Loans And Allowance For Credit Losses (Credit Quality Indicators Commercial Loan Portfolio) (Details) - Commercial Portfolio Segment [Member] $ in Thousands	Mar. 31, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 963,313
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,673,199
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,333,142
Financing Receivable, Originated Three Years before Latest Fiscal Year	976,119
Financing Receivable, Originated Four Years before Latest Fiscal Year	751,377
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	797,282
Financing Receivable, Revolving	2,113,143
Financing Receivable, before Allowance for Credit Loss, Total	9,607,575
Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	620,444
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	1,466,157
Financing Receivable, Originated Two Years before Latest Fiscal Year	633,053
Financing Receivable, Originated Three Years before Latest Fiscal Year	432,382
Financing Receivable, Originated Four Years before Latest Fiscal Year	240,968
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	384,839
Financing Receivable, Revolving	1,996,022
Financing Receivable, before Allowance for Credit Loss, Total	5,773,865
Real Estate - Construction And Land [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	85,223
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	387,328
Financing Receivable, Originated Two Years before Latest Fiscal Year	169,002
Financing Receivable, Originated Three Years before Latest Fiscal Year	101,561
Financing Receivable, Originated Four Years before Latest Fiscal Year	57,393
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	28,765
Financing Receivable, Revolving	44,130
Financing Receivable, before Allowance for Credit Loss, Total	873,402
Real Estate - Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	257,646
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	819,714
Financing Receivable, Originated Two Years before Latest Fiscal Year	531,087
Financing Receivable, Originated Three Years before Latest Fiscal Year	442,176
Financing Receivable, Originated Four Years before Latest Fiscal Year	453,016
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	383,678
Financing Receivable, Revolving	72,991
Financing Receivable, before Allowance for Credit Loss, Total	2,960,308
Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	902,573
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,621,108
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,310,352
Financing Receivable, Originated Three Years before Latest Fiscal Year	851,941
Financing Receivable, Originated Four Years before Latest Fiscal Year	722,246
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	707,214
Financing Receivable, Revolving	2,019,150
Financing Receivable, before Allowance for Credit Loss, Total	9,134,584
Pass [Member] | Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	564,816
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	1,429,136
Financing Receivable, Originated Two Years before Latest Fiscal Year	627,725
Financing Receivable, Originated Three Years before Latest Fiscal Year	424,625
Financing Receivable, Originated Four Years before Latest Fiscal Year	236,325
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	364,452
Financing Receivable, Revolving	1,907,436
Financing Receivable, before Allowance for Credit Loss, Total	5,554,515
Pass [Member] | Real Estate - Construction And Land [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	84,761
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	386,165
Financing Receivable, Originated Two Years before Latest Fiscal Year	158,298
Financing Receivable, Originated Three Years before Latest Fiscal Year	88,418
Financing Receivable, Originated Four Years before Latest Fiscal Year	57,393
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	1,228
Financing Receivable, Revolving	44,130
Financing Receivable, before Allowance for Credit Loss, Total	820,393
Pass [Member] | Real Estate - Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	252,996
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	805,807
Financing Receivable, Originated Two Years before Latest Fiscal Year	524,329
Financing Receivable, Originated Three Years before Latest Fiscal Year	338,898
Financing Receivable, Originated Four Years before Latest Fiscal Year	428,528
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	341,534
Financing Receivable, Revolving	67,584
Financing Receivable, before Allowance for Credit Loss, Total	2,759,676
Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	41,682
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	21,962
Financing Receivable, Originated Two Years before Latest Fiscal Year	11,763
Financing Receivable, Originated Three Years before Latest Fiscal Year	74,436
Financing Receivable, Originated Four Years before Latest Fiscal Year	12,595
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	32,269
Financing Receivable, Revolving	27,464
Financing Receivable, before Allowance for Credit Loss, Total	222,171
Special Mention [Member] | Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	40,720
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	14,556
Financing Receivable, Originated Two Years before Latest Fiscal Year	596
Financing Receivable, Originated Three Years before Latest Fiscal Year	2,704
Financing Receivable, Originated Four Years before Latest Fiscal Year	2,699
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	712
Financing Receivable, Revolving	27,422
Financing Receivable, before Allowance for Credit Loss, Total	89,409
Special Mention [Member] | Real Estate - Construction And Land [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	1,163
Financing Receivable, Originated Two Years before Latest Fiscal Year	10,110
Financing Receivable, Originated Three Years before Latest Fiscal Year	13,143
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	27,535
Financing Receivable, Revolving	0
Financing Receivable, before Allowance for Credit Loss, Total	51,951
Special Mention [Member] | Real Estate - Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	962
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	6,243
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,057
Financing Receivable, Originated Three Years before Latest Fiscal Year	58,589
Financing Receivable, Originated Four Years before Latest Fiscal Year	9,896
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	4,022
Financing Receivable, Revolving	42
Financing Receivable, before Allowance for Credit Loss, Total	80,811
Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	16,182
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	29,726
Financing Receivable, Originated Two Years before Latest Fiscal Year	10,485
Financing Receivable, Originated Three Years before Latest Fiscal Year	49,646
Financing Receivable, Originated Four Years before Latest Fiscal Year	15,996
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	53,366
Financing Receivable, Revolving	66,529
Financing Receivable, before Allowance for Credit Loss, Total	241,930
Substandard [Member] | Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	12,032
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	22,378
Financing Receivable, Originated Two Years before Latest Fiscal Year	4,732
Financing Receivable, Originated Three Years before Latest Fiscal Year	4,957
Financing Receivable, Originated Four Years before Latest Fiscal Year	1,944
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	15,378
Financing Receivable, Revolving	61,164
Financing Receivable, before Allowance for Credit Loss, Total	122,585
Substandard [Member] | Real Estate - Construction And Land [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	462
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	594
Financing Receivable, Originated Three Years before Latest Fiscal Year	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	0
Financing Receivable, Revolving	0
Financing Receivable, before Allowance for Credit Loss, Total	1,056
Substandard [Member] | Real Estate - Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	3,688
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	7,348
Financing Receivable, Originated Two Years before Latest Fiscal Year	5,159
Financing Receivable, Originated Three Years before Latest Fiscal Year	44,689
Financing Receivable, Originated Four Years before Latest Fiscal Year	14,052
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	37,988
Financing Receivable, Revolving	5,365
Financing Receivable, before Allowance for Credit Loss, Total	118,289
Non-Accrual [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	2,876
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	403
Financing Receivable, Originated Two Years before Latest Fiscal Year	542
Financing Receivable, Originated Three Years before Latest Fiscal Year	96
Financing Receivable, Originated Four Years before Latest Fiscal Year	540
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	4,433
Financing Receivable, Revolving	0
Financing Receivable, before Allowance for Credit Loss, Total	8,890
Non-Accrual [Member] | Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	2,876
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	87
Financing Receivable, Originated Two Years before Latest Fiscal Year	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	96
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	4,297
Financing Receivable, Revolving	0
Financing Receivable, before Allowance for Credit Loss, Total	7,356
Non-Accrual [Member] | Real Estate - Construction And Land [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	2
Financing Receivable, Revolving	0
Financing Receivable, before Allowance for Credit Loss, Total	2
Non-Accrual [Member] | Real Estate - Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	316
Financing Receivable, Originated Two Years before Latest Fiscal Year	542
Financing Receivable, Originated Three Years before Latest Fiscal Year	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	540
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	134
Financing Receivable, Revolving	0
Financing Receivable, before Allowance for Credit Loss, Total	$ 1,532