Loans And Allowance For Loan Losses (Aging Information On Past Due And Accruing Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	$ 13,860,692	$ 13,897,272
30 - 89 Days Past Due	72,507	56,292
90 Days Past Due and Still Accruing	13,991	18,127
Non-accrual loans	8,369	11,983
Total	13,955,559	13,983,674
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	4,966,722	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	4,957,570	4,949,148
30 - 89 Days Past Due	3,673	3,085
90 Days Past Due and Still Accruing	348	374
Non-accrual loans	5,131	5,947
Total	4,966,722	4,958,554
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	999,691	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	995,134	967,321
30 - 89 Days Past Due	4,553	1,473
90 Days Past Due and Still Accruing	0	21
Non-accrual loans	4	5
Total	999,691	968,820
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,726,042	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	2,708,294	2,694,234
30 - 89 Days Past Due	16,281	482
90 Days Past Due and Still Accruing	0	0
Non-accrual loans	1,467	2,736
Total	2,726,042	2,697,452
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,120,672	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	2,110,198	2,050,787
30 - 89 Days Past Due	7,571	6,218
90 Days Past Due and Still Accruing	1,136	3,321
Non-accrual loans	1,767	2,461
Total	2,120,672	2,062,787
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	1,967,465	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	1,936,208	2,067,025
30 - 89 Days Past Due	28,249	32,674
90 Days Past Due and Still Accruing	3,008	3,954
Non-accrual loans	0	834
Total	1,967,465	2,104,487
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	375,322	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	372,931	397,349
30 - 89 Days Past Due	1,517	1,962
90 Days Past Due and Still Accruing	874	1,276
Non-accrual loans	0	0
Total	375,322	400,587
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	788,111	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	769,158	764,568
30 - 89 Days Past Due	10,328	10,115
90 Days Past Due and Still Accruing	8,625	9,181
Non-accrual loans	0	0
Total	788,111	783,864
Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	11,534	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	11,199	6,840
30 - 89 Days Past Due	335	283
90 Days Past Due and Still Accruing	0	0
Non-accrual loans	0	0
Total	$ 11,534	$ 7,123