Loans (Composition Of Loan Portfolio By Class Of Loan) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Impaired Financing Receivable, Recorded Investment		$ 74,478	$ 46,760	$ 74,478	$ 46,760	$ 48,144
Loan balance		6,403,647		6,403,647		5,692,132
Accrued interest receivable		24,721		24,721		22,974
Recorded Investment		6,423,755		6,423,755		5,709,798
Impaired Financing Receivable, Average Recorded Investment		57,236	54,679	52,490	52,015
Impaired Financing Receivable, Interest Income, Cash Basis Method		412	485	1,142	1,292
Construction Real Estate Commercial [Domain]
Financing Receivable, Credit Quality Indicator [Line Items]
Impaired Financing Receivable, Recorded Investment		1,868	2,016	1,868	2,016
Loan balance		223,603		223,603		175,300
Accrued interest receivable		777		777		801
Recorded Investment		224,380		224,380		176,101
Impaired Financing Receivable, Average Recorded Investment		1,922	2,246	2,176	1,661
Impaired Financing Receivable, Interest Income, Cash Basis Method		1	4	23	31
Commercial Financial And Agricultural [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Impaired Financing Receivable, Recorded Investment		31,485	16,026	31,485	16,026
Impaired Financing Receivable, Average Recorded Investment		23,468	23,247	18,368	22,686
Impaired Financing Receivable, Interest Income, Cash Basis Method		107	187	244	506
Construction Real Estate - Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		92,985		92,985		70,541
Accrued interest receivable		232		232		151
Recorded Investment		93,217		93,217		70,692
Construction Real Estate - Installment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		1,581		1,581		2,433
Accrued interest receivable		5		5		7
Recorded Investment		1,586		1,586		2,440
Residential Real Estate Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Impaired Financing Receivable, Recorded Investment		2,238	2,913	2,238	2,913
Loan balance		465,656		465,656		429,730
Accrued interest receivable		1,199		1,199		1,150
Recorded Investment		466,855		466,855		430,880
Impaired Financing Receivable, Average Recorded Investment		1,977	2,758	2,198	6,086
Impaired Financing Receivable, Interest Income, Cash Basis Method		27	26	72	84
Residential Real Estate - Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		1,174,421		1,174,421		1,134,278
Accrued interest receivable		1,529		1,529		1,227
Recorded Investment		1,175,950		1,175,950		1,135,505
Residential Real Estate - HELOC [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		231,007		231,007		215,283
Accrued interest receivable		1,185		1,185		1,159
Recorded Investment		232,192		232,192		216,442
Residential Real Estate - Installment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		13,027		13,027		14,327
Accrued interest receivable		34		34		36
Recorded Investment		13,061		13,061		14,363
Loans Receivable [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Accrued interest receivable		20,108		20,108		17,666
Commercial Financial And Agricultural [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance	[1]	1,140,138		1,140,138		1,072,786
Accrued interest receivable	[1]	5,404		5,404		4,603
Recorded Investment	[1]	1,145,542		1,145,542		1,077,389
Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Impaired Financing Receivable, Recorded Investment		38,799	25,805	38,799	25,805
Loan balance	[1]	1,599,697		1,599,697		1,283,045
Accrued interest receivable	[1]	5,767		5,767		4,750
Recorded Investment	[1]	1,605,464		1,605,464		1,287,795
Impaired Financing Receivable, Average Recorded Investment		29,779	26,428	29,712	21,582
Impaired Financing Receivable, Interest Income, Cash Basis Method		277	$ 268	803	$ 671
Consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		1,430,400		1,430,400		1,292,136
Accrued interest receivable		3,946		3,946		3,756
Recorded Investment		1,434,346		1,434,346		1,295,892
Finance Leases Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		31,132		31,132		2,273
Accrued interest receivable		30		30		26
Recorded Investment		31,162		31,162		$ 2,299
Finance Leases Portfolio Segment [Member] | Residential Real Estate Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Impaired Financing Receivable, Recorded Investment		88		88
Impaired Financing Receivable, Average Recorded Investment		$ 90		$ 36

[1] Included within each of commercial, financial and agricultural loans and commercial real estate loans is an immaterial amount of consumer loans that are not broken out by class.