Earnings per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Basic EPS:
Net income attributable to City National Corporation	$ 54,758	$ 47,471	$ 101,023	$ 87,163
Less: Earnings allocated to participating securities	788	759	1,532	1,333
Earnings allocated to common shareholders	53,970	46,712	99,491	85,830
Weighted average common shares outstanding	53,105,000	52,462,000	52,923,000	52,392,000
Basic earnings per common share (in dollars per share)	$ 1.02	$ 0.89	$ 1.88	$ 1.64
Diluted EPS:
Earnings allocated to common shareholders	$ 53,972	$ 46,718	$ 99,496	$ 85,841
Weighted average common shares outstanding	53,105,000	52,462,000	52,923,000	52,392,000
Dilutive effect of equity awards (in shares)	268,000	515,000	294,000	539,000
Weighted average diluted common shares outstanding	53,373,000	52,977,000	53,217,000	52,931,000
Diluted earnings per common share (in dollars per share)	$ 1.01	$ 0.88	$ 1.87	$ 1.62
Average outstanding stock options
Antidilutive securities not included in calculation of diluted EPS:
Antidilutive securities not included in calculation of diluted EPS (in shares)	2,700,000	2,000,000	2,800,000	1,800,000