Allowance for Credit Losses (Loan Portfolio by Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
2021	$ 11,520,155
2020	4,412,264
2019	3,363,987
2018	2,442,541
2017	2,121,979
Prior	6,575,664
Revolving	4,306,793
Revolving to Term	45,721
Total Loans	34,789,104	$ 32,079,073
Loans with COVID-19 related modifications	31,700
Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2021	2,930,635
2020	1,589,370
2019	1,075,508
2018	747,236
2017	485,480
Prior	712,950
Revolving	3,780,351
Revolving to Term	24,255
Total Loans	11,345,785
Commercial PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2021	483,871
2020	74,412
2019	0
2018	0
2017	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	558,283
Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2021	371,051
2020	424,590
2019	299,554
2018	83,504
2017	73,869
Prior	89,011
Revolving	11,817
Revolving to Term	2,808
Total Loans	1,356,204
Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,559,227
2020	1,153,621
2019	1,007,176
2018	833,830
2017	743,376
Prior	2,135,464
Revolving	185,525
Revolving to Term	15,863
Total Loans	7,634,082
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2021	2
2020	0
2019	108
2018	183
2017	137
Prior	15,629
Revolving	316,301
Revolving to Term	2,795
Total Loans	335,155	425,263
Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2021	845,193
2020	283,628
2019	172,329
2018	72,542
2017	82,550
Prior	180,857
Revolving	0
Revolving to Term	0
Total Loans	1,637,099	1,259,598
Premium finance receivables - property & casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2021	4,816,550
2020	28,197
2019	9,637
2018	1,055
2017	48
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	4,855,487
Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2021	510,661
2020	857,553
2019	798,535
2018	702,894
2017	736,384
Prior	3,436,783
Revolving	0
Revolving to Term	0
Total Loans	7,042,810
Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2021	2,965
2020	893
2019	1,140
2018	1,297
2017	135
Prior	4,970
Revolving	12,799
Revolving to Term	0
Total Loans	24,199	$ 32,188
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	11,410,582
2020	4,303,106
2019	3,176,215
2018	2,289,947
2017	2,015,884
Prior	6,291,757
Revolving	4,176,612
Revolving to Term	36,621
Total Loans	33,700,724
Pass | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2021	2,878,530
2020	1,517,832
2019	971,713
2018	692,439
2017	466,042
Prior	661,422
Revolving	3,656,205
Revolving to Term	18,101
Total Loans	10,862,284
Pass | Commercial PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2021	483,710
2020	66,051
2019	0
2018	0
2017	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	549,761
Pass | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2021	370,769
2020	416,115
2019	286,959
2018	55,842
2017	41,015
Prior	87,517
Revolving	11,817
Revolving to Term	2,657
Total Loans	1,272,691
Pass | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,555,684
2020	1,137,883
2019	938,729
2018	767,775
2017	696,357
Prior	1,940,673
Revolving	185,525
Revolving to Term	15,863
Total Loans	7,238,489
Pass | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2021	2
2020	0
2019	0
2018	0
2017	28
Prior	6,252
Revolving	310,285
Revolving to Term	0
Total Loans	316,567
Pass | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2021	842,095
2020	280,081
2019	169,515
2018	68,780
2017	75,953
Prior	154,674
Revolving	0
Revolving to Term	0
Total Loans	1,591,098
Pass | Premium finance receivables - property & casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2021	4,766,171
2020	26,706
2019	9,637
2018	1,020
2017	48
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	4,803,582
Pass | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2021	510,661
2020	857,553
2019	798,535
2018	702,894
2017	736,384
Prior	3,436,783
Revolving	0
Revolving to Term	0
Total Loans	7,042,810
Pass | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2021	2,960
2020	885
2019	1,127
2018	1,197
2017	57
Prior	4,436
Revolving	12,780
Revolving to Term	0
Total Loans	23,442
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2021	99,355
2020	88,302
2019	141,058
2018	91,504
2017	58,446
Prior	157,777
Revolving	113,449
Revolving to Term	5,968
Total Loans	755,859
Special mention | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2021	48,867
2020	56,220
2019	74,411
2018	26,005
2017	11,261
Prior	39,945
Revolving	108,572
Revolving to Term	5,727
Total Loans	371,008
Special mention | Commercial PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2021	161
2020	7,466
2019	0
2018	0
2017	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	7,627
Special mention | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2021	282
2020	8,475
2019	12,282
2018	25,115
2017	18,172
Prior	116
Revolving	0
Revolving to Term	0
Total Loans	64,442
Special mention | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2021	3,543
2020	15,452
2019	53,902
2018	38,721
2017	27,169
Prior	110,332
Revolving	0
Revolving to Term	0
Total Loans	249,119
Special mention | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0
2019	0
2018	0
2017	0
Prior	438
Revolving	4,868
Revolving to Term	241
Total Loans	5,547
Special mention | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,849
2020	264
2019	450
2018	1,663
2017	1,766
Prior	6,892
Revolving	0
Revolving to Term	0
Total Loans	12,884
Special mention | Premium finance receivables - property & casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2021	44,648
2020	423
2019	0
2018	0
2017	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	45,071
Special mention | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0
2019	0
2018	0
2017	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	0
Special mention | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2021	5
2020	2
2019	13
2018	0
2017	78
Prior	54
Revolving	9
Revolving to Term	0
Total Loans	161
Substandard accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021	5,369
2020	15,030
2019	37,683
2018	58,590
2017	41,046
Prior	88,478
Revolving	16,372
Revolving to Term	2,884
Total Loans	265,452
Substandard accrual | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2021	3,034
2020	11,359
2019	22,101
2018	27,428
2017	5,739
Prior	6,752
Revolving	15,502
Revolving to Term	179
Total Loans	92,094
Substandard accrual | Commercial PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	895
2019	0
2018	0
2017	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	895
Substandard accrual | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0
2019	313
2018	2,547
2017	14,682
Prior	0
Revolving	0
Revolving to Term	151
Total Loans	17,693
Substandard accrual | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	286
2019	14,545
2018	27,322
2017	18,133
Prior	65,820
Revolving	0
Revolving to Term	0
Total Loans	126,106
Substandard accrual | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0
2019	0
2018	183
2017	67
Prior	6,803
Revolving	860
Revolving to Term	2,554
Total Loans	10,467
Substandard accrual | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,249
2020	2,208
2019	724
2018	1,075
2017	2,425
Prior	8,996
Revolving	0
Revolving to Term	0
Total Loans	16,677
Substandard accrual | Premium finance receivables - property & casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,086
2020	280
2019	0
2018	35
2017	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	1,401
Substandard accrual | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0
2019	0
2018	0
2017	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	0
Substandard accrual | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	2
2019	0
2018	0
2017	0
Prior	107
Revolving	10
Revolving to Term	0
Total Loans	119
Substandard nonaccrual/doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2021	4,849
2020	5,826
2019	9,031
2018	2,500
2017	6,603
Prior	37,652
Revolving	360
Revolving to Term	248
Total Loans	67,069
Substandard nonaccrual/doubtful | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2021	204
2020	3,959
2019	7,283
2018	1,364
2017	2,438
Prior	4,831
Revolving	72
Revolving to Term	248
Total Loans	20,399
Substandard nonaccrual/doubtful | Commercial PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0
2019	0
2018	0
2017	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	0
Substandard nonaccrual/doubtful | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0
2019	0
2018	0
2017	0
Prior	1,378
Revolving	0
Revolving to Term	0
Total Loans	1,378
Substandard nonaccrual/doubtful | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0
2019	0
2018	12
2017	1,717
Prior	18,639
Revolving	0
Revolving to Term	0
Total Loans	20,368
Substandard nonaccrual/doubtful | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0
2019	108
2018	0
2017	42
Prior	2,136
Revolving	288
Revolving to Term	0
Total Loans	2,574
Substandard nonaccrual/doubtful | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	1,075
2019	1,640
2018	1,024
2017	2,406
Prior	10,295
Revolving	0
Revolving to Term	0
Total Loans	16,440
Substandard nonaccrual/doubtful | Premium finance receivables - property & casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2021	4,645
2020	788
2019	0
2018	0
2017	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	5,433
Substandard nonaccrual/doubtful | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0
2019	0
2018	0
2017	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	0
Substandard nonaccrual/doubtful | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	4
2019	0
2018	100
2017	0
Prior	373
Revolving	0
Revolving to Term	0
Total Loans	$ 477