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		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 50,097,519		$ 50,097,519		$ 46,917,200
Gross loan charge-offs
Total	8,918	$ 9,995	52,818	$ 17,857
90 Days or More Past Due Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	12,358		12,358		26,587
Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	427,681		427,681		1,302,279
Year two, fiscal year before current fiscal year	1,308,323		1,308,323		1,502,819
Year three, two years before current fiscal year	1,523,120		1,523,120		571,607
Year four, three years before current fiscal year	547,401		547,401		502,032
Year five, four years before current fiscal year	443,875		443,875		340,938
More than five years before current fiscal year	1,239,718		1,239,718		1,078,169
Revolving Loans Amortized Cost Basis	72,547		72,547		66,706
Revolving Loans Converted to Term Loans	0		0		0
Total	5,562,665		5,562,665		5,364,550
Gross loan charge-offs
Total	20	0	169	27
Residential mortgage | 90 Days or More Past Due Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,348		1,348		1,866
Residential mortgage | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	427,681		427,681		1,302,279
Year two, fiscal year before current fiscal year	1,308,323		1,308,323		1,502,622
Year three, two years before current fiscal year	1,522,152		1,522,152		571,390
Year four, three years before current fiscal year	547,398		547,398		500,197
Year five, four years before current fiscal year	441,864		441,864		338,062
More than five years before current fiscal year	1,236,520		1,236,520		1,073,995
Revolving Loans Amortized Cost Basis	72,547		72,547		66,706
Revolving Loans Converted to Term Loans	0		0		0
Total	5,556,485		5,556,485		5,355,251
Residential mortgage | Non-Performing Loans | 90 Days or More Past Due Loans
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		197
Year three, two years before current fiscal year	968		968		217
Year four, three years before current fiscal year	3		3		1,835
Year five, four years before current fiscal year	2,011		2,011		2,876
More than five years before current fiscal year	3,198		3,198		4,174
Revolving Loans Amortized Cost Basis	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	6,180		6,180		9,299
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	365,697		365,697		795,819
Year two, fiscal year before current fiscal year	649,650		649,650		547,709
Year three, two years before current fiscal year	411,993		411,993		217,412
Year four, three years before current fiscal year	153,593		153,593		178,742
Year five, four years before current fiscal year	117,417		117,417		93,100
More than five years before current fiscal year	93,086		93,086		74,268
Revolving Loans Amortized Cost Basis	1,555,786		1,555,786		1,368,622
Revolving Loans Converted to Term Loans	38,683		38,683		39,280
Total	3,385,905		3,385,905		3,314,952
Gross loan charge-offs
Total	1,156	$ 962	3,024	$ 2,513
Consumer | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	28,808		28,808		47,084
Year two, fiscal year before current fiscal year	44,166		44,166		12,432
Year three, two years before current fiscal year	11,447		11,447		4,592
Year four, three years before current fiscal year	4,111		4,111		5,024
Year five, four years before current fiscal year	4,425		4,425		5,581
More than five years before current fiscal year	16,182		16,182		13,007
Revolving Loans Amortized Cost Basis	401,096		401,096		376,884
Revolving Loans Converted to Term Loans	38,683		38,683		39,280
Total	548,918		548,918		503,884
Consumer | Automobile
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	306,230		306,230		724,595
Year two, fiscal year before current fiscal year	584,134		584,134		525,133
Year three, two years before current fiscal year	396,394		396,394		204,614
Year four, three years before current fiscal year	141,149		141,149		166,283
Year five, four years before current fiscal year	104,299		104,299		80,113
More than five years before current fiscal year	53,781		53,781		45,487
Revolving Loans Amortized Cost Basis	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	1,585,987		1,585,987		1,746,225
Consumer | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	30,659		30,659		24,140
Year two, fiscal year before current fiscal year	21,350		21,350		10,144
Year three, two years before current fiscal year	4,152		4,152		8,206
Year four, three years before current fiscal year	8,333		8,333		7,435
Year five, four years before current fiscal year	8,693		8,693		7,406
More than five years before current fiscal year	23,123		23,123		15,774
Revolving Loans Amortized Cost Basis	1,154,690		1,154,690		991,738
Revolving Loans Converted to Term Loans	0		0		0
Total	1,251,000		1,251,000		1,064,843
Consumer | 90 Days or More Past Due Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	391		391		47
Consumer | 90 Days or More Past Due Loans | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0		0		0
Consumer | 90 Days or More Past Due Loans | Automobile
Financing Receivable, Credit Quality Indicator [Line Items]
Total	296		296		1
Consumer | 90 Days or More Past Due Loans | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	95		95		46
Consumer | Performing | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	28,808		28,808		47,084
Year two, fiscal year before current fiscal year	44,166		44,166		12,432
Year three, two years before current fiscal year	11,447		11,447		4,592
Year four, three years before current fiscal year	4,111		4,111		5,024
Year five, four years before current fiscal year	4,425		4,425		5,581
More than five years before current fiscal year	16,141		16,141		13,007
Revolving Loans Amortized Cost Basis	400,726		400,726		376,608
Revolving Loans Converted to Term Loans	38,373		38,373		38,570
Total	548,197		548,197		502,898
Consumer | Performing | Automobile
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	306,205		306,205		724,557
Year two, fiscal year before current fiscal year	584,045		584,045		525,017
Year three, two years before current fiscal year	396,302		396,302		204,578
Year four, three years before current fiscal year	141,124		141,124		166,103
Year five, four years before current fiscal year	104,149		104,149		80,012
More than five years before current fiscal year	53,739		53,739		45,415
Revolving Loans Amortized Cost Basis	0		0		0
Revolving Loans Converted to Term Loans					0
Total	1,585,564		1,585,564		1,745,682
Consumer | Performing | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	30,659		30,659		24,140
Year two, fiscal year before current fiscal year	21,337		21,337		10,144
Year three, two years before current fiscal year	4,152		4,152		8,206
Year four, three years before current fiscal year	8,333		8,333		7,435
Year five, four years before current fiscal year	8,693		8,693		7,406
More than five years before current fiscal year	23,085		23,085		15,736
Revolving Loans Amortized Cost Basis	1,154,094		1,154,094		991,737
Revolving Loans Converted to Term Loans	0		0		0
Total	1,250,353		1,250,353		1,064,804
Consumer | Non-Performing Loans | 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		0
Year three, two years before current fiscal year	0		0		0
Year four, three years before current fiscal year	0		0		0
Year five, four years before current fiscal year	0		0		0
More than five years before current fiscal year	41		41		0
Revolving Loans Amortized Cost Basis	370		370		276
Revolving Loans Converted to Term Loans	310		310		710
Total	721		721		986
Consumer | Non-Performing Loans | 90 Days or More Past Due Loans | Automobile
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	25		25		38
Year two, fiscal year before current fiscal year	89		89		116
Year three, two years before current fiscal year	92		92		36
Year four, three years before current fiscal year	25		25		180
Year five, four years before current fiscal year	150		150		101
More than five years before current fiscal year	42		42		72
Revolving Loans Amortized Cost Basis	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	423		423		543
Consumer | Non-Performing Loans | 90 Days or More Past Due Loans | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0		0
Year two, fiscal year before current fiscal year	13		13		0
Year three, two years before current fiscal year	0		0		0
Year four, three years before current fiscal year	0		0		0
Year five, four years before current fiscal year	0		0		0
More than five years before current fiscal year	38		38		38
Revolving Loans Amortized Cost Basis	596		596		1
Revolving Loans Converted to Term Loans	0		0		0
Total	$ 647		647		$ 39
Residential Mortgage and Consumer
Gross loan charge-offs
2023			97
2022			557
2021			314
2020			143
2019			610
Prior to 2019			1,348
Revolving Loans Amortized Cost Basis			124
Revolving Loans Converted to Term Loans			0
Total			$ 3,193