Loans And Allowance For Loan Losses (Credit Quality Of Commercial Loan Portfolio) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Line Items]
Loans	$ 13,626,592	$ 13,412,736
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	4,852,408	4,776,365
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	848,152	791,236
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	2,727,349	2,643,374
Commercial Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	8,427,909	8,210,975
Commercial Portfolio Segment [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	8,090,533	7,939,679
Commercial Portfolio Segment [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	226,413	162,843
Commercial Portfolio Segment [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	102,256	97,573
Commercial Portfolio Segment [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	8,707	10,880
Commercial Portfolio Segment [Member] | Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	4,852,408	4,776,365
Commercial Portfolio Segment [Member] | Business [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	4,617,838	4,607,553
Commercial Portfolio Segment [Member] | Business [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	180,380	116,642
Commercial Portfolio Segment [Member] | Business [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	47,860	43,488
Commercial Portfolio Segment [Member] | Business [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	6,330	8,682
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	848,152	791,236
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	843,151	788,778
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	1,754	722
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	2,703	1,172
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	544	564
Commercial Portfolio Segment [Member] | Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	2,727,349	2,643,374
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	2,629,544	2,543,348
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	44,279	45,479
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	51,693	52,913
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	$ 1,833	$ 1,634