Summary Of Significant Accounting And Reporting Policies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) branch	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Condensed Financial Statements, Captions [Line Items]
Number of Reportable Segments	1
Gain on divestiture of business, net of tax			$ 5,800
DiscontinuationofInterestThresholdDays	90 days
Past Due Threshold in Days	30 days
Other real estate, foreclosed assets, and repossessed assets	$ 3,600	$ 4,600
Investments in affordable housing limited partnerships	1,300	300
ReclasificationofResidualtTaxImpactofTaxRateChange	0
Cash paid for interest	16,400	13,100	11,800
Income taxes paid	$ 22,600	$ 16,300	$ 26,300
City National
Condensed Financial Statements, Captions [Line Items]
Number of offices | branch	86
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
Accumulated Other Comprehensive Income (Loss) [Member]
Condensed Financial Statements, Captions [Line Items]
ReclasificationofResidualtTaxImpactofTaxRateChange	$ (999)