Loans And Allowance For Credit Losses (Aging Information On Past Due And Accruing Loans) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	$ 14,959,408	$ 14,627,638
30 - 89 Days Past Due	87,251	80,100
90 Days Past Due and Still Accruing	16,520	19,859
Non-accrual loans	10,633	10,220
Total	15,073,812	14,737,817
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	5,773,865	5,565,449
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	873,402	899,377
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,960,308	2,833,554
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,464,819	2,354,760
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	1,941,787	1,964,145
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	349,735	349,251
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	706,753	764,977
Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	3,143	6,304
Commercial Portfolio Segment [Member] | Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	5,750,172	5,545,104
30 - 89 Days Past Due	15,927	12,064
90 Days Past Due and Still Accruing	410	792
Non-accrual loans	7,356	7,489
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	853,400	882,826
30 - 89 Days Past Due	19,997	13,046
90 Days Past Due and Still Accruing	3	3,503
Non-accrual loans	2	2
Commercial Portfolio Segment [Member] | Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	2,954,825	2,830,494
30 - 89 Days Past Due	3,771	2,030
90 Days Past Due and Still Accruing	180	0
Non-accrual loans	1,532	1,030
Personal Banking Portfolio Segment [Member] | Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	2,450,868	2,345,243
30 - 89 Days Past Due	9,952	6,129
90 Days Past Due and Still Accruing	2,256	1,689
Non-accrual loans	1,743	1,699
Personal Banking Portfolio Segment [Member] | Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	1,911,853	1,928,082
30 - 89 Days Past Due	27,724	34,053
90 Days Past Due and Still Accruing	2,210	2,010
Non-accrual loans	0	0
Personal Banking Portfolio Segment [Member] | Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	347,992	347,258
30 - 89 Days Past Due	1,208	1,743
90 Days Past Due and Still Accruing	535	250
Non-accrual loans	0	0
Personal Banking Portfolio Segment [Member] | Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	687,394	742,659
30 - 89 Days Past Due	8,433	10,703
90 Days Past Due and Still Accruing	10,926	11,615
Non-accrual loans	0	0
Personal Banking Portfolio Segment [Member] | Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 Days Past Due	2,904	5,972
30 - 89 Days Past Due	239	332
90 Days Past Due and Still Accruing	0	0
Non-accrual loans	$ 0	$ 0