Loans (Composition Of Loan Portfolio By Class Of Loan) (Details) - USD ($) $ in Thousands		Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020		Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		$ 7,035,646		$ 7,177,785
Financing Receivable, Allowance for Credit Loss		(83,577)	$ (86,886)	(85,675)		$ (73,476)	$ (61,503)	$ (56,679)
Loans and Leases Receivable, Net Amount		6,952,069		7,092,110
Financing Receivable, Accrued Interest, before Allowance for Credit Loss		18,100		20,653
Loans and Leases Receivable, Recorded Investment				7,198,438
Construction Real Estate Commercial [Domain]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		210,681		226,991
Financing Receivable, Accrued Interest, before Allowance for Credit Loss				572
Loans and Leases Receivable, Recorded Investment				227,563
Construction Real Estate Retail
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		118,819		116,430
Financing Receivable, Accrued Interest, before Allowance for Credit Loss				235
Loans and Leases Receivable, Recorded Investment				116,665
Construction Real Estate - Installment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Recorded Investment				941
Residential Real Estate Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		517,114		526,222
Financing Receivable, Accrued Interest, before Allowance for Credit Loss				1,161
Loans and Leases Receivable, Recorded Investment				527,383
Residential Real Estate - Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		1,062,865		1,096,358
Financing Receivable, Accrued Interest, before Allowance for Credit Loss				947
Loans and Leases Receivable, Recorded Investment				1,097,305
Residential Real Estate - HELOC [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		167,522		182,028
Financing Receivable, Accrued Interest, before Allowance for Credit Loss				647
Loans and Leases Receivable, Recorded Investment				182,675
Residential Real Estate - Installment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		6,911		8,436
Financing Receivable, Accrued Interest, before Allowance for Credit Loss				22
Loans and Leases Receivable, Recorded Investment				8,458
Commercial, Financial, and Agricultural [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Recorded Investment				1,595,517
Commercial Financial And Agricultural [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		1,461,674		1,588,989	[1]
Financing Receivable, Allowance for Credit Loss		(15,222)	(16,279)	(25,608)		(23,476)	(21,544)	(20,203)
Financing Receivable, Accrued Interest, before Allowance for Credit Loss				6,528
Loans and Leases Receivable, Recorded Investment	[1]			1,595,517
PPP loans receivable [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		248,880
Bank Overdrafts
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		1,536
Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance	[1]	1,777,806		1,748,189
Financing Receivable, Allowance for Credit Loss		(22,749)	(24,487)	(23,480)		(16,469)	(11,591)	(10,229)
Financing Receivable, Accrued Interest, before Allowance for Credit Loss				6,017
Loans and Leases Receivable, Recorded Investment				1,754,206
Consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		1,689,581		1,659,704
Financing Receivable, Allowance for Credit Loss		(26,261)	(25,729)	(17,418)		(15,624)	(13,728)	(12,211)
Financing Receivable, Accrued Interest, before Allowance for Credit Loss				4,510
Loans and Leases Receivable, Recorded Investment				1,664,214
GFSC loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		3,750
Check loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		2,082
Finance Leases Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		22,673		24,438
Financing Receivable, Allowance for Credit Loss		(562)	$ (541)	(518)		$ (572)	$ (130)	$ (115)
Financing Receivable, Accrued Interest, before Allowance for Credit Loss				14
Loans and Leases Receivable, Recorded Investment				$ 24,452
Consumer less GFSC and Check Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		1,683,749
Commercial Financial Agricultural less PPP and Overdrafts
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		$ 1,211,258

[1] Included within each of commercial, financial and agricultural loans and commercial real estate loans is an immaterial amount of consumer loans that were not broken out by class.(2) Results for reporting periods beginning after January 1, 2021 are presented under ASC 326, while prior period amounts continue to be reported in accordance with previously applicable U.S. GAAP. Category was not broken out as a separate class at December 31, 2020.