Loans And Allowance For Loan Losses (Aging Information On Past Due And Accruing Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	$ 13,547,465	$ 13,324,515
30 - 89 Days Past Due	51,135	57,542
90 Days Past Due and Still Accruing	14,630	16,396
Non-accrual loans	13,362	14,283
Total	13,626,592	13,412,736
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	4,852,408	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	4,842,945	4,763,274
30 - 89 Days Past Due	2,761	3,735
90 Days Past Due and Still Accruing	372	674
Non-accrual loans	6,330	8,682
Total	4,852,408	4,776,365
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	848,152	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	843,289	789,633
30 - 89 Days Past Due	4,319	1,039
90 Days Past Due and Still Accruing	0	0
Non-accrual loans	544	564
Total	848,152	791,236
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,727,349	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	2,721,612	2,639,586
30 - 89 Days Past Due	3,904	2,154
90 Days Past Due and Still Accruing	0	0
Non-accrual loans	1,833	1,634
Total	2,727,349	2,643,374
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,009,203	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	1,997,661	1,995,724
30 - 89 Days Past Due	6,060	9,162
90 Days Past Due and Still Accruing	1,978	2,108
Non-accrual loans	3,504	3,403
Total	2,009,203	2,010,397
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,038,514	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	2,012,634	1,957,358
30 - 89 Days Past Due	22,526	29,783
90 Days Past Due and Still Accruing	2,203	3,660
Non-accrual loans	1,151	0
Total	2,038,514	1,990,801
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	403,387	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	400,306	411,483
30 - 89 Days Past Due	2,154	1,032
90 Days Past Due and Still Accruing	927	1,119
Non-accrual loans	0	0
Total	403,387	413,634
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	740,865	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	722,604	757,443
30 - 89 Days Past Due	9,111	10,187
90 Days Past Due and Still Accruing	9,150	8,835
Non-accrual loans	0	0
Total	740,865	776,465
Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	6,714	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	6,414	10,014
30 - 89 Days Past Due	300	450
90 Days Past Due and Still Accruing	0	0
Non-accrual loans	0	0
Total	$ 6,714	$ 10,464