Loans And Allowance For Loan Losses (Credit Quality Of Commercial Loan Portfolio) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	$ 8,210,975	$ 7,377,507
Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	7,939,679	7,179,210
Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	162,843	65,344
Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	97,573	111,126
Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	10,880	21,827
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	4,776,365	4,397,893
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	791,236	624,070
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	2,643,374	2,355,544
Commercial Portfolio Segment [Member] | Business [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	4,607,553	4,278,857
Commercial Portfolio Segment [Member] | Business [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	116,642	49,302
Commercial Portfolio Segment [Member] | Business [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	43,488	58,860
Commercial Portfolio Segment [Member] | Business [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	8,682	10,874
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	788,778	618,788
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	722	1,033
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	1,172	1,159
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	564	3,090
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	2,543,348	2,281,565
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	45,479	15,009
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	52,913	51,107
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial loans, Carrying Amount	$ 1,634	$ 7,863