Loans (Recorded Investment By Loan Grade) (Details) - USD ($)		Mar. 31, 2019		Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		$ 5,740,760,000		$ 5,692,132,000
Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		168,880,000		175,300,000
Residential Real Estate Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		429,637,000		429,730,000
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	[1]	1,326,894,000		1,283,045,000
Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		2,117,000		2,273,000
5 Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		19,646,000		16,048,000
5 Rated [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		493,000		1,560,000
5 Rated [Member] | Residential Real Estate Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		1,761,000		272,000
5 Rated [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		12,980,000	[2]	11,509,000	[3]
5 Rated [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		4,412,000	[2]	2,707,000	[3]
5 Rated [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		0		0
6 Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		658,000		485,000
6 Rated [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		2,000		0
6 Rated [Member] | Residential Real Estate Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		104,000		41,000
6 Rated [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		543,000	[2]	444,000	[3]
6 Rated [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment	[2]	9,000
6 Rated [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		0		0
Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		50,962,000		48,218,000
Impaired [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		2,879,000		1,866,000
Impaired [Member] | Residential Real Estate Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		2,046,000		2,732,000
Impaired [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		14,899,000	[2]	15,194,000	[3]
Impaired [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		31,138,000	[2]	28,426,000	[3]
Impaired [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		0		0
Purchased credit impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		3,372,000		3,961,000
Purchased credit impaired [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment				503,000
Purchased credit impaired [Member] | Residential Real Estate Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		30,000		251,000
Purchased credit impaired [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment	[2]	330,000		148,000
Purchased credit impaired [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment	[2]	3,012,000		3,059,000
Purchased credit impaired [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		0		0
Pass Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		2,952,070,000		2,905,752,000
Pass Rated [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		166,266,000		172,172,000
Pass Rated [Member] | Residential Real Estate Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		426,999,000		427,584,000
Pass Rated [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment	[2]	1,063,512,000		1,050,094,000
Pass Rated [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment	[2]	1,293,152,000		1,253,603,000
Pass Rated [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		2,141,000		2,299,000
Recorded Investment [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		3,026,708,000		2,974,464,000
Recorded Investment [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		169,640,000		176,101,000
Recorded Investment [Member] | Residential Real Estate Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		430,940,000		430,880,000
Recorded Investment [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	[2]	1,092,264,000		1,077,389,000
Recorded Investment [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	[2]	1,331,723,000		1,287,795,000
Recorded Investment [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		2,141,000		2,299,000
Financial Asset Acquired with Credit Deterioration [Member] | Nonperforming Financial Instruments [Member] | Purchased credit impaired [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		$ 924,000		$ 475,000

[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.

[2] * 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.

[3] * 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.