Earnings per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Basic EPS:
Net income attributable to City National Corporation	$ 172,421	$ 131,177	$ 51,339
Less: Dividends and accretion on preferred stock		5,702	25,903
Net income available to common shareholders	172,421	125,475	25,436
Less: Earnings allocated to participating securities	2,678	1,605	253
Earnings allocated to common shareholders	169,743	123,870	25,183
Weighted average common shares outstanding (in shares)	52,439,000	51,992,000	50,272,000
Basic earnings per common share (in dollars per share)	$ 3.24	$ 2.38	$ 0.50
Diluted EPS:
Earnings allocated to common shareholders	$ 169,759	$ 123,882	$ 25,183
Weighted average common shares outstanding (in shares)	52,439,000	51,992,000	50,272,000
Dilutive effect of equity awards (in shares)	410,000	463,000	149,000
Weighted average diluted common shares outstanding (in shares)	52,849,000	52,455,000	50,421,000
Diluted earnings per common share (in dollars per share)	$ 3.21	$ 2.36	$ 0.50
Average outstanding stock options
Antidilutive securities not included in calculation of diluted EPS:
Antidilutive securities not included in calculation of diluted EPS (in shares)	2,900,000	1,900,000	3,400,000
Average outstanding common stock warrant
Antidilutive securities not included in calculation of diluted EPS:
Antidilutive securities not included in calculation of diluted EPS (in shares)		300,000	1,100,000