Segment Results (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 segment	Sep. 30, 2011
Segment Results
Number of reportable segments			3
Earnings Summary:
Net interest income	$ 209,922	$ 199,316	$ 627,114	$ 571,433
Provision for credit losses on loans and leases, excluding covered loans	2,000	7,500	3,000	7,500
Provision for losses on covered loans	18,089	5,147	38,848	25,979
Noninterest income	107,257	69,635	257,725	255,465
Depreciation and amortization	10,256	9,035	29,101	26,959
Noninterest expense	197,630	188,602	574,021	579,907
Income before income taxes	89,204	58,667	239,869	186,553
Provision (benefit) for income taxes	29,052	16,267	78,042	54,803
Net income	60,152	42,400	161,827	131,750
Less: Net income attributable to noncontrolling interest	372	1,002	1,024	3,189
Net income attributable to City National Corporation	59,780	41,398	160,803	128,561
Selected Average Balances:
Loans and leases, excluding covered loans	13,587,508	11,796,644	13,050,523	11,524,821
Covered loans	1,207,031	1,664,349	1,328,484	1,748,033
Total assets	25,654,594	22,998,562	24,558,030	22,134,675
Deposits	21,940,820	19,724,598	21,038,791	18,903,183
Goodwill	632,473	486,383	551,065	486,543
Customer-relationship intangibles, net	54,751	38,917	41,413	40,306
Commercial and Private Banking
Earnings Summary:
Net interest income	184,597	189,999	541,163	543,719
Provision for credit losses on loans and leases, excluding covered loans	2,000	7,500	3,000	7,500
Provision for losses on covered loans	18,089	5,147	38,848	25,979
Noninterest income	60,203	39,139	157,758	162,470
Depreciation and amortization	3,569	3,689	10,565	10,976
Noninterest expense	170,040	169,073	507,450	513,215
Income before income taxes	51,102	43,729	139,058	148,519
Provision (benefit) for income taxes	21,463	18,367	58,405	62,378
Net income	29,639	25,362	80,653	86,141
Net income attributable to City National Corporation	29,639	25,362	80,653	86,141
Selected Average Balances:
Loans and leases, excluding covered loans	13,526,284	11,747,735	12,994,726	11,468,231
Covered loans	1,207,031	1,664,349	1,328,484	1,748,033
Total assets	15,098,090	13,882,867	14,656,195	13,718,262
Deposits	21,298,105	19,274,187	20,469,604	18,463,503
Goodwill	393,176	324,761	362,868	324,910
Customer-relationship intangibles, net	7,392	11,597	8,173	12,200
Wealth Management
Earnings Summary:
Net interest income	1,133	479	2,399	1,578
Noninterest income	54,405	41,070	133,743	124,011
Depreciation and amortization	1,996	1,525	4,980	4,471
Noninterest expense	45,233	34,613	117,336	111,334
Income before income taxes	8,309	5,411	13,826	9,784
Provision (benefit) for income taxes	3,334	1,852	5,377	2,770
Net income	4,975	3,559	8,449	7,014
Less: Net income attributable to noncontrolling interest	372	1,002	1,024	3,189
Net income attributable to City National Corporation	4,603	2,557	7,425	3,825
Selected Average Balances:
Total assets	638,445	556,584	569,043	554,570
Deposits	104,195	58,884	100,038	55,659
Goodwill	239,297	161,622	188,197	161,633
Customer-relationship intangibles, net	47,359	27,320	33,240	28,106
Other
Earnings Summary:
Net interest income	24,192	8,838	83,552	26,136
Noninterest income	(7,351)	(10,574)	(33,776)	(31,016)
Depreciation and amortization	4,691	3,821	13,556	11,512
Noninterest expense	(17,643)	(15,084)	(50,765)	(44,642)
Income before income taxes	29,793	9,527	86,985	28,250
Provision (benefit) for income taxes	4,255	(3,952)	14,260	(10,345)
Net income	25,538	13,479	72,725	38,595
Net income attributable to City National Corporation	25,538	13,479	72,725	38,595
Selected Average Balances:
Loans and leases, excluding covered loans	61,224	48,909	55,797	56,590
Total assets	9,918,059	8,559,111	9,332,792	7,861,843
Deposits	$ 538,520	$ 391,527	$ 469,149	$ 384,021