Loans And Allowance For Loan Losses (Credit Quality Of Commercial Loan Portfolio) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Loans And Allowance For Loan Losses [Line Items]
Loans	$ 12,697,870	$ 12,436,692
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	4,575,081	4,397,893
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	745,369	624,070
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	2,395,933	2,355,544
Commercial Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	7,716,383	7,377,507
Commercial Portfolio Segment [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	7,487,338	7,179,210
Commercial Portfolio Segment [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	93,170	65,344
Commercial Portfolio Segment [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	110,833	111,126
Commercial Portfolio Segment [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	25,042	21,827
Commercial Portfolio Segment [Member] | Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	4,575,081	4,397,893
Commercial Portfolio Segment [Member] | Business [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	4,435,061	4,278,857
Commercial Portfolio Segment [Member] | Business [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	64,964	49,302
Commercial Portfolio Segment [Member] | Business [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	58,958	58,860
Commercial Portfolio Segment [Member] | Business [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	16,098	10,874
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	745,369	624,070
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	733,542	618,788
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	8,026	1,033
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	1,091	1,159
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	2,710	3,090
Commercial Portfolio Segment [Member] | Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	2,395,933	2,355,544
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	2,318,735	2,281,565
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	20,180	15,009
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	50,784	51,107
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans	$ 6,234	$ 7,863