Regulatory Requirements And Capital Ratios (Schedule Of Capital Amounts And Ratios) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Parent Company
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CET1 capital	$ 430,154	$ 371,677
CET1 ratio	15.10%	13.30%
CET1 capital, minimum capital required basel III phase in schedule	$ 163,441	$ 142,845
CET1 ratio, minimum capital required basel III phase in schedule	5.75%	5.125%
CET1 capital, minimum capital required basel III fully phased in	$ 198,972	$ 195,105
CET1 ratio, minimum capital required basel III fully phased in	7.00%	7.00%
CET1 capital, required to be well-capitalized	$ 184,760	$ 181,169
CET1 ratio, required to be well capitalized	6.50%	6.50%
Tier I capital	$ 446,154	$ 387,677
Tier I capital, ratio	15.70%	13.90%
Tier 1, capital, minimum capital required basel III phase in schedule	$ 206,078	$ 184,653
Tier 1, ratio, minimum capital required basel III phase in schedule	7.25%	6.625%
Tier 1, capital, minimum capital required basel III fully phased in	$ 241,609	$ 236,913
Tier 1, ratio, minimum capital required basel III fully phased in	8.50%	8.50%
Tier 1, capital, required to be well-capitalized	$ 227,397	$ 222,977
Tier 1, ratio, required to be well-capitalized	8.00%	8.00%
Total capital	$ 465,292	$ 408,406
Total capital, ratio	16.40%	14.70%
Total capital, minimum capital required basel III phase in schedule	$ 262,927	$ 240,397
Total capital, ratio, minimum capital required basel iIII phase in schedule	9.25%	8.625%
Total capital, minimum capital required basel III fully phased in	$ 298,458	$ 292,658
Total capital, ratio, minimum capital required basel III fully phased in	10.50%	10.50%
Total capital, required to be well-capitalized	$ 284,246	$ 278,722
Total capital, ratio, required to be well-capitalized	10.00%	10.00%
Tier 1 Leverage Capital, Average Assets	$ 446,154	$ 387,677
Tier I Leverage Ratio, Average Assets	11.00%	10.10%
Tier 1 Leverage Capital, minimum capital required basel III phase in schedule	$ 161,834	$ 153,864
Tier 1 Leverage Ratio, minimum capital required basel III phase in schedule	4.00%	4.00%
Tier 1 Leverage Capital, minimum capital required basel III fully phased in	$ 161,834	$ 153,864
Tier 1 Leverage Ratio, minimum capital required basel III fully phased in	4.00%	4.00%
Tier 1 Leverage Capital Required to be Well Capitalized	$ 202,293	$ 192,330
Tier 1 Leverage Capital, Average Assets, Well Capitalized Ratio	5.00%	5.00%
City National
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CET1 capital	$ 338,105	$ 310,912
CET1 ratio	12.00%	11.20%
CET1 capital, minimum capital required basel III phase in schedule	$ 162,164	$ 141,860
CET1 ratio, minimum capital required basel III phase in schedule	5.75%	5.125%
CET1 capital, minimum capital required basel III fully phased in	$ 197,418	$ 193,761
CET1 ratio, minimum capital required basel III fully phased in	7.00%	7.00%
CET1 capital, required to be well-capitalized	$ 183,316	$ 179,921
CET1 ratio, required to be well capitalized	6.50%	6.50%
Tier I capital	$ 338,105	$ 318,872
Tier I capital, ratio	12.00%	11.50%
Tier 1, capital, minimum capital required basel III phase in schedule	$ 204,468	$ 183,381
Tier 1, ratio, minimum capital required basel III phase in schedule	7.25%	6.625%
Tier 1, capital, minimum capital required basel III fully phased in	$ 239,721	$ 235,281
Tier 1, ratio, minimum capital required basel III fully phased in	8.50%	8.50%
Tier 1, capital, required to be well-capitalized	$ 225,620	$ 221,441
Tier 1, ratio, required to be well-capitalized	8.00%	8.00%
Total capital	$ 357,243	$ 338,675
Total capital, ratio	12.70%	12.20%
Total capital, minimum capital required basel III phase in schedule	$ 260,873	$ 238,741
Total capital, ratio, minimum capital required basel iIII phase in schedule	9.25%	8.625%
Total capital, minimum capital required basel III fully phased in	$ 296,126	$ 290,641
Total capital, ratio, minimum capital required basel III fully phased in	10.50%	10.50%
Total capital, required to be well-capitalized	$ 282,025	$ 276,801
Total capital, ratio, required to be well-capitalized	10.00%	10.00%
Tier 1 Leverage Capital, Average Assets	$ 338,105	$ 318,872
Tier I Leverage Ratio, Average Assets	8.50%	8.30%
Tier 1 Leverage Capital, minimum capital required basel III phase in schedule	$ 159,625	$ 153,088
Tier 1 Leverage Ratio, minimum capital required basel III phase in schedule	4.00%	4.00%
Tier 1 Leverage Capital, minimum capital required basel III fully phased in	$ 159,625	$ 153,088
Tier 1 Leverage Ratio, minimum capital required basel III fully phased in	4.00%	4.00%
Tier 1 Leverage Capital Required to be Well Capitalized	$ 199,531	$ 191,359
Tier 1 Leverage Capital, Average Assets, Well Capitalized Ratio	5.00%	5.00%