Loans And Allowance For Loan Losses (Credit Quality Of Commercial Loan Portfolio) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	$ 8,851,874	$ 8,624,826
Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	8,558,943	8,288,517
Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	138,153	120,368
Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	144,074	207,253
Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	10,704	8,688
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	5,106,427	4,958,554
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	869,659	968,820
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	2,875,788	2,697,452
Commercial Portfolio Segment [Member] | Business [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	4,915,042	4,740,013
Commercial Portfolio Segment [Member] | Business [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	84,391	59,177
Commercial Portfolio Segment [Member] | Business [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	98,009	153,417
Commercial Portfolio Segment [Member] | Business [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	8,985	5,947
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	866,527	955,499
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	1,917	10,614
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	1,211	2,702
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	4	5
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	2,777,374	2,593,005
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	51,845	50,577
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	44,854	51,134
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	$ 1,715	$ 2,736