Loans (Composition Of Loan Portfolio By Class Of Loan) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Impaired Financing Receivable, Recorded Investment		$ 50,255	$ 61,750	$ 50,255	$ 61,750	$ 48,144
Loan balance		6,376,737		6,376,737		5,692,132
Accrued interest receivable		26,295		26,295		22,974
Recorded Investment		6,397,683		6,397,683		5,709,798
Impaired Financing Receivable, Average Recorded Investment		50,677	52,511	49,457	51,883
Impaired Financing Receivable, Interest Income, Cash Basis Method		380	386	730	807
Construction Real Estate Commercial [Domain]
Financing Receivable, Credit Quality Indicator [Line Items]
Impaired Financing Receivable, Recorded Investment		2,243	2,529	2,243	2,529
Loan balance		222,505		222,505		175,300
Accrued interest receivable		869		869		801
Recorded Investment		223,374		223,374		176,101
Impaired Financing Receivable, Average Recorded Investment		2,559	1,510	2,330	1,451
Impaired Financing Receivable, Interest Income, Cash Basis Method		10	13	22	27
Commercial Financial And Agricultural [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Impaired Financing Receivable, Recorded Investment		19,586	29,943	19,586	29,943
Impaired Financing Receivable, Average Recorded Investment		16,136	27,637	15,628	23,402
Impaired Financing Receivable, Interest Income, Cash Basis Method		90	145	137	319
Construction Real Estate - Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		89,457		89,457		70,541
Accrued interest receivable		250		250		151
Recorded Investment		89,707		89,707		70,692
Construction Real Estate - Installment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		1,985		1,985		2,433
Accrued interest receivable		7		7		7
Recorded Investment		1,992		1,992		2,440
Residential Real Estate Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Impaired Financing Receivable, Recorded Investment		1,874	2,750	1,874	2,750
Loan balance		476,991		476,991		429,730
Accrued interest receivable		1,354		1,354		1,150
Recorded Investment		478,345		478,345		430,880
Impaired Financing Receivable, Average Recorded Investment		1,909	2,653	2,277	7,511
Impaired Financing Receivable, Interest Income, Cash Basis Method		25	27	45	58
Residential Real Estate - Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		1,167,808		1,167,808		1,134,278
Accrued interest receivable		1,893		1,893		1,227
Recorded Investment		1,169,701		1,169,701		1,135,505
Residential Real Estate - HELOC [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		239,017		239,017		215,283
Accrued interest receivable		1,324		1,324		1,159
Recorded Investment		240,341		240,341		216,442
Residential Real Estate - Installment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		13,387		13,387		14,327
Accrued interest receivable		36		36		36
Recorded Investment		13,423		13,423		14,363
Loans Receivable [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Accrued interest receivable		20,946		20,946		17,666
Commercial Financial And Agricultural [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance	[1]	1,159,056		1,159,056		1,072,786
Accrued interest receivable	[1]	5,396		5,396		4,603
Recorded Investment	[1]	1,164,452		1,164,452		1,077,389
Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Impaired Financing Receivable, Recorded Investment		26,461	26,528	26,461	26,528
Loan balance	[1]	1,612,291		1,612,291		1,283,045
Accrued interest receivable	[1]	5,661		5,661		4,750
Recorded Investment	[1]	1,617,952		1,617,952		1,287,795
Impaired Financing Receivable, Average Recorded Investment		30,050	20,711	29,209	19,519
Impaired Financing Receivable, Interest Income, Cash Basis Method		255	$ 201	526	$ 403
Consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		1,363,186		1,363,186		1,292,136
Accrued interest receivable		4,138		4,138		3,756
Recorded Investment		1,367,324		1,367,324		1,295,892
Finance Leases Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan balance		31,054		31,054		2,273
Accrued interest receivable		18		18		26
Recorded Investment		31,072		31,072		$ 2,299
Finance Leases Portfolio Segment [Member] | Residential Real Estate Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Impaired Financing Receivable, Recorded Investment		91		91
Impaired Financing Receivable, Average Recorded Investment		$ 23		$ 13

[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.