Allowance for Credit Losses - Schedule of Loan Portfolio by Credit Quality Indicator (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
2024	$ 12,511,611		$ 12,511,611
2023	12,102,441		12,102,441
2022	5,803,751		5,803,751
2021	3,950,457		3,950,457
2020	1,773,105		1,773,105
Prior	4,871,250		4,871,250
Revolving	6,031,596		6,031,596
Revolving to term	23,236		23,236
Total Loans	47,067,447	$ 41,446,032	47,067,447	$ 41,446,032	$ 42,131,831
Gross write offs
2024			8,223
2023			30,985
2022			5,797
2021			20,094
2020			2,206
Prior			22,310
Revolving			0
Revolving to term			0
Total loans	31,018	10,477	89,615	36,344
Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2024	2,471,209		2,471,209
2023	2,489,122		2,489,122
2022	1,964,100		1,964,100
2021	1,338,727		1,338,727
2020	485,323		485,323
Prior	1,154,974		1,154,974
Revolving	5,328,312		5,328,312
Revolving to term	15,926		15,926
Total Loans	15,247,693		15,247,693
Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2024	196,556		196,556
2023	574,767		574,767
2022	999,643		999,643
2021	290,426		290,426
2020	99,003		99,003
Prior	221,955		221,955
Revolving	21,340		21,340
Revolving to term	0		0
Total Loans	2,403,690		2,403,690
Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2024	1,082,442		1,082,442
2023	1,545,615		1,545,615
2022	1,978,827		1,978,827
2021	1,527,432		1,527,432
2020	968,801		968,801
Prior	3,065,541		3,065,541
Revolving	218,925		218,925
Revolving to term	2,144		2,144
Total Loans	10,389,727		10,389,727
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2024	70		70
2023	64		64
2022	762		762
2021	369		369
2020	176		176
Prior	14,880		14,880
Revolving	405,556		405,556
Revolving to term	5,166		5,166
Total Loans	427,043	343,258	427,043	343,258	343,976
Gross write offs
Total loans	0	227	74	227
Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2024	584,925		584,925
2023	544,517		544,517
2022	855,216		855,216
2021	786,145		786,145
2020	219,642		219,642
Prior	397,593		397,593
Revolving	0		0
Revolving to term	0		0
Total Loans	3,388,038	2,707,603	3,388,038	2,707,603	2,769,666
Gross write offs
Total loans	0	78	61	78
Premium finance receivables - property and casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2024	6,933,253		6,933,253
2023	191,648		191,648
2022	339		339
2021	6,369		6,369
2020	72		72
Prior	0		0
Revolving	0		0
Revolving to term	0		0
Total Loans	7,131,681		7,131,681
Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2024	1,239,820		1,239,820
2023	6,753,150		6,753,150
2022	3,929		3,929
2021	0		0
2020	0		0
Prior	0		0
Revolving	0		0
Revolving to term	0		0
Total Loans	7,996,899		7,996,899
Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2024	3,336		3,336
2023	3,558		3,558
2022	935		935
2021	989		989
2020	88		88
Prior	16,307		16,307
Revolving	57,463		57,463
Revolving to term	0		0
Total Loans	82,676	68,963	82,676	68,963	$ 60,500
Gross write offs
Total loans	154	$ 184	398	$ 447
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2024	12,384,052		12,384,052
2023	11,917,419		11,917,419
2022	5,581,704		5,581,704
2021	3,751,436		3,751,436
2020	1,704,373		1,704,373
Prior	4,476,188		4,476,188
Revolving	5,744,582		5,744,582
Revolving to term	20,320		20,320
Total Loans	45,580,074		45,580,074
Pass | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2024	2,460,772		2,460,772
2023	2,366,998		2,366,998
2022	1,841,838		1,841,838
2021	1,219,759		1,219,759
2020	463,726		463,726
Prior	1,115,942		1,115,942
Revolving	5,053,494		5,053,494
Revolving to term	13,568		13,568
Total Loans	14,536,097		14,536,097
Pass | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2024	196,556		196,556
2023	573,342		573,342
2022	965,654		965,654
2021	289,324		289,324
2020	95,193		95,193
Prior	149,561		149,561
Revolving	17,560		17,560
Revolving to term	0		0
Total Loans	2,287,190		2,287,190
Pass | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2024	1,078,671		1,078,671
2023	1,527,560		1,527,560
2022	1,934,856		1,934,856
2021	1,460,051		1,460,051
2020	933,785		933,785
Prior	2,929,344		2,929,344
Revolving	217,237		217,237
Revolving to term	2,144		2,144
Total Loans	10,083,648		10,083,648
Pass | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2024	70		70
2023	0		0
2022	45		45
2021	175		175
2020	0		0
Prior	6,771		6,771
Revolving	398,843		398,843
Revolving to term	4,608		4,608
Total Loans	410,512		410,512
Pass | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2024	584,491		584,491
2023	535,419		535,419
2022	834,543		834,543
2021	774,793		774,793
2020	211,510		211,510
Prior	258,425		258,425
Revolving	0		0
Revolving to term	0		0
Total Loans	3,199,181		3,199,181
Pass | Premium finance receivables - property and casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2024	6,827,867		6,827,867
2023	169,649		169,649
2022	0		0
2021	6,351		6,351
2020	71		71
Prior	0		0
Revolving	0		0
Revolving to term	0		0
Total Loans	7,003,938		7,003,938
Pass | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2024	1,232,306		1,232,306
2023	6,740,906		6,740,906
2022	3,929		3,929
2021	0		0
2020	0		0
Prior	0		0
Revolving	0		0
Revolving to term	0		0
Total Loans	7,977,141		7,977,141
Pass | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2024	3,319		3,319
2023	3,545		3,545
2022	839		839
2021	983		983
2020	88		88
Prior	16,145		16,145
Revolving	57,448		57,448
Revolving to term	0		0
Total Loans	82,367		82,367
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2024	95,122		95,122
2023	96,744		96,744
2022	126,698		126,698
2021	117,580		117,580
2020	19,251		19,251
Prior	96,329		96,329
Revolving	175,815		175,815
Revolving to term	1,928		1,928
Total Loans	729,467		729,467
Special mention | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2024	6,148		6,148
2023	68,788		68,788
2022	72,908		72,908
2021	80,229		80,229
2020	13,257		13,257
Prior	17,456		17,456
Revolving	164,169		164,169
Revolving to term	1,474		1,474
Total Loans	424,429		424,429
Special mention | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	417		417
2022	14,990		14,990
2021	0		0
2020	0		0
Prior	14,794		14,794
Revolving	3,780		3,780
Revolving to term	0		0
Total Loans	33,981		33,981
Special mention | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2024	3,613		3,613
2023	13,006		13,006
2022	29,415		29,415
2021	35,222		35,222
2020	5,298		5,298
Prior	51,144		51,144
Revolving	1,688		1,688
Revolving to term	0		0
Total Loans	139,386		139,386
Special mention | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	48		48
2022	220		220
2021	59		59
2020	119		119
Prior	2,871		2,871
Revolving	6,172		6,172
Revolving to term	454		454
Total Loans	9,943		9,943
Special mention | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2024	250		250
2023	2,846		2,846
2022	9,093		9,093
2021	2,063		2,063
2020	577		577
Prior	9,928		9,928
Revolving	0		0
Revolving to term	0		0
Total Loans	24,757		24,757
Special mention | Premium finance receivables - property and casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2024	85,094		85,094
2023	3,442		3,442
2022	64		64
2021	2		2
2020	0		0
Prior	0		0
Revolving	0		0
Revolving to term	0		0
Total Loans	88,602		88,602
Special mention | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	8,188		8,188
2022	0		0
2021	0		0
2020	0		0
Prior	0		0
Revolving	0		0
Revolving to term	0		0
Total Loans	8,188		8,188
Special mention | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2024	17		17
2023	9		9
2022	8		8
2021	5		5
2020	0		0
Prior	136		136
Revolving	6		6
Revolving to term	0		0
Total Loans	181		181
Substandard accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2024	13,234		13,234
2023	58,402		58,402
2022	78,965		78,965
2021	62,993		62,993
2020	39,930		39,930
Prior	127,683		127,683
Revolving	79,580		79,580
Revolving to term	671		671
Total Loans	461,458		461,458
Substandard accrual | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2024	3,789		3,789
2023	47,800		47,800
2022	42,374		42,374
2021	29,408		29,408
2020	7,256		7,256
Prior	13,029		13,029
Revolving	79,030		79,030
Revolving to term	655		655
Total Loans	223,341		223,341
Substandard accrual | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	757		757
2022	18,999		18,999
2021	1,102		1,102
2020	1,777		1,777
Prior	57,600		57,600
Revolving	0		0
Revolving to term	0		0
Total Loans	80,235		80,235
Substandard accrual | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2024	158		158
2023	3,876		3,876
2022	14,103		14,103
2021	31,573		31,573
2020	29,718		29,718
Prior	47,478		47,478
Revolving	0		0
Revolving to term	0		0
Total Loans	126,906		126,906
Substandard accrual | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	16		16
2022	0		0
2021	0		0
2020	57		57
Prior	4,836		4,836
Revolving	541		541
Revolving to term	16		16
Total Loans	5,466		5,466
Substandard accrual | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2024	24		24
2023	585		585
2022	3,401		3,401
2021	906		906
2020	1,122		1,122
Prior	4,714		4,714
Revolving	0		0
Revolving to term	0		0
Total Loans	10,752		10,752
Substandard accrual | Premium finance receivables - property and casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2024	1,749		1,749
2023	1,308		1,308
2022	1		1
2021	4		4
2020	0		0
Prior	0		0
Revolving	0		0
Revolving to term	0		0
Total Loans	3,062		3,062
Substandard accrual | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2024	7,514		7,514
2023	4,056		4,056
2022	0		0
2021	0		0
2020	0		0
Prior	0		0
Revolving	0		0
Revolving to term	0		0
Total Loans	11,570		11,570
Substandard accrual | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	4		4
2022	87		87
2021	0		0
2020	0		0
Prior	26		26
Revolving	9		9
Revolving to term	0		0
Total Loans	126		126
Substandard nonaccrual/doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2024	19,203		19,203
2023	25,282		25,282
2022	12,641		12,641
2021	14,689		14,689
2020	4,345		4,345
Prior	52,963		52,963
Revolving	31,619		31,619
Revolving to term	317		317
Total Loans	161,059		161,059
Substandard nonaccrual/doubtful | Commercial, industrial and other
Financing Receivable, Credit Quality Indicator [Line Items]
2024	500		500
2023	5,536		5,536
2022	6,980		6,980
2021	9,331		9,331
2020	1,084		1,084
Prior	8,547		8,547
Revolving	31,619		31,619
Revolving to term	229		229
Total Loans	63,826		63,826
Substandard nonaccrual/doubtful | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	251		251
2022	0		0
2021	0		0
2020	2,033		2,033
Prior	0		0
Revolving	0		0
Revolving to term	0		0
Total Loans	2,284		2,284
Substandard nonaccrual/doubtful | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	1,173		1,173
2022	453		453
2021	586		586
2020	0		0
Prior	37,575		37,575
Revolving	0		0
Revolving to term	0		0
Total Loans	39,787		39,787
Substandard nonaccrual/doubtful | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	0		0
2022	497		497
2021	135		135
2020	0		0
Prior	402		402
Revolving	0		0
Revolving to term	88		88
Total Loans	1,122		1,122
Substandard nonaccrual/doubtful | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2024	160		160
2023	1,073		1,073
2022	4,436		4,436
2021	4,624		4,624
2020	1,227		1,227
Prior	6,439		6,439
Revolving	0		0
Revolving to term	0		0
Total Loans	17,959		17,959
Substandard nonaccrual/doubtful | Premium finance receivables - property and casualty
Financing Receivable, Credit Quality Indicator [Line Items]
2024	18,543		18,543
2023	17,249		17,249
2022	274		274
2021	12		12
2020	1		1
Prior	0		0
Revolving	0		0
Revolving to term	0		0
Total Loans	36,079		36,079
Substandard nonaccrual/doubtful | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	0		0
2022	0		0
2021	0		0
2020	0		0
Prior	0		0
Revolving	0		0
Revolving to term	0		0
Total Loans	0		0
Substandard nonaccrual/doubtful | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	0		0
2022	1		1
2021	1		1
2020	0		0
Prior	0		0
Revolving	0		0
Revolving to term	0		0
Total Loans	2		2
Early buy-out loans guaranteed by U.S. government agencies
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	4,594		4,594
2022	3,743		3,743
2021	3,759		3,759
2020	5,206		5,206
Prior	118,087		118,087
Revolving	0		0
Revolving to term	0		0
Total Loans	135,389		135,389
Early buy-out loans guaranteed by U.S. government agencies | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0		0
2023	4,594		4,594
2022	3,743		3,743
2021	3,759		3,759
2020	5,206		5,206
Prior	118,087		118,087
Revolving	0		0
Revolving to term	0		0
Total Loans	$ 135,389		$ 135,389