Segment Results (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 segment	Dec. 31, 2011	Dec. 31, 2010
Segment Results
Number of reportable segments	3
Earnings Summary:
Net interest income	$ 830,836	$ 772,990	$ 730,325
Provision for credit losses on loans and leases, excluding covered loans	10,000	12,500	103,000
Provision for losses on covered loans	45,346	43,646	76,218
Noninterest income	357,603	341,867	361,375
Depreciation and amortization	39,753	35,323	34,881
Noninterest expense	785,385	769,772	716,449
Income before income taxes	307,955	253,616	161,152
Provision (benefit) for income taxes	98,822	77,561	26,055
Net income	209,133	176,055	135,097
Less: Net income attributable to noncontrolling interest	1,084	3,634	3,920
Net income attributable to City National Corporation	208,049	172,421	131,177
Selected Average Balances:
Loans and leases, excluding covered loans	13,285,220	11,698,388	11,576,380
Covered loans	1,268,513	1,699,182	1,940,316
Total assets	25,236,172	22,527,750	21,156,661
Deposits	21,628,868	19,305,703	17,868,392
Goodwill	573,849	486,502	481,018
Customer-relationship intangibles, net	43,388	39,428	43,171
Commercial and Private Banking
Earnings Summary:
Net interest income	724,610	740,445	702,788
Provision for credit losses on loans and leases, excluding covered loans	10,000	12,500	103,000
Provision for losses on covered loans	45,346	43,646	76,218
Noninterest income	215,397	222,279	277,883
Depreciation and amortization	14,207	14,656	13,764
Noninterest expense	686,295	683,816	629,692
Income before income taxes	184,159	208,106	157,997
Provision (benefit) for income taxes	77,347	87,405	66,358
Net income	106,812	120,701	91,639
Net income attributable to City National Corporation	106,812	120,701	91,639
Selected Average Balances:
Loans and leases, excluding covered loans	13,223,860	11,641,976	11,530,140
Covered loans	1,268,513	1,699,182	1,940,316
Total assets	14,835,858	13,820,611	14,134,625
Deposits	21,063,846	18,862,701	17,289,288
Goodwill	370,487	324,872	319,376
Customer-relationship intangibles, net	7,790	11,713	12,563
Wealth Management
Earnings Summary:
Net interest income	3,671	2,113	1,694
Noninterest income	187,838	162,238	155,724
Depreciation and amortization	7,289	5,205	6,507
Noninterest expense	167,909	147,307	145,175
Income before income taxes	16,311	11,839	5,736
Provision (benefit) for income taxes	6,395	4,151	1,662
Net income	9,916	7,688	4,074
Less: Net income attributable to noncontrolling interest	1,084	1,956	1,779
Net income attributable to City National Corporation	8,832	5,732	2,295
Selected Average Balances:
Loans and leases, excluding covered loans			50
Total assets	589,948	549,917	557,818
Deposits	102,144	64,919	47,450
Goodwill	203,362	161,630	161,642
Customer-relationship intangibles, net	35,598	27,715	30,608
Other
Earnings Summary:
Net interest income	102,555	30,432	25,843
Noninterest income	(45,632)	(42,650)	(72,232)
Depreciation and amortization	18,257	15,462	14,610
Noninterest expense	(68,819)	(61,351)	(58,418)
Income before income taxes	107,485	33,671	(2,581)
Provision (benefit) for income taxes	15,080	(13,995)	(41,965)
Net income	92,405	47,666	39,384
Less: Net income attributable to noncontrolling interest		1,678	2,141
Net income attributable to City National Corporation	92,405	45,988	37,243
Selected Average Balances:
Loans and leases, excluding covered loans	61,360	56,412	46,190
Total assets	9,810,366	8,157,222	6,464,218
Deposits	$ 462,878	$ 378,083	$ 531,654