Loans and Allowance for Credit Losses for Loans - Amortized Cost In Those Loan Classes Based on Payment Activity by Origination Year (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 49,391,420		$ 49,391,420		$ 48,799,711
Gross loan charge-offs
Total	42,071	$ 38,339	86,090	$ 63,239
90 Days or More Past Due Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,921		2,921		5,889
Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	248,495		248,495		428,668
Year two, fiscal year before current fiscal year	405,054		405,054		414,299
Year three, two years before current fiscal year	406,613		406,613		1,283,554
Year four, three years before current fiscal year	1,270,325		1,270,325		1,422,368
Year five, four years before current fiscal year	1,386,188		1,386,188		499,716
More than five years before current fiscal year	1,914,587		1,914,587		1,506,797
Revolving Loans Amortized Cost Basis	78,028		78,028		75,479
Revolving Loans Converted to Term Loans	681		681		1,635
Total	5,709,971		5,709,971		5,632,516
Gross loan charge-offs
Total	46	0	46	0
Residential mortgage | 90 Days or More Past Due Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,062		2,062		3,533
Residential mortgage | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	248,495		248,495		428,138
Year two, fiscal year before current fiscal year	404,738		404,738		413,528
Year three, two years before current fiscal year	405,835		405,835		1,282,524
Year four, three years before current fiscal year	1,264,594		1,264,594		1,420,835
Year five, four years before current fiscal year	1,385,458		1,385,458		494,430
More than five years before current fiscal year	1,899,165		1,899,165		1,490,512
Revolving Loans Amortized Cost Basis	78,028		78,028		75,479
Revolving Loans Converted to Term Loans	0		0		954
Total	5,686,313		5,686,313		5,606,400
Residential mortgage | Non-performing loan held for sale | 90 Days or More Past Due Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0		530
Year two, fiscal year before current fiscal year	316		316		771
Year three, two years before current fiscal year	778		778		1,030
Year four, three years before current fiscal year	5,731		5,731		1,533
Year five, four years before current fiscal year	730		730		5,286
More than five years before current fiscal year	15,422		15,422		16,285
Revolving Loans Amortized Cost Basis	0		0		0
Revolving Loans Converted to Term Loans	681		681		681
Total	23,658		23,658		26,116
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	692,923		692,923		901,463
Year two, fiscal year before current fiscal year	747,671		747,671		398,761
Year three, two years before current fiscal year	322,534		322,534		418,714
Year four, three years before current fiscal year	333,278		333,278		223,255
Year five, four years before current fiscal year	164,716		164,716		62,967
More than five years before current fiscal year	198,201		198,201		165,116
Revolving Loans Amortized Cost Basis	1,499,552		1,499,552		1,395,156
Revolving Loans Converted to Term Loans	26,618		26,618		25,405
Total	3,985,493		3,985,493		3,590,837
Gross loan charge-offs
Total	2,213	1,262	4,353	3,071
Consumer loans | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	14,196		14,196		22,947
Year two, fiscal year before current fiscal year	22,375		22,375		29,493
Year three, two years before current fiscal year	27,173		27,173		38,825
Year four, three years before current fiscal year	37,652		37,652		10,303
Year five, four years before current fiscal year	9,580		9,580		3,340
More than five years before current fiscal year	53,330		53,330		51,468
Revolving Loans Amortized Cost Basis	462,203		462,203		438,817
Revolving Loans Converted to Term Loans	8,044		8,044		9,240
Total	634,553		634,553		604,433
Consumer loans | Automobile
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	673,088		673,088		863,352
Year two, fiscal year before current fiscal year	713,646		713,646		343,325
Year three, two years before current fiscal year	275,872		275,872		364,041
Year four, three years before current fiscal year	281,619		281,619		211,364
Year five, four years before current fiscal year	150,182		150,182		59,290
More than five years before current fiscal year	84,434		84,434		59,693
Revolving Loans Amortized Cost Basis	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	2,178,841		2,178,841		1,901,065
Consumer loans | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	5,639		5,639		15,164
Year two, fiscal year before current fiscal year	11,650		11,650		25,943
Year three, two years before current fiscal year	19,489		19,489		15,848
Year four, three years before current fiscal year	14,007		14,007		1,588
Year five, four years before current fiscal year	4,954		4,954		337
More than five years before current fiscal year	60,437		60,437		53,955
Revolving Loans Amortized Cost Basis	1,037,349		1,037,349		956,339
Revolving Loans Converted to Term Loans	18,574		18,574		16,165
Total	1,172,099		1,172,099		1,085,339
Consumer loans | 90 Days or More Past Due Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	859		859		1,049
Consumer loans | 90 Days or More Past Due Loans | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0		0
Consumer loans | 90 Days or More Past Due Loans | Automobile
Financing Receivable, Credit Quality Indicator [Line Items]
Total	439		439		407
Consumer loans | 90 Days or More Past Due Loans | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	420		420		642
Consumer loans | Performing | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	14,196		14,196		22,947
Year two, fiscal year before current fiscal year	22,375		22,375		29,445
Year three, two years before current fiscal year	27,170		27,170		38,774
Year four, three years before current fiscal year	37,519		37,519		10,302
Year five, four years before current fiscal year	9,579		9,579		3,340
More than five years before current fiscal year	52,232		52,232		50,613
Revolving Loans Amortized Cost Basis	462,203		462,203		438,817
Revolving Loans Converted to Term Loans	7,758		7,758		9,061
Total	633,032		633,032		603,299
Consumer loans | Performing | Automobile
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	673,088		673,088		863,281
Year two, fiscal year before current fiscal year	713,485		713,485		343,203
Year three, two years before current fiscal year	275,710		275,710		363,901
Year four, three years before current fiscal year	281,523		281,523		211,294
Year five, four years before current fiscal year	150,135		150,135		59,288
More than five years before current fiscal year	84,287		84,287		59,512
Revolving Loans Amortized Cost Basis	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	2,178,228		2,178,228		1,900,479
Consumer loans | Performing | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	5,634		5,634		15,164
Year two, fiscal year before current fiscal year	11,650		11,650		25,884
Year three, two years before current fiscal year	19,464		19,464		15,787
Year four, three years before current fiscal year	14,006		14,006		1,588
Year five, four years before current fiscal year	4,954		4,954		337
More than five years before current fiscal year	60,437		60,437		53,917
Revolving Loans Amortized Cost Basis	1,037,349		1,037,349		956,339
Revolving Loans Converted to Term Loans	18,225		18,225		15,917
Total	1,171,719		1,171,719		1,084,933
Consumer loans | Non-performing loan held for sale | 90 Days or More Past Due Loans | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0		0
Year two, fiscal year before current fiscal year	0		0		48
Year three, two years before current fiscal year	3		3		51
Year four, three years before current fiscal year	133		133		1
Year five, four years before current fiscal year	1		1		0
More than five years before current fiscal year	1,098		1,098		855
Revolving Loans Amortized Cost Basis	0		0		0
Revolving Loans Converted to Term Loans	286		286		179
Total	1,521		1,521		1,134
Consumer loans | Non-performing loan held for sale | 90 Days or More Past Due Loans | Automobile
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0		71
Year two, fiscal year before current fiscal year	161		161		122
Year three, two years before current fiscal year	162		162		140
Year four, three years before current fiscal year	96		96		70
Year five, four years before current fiscal year	47		47		2
More than five years before current fiscal year	147		147		181
Revolving Loans Amortized Cost Basis	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	613		613		586
Consumer loans | Non-performing loan held for sale | 90 Days or More Past Due Loans | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	5		5		0
Year two, fiscal year before current fiscal year	0		0		59
Year three, two years before current fiscal year	25		25		61
Year four, three years before current fiscal year	1		1		0
Year five, four years before current fiscal year	0		0		0
More than five years before current fiscal year	0		0		38
Revolving Loans Amortized Cost Basis	0		0		0
Revolving Loans Converted to Term Loans	349		349		248
Total	380		380		406
Gross loan charge-offs
Gross loan charge-offs
Year one, gross loan charge-offs			0		1,014
Year two, gross loan charge-offs			1,161		1,883
Year three, gross loan charge-offs			626		1,511
Year four, gross loan charge-offs			570		1,015
Year five, gross loan charge-offs			273		519
More than five years gross loan charge-offs			1,686		2,245
Revolving Loans Amortized Cost Basis			0		0
Revolving Loans Converted to Term Loans			83		131
Total			4,399		8,318
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	901,078		901,078		1,824,953
Year two, fiscal year before current fiscal year	1,607,140		1,607,140		854,030
Year three, two years before current fiscal year	826,398		826,398		772,815
Year four, three years before current fiscal year	665,363		665,363		492,961
Year five, four years before current fiscal year	402,610		402,610		250,075
More than five years before current fiscal year	720,154		720,154		524,794
Revolving Loans Amortized Cost Basis	5,713,178		5,713,178		5,155,993
Revolving Loans Converted to Term Loans	34,115		34,115		55,779
Total	10,870,036		10,870,036		9,931,400
Gross loan charge-offs
Total	25,189	14,721	53,645	29,014
Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	899,962		899,962		1,769,585
Year two, fiscal year before current fiscal year	1,579,211		1,579,211		828,087
Year three, two years before current fiscal year	784,023		784,023		703,962
Year four, three years before current fiscal year	594,156		594,156		476,091
Year five, four years before current fiscal year	378,487		378,487		246,992
More than five years before current fiscal year	602,119		602,119		392,834
Revolving Loans Amortized Cost Basis	5,322,292		5,322,292		4,804,095
Revolving Loans Converted to Term Loans	8,655		8,655		6,006
Total	10,168,905		10,168,905		9,227,652
Commercial and industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	1,116		1,116		30,755
Year two, fiscal year before current fiscal year	1,566		1,566		3,553
Year three, two years before current fiscal year	12,373		12,373		59,434
Year four, three years before current fiscal year	8,970		8,970		11,646
Year five, four years before current fiscal year	20,015		20,015		270
More than five years before current fiscal year	5,316		5,316		72,514
Revolving Loans Amortized Cost Basis	169,498		169,498		147,254
Revolving Loans Converted to Term Loans	4,699		4,699		10,762
Total	223,553		223,553		336,188
Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0		24,613
Year two, fiscal year before current fiscal year	26,363		26,363		13,479
Year three, two years before current fiscal year	23,749		23,749		9,415
Year four, three years before current fiscal year	62,235		62,235		4,296
Year five, four years before current fiscal year	3,787		3,787		2,813
More than five years before current fiscal year	63,259		63,259		7,382
Revolving Loans Amortized Cost Basis	218,750		218,750		201,053
Revolving Loans Converted to Term Loans	20,761		20,761		39,011
Total	418,904		418,904		302,062
Commercial and industrial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0		0
Year two, fiscal year before current fiscal year	0		0		8,911
Year three, two years before current fiscal year	6,253		6,253		4
Year four, three years before current fiscal year	2		2		928
Year five, four years before current fiscal year	321		321		0
More than five years before current fiscal year	49,460		49,460		52,064
Revolving Loans Amortized Cost Basis	2,638		2,638		3,591
Revolving Loans Converted to Term Loans	0		0		0
Total	58,674		58,674		65,498
Commercial and industrial | 90 Days or More Past Due Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0		1,307
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	28,825,920		28,825,920		29,644,958
Gross loan charge-offs
Total	14,623	$ 22,356	28,046	$ 31,154
Commercial Real Estate | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	907,880		907,880		2,338,118
Year two, fiscal year before current fiscal year	2,244,084		2,244,084		3,433,126
Year three, two years before current fiscal year	3,100,906		3,100,906		5,988,114
Year four, three years before current fiscal year	5,739,935		5,739,935		4,400,609
Year five, four years before current fiscal year	4,086,600		4,086,600		2,604,959
More than five years before current fiscal year	9,116,669		9,116,669		6,937,081
Revolving Loans Amortized Cost Basis	721,125		721,125		749,597
Revolving Loans Converted to Term Loans	53,862		53,862		78,621
Total	25,971,061		25,971,061		26,530,225
Commercial Real Estate | Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	906,097		906,097		2,097,314
Year two, fiscal year before current fiscal year	2,046,206		2,046,206		2,941,270
Year three, two years before current fiscal year	2,631,836		2,631,836		5,310,807
Year four, three years before current fiscal year	5,034,673		5,034,673		3,883,333
Year five, four years before current fiscal year	3,508,472		3,508,472		2,302,480
More than five years before current fiscal year	7,948,426		7,948,426		6,086,608
Revolving Loans Amortized Cost Basis	493,466		493,466		597,266
Revolving Loans Converted to Term Loans	53,795		53,795		78,621
Total	22,622,971		22,622,971		23,297,699
Commercial Real Estate | Commercial real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	1,783		1,783		156,394
Year two, fiscal year before current fiscal year	131,233		131,233		380,852
Year three, two years before current fiscal year	262,912		262,912		289,669
Year four, three years before current fiscal year	291,603		291,603		192,614
Year five, four years before current fiscal year	149,396		149,396		55,739
More than five years before current fiscal year	251,288		251,288		327,732
Revolving Loans Amortized Cost Basis	150,586		150,586		141,164
Revolving Loans Converted to Term Loans	0		0		0
Total	1,238,801		1,238,801		1,544,164
Commercial Real Estate | Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0		84,410
Year two, fiscal year before current fiscal year	66,645		66,645		107,944
Year three, two years before current fiscal year	203,098		203,098		387,638
Year four, three years before current fiscal year	413,659		413,659		288,906
Year five, four years before current fiscal year	399,249		399,249		236,927
More than five years before current fiscal year	906,389		906,389		520,858
Revolving Loans Amortized Cost Basis	77,073		77,073		11,167
Revolving Loans Converted to Term Loans	67		67		0
Total	2,066,180		2,066,180		1,637,850
Commercial Real Estate | Commercial real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0		0
Year two, fiscal year before current fiscal year	0		0		3,060
Year three, two years before current fiscal year	3,060		3,060		0
Year four, three years before current fiscal year	0		0		35,756
Year five, four years before current fiscal year	29,483		29,483		9,813
More than five years before current fiscal year	10,566		10,566		1,883
Revolving Loans Amortized Cost Basis	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	43,109		43,109		50,512
Commercial Real Estate | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	283,613		283,613		568,710
Year two, fiscal year before current fiscal year	576,857		576,857		680,260
Year three, two years before current fiscal year	502,805		502,805		346,587
Year four, three years before current fiscal year	333,265		333,265		102,776
Year five, four years before current fiscal year	93,676		93,676		25,228
More than five years before current fiscal year	64,417		64,417		47,665
Revolving Loans Amortized Cost Basis	942,564		942,564		1,284,863
Revolving Loans Converted to Term Loans	57,662		57,662		58,644
Total	2,854,859		2,854,859		3,114,733
Commercial Real Estate | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	283,613		283,613		545,597
Year two, fiscal year before current fiscal year	565,391		565,391		680,260
Year three, two years before current fiscal year	447,756		447,756		334,899
Year four, three years before current fiscal year	322,573		322,573		92,765
Year five, four years before current fiscal year	64,401		64,401		17,955
More than five years before current fiscal year	53,919		53,919		45,161
Revolving Loans Amortized Cost Basis	775,127		775,127		1,224,698
Revolving Loans Converted to Term Loans	17,671		17,671		58,644
Total	2,530,451		2,530,451		2,999,979
Commercial Real Estate | Construction | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0		13,278
Year two, fiscal year before current fiscal year	10,895		10,895		0
Year three, two years before current fiscal year	21,510		21,510		664
Year four, three years before current fiscal year	1,742		1,742		5,069
Year five, four years before current fiscal year	23,047		23,047		0
More than five years before current fiscal year	1,969		1,969		2,504
Revolving Loans Amortized Cost Basis	96,667		96,667		16,691
Revolving Loans Converted to Term Loans	7,048		7,048		0
Total	162,878		162,878		38,206
Commercial Real Estate | Construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0		9,835
Year two, fiscal year before current fiscal year	571		571		0
Year three, two years before current fiscal year	33,539		33,539		8,950
Year four, three years before current fiscal year	8,950		8,950		4,942
Year five, four years before current fiscal year	6,228		6,228		0
More than five years before current fiscal year	8,529		8,529		0
Revolving Loans Amortized Cost Basis	70,770		70,770		43,474
Revolving Loans Converted to Term Loans	32,943		32,943		0
Total	161,530		161,530		67,201
Commercial Real Estate | Construction | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year					0
Year two, fiscal year before current fiscal year					0
Year three, two years before current fiscal year					2,074
Year four, three years before current fiscal year					0
Year five, four years before current fiscal year					7,273
More than five years before current fiscal year					0
Revolving Loans Amortized Cost Basis					0
Revolving Loans Converted to Term Loans					0
Total					9,347
Commercial Real Estate | 90 Days or More Past Due Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0		0
Commercial Real Estate | 90 Days or More Past Due Loans | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0		0
Commercial Real Estate | 90 Days or More Past Due Loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 0		0		0
Commercial and Industrial and Commercial Real Estate
Gross loan charge-offs
Year one, gross loan charge-offs			0		706
Year two, gross loan charge-offs			6,503		31,809
Year three, gross loan charge-offs			3,328		7,523
Year four, gross loan charge-offs			4,109		44,610
Year five, gross loan charge-offs			13,657		66,632
More than five years gross loan charge-offs			15,654		49,436
Revolving Loans Amortized Cost Basis			23,450		3,930
Revolving Loans Converted to Term Loans			14,990		2,148
Total			$ 81,691		$ 206,794