Deposits and Borrowed Funds (Details 2) (USD $)												12 Months Ended		12 Months Ended				12 Months Ended		1 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 First American Equipment Finance	Apr. 30, 2012 First American Equipment Finance	Dec. 31, 2012 City National Corporation	Dec. 31, 2011 City National Corporation	Dec. 31, 2012 5.125% Senior Notes Due February 2013 City National Corporation	Dec. 31, 2011 5.125% Senior Notes Due February 2013 City National Corporation	Dec. 31, 2012 5.25% Senior Notes Due September 2020 City National Corporation	Dec. 31, 2011 5.25% Senior Notes Due September 2020 City National Corporation	Dec. 31, 2012 9.00% Subordinated Notes Due July 2019 City National Bank Y	Dec. 31, 2011 9.00% Subordinated Notes Due July 2019 City National Bank	Dec. 31, 2012 9.00% Subordinated Notes Due July 2019 City National Bank LIBOR	Dec. 31, 2012 9.00% Subordinated Notes Due July 2019 City National Bank Prime rate	Dec. 31, 2012 9.00% Subordinated Notes Due August 2019 City National Bank	Dec. 31, 2011 9.00% Subordinated Notes Due August 2019 City National Bank	Dec. 31, 2012 Fixed and Floating Subordinated Notes due August 2019 City National Bank Y	Dec. 31, 2011 Fixed and Floating Subordinated Notes due August 2019 City National Bank	Jun. 30, 2012 5.375% Subordinated Notes Due July 2022 City National Bank	Dec. 31, 2012 5.375% Subordinated Notes Due July 2022 City National Bank	Dec. 31, 2012 Floating Rate Securities Due November 2034 Business Bancorp Capital Trust I	Dec. 31, 2011 Floating Rate Securities Due November 2034 Business Bancorp Capital Trust I	Dec. 31, 2012 Nonrecourse debt
Short-term borrowings and long-term debt
Fixed interest rate (as a percent)								5.125%	5.125%	5.25%	5.25%	9.00%	9.00%			9.00%	9.00%				5.375%
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)																						2.28%
Average interest rate (as a percent)	0.09%	0.06%	3.23%																					3.95%
Short-term borrowings
Federal funds purchased	$ 1,214,200,000	$ 50,000,000
Current portion of senior notes								206,581,000
Total short-term borrowings	1,423,798,000	50,000,000				206,581,000																		3,017,000
Long-term debt
Long-term debt	706,051,000	697,778,000				302,765,000	518,307,000		215,848,000	297,613,000	297,308,000	49,755,000	49,718,000			74,876,000	74,858,000	54,909,000	54,895,000		148,642,000	5,152,000	5,151,000	75,104,000
Borrowings and nonrecourse debt					320,900,000
Borrowings and nonrecourse debt				78,100,000
Long-term debt excluding discount and cost of issuance																				$ 150,000,000