Loans (Recorded Investment By Loan Grade) (Details) - USD ($) $ in Thousands		Mar. 31, 2018		Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		$ 5,292,349		$ 5,372,483
Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		126,561		125,389
Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		389,766		393,094
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	[1]	1,156,563		1,167,607
Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		2,905		2,993
5 Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		3,063		23,088
5 Rated [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment				278
5 Rated [Member] | Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		412		216
5 Rated [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		475	[2]	17,272	[3]
5 Rated [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		2,176	[2]	5,322	[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		474		611
6 Rated [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		344		0
6 Rated [Member] | Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment				1
6 Rated [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		130	[2]	153	[3]
6 Rated [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment	[3]			457
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		50,345		56,589
Impaired [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		1,393		1,324
Impaired [Member] | Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		2,896		19,059
Impaired [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		27,073	[2]	18,064	[3]
Impaired [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		18,983	[2]	18,142	[3]
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		2,632,453		2,672,410
Pass Rated [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		125,199		124,188
Pass Rated [Member] | Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		387,501		374,847
Pass Rated [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		977,351	[2]	1,022,377	[3]
Pass Rated [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		1,139,451	[2]	1,147,969	[3]
Pass Rated [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		2,951		3,029
Recorded Investment [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		2,686,335		2,752,698
Recorded Investment [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		126,936		125,790
Recorded Investment [Member] | Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		390,809		394,123
Recorded Investment [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		1,005,029	[2]	1,057,866	[3]
Recorded Investment [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		1,160,610	[2]	1,171,890	[3]
Recorded Investment [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		$ 2,951		$ 3,029

[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.