Loans and Allowances for Credit Losses (Tables)

12 Months Ended

Dec. 31, 2024

Dec. 31, 2023

Loans and Leases Receivable, Net Amount [Abstract]

Schedule of the Loans by Portfolio Segment [Table Text Block]

The portfolio segments of the loan portfolio are as follows (in thousands):

	December 31, 2024								December 31, 2023
	Fixed Rate		Variable Rate		Non-accrual		Total		Fixed Rate		Variable Rate		Non- accrual		Total
Commercial	$	3,450,238	$	11,565,251	$	14,647	$	15,030,136	$	3,558,563	$	11,135,075	$	110,131	$	14,803,769
Commercial real estate	668,532		4,380,015		9,905		5,058,452		791,757		4,538,570		7,320		5,337,647
Loans to individuals	2,620,936		1,383,027		22,173		4,026,136		2,282,914		1,452,620		28,018		3,763,552
Total	$	6,739,706	$	17,328,293	$	46,725	$	24,114,724	$	6,633,234	$	17,126,265	$	145,469	$	23,904,968
Foregone interest on nonaccrual loans							$	10,061							$	7,863

Rollforward of Allowance For Loan Losses And Accrual for Off-Balnace Sheet Credit Losses [Table Text Block]

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit for the year ended December 31, 2024 is summarized as follows (in thousands):

	Commercial		Commercial Real Estate		Loans to Individuals		Total
Allowance for loan losses:
Beginning balance	$	141,232	$	94,718	$	41,173	$	277,123
Provision for loan losses	12,614		(2,481)		5,658		15,791
Loans charged off	(11,763)		(1,455)		(5,617)		(18,835)
Recoveries of loans previously charged off	3,070		290		2,596		5,956
Ending balance	$	145,153	$	91,072	$	43,810	$	280,035
Allowance for off-balance sheet credit risk from unfunded loan commitments:
Beginning balance	$	19,762	$	27,439	$	1,776	$	48,977
Provision for off-balance sheet credit risk	(1,716)		4,520		(141)		2,663
Ending balance	$	18,046	$	31,959	$	1,635	$	51,640

An $18.0 million provision for credit losses was recorded for the year ended December 31, 2024. Improvement in the forecasted economic outlook during the year was offset by the impact of loan growth and some risk grade migration.

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit for the year ended December 31, 2023 is summarized as follows (in thousands):

	Commercial		Commercial Real Estate		Loans to Individuals		Total
Allowance for loan losses:
Beginning balance	$	131,586	$	57,648	$	46,470	$	235,704
Provision for loan losses	19,308		42,151		(1,941)		59,518
Loans charged off	(12,898)		(8,446)		(5,972)		(27,316)
Recoveries of loans previously charged off	3,236		3,365		2,616		9,217
Ending balance	$	141,232	$	94,718	$	41,173	$	277,123
Allowance for off-balance sheet credit risk from unfunded loan commitments:
Beginning balance	$	18,246	$	40,490	$	2,183	$	60,919
Provision for off-balance sheet credit risk	1,516		(13,051)		(407)		(11,942)
Ending balance	$	19,762	$	27,439	$	1,776	$	48,977

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit is for the year ended December 31, 2022 summarized as follows (in thousands):

	Commercial		Commercial Real Estate		Loans to Individuals		Total
Allowance for loan losses:
Beginning balance	$	162,056	$	58,553	$	35,812	$	256,421
Provision for loan losses	(12,782)		(813)		14,023		428
Loans charged off	(22,382)		(269)		(6,095)		(28,746)
Recoveries of loans previously charged off	4,694		177		2,730		7,601
Ending balance	$	131,586	$	57,648	$	46,470	$	235,704
Allowance for off-balance sheet credit risk from unfunded loan commitments:
Beginning balance	$	13,812	$	17,442	$	1,723	$	32,977
Provision for off-balance sheet credit losses	4,434		23,048		460		27,942
Ending balance	$	18,246	$	40,490	$	2,183	$	60,919

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2024 is as follows (in thousands):

	Collectively Measured for General Allowances				Individually Measured for Specific Allowances				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	15,015,489	$	144,877	$	14,647	$	276	$	15,030,136	$	145,153
Commercial real estate	5,048,547		91,072		9,905		—		5,058,452		91,072
Loans to individuals	4,003,963		43,810		22,173		—		4,026,136		43,810
Total	$	24,067,999	$	279,759	$	46,725	$	276	$	24,114,724	$	280,035

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2023 is as follows (in thousands):

	Collectively Measured for General Allowances				Individually Measured for Specific Allowances				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	14,693,638	$	138,540	$	110,131	$	2,692	$	14,803,769	$	141,232
Commercial real estate	5,330,327		94,718		7,320		—		5,337,647		94,718
Loans to individuals	3,735,534		41,173		28,018		—		3,763,552		41,173
Total	$	23,759,499	$	274,431	$	145,469	$	2,692	$	23,904,968	$	277,123

Schedule of Credit Quality Indicators [Table Text Block]

	Origination Year
	2024		2023		2022		2021		2020		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Commercial:
Healthcare
Pass	$	539,305	$	544,103	$	896,042	$	481,816	$	344,609	$	644,441	$	249,793	$	10	$	3,700,119
Special Mention	—		15,000		64,895		110		—		32,555		255		—		112,815
Accruing Substandard	—		38,180		5,253		15,529		51,134		29,151		1,635		—		140,882
Nonaccrual	—		—		96		463		—		13,158		—		—		13,717
Total healthcare	539,305		597,283		966,286		497,918		395,743		719,305		251,683		10		3,967,533
Loans charged off, year-to-date	—		—		—		—		—		7,240		—		—		7,240
Energy
Pass	148,972		46,094		39,050		2,621		6,488		16,989		2,985,161		—		3,245,375
Accruing Substandard	—		—		—		—		—		—		9,300		—		9,300
Nonaccrual	—		—		—		—		—		49		—		—		49
Total energy	148,972		46,094		39,050		2,621		6,488		17,038		2,994,461		—		3,254,724
Loans charged off, year-to-date	—		—		—		—		—		—		226		—		226
Services
Pass	629,978		625,969		422,015		404,949		187,324		570,775		745,853		379		3,587,242
Special Mention	—		3,324		123		1,537		—		11,796		17,923		—		34,703
Accruing Substandard	—		675		9,030		20		1,217		7,750		1,399		400		20,491
Nonaccrual	—		—		—		—		—		—		767		—		767
Total services	629,978		629,968		431,168		406,506		188,541		590,321		765,942		779		3,643,203
Loans charged off, year-to-date	—		—		—		—		22		80		9		—		111
General business
Pass	740,440		571,897		267,528		176,468		117,755		319,986		1,862,643		1,938		4,058,655
Special Mention	4,399		5,749		4,285		7,002		224		1,736		3,037		—		26,432
Accruing Substandard	3,980		15,872		43,300		4,764		992		4,708		5,859		—		79,475
Nonaccrual	—		32		—		—		—		23		—		59		114
Total general business	748,819		593,550		315,113		188,234		118,971		326,453		1,871,539		1,997		4,164,676
Loans charged off, year-to-date	—		27		1,465		—		—		166		2,425		103		4,186
Total commercial	2,067,074		1,866,895		1,751,617		1,095,279		709,743		1,653,117		5,883,625		2,786		15,030,136
Commercial real estate:
Pass	436,206		512,614		2,004,558		793,161		233,619		810,497		141,307		—		4,931,962
Special Mention	—		313		14,907		32,131		—		—		—		—		47,351
Accruing Substandard	—		—		36,981		—		—		32,253		—		—		69,234
Nonaccrual	—		—		—		—		—		9,905		—		—		9,905
Total commercial real estate	436,206		512,927		2,056,446		825,292		233,619		852,655		141,307		—		5,058,452
Loans charged off, year-to-date	—		—		—		—		—		1,455		—		—		1,455

	Origination Year
	2024		2023		2022		2021		2020		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Loans to individuals:
Residential mortgage
Pass	530,186		338,187		286,865		318,935		314,814		210,251		395,943		22,929		2,418,110
Special Mention	—		167		148		219		—		113		1,767		—		2,414
Accruing Substandard	—		—		163		—		—		45		898		67		1,173
Nonaccrual	245		1,758		990		522		583		7,420		3,221		522		15,261
Total residential mortgage	530,431		340,112		288,166		319,676		315,397		217,829		401,829		23,518		2,436,958
Loans charged off, year-to-date	—		43		—		—		—		18		10		—		71
Residential mortgage guaranteed by U.S. government agencies
Pass	462		4,337		6,618		2,432		3,506		112,491		—		—		129,846
Nonaccrual	—		—		—		—		280		6,523		—		—		6,803
Total residential mortgage guaranteed by U.S. government agencies	462		4,337		6,618		2,432		3,786		119,014		—		—		136,649
Personal
Pass	245,737		149,572		167,272		115,710		107,291		151,030		510,147		2,619		1,449,378
Special Mention	18		17		30		825		8		—		8		—		906
Accruing Substandard	16		—		—		—		1		129		1,990		—		2,136
Nonaccrual	31		3		30		13		4		5		23		—		109
Total personal	245,802		149,592		167,332		116,548		107,304		151,164		512,168		2,619		1,452,529
Loans charged off, year-to-date1	5,269		69		101		52		9		—		26		20		5,546
Total loans to individuals	776,695		494,041		462,116		438,656		426,487		488,007		913,997		26,137		4,026,136
Total loans	$	3,279,975	$	2,873,863	$	4,270,179	$	2,359,227	$	1,369,849	$	2,993,779	$	6,938,929	$	28,923	$	24,114,724

1    Includes charge-offs on deposit overdrafts, which are generally charged off at 60 days past due.

The following table summarizes the Company's loan portfolio at December 31, 2023 by the risk grade categories and vintage (in thousands):

	Origination Year
	2023		2022		2021		2020		2019		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Commercial:
Healthcare
Pass	$	650,768	$	895,602	$	590,736	$	409,001	$	331,897	$	809,858	$	281,378	$	15	$	3,969,255
Special Mention	—		—		—		21,791		—		31,235		5		—		53,031
Accruing Substandard	—		2,128		18,508		6,911		—		10,896		975		—		39,418
Nonaccrual	—		—		—		30,290		23,129		28,110		—		—		81,529
Total healthcare	650,768		897,730		609,244		467,993		355,026		880,099		282,358		15		4,143,233
Loans charged off, year-to-date	—		—		—		—		2,500		—		—		—		2,500
Energy
Pass	190,122		100,006		43,769		7,876		9,562		11,583		3,025,590		—		3,388,508
Special Mention	—		—		—		—		—		—		13,950		—		13,950
Accruing Substandard	—		—		—		—		—		—		16,800		—		16,800
Nonaccrual	—		—		—		—		—		99		17,744		—		17,843
Total energy	190,122		100,006		43,769		7,876		9,562		11,682		3,074,084		—		3,437,101
Services
Pass	900,090		526,776		401,872		228,818		106,112		643,477		730,729		595		3,538,469
Special Mention	—		1,085		1,520		1,341		534		4,522		81		—		9,083
Accruing Substandard	—		13,712		178		326		3,972		3,746		3,108		13		25,055
Nonaccrual	—		—		1,635		338		—		—		1,643		—		3,616
Total services	900,090		541,573		405,205		230,823		110,618		651,745		735,561		608		3,576,223
Loans charged off, year-to-date	—		—		3,060		—		—		—		2,642		—		5,702
General business
Pass	942,468		436,832		224,735		138,951		101,100		287,744		1,389,128		2,164		3,523,122
Special Mention	10,264		16,167		8,420		1,253		321		8,295		897		—		45,617
Accruing Substandard	4,401		33,194		1,716		27		—		—		31,992		—		71,330
Nonaccrual	—		1,134		—		—		—		48		5,956		5		7,143
Total general business	957,133		487,327		234,871		140,231		101,421		296,087		1,427,973		2,169		3,647,212
Loans charged off, year-to-date	—		—		4,598		2		—		48		10		38		4,696
Total commercial	2,698,113		2,026,636		1,293,089		846,923		576,627		1,839,613		5,519,976		2,792		14,803,769
Commercial real estate:
Pass	396,891		1,941,913		1,194,759		416,647		513,555		705,092		136,095		—		5,304,952
Special Mention	—		476		—		—		—		19,171		—		—		19,647
Accruing Substandard	2,992		—		3		—		—		2,733		—		—		5,728
Nonaccrual	—		—		—		—		7,170		150		—		—		7,320
Total commercial real estate	399,883		1,942,389		1,194,762		416,647		520,725		727,146		136,095		—		5,337,647
Loans charged off, year-to-date	—		—		—		—		—		8,446		—		—		8,446

	Origination Year
	2023		2022		2021		2020		2019		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Loans to individuals:
Residential mortgage
Pass	426,089		320,733		342,927		349,742		54,801		243,356		375,739		23,895		2,137,282
Special Mention	157		140		131		1,361		18		134		2,982		93		5,016
Accruing Substandard	—		150		—		—		37		49		50		—		286
Nonaccrual	79		1,419		237		544		344		12,381		2,387		665		18,056
Total residential mortgage	426,325		322,442		343,295		351,647		55,200		255,920		381,158		24,653		2,160,640
Loans charged off, year-to-date	—		—		51		4		—		17		—		1		73
Residential mortgage guaranteed by U.S. government agencies
Pass	633		1,788		2,220		4,297		6,441		124,719		—		—		140,098
Nonaccrual	—		—		—		280		375		9,054		—		—		9,709
Total residential mortgage guaranteed by U.S. government agencies	633		1,788		2,220		4,577		6,816		133,773		—		—		149,807
Personal
Pass	218,401		229,580		149,291		136,215		75,348		137,629		503,841		145		1,450,450
Special Mention	66		39		106		30		8		—		1,918		3		2,170
Accruing Substandard	—		64		12		9		144		—		3		—		232
Nonaccrual	4		51		9		16		3		12		158		—		253
Total personal	218,471		229,734		149,418		136,270		75,503		137,641		505,920		148		1,453,105
Loans charged off, year-to-date1	5,636		82		96		43		—		10		6		26		5,899
Total loans to individuals	645,429		553,964		494,933		492,494		137,519		527,334		887,078		24,801		3,763,552
Total loans	$	3,743,425	$	4,522,989	$	2,982,784	$	1,756,064	$	1,234,871	$	3,094,093	$	6,543,149	$	27,593	$	23,904,968

1    Includes charge-offs on deposit overdrafts, which are generally charged off at 60 days past due.

Financing Receivable, Nonaccrual [Table Text Block]

A summary of nonaccruing loans as of December 31, 2024 follows (in thousands): 

	Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Healthcare	$	13,717	$	13,717	$	—	$	—
Energy	49		49		—		—
Services	767		491		276		276
General business	114		114		—		—
Total commercial	14,647		14,371		276		276
Commercial real estate	9,905		9,905		—		—
Loans to individuals:
Residential mortgage	15,261		15,261		—		—
Residential mortgage guaranteed by U.S. government agencies	6,803		6,803		—		—
Personal	109		109		—		—
Total loans to individuals	22,173		22,173		—		—
Total	$	46,725	$	46,449	$	276	$	276

The majority of our nonaccruing loans are considered collateral dependent where repayment is expected to be provided through operation or sale of the collateral. Nonaccruing commercial and commercial real estate loans are primarily secured by commercial real estate and nonaccruing residential mortgage loans are secured by residential real estate.

A summary of nonaccruing loans as of December 31, 2023 follows (in thousands):

	Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Healthcare	$	81,529	$	40,372	$	41,157	$	1,478
Energy	17,843		17,843		—		—
Services	3,616		1,684		1,932		1,214
General business	7,143		7,143		—		—
Total commercial	110,131		67,042		43,089		2,692
Commercial real estate	7,320		7,320		—		—
Loans to individuals:
Residential mortgage	18,056		18,056		—		—
Residential mortgage guaranteed by U.S. government agencies	9,709		9,709		—		—
Personal	253		253		—		—
Total loans to individuals	28,018		28,018		—		—
Total	$	145,469	$	102,380	$	43,089	$	2,692

Summary of Loans by Aging Status [Table Text Block]

A summary of loans currently performing and past due as of December 31, 2024 is as follows (in thousands):

			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Total		Past Due 90 Days or More and Accruing
Commercial:
Healthcare	$	3,932,142	$	25,778	$	—	$	9,613	$	3,967,533	$	—
Services	3,642,436		—		767		—		3,643,203		—
Energy	3,254,724		—		—		—		3,254,724		—
General business	4,161,510		3,067		70		29		4,164,676		—
Total commercial	14,990,812		28,845		837		9,642		15,030,136		—
Commercial real estate	5,048,667		—		—		9,785		5,058,452		—
Loans to individuals:
Permanent mortgage	2,416,633		10,930		5,622		3,773		2,436,958		—
Permanent mortgages guaranteed by U.S. government agencies	45,910		18,514		15,268		56,957		136,649		52,504
Personal	1,451,397		1,061		48		23		1,452,529		—
Total loans to individuals	3,913,940		30,505		20,938		60,753		4,026,136		52,504
Total	$	23,953,419	$	59,350	$	21,775	$	80,180	$	24,114,724	$	52,504

A summary of loans currently performing and past due as of December 31, 2023 is as follows (in thousands):

			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Total		Past Due 90 Days or More and Accruing
Commercial:
Healthcare	$	4,071,336	$	18,019	$	30,290	$	23,588	$	4,143,233	$	—
Services	3,575,787		2		—		434		3,576,223		—
Energy	3,437,101		—		—		—		3,437,101		—
General business	3,639,775		412		1,157		5,868		3,647,212		—
Total commercial	14,723,999		18,433		31,447		29,890		14,803,769		—
Commercial real estate	5,327,481		2,992		—		7,174		5,337,647		3
Loans to individuals:
Permanent mortgage	2,149,927		6,340		1,494		2,879		2,160,640		36
Permanent mortgages guaranteed by U.S. government agencies	54,122		25,085		17,053		53,547		149,807		48,201
Personal	1,450,302		2,561		88		154		1,453,105		131
Total loans to individuals	3,654,351		33,986		18,635		56,580		3,763,552		48,368
Total	$	23,705,831	$	55,411	$	50,082	$	93,644	$	23,904,968	$	48,371