Summary Of Significant Accounting And Reporting Policies (Details) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2018 USD ($) branch	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) branch	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Condensed Financial Statements, Captions [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification					$ 0	$ 0
Equity Securities, FV-NI, Unrealized Gain (Loss)	$ (1,246)	$ 384	$ 492	$ 280	$ (90)
Number of Reportable Segments					1
DiscontinuationofInterestThresholdDays					90 days
Past Due Threshold in Days					30 days
Other real estate, foreclosed assets, and repossessed assets	4,600				$ 4,600	3,600
Investments in affordable housing limited partnerships	$ 5,400				5,400	1,300
Cash paid for interest					24,800	16,400	$ 13,100
Income taxes paid					$ 20,800	22,600	$ 16,300
City National
Condensed Financial Statements, Captions [Line Items]
Number of offices | branch	100				100
Residential real estate
Condensed Financial Statements, Captions [Line Items]
Threshold period past due for write-off of financing receivable					120 days
Commercial Industrial Loans And Commercial Real Estate
Condensed Financial Statements, Captions [Line Items]
Threshold period past due for write-off of financing receivable					120 days
Consumer Loan
Condensed Financial Statements, Captions [Line Items]
Threshold period past due for write-off of financing receivable					120 days
Accounting Standards Update 2018-02 [Member]
Condensed Financial Statements, Captions [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification						$ 999
Accounting Standards Update 2016-01 [Member]
Condensed Financial Statements, Captions [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification					$ 2,657