Covered loans that are less than 90 days past due but more than 29 days past due.

No definition available.

Name:	cyn_CoveredLoans30To89DaysPastDue
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Covered loans that are 90 days or more past due and still accruing.

+ References

No definition available.

+ Details

Name:	cyn_CoveredLoans90DaysPastDueAndStillAccruing
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount by which the allowance for loan losses on covered loans is reduced, due to the related loan being fully paid-off, fully charged off, sold or transferred to Other Real Estate Owned.

+ References

No definition available.

+ Details

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

- Definition

Covered loans that are on nonaccrual status as of the balance sheet date.

+ References

No definition available.

+ Details

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

- Definition

The sum of the periodic provision charged to earnings, related to covered loans and based on reassessments of cash flows.

+ References

No definition available.

+ Details

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

- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(4)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 9) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	$ 20,337,206,000	$ 17,170,438,000
Covered Loans Allowance
Balance, beginning of period	15,922,000	44,781,000
Provision for losses	3,829,000cyn_ProvisionForLossesOnCoveredLoans	635,000cyn_ProvisionForLossesOnCoveredLoans	45,346,000cyn_ProvisionForLossesOnCoveredLoans
Net recoveries		9,000
Reduction in allowance due to loan removals	(11,143,000)cyn_CoveredLoansAllowanceRemoval	(29,503,000)cyn_CoveredLoansAllowanceRemoval
Balance, end of period	8,608,000	15,922,000	44,781,000
Covered loans
Covered Loans Allowance
Loans on nonaccrual status		0	0
Covered loans 30 to 89 days delinquent	7,400,000	15,500,000
Loans 90 days or more past due on accrual status	28,300,000	45,700,000
Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	9,360,976,000	7,562,300,000
Commercial \| Loans previously reported as lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans		158,200,000
Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	3,539,703,000	3,223,001,000
Residential mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	5,106,803,000	4,554,311,000
Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	1,401,952,000	1,440,451,000
Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	3,704,851,000	3,113,860,000
Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	710,224,000	367,004,000
Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	686,990,000	337,598,000
Land.
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	23,234,000	29,406,000
Home equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	785,796,000	709,344,000
Installment
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	184,613,000	151,955,000
Commercial Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	298,000	362,000
Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	184,315,000	151,593,000
Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	649,091,000	602,523,000
Lease financing \| Loans previously reported as lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans		(158,200,000)
Nonclassified \| Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	9,304,636,000	7,416,487,000
Nonclassified \| Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	3,511,229,000	3,139,707,000
Nonclassified \| Residential mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	5,050,898,000	4,512,723,000
Nonclassified \| Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	1,375,175,000	1,425,087,000
Nonclassified \| Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	3,675,723,000	3,087,636,000
Nonclassified \| Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	696,380,000	347,653,000
Nonclassified \| Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	679,744,000	332,131,000
Nonclassified \| Land.
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	16,636,000	15,522,000
Nonclassified \| Home equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	754,694,000	687,732,000
Nonclassified \| Installment
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	183,488,000	151,830,000
Nonclassified \| Commercial Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	298,000	362,000
Nonclassified \| Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	183,190,000	151,468,000
Nonclassified \| Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	645,049,000	598,821,000
Classified \| Commercial
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	56,340,000	145,813,000
Classified \| Commercial real estate mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	28,474,000	83,294,000
Classified \| Residential mortgages
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	55,905,000	41,588,000
Classified \| Fixed
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	26,777,000	15,364,000
Classified \| Variable
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	29,128,000	26,224,000
Classified \| Real estate construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	13,844,000	19,351,000
Classified \| Construction
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	7,246,000	5,467,000
Classified \| Land.
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	6,598,000	13,884,000
Classified \| Home equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	31,102,000	21,612,000
Classified \| Installment
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	1,125,000	125,000
Classified \| Consumer Installment loan
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	1,125,000	125,000
Classified \| Lease financing
Financing Receivable, Recorded Investment
Loans and leases, excluding covered loans	$ 4,042,000	$ 3,702,000