents the expected reimbursement from the Federal Deposit Insurance Corporation related to expected losses on acquired loans, other real estate owned, and unfunded loan commitments.

No definition available.

Name:	cyn_FDICIndemnificationAsset
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

Represents the period for which the loss-sharing agreements is applicable for all loans, excluding single family residential loans, expressed in number of years.

No definition available.

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

Represents the period for which the loss-sharing agreements is applicable for single family residential loans expressed in number of years.

No definition available.

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

- Details

Name:	us-gaap_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 59

-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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

-Paragraph 23

-URI http://asc.fasb.org/extlink&oid=6909708&loc=d3e1043-128460

Name:	us-gaap_BusinessCombinationAcquisitionRelatedCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of the excess of the fair value of acquired net assets over the cost of an acquired business after pro rata reduction of the amounts that otherwise would have been assigned to acquired assets except financial assets other than investments accounted for by the equity method, assets to be disposed of by sale, deferred tax assets, prepaid assets relating to pension and postretirement benefit plans, and other current assets. This amount is considered an extraordinary item and often referred to as negative goodwill. This element is gross of the related tax effect.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 44, 45, 46

-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.