Allowance for Credit Losses - Schedule of Loan Portfolio by Credit Quality Indicator (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
2025	$ 5,260,337
2024	10,220,397
2023	5,240,928
2022	5,883,869
2021	4,502,418
Prior	11,315,919
Revolving	6,274,954
Revolving to Term	9,568
Total Loans	48,708,390	$ 43,230,706	$ 48,055,037
Gross write offs
2025	123
2024	7,686
2023	1,810
2022	2,090
2021	1,829
Prior	3,911
Revolving	0
Revolving to Term	0
Total Loans	17,449	23,841
Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2025	962,987
2024	3,217,963
2023	2,142,762
2022	1,606,369
2021	1,137,761
Prior	1,359,419
Revolving	5,497,431
Revolving to Term	6,634
Total Loans	15,931,326
Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2025	32,130
2024	453,983
2023	613,665
2022	931,899
2021	172,986
Prior	217,216
Revolving	27,002
Revolving to Term	0
Total Loans	2,448,881
Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2025	390,433
2024	1,409,125
2023	1,463,848
2022	1,847,874
2021	1,410,260
Prior	3,688,462
Revolving	256,018
Revolving to Term	0
Total Loans	10,466,020
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	70
2023	59
2022	642
2021	209
Prior	21,163
Revolving	430,606
Revolving to Term	2,934
Total Loans	455,683	340,349	445,028
Gross write offs
Total Loans	0	74
Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2025	169,772
2024	865,861
2023	492,748
2022	816,864
2021	760,504
Prior	579,410
Revolving	0
Revolving to Term	0
Total Loans	3,685,159	2,890,266	3,612,765
Gross write offs
Total Loans	0	38
Premium finance receivables - property and casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2025	3,580,271
2024	3,637,284
2023	15,503
2022	3,646
2021	3,158
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	7,239,862
Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2025	123,243
2024	632,441
2023	509,590
2022	675,935
2021	1,016,825
Prior	5,407,106
Revolving	0
Revolving to Term	0
Total Loans	8,365,140
Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2025	1,501
2024	3,670
2023	2,753
2022	640
2021	715
Prior	43,143
Revolving	63,897
Revolving to Term	0
Total Loans	116,319	51,121	$ 99,562
Gross write offs
Total Loans	147	$ 107
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2025	5,238,011
2024	10,089,539
2023	5,070,574
2022	5,490,643
2021	4,297,050
Prior	10,940,681
Revolving	5,985,515
Revolving to Term	6,938
Total Loans	47,118,951
Pass | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2025	962,463
2024	3,196,212
2023	2,028,320
2022	1,467,054
2021	1,049,258
Prior	1,321,270
Revolving	5,220,680
Revolving to Term	4,004
Total Loans	15,249,261
Pass | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2025	32,130
2024	453,983
2023	610,151
2022	787,344
2021	152,775
Prior	156,009
Revolving	23,362
Revolving to Term	0
Total Loans	2,215,754
Pass | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2025	390,334
2024	1,391,830
2023	1,426,474
2022	1,756,751
2021	1,326,456
Prior	3,559,520
Revolving	253,772
Revolving to Term	0
Total Loans	10,105,137
Pass | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	70
2023	0
2022	89
2021	0
Prior	12,842
Revolving	423,925
Revolving to Term	2,934
Total Loans	439,860
Pass | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2025	169,711
2024	864,689
2023	481,004
2022	799,299
2021	747,872
Prior	445,181
Revolving	0
Revolving to Term	0
Total Loans	3,507,756
Pass | Premium finance receivables - property and casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2025	3,558,629
2024	3,546,697
2023	12,676
2022	3,618
2021	3,149
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	7,124,769
Pass | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2025	123,243
2024	632,441
2023	509,210
2022	675,935
2021	1,016,825
Prior	5,402,741
Revolving	0
Revolving to Term	0
Total Loans	8,360,395
Pass | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2025	1,501
2024	3,617
2023	2,739
2022	553
2021	715
Prior	43,118
Revolving	63,776
Revolving to Term	0
Total Loans	116,019
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2025	19,690
2024	80,657
2023	127,454
2022	258,710
2021	82,928
Prior	73,747
Revolving	180,031
Revolving to Term	1,162
Total Loans	824,379
Special mention | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2025	327
2024	14,077
2023	90,207
2022	62,439
2021	44,650
Prior	17,495
Revolving	173,427
Revolving to Term	1,162
Total Loans	403,784
Special mention | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	2,511
2022	143,224
2021	19,000
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	164,735
Special mention | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2025	99
2024	11,149
2023	32,632
2022	48,810
2021	17,951
Prior	44,048
Revolving	1,414
Revolving to Term	0
Total Loans	156,103
Special mention | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	44
2022	217
2021	0
Prior	3,210
Revolving	5,076
Revolving to Term	0
Total Loans	8,547
Special mention | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	330
2023	2,046
2022	4,012
2021	1,327
Prior	8,989
Revolving	0
Revolving to Term	0
Total Loans	16,704
Special mention | Premium finance receivables - property and casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2025	19,264
2024	55,065
2023	3
2022	4
2021	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	74,336
Special mention | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	0
Special mention | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	36
2023	11
2022	4
2021	0
Prior	5
Revolving	114
Revolving to Term	0
Total Loans	170
Substandard accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2025	2,452
2024	21,577
2023	22,579
2022	104,477
2021	103,662
Prior	151,656
Revolving	82,328
Revolving to Term	1,384
Total Loans	490,115
Substandard accrual | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2025	197
2024	6,030
2023	17,208
2022	56,774
2021	35,016
Prior	14,142
Revolving	76,970
Revolving to Term	1,384
Total Loans	207,721
Substandard accrual | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	752
2022	0
2021	1,211
Prior	59,176
Revolving	3,640
Revolving to Term	0
Total Loans	64,779
Substandard accrual | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	6,146
2023	3,366
2022	41,015
2021	65,702
Prior	65,145
Revolving	832
Revolving to Term	0
Total Loans	182,206
Substandard accrual | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	15
2022	0
2021	0
Prior	4,312
Revolving	879
Revolving to Term	0
Total Loans	5,206
Substandard accrual | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2025	61
2024	688
2023	854
2022	6,603
2021	1,730
Prior	4,499
Revolving	0
Revolving to Term	0
Total Loans	14,435
Substandard accrual | Premium finance receivables - property and casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2025	2,194
2024	8,710
2023	2
2022	2
2021	3
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	10,911
Substandard accrual | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	380
2022	0
2021	0
Prior	4,365
Revolving	0
Revolving to Term	0
Total Loans	4,745
Substandard accrual | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	3
2023	2
2022	83
2021	0
Prior	17
Revolving	7
Revolving to Term	0
Total Loans	112
Substandard nonaccrual/doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2025	184
2024	28,624
2023	16,411
2022	27,571
2021	15,079
Prior	36,170
Revolving	27,080
Revolving to Term	84
Total Loans	151,203
Substandard nonaccrual/doubtful | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	1,644
2023	7,027
2022	20,102
2021	8,837
Prior	6,512
Revolving	26,354
Revolving to Term	84
Total Loans	70,560
Substandard nonaccrual/doubtful | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	251
2022	1,331
2021	0
Prior	2,031
Revolving	0
Revolving to Term	0
Total Loans	3,613
Substandard nonaccrual/doubtful | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	1,376
2022	1,298
2021	151
Prior	19,749
Revolving	0
Revolving to Term	0
Total Loans	22,574
Substandard nonaccrual/doubtful | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	336
2021	209
Prior	799
Revolving	726
Revolving to Term	0
Total Loans	2,070
Substandard nonaccrual/doubtful | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	154
2023	4,934
2022	4,482
2021	5,876
Prior	7,076
Revolving	0
Revolving to Term	0
Total Loans	22,522
Substandard nonaccrual/doubtful | Premium finance receivables - property and casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2025	184
2024	26,812
2023	2,822
2022	22
2021	6
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	29,846
Substandard nonaccrual/doubtful | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	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]
2025	0
2024	14
2023	1
2022	0
2021	0
Prior	3
Revolving	0
Revolving to Term	0
Total Loans	18
Early buy-out loans guaranteed by U.S. government agencies
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	3,910
2022	2,468
2021	3,699
Prior	113,665
Revolving	0
Revolving to Term	0
Total Loans	123,742
Early buy-out loans guaranteed by U.S. government agencies | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	3,910
2022	2,468
2021	3,699
Prior	113,665
Revolving	0
Revolving to Term	0
Total Loans	$ 123,742