Borrowed Funds (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Short-term borrowings
Total short-term borrowings	$ 4,400us-gaap_DebtCurrent	$ 322,861us-gaap_DebtCurrent
Long-term debt
Long-term debt	634,425us-gaap_LongTermDebt	638,600us-gaap_LongTermDebt
5.25% Senior Notes Due September 2020 \| City National Corporation
Long-term debt
Long-term debt	299,559	299,540
Fixed interest rate (as a percent)	5.25%	5.25%
9.00% Subordinated Notes Due August 2019 \| City National Bank:
Long-term debt
Long-term debt	75,000	75,000
Fixed interest rate (as a percent)	9.00%	9.00%
5.375% Subordinated Notes Due July 2022 \| City National Bank:
Long-term debt
Long-term debt	149,995	149,994
Fixed interest rate (as a percent)	5.375%	5.375%
Floating Rate Securities Due November 2034 \| Business Bancorp Capital Trust I
Long-term debt
Long-term debt	5,155	5,155
Variable rate basis	three-month LIBOR
Basis spread (as a percent)	1.965%
Interest rate as of reporting date (as a percent)	2.23%
Nonrecourse debt
Short-term borrowings
Current portion of nonrecourse debt	4,400	2,861
Long-term debt
Long-term debt	94,997	99,139
Average interest rate (as a percent)	3.88%
Other long-term debt
Long-term debt
Long-term debt	9,719	9,772
Fixed interest rate (as a percent)	5.64%
Federal funds purchased
Short-term borrowings
Federal funds purchased		$ 320,000

Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Weighted average interest rate of debt outstanding.

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Amount of short term borrowing where a bank borrows, at the federal funds rate, from another bank.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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