Borrowed Funds (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 Y	Dec. 31, 2011
Short-term borrowings
Federal funds purchased	$ 10,000	$ 50,000
Total short-term borrowings	222,776	50,000
Long-term debt
Long-term debt	482,024	697,778
5.125% Senior Notes Due February 2013 | City National Corporation
Short-term borrowings
Current portion of senior notes	212,776
Long-term debt
Long-term debt		215,848
Fixed interest rate (as a percent)	5.125%	5.125%
5.25% Senior Notes Due September 2020 | City National Corporation
Long-term debt
Long-term debt	297,385	297,308
Fixed interest rate (as a percent)	5.25%	5.25%
9.00% Subordinated Notes Due July 2019 | City National Bank
Long-term debt
Long-term debt	49,727	49,718
Fixed interest rate (as a percent)	9.00%	9.00%
Interest rate for initial period (as a percent)	9.00%
Initial interest rate period (in years)	5
9.00% Subordinated Notes Due July 2019 | City National Bank | LIBOR
Long-term debt
Variable rate basis	LIBOR
Basis spread after initial period (as a percent)	6.00%
9.00% Subordinated Notes Due July 2019 | City National Bank | Prime rate
Long-term debt
Variable rate basis	Prime rate
Basis spread after initial period (as a percent)	5.00%
9.00% Subordinated Notes Due August 2019 | City National Bank
Long-term debt
Long-term debt	74,862	74,858
Fixed interest rate (as a percent)	9.00%	9.00%
Fixed and Floating Subordinated Notes due August 2019 | City National Bank
Long-term debt
Long-term debt	54,899	54,895
Variable rate basis	three-month LIBOR
Frequency to reset interest rate	Quarterly
Interest rate cap (as a percent)	10.00%
Interest rate for initial period (as a percent)	9.00%
Initial interest rate period (in years)	5
Basis spread after initial period (as a percent)	6.00%
Floating Rate Securities Due November 2034 | Business Bancorp Capital Trust I
Long-term debt
Long-term debt	$ 5,151	$ 5,151
Variable rate basis	three-month LIBOR
Frequency to reset interest rate	Quarterly
Basis spread (as a percent)	1.965%
Interest rate as of reporting date (as a percent)	2.46%