Deposits and Borrowed Funds (Details 2) (USD $) In Thousands, unless otherwise specified								12 Months Ended		12 Months Ended				12 Months Ended								12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 City National Corporation	Dec. 31, 2010 City National Corporation	Dec. 31, 2011 6.75% Subordinated Notes Due September 2011 City National Bank	Dec. 31, 2010 6.75% Subordinated Notes Due September 2011 City National Bank	Dec. 31, 2011 9.00% Subordinated Notes Due July 2019 City National Bank Y	Dec. 31, 2010 9.00% Subordinated Notes Due July 2019 City National Bank	Dec. 31, 2011 9.00% Subordinated Notes Due July 2019 City National Bank LIBOR	Dec. 31, 2011 9.00% Subordinated Notes Due July 2019 City National Bank Prime rate	Dec. 31, 2011 9.00% Subordinated Notes Due August 2019 City National Bank	Dec. 31, 2010 9.00% Subordinated Notes Due August 2019 City National Bank	Dec. 31, 2011 Fixed and Floating Subordinated Notes due August 2019 City National Bank Y	Dec. 31, 2010 Fixed and Floating Subordinated Notes due August 2019 City National Bank	Dec. 31, 2011 5.125% Senior Notes Due February 2013 City National Corporation	Dec. 31, 2010 5.125% Senior Notes Due February 2013 City National Corporation	Dec. 31, 2011 5.25% Senior Notes Due September 2020 City National Corporation	Dec. 31, 2010 5.25% Senior Notes Due September 2020 City National Corporation	Dec. 31, 2011 5.25% Senior Notes Due September 2020 City National Bank	Dec. 31, 2010 5.25% Senior Notes Due September 2020 City National Bank	Dec. 31, 2011 Floating Rate Securities Due November 2034 Bancorp Capital Trust I	Dec. 31, 2010 Floating Rate Securities Due November 2034 Bancorp Capital Trust I
Short-term borrowings and long-term debt
Fixed interest rate (as a percent)						6.75%	6.75%	9.00%	9.00%			9.00%	9.00%			5.125%	5.125%	5.25%	5.25%
Variable rate basis										LIBOR	Prime rate			three-month LIBOR								three-month LIBOR
Frequency to reset interest rate														Quarterly								Quarterly
Interest rate cap (as a percent)														10.00%
Interest rate for initial period (as a percent)								9.00%						9.00%
Initial interest rate period (in years)								5						5
Basis spread after initial period (as a percent)										6.00%	5.00%			6.00%
Basis spread (as a percent)																						1.965%
Interest rate as of reporting date (as a percent)																						2.46%
Short-term borrowings
Current portion of subordinated debt							$ 152,824
Federal funds purchased	50,000
Other short-term borrowings		620
Total short-term borrowings	50,000	153,444	627,469
Long-term debt
Long-term debt	$ 697,778	$ 704,971		$ 518,307	$ 525,569			$ 49,718	$ 49,680			$ 74,858	$ 74,839	$ 54,895	$ 54,882	$ 215,848	$ 223,416			$ 297,308	$ 297,003	$ 5,151	$ 5,151