Loans And Allowance For Loan Losses (Aging Information On Past Due And Accruing Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	$ 13,650,861	$ 13,324,515
30 - 89 Days Past Due	64,527	57,542
90 Days Past Due and Still Accruing	16,464	16,396
Non-accrual loans	13,640	14,283
Total	13,745,492	13,412,736
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	4,834,037	4,776,365
Business [Member] | Commercial Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	4,823,779	4,763,274
30 - 89 Days Past Due	2,630	3,735
90 Days Past Due and Still Accruing	807	674
Non-accrual loans	6,821	8,682
Total	4,834,037	4,776,365
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	921,609	791,236
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	917,128	789,633
30 - 89 Days Past Due	3,913	1,039
90 Days Past Due and Still Accruing	35	0
Non-accrual loans	533	564
Total	921,609	791,236
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,700,174	2,643,374
Real Estate - Business [Member] | Commercial Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	2,688,625	2,639,586
30 - 89 Days Past Due	8,580	2,154
90 Days Past Due and Still Accruing	623	0
Non-accrual loans	2,346	1,634
Total	2,700,174	2,643,374
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,029,302	2,010,397
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	2,013,632	1,995,724
30 - 89 Days Past Due	11,141	9,162
90 Days Past Due and Still Accruing	1,666	2,108
Non-accrual loans	2,863	3,403
Total	2,029,302	2,010,397
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,113,438	1,990,801
Consumer [Member] | Personal Banking Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	2,082,203	1,957,358
30 - 89 Days Past Due	27,450	29,783
90 Days Past Due and Still Accruing	2,708	3,660
Non-accrual loans	1,077	0
Total	2,113,438	1,990,801
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	391,308	413,634
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	388,346	411,483
30 - 89 Days Past Due	1,530	1,032
90 Days Past Due and Still Accruing	1,432	1,119
Non-accrual loans	0	0
Total	391,308	413,634
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	752,379	776,465
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	734,215	757,443
30 - 89 Days Past Due	8,971	10,187
90 Days Past Due and Still Accruing	9,193	8,835
Non-accrual loans	0	0
Total	752,379	776,465
Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	3,245	10,464
Overdrafts [Member] | Personal Banking Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	2,933	10,014
30 - 89 Days Past Due	312	450
90 Days Past Due and Still Accruing	0	0
Non-accrual loans	0	0
Total	$ 3,245	$ 10,464