Loans And Allowance For Loan Losses (Aging Information On Past Due And Accruing Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	$ 13,878,250	$ 13,897,272
30 - 89 Days Past Due	52,936	56,292
90 Days Past Due and Still Accruing	13,453	18,127
Non-accrual loans	9,472	11,983
Total	13,954,111	13,983,674
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	4,990,298	4,958,554
Business [Member] | Commercial Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	4,983,337	4,949,148
30 - 89 Days Past Due	1,404	3,085
90 Days Past Due and Still Accruing	443	374
Non-accrual loans	5,114	5,947
Total	4,990,298	4,958,554
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	967,151	968,820
Real Estate - Construction And Land [Member] | Commercial Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	963,654	967,321
30 - 89 Days Past Due	3,492	1,473
90 Days Past Due and Still Accruing	0	21
Non-accrual loans	5	5
Total	967,151	968,820
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,727,580	2,697,452
Real Estate - Business [Member] | Commercial Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	2,718,888	2,694,234
30 - 89 Days Past Due	6,227	482
90 Days Past Due and Still Accruing	0	0
Non-accrual loans	2,465	2,736
Total	2,727,580	2,697,452
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,102,586	2,062,787
Real Estate - Personal [Member] | Personal Banking Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	2,092,350	2,050,787
30 - 89 Days Past Due	7,155	6,218
90 Days Past Due and Still Accruing	1,193	3,321
Non-accrual loans	1,888	2,461
Total	2,102,586	2,062,787
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,012,644	2,104,487
Consumer [Member] | Personal Banking Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	1,985,195	2,067,025
30 - 89 Days Past Due	25,096	32,674
90 Days Past Due and Still Accruing	2,353	3,954
Non-accrual loans	0	834
Total	2,012,644	2,104,487
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	374,557	400,587
Revolving Home Equity [Member] | Personal Banking Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	372,865	397,349
30 - 89 Days Past Due	708	1,962
90 Days Past Due and Still Accruing	984	1,276
Non-accrual loans	0	0
Total	374,557	400,587
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	775,214	783,864
Consumer Credit Card [Member] | Personal Banking Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	758,230	764,568
30 - 89 Days Past Due	8,504	10,115
90 Days Past Due and Still Accruing	8,480	9,181
Non-accrual loans	0	0
Total	775,214	783,864
Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	4,081	7,123
Overdrafts [Member] | Personal Banking Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	3,731	6,840
30 - 89 Days Past Due	350	283
90 Days Past Due and Still Accruing	0	0
Non-accrual loans	0	0
Total	$ 4,081	$ 7,123