Loans (Recorded Investment By Loan Grade) (Details) - USD ($) $ in Thousands		Jun. 30, 2018		Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		$ 5,324,974		$ 5,372,483
Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		136,058		125,389
Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		390,651		393,094
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	[1]	1,150,845		1,167,607
Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		2,667		2,993
5 Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		4,593		23,088
5 Rated [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		21		278
5 Rated [Member] | Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		317		216
5 Rated [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		1,195	[2]	17,272	[3]
5 Rated [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		3,060	[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		103		611
6 Rated [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment				0
6 Rated [Member] | Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		46		1
6 Rated [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		57	[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		61,841		56,589
Impaired [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		2,529		1,324
Impaired [Member] | Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		2,750		19,059
Impaired [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		30,034	[2]	18,064	[3]
Impaired [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		26,528	[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		2,638,829		2,672,410
Pass Rated [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		133,931		124,188
Pass Rated [Member] | Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		388,607		374,847
Pass Rated [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		988,103	[2]	1,022,377	[3]
Pass Rated [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		1,125,498	[2]	1,147,969	[3]
Pass Rated [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total ending loan balance, recorded investment		2,690		3,029
Recorded Investment [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		2,705,366		2,752,698
Recorded Investment [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		136,481		125,790
Recorded Investment [Member] | Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		391,720		394,123
Recorded Investment [Member] | Commercial, Financial, and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		1,019,389	[2]	1,057,866	[3]
Recorded Investment [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		1,155,086	[2]	1,171,890	[3]
Recorded Investment [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment		$ 2,690		$ 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.