Loans And Allowance For Loan Losses (Aging Information On Past Due And Accruing Loans) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	$ 14,021,168	$ 14,038,417
30 - 89 Days Past Due	70,732	72,687
90 Days Past Due and Still Accruing	16,655	16,658
Non-accrual loans	12,167	12,536
Total	14,120,722	14,140,298
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	5,175,541	5,106,427
Business [Member] | Commercial Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	5,154,124	5,086,912
30 - 89 Days Past Due	12,178	10,057
90 Days Past Due and Still Accruing	670	473
Non-accrual loans	8,569	8,985
Total	5,175,541	5,106,427
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	925,269	869,659
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	924,028	867,692
30 - 89 Days Past Due	1,237	1,963
90 Days Past Due and Still Accruing	0	0
Non-accrual loans	4	4
Total	925,269	869,659
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,859,614	2,875,788
Real Estate - Business [Member] | Commercial Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	2,844,335	2,867,347
30 - 89 Days Past Due	13,412	6,704
90 Days Past Due and Still Accruing	121	22
Non-accrual loans	1,746	1,715
Total	2,859,614	2,875,788
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,125,087	2,127,083
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	2,113,316	2,118,045
30 - 89 Days Past Due	7,335	6,041
90 Days Past Due and Still Accruing	2,588	1,165
Non-accrual loans	1,848	1,832
Total	2,125,087	2,127,083
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	1,893,212	1,955,572
Consumer [Member] | Personal Banking Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	1,866,038	1,916,320
30 - 89 Days Past Due	24,905	35,608
90 Days Past Due and Still Accruing	2,269	3,644
Non-accrual loans	0	0
Total	1,893,212	1,955,572
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	364,010	376,399
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	362,373	374,830
30 - 89 Days Past Due	1,167	875
90 Days Past Due and Still Accruing	470	694
Non-accrual loans	0	0
Total	364,010	376,399
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	772,396	814,134
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	751,639	792,334
30 - 89 Days Past Due	10,220	11,140
90 Days Past Due and Still Accruing	10,537	10,660
Non-accrual loans	0	0
Total	772,396	814,134
Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	5,593	15,236
Overdrafts [Member] | Personal Banking Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	5,315	14,937
30 - 89 Days Past Due	278	299
90 Days Past Due and Still Accruing	0	0
Non-accrual loans	0	0
Total	$ 5,593	$ 15,236