Earnings per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Basic EPS:
Net income attributable to City National Corporation	$ 59,780	$ 41,398	$ 160,803	$ 128,561
Less: Earnings allocated to participating securities	842	655	2,380	1,988
Earnings allocated to common shareholders	58,938	40,743	158,423	126,573
Weighted average common shares outstanding	53,425,000	52,481,000	53,092,000	52,422,000
Basic earnings per common share (in dollars per share)	$ 1.10	$ 0.78	$ 2.98	$ 2.41
Diluted EPS:
Earnings allocated to common shareholders	$ 58,941	$ 40,745	$ 158,432	$ 126,586
Weighted average common shares outstanding	53,425,000	52,481,000	53,092,000	52,422,000
Dilutive effect of equity awards (in shares)	286,000	239,000	284,000	460,000
Weighted average diluted common shares outstanding	53,711,000	52,720,000	53,376,000	52,882,000
Diluted earnings per common share (in dollars per share)	$ 1.10	$ 0.77	$ 2.97	$ 2.39
Average outstanding stock options
Antidilutive securities not included in calculation of diluted EPS:
Antidilutive securities not included in calculation of diluted EPS (in shares)	2,400,000	3,800,000	2,700,000	2,500,000