Earnings per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basic EPS:
Net income attributable to City National Corporation	$ 255,819	$ 230,009	$ 208,049
Less: Dividends on preferred stock	16,375	9,625
Net income available to common shareholders	239,444	220,384	208,049
Less: Earnings allocated to participating securities	2,402	2,555	3,008
Earnings allocated to common shareholders	237,042	217,829	205,041
Weighted-average common shares outstanding	54,959,000	54,139,000	53,211,000
Basic earnings per common share (in dollars per share)	$ 4.31	$ 4.02	$ 3.85
Diluted EPS:
Earnings allocated to common shareholders	$ 237,063	$ 217,848	$ 205,050
Weighted-average common shares outstanding	54,959,000	54,139,000	53,211,000
Dilutive effect of equity awards (in shares)	732,000	501,000	264,000
Weighted-average diluted common shares outstanding	55,691,000	54,640,000	53,475,000
Diluted earnings per common share (in dollars per share)	$ 4.26	$ 3.99	$ 3.83
Stock options
Antidilutive securities not included in calculation of diluted EPS:
Antidilutive securities not included in calculation of diluted EPS (in shares)	700,000	1,500,000	2,800,000