Allowance for Credit Losses (Loan Portfolio by Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
2022	$ 12,179,209
2021	6,132,815
2020	3,744,770
2019	2,807,417
2018	2,001,722
Prior	7,592,801
Revolving	4,672,976
Revolving to Term	64,775
Total Loans	39,196,485	$ 34,789,104
Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2022	2,761,735
2021	2,433,733
2020	1,103,489
2019	701,788
2018	503,047
Prior	869,920
Revolving	4,131,511
Revolving to Term	43,941
Total Loans	12,549,164
Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2022	415,454
2021	470,679
2020	283,869
2019	148,130
2018	53,469
Prior	103,329
Revolving	12,000
Revolving to Term	0
Total Loans	1,486,930
Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2022	1,913,542
2021	1,543,368
2020	1,052,539
2019	877,773
2018	644,796
Prior	2,231,113
Revolving	181,096
Revolving to Term	19,790
Total Loans	8,464,017
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2022	198
2021	1
2020	118
2019	74
2018	255
Prior	15,217
Revolving	315,791
Revolving to Term	1,044
Total Loans	332,698	335,155
Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2022	792,501
2021	840,690
2020	242,347
2019	146,185
2018	73,004
Prior	277,656
Revolving	0
Revolving to Term	0
Total Loans	2,372,383	1,637,099
Premium finance receivables - property & casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2022	5,782,156
2021	58,687
2020	6,909
2019	1,707
2018	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	5,849,459
Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2022	510,675
2021	784,056
2020	1,055,247
2019	931,276
2018	726,763
Prior	4,082,981
Revolving	0
Revolving to Term	0
Total Loans	8,090,998
Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2022	2,948
2021	1,601
2020	252
2019	484
2018	388
Prior	12,585
Revolving	32,578
Revolving to Term	0
Total Loans	50,836	$ 24,199
Early buy-out loans guaranteed by U.S. government agencies
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	901
2020	9,424
2019	21,662
2018	19,700
Prior	113,101
Revolving	0
Revolving to Term	0
Total Loans	164,788
Early buy-out loans guaranteed by U.S. government agencies | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	901
2020	9,424
2019	21,662
2018	19,700
Prior	113,101
Revolving	0
Revolving to Term	0
Total Loans	164,788
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2022	12,046,682
2021	5,986,991
2020	3,662,460
2019	2,661,645
2018	1,863,618
Prior	7,336,246
Revolving	4,537,246
Revolving to Term	62,489
Total Loans	38,157,377
Pass | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2022	2,740,821
2021	2,314,421
2020	1,064,680
2019	631,670
2018	460,898
Prior	847,955
Revolving	3,999,401
Revolving to Term	42,699
Total Loans	12,102,545
Pass | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2022	413,322
2021	470,162
2020	261,173
2019	124,818
2018	36,591
Prior	90,294
Revolving	12,000
Revolving to Term	0
Total Loans	1,408,360
Pass | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2022	1,908,428
2021	1,530,812
2020	1,045,330
2019	851,041
2018	589,268
Prior	2,149,357
Revolving	181,096
Revolving to Term	19,790
Total Loans	8,275,122
Pass | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2022	198
2021	0
2020	0
2019	56
2018	0
Prior	5,445
Revolving	312,183
Revolving to Term	0
Total Loans	317,882
Pass | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2022	787,652
2021	835,672
2020	228,945
2019	120,596
2018	49,710
Prior	150,024
Revolving	0
Revolving to Term	0
Total Loans	2,172,599
Pass | Premium finance receivables - property & casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2022	5,682,665
2021	55,275
2020	6,833
2019	1,707
2018	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	5,746,480
Pass | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2022	510,675
2021	779,057
2020	1,055,247
2019	931,276
2018	726,763
Prior	4,080,764
Revolving	0
Revolving to Term	0
Total Loans	8,083,782
Pass | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2022	2,921
2021	1,592
2020	252
2019	481
2018	388
Prior	12,407
Revolving	32,566
Revolving to Term	0
Total Loans	50,607
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2022	100,155
2021	91,520
2020	33,122
2019	70,675
2018	87,653
Prior	67,880
Revolving	88,414
Revolving to Term	1,380
Total Loans	540,799
Special mention | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2022	6,780
2021	71,263
2020	10,279
2019	27,533
2018	36,874
Prior	17,972
Revolving	85,813
Revolving to Term	1,232
Total Loans	257,746
Special mention | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	517
2020	14,341
2019	23,312
2018	16,778
Prior	82
Revolving	0
Revolving to Term	0
Total Loans	55,030
Special mention | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2022	5,114
2021	12,556
2020	6,377
2019	18,225
2018	31,849
Prior	41,236
Revolving	0
Revolving to Term	0
Total Loans	115,357
Special mention | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	1
2020	0
2019	0
2018	255
Prior	991
Revolving	2,598
Revolving to Term	148
Total Loans	3,993
Special mention | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2022	3,523
2021	1,720
2020	2,100
2019	1,602
2018	1,897
Prior	5,247
Revolving	0
Revolving to Term	0
Total Loans	16,089
Special mention | Premium finance receivables - property & casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2022	84,728
2021	462
2020	25
2019	0
2018	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	85,215
Special mention | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	4,999
2020	0
2019	0
2018	0
Prior	2,217
Revolving	0
Revolving to Term	0
Total Loans	7,216
Special mention | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2022	10
2021	2
2020	0
2019	3
2018	0
Prior	135
Revolving	3
Revolving to Term	0
Total Loans	153
Substandard accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2022	20,888
2021	44,402
2020	36,550
2019	25,760
2018	28,936
Prior	61,763
Revolving	47,216
Revolving to Term	906
Total Loans	266,421
Substandard accrual | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2022	13,560
2021	42,091
2020	26,252
2019	17,104
2018	5,078
Prior	2,902
Revolving	46,297
Revolving to Term	10
Total Loans	153,294
Substandard accrual | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2022	2,132
2021	0
2020	8,355
2019	0
2018	100
Prior	12,537
Revolving	0
Revolving to Term	0
Total Loans	23,124
Substandard accrual | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	832
2019	8,507
2018	23,330
Prior	34,898
Revolving	0
Revolving to Term	0
Total Loans	67,567
Substandard accrual | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	7,530
Revolving	910
Revolving to Term	896
Total Loans	9,336
Substandard accrual | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2022	1,214
2021	1,981
2020	1,111
2019	149
2018	428
Prior	3,853
Revolving	0
Revolving to Term	0
Total Loans	8,736
Substandard accrual | Premium finance receivables - property & casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2022	3,965
2021	329
2020	0
2019	0
2018	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	4,294
Substandard accrual | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	0
Substandard accrual | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2022	17
2021	1
2020	0
2019	0
2018	0
Prior	43
Revolving	9
Revolving to Term	0
Total Loans	70
Substandard nonaccrual/doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2022	11,484
2021	9,001
2020	3,214
2019	27,675
2018	1,815
Prior	13,811
Revolving	100
Revolving to Term	0
Total Loans	67,100
Substandard nonaccrual/doubtful | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2022	574
2021	5,958
2020	2,278
2019	25,481
2018	197
Prior	1,091
Revolving	0
Revolving to Term	0
Total Loans	35,579
Substandard nonaccrual/doubtful | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	416
Revolving	0
Revolving to Term	0
Total Loans	416
Substandard nonaccrual/doubtful | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	349
Prior	5,622
Revolving	0
Revolving to Term	0
Total Loans	5,971
Substandard nonaccrual/doubtful | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	118
2019	18
2018	0
Prior	1,251
Revolving	100
Revolving to Term	0
Total Loans	1,487
Substandard nonaccrual/doubtful | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2022	112
2021	416
2020	767
2019	2,176
2018	1,269
Prior	5,431
Revolving	0
Revolving to Term	0
Total Loans	10,171
Substandard nonaccrual/doubtful | Premium finance receivables - property & casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2022	10,798
2021	2,621
2020	51
2019	0
2018	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	13,470
Substandard nonaccrual/doubtful | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	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]
2022	0
2021	6
2020	0
2019	0
2018	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	$ 6