Loans and Allowances for Credit Losses (Tables)

3 Months Ended

Mar. 31, 2024

Loans and Leases Receivable, Net Amount [Abstract]

Schedule of Loans by Portfolio Segment [Table Text Block]

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

	March 31, 2024								December 31, 2023
	Fixed Rate		Variable Rate		Non-accrual		Total		Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	3,597,543	$	11,460,704	$	74,620	$	15,132,867	$	3,558,563	$	11,135,075	$	110,131	$	14,803,769
Commercial real estate	784,301		4,430,289		22,087		5,236,677		791,757		4,538,570		7,320		5,337,647
Loans to individuals	2,315,236		1,464,972		22,808		3,803,016		2,282,914		1,452,620		28,018		3,763,552
Total	$	6,697,080	$	17,355,965	$	119,515	$	24,172,560	$	6,633,234	$	17,126,265	$	145,469	$	23,904,968

Rollforward of Allowance For Loan Losses And Accrual for Off-Balance 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 is summarized as follows (in thousands):

	Three Months Ended
	March 31, 2024
	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	8,311		3,995		(2,346)		9,960
Loans charged off	(4,240)		(1,250)		(1,570)		(7,060)
Recoveries of loans previously charged off	964		16		620		1,600
Ending balance	$	146,267	$	97,479	$	37,877	$	281,623
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	(1,972)		426		(112)		(1,658)
Ending balance	$	17,790	$	27,865	$	1,664	$	47,319

	Three Months Ended
	March 31, 2023
	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	6,330		10,426		(2,231)		14,525
Loans charged off	(12)		(2,208)		(1,447)		(3,667)
Recoveries of loans previously charged off	1,994		137		767		2,898
Ending balance	$	139,898	$	66,003	$	43,559	$	249,460
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	2,362		(279)		(59)		2,024
Ending balance	$	20,608	$	40,211	$	2,124	$	62,943

An $8.0 million provision for credit losses was necessary for the first quarter of 2024, reflecting continued loan growth and a stable economic outlook.

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each measurement method at March 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	$	15,058,247	$	143,307	$	74,620	$	2,960	$	15,132,867	$	146,267
Commercial real estate	5,214,590		97,479		22,087		—		5,236,677		97,479
Loans to individuals	3,780,208		37,877		22,808		—		3,803,016		37,877
Total	$	24,053,045	$	278,663	$	119,515	$	2,960	$	24,172,560	$	281,623

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each 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]

The following table summarizes the Company’s loan portfolio at March 31, 2024 by the risk grade categories and vintage (in thousands): 

	Origination Year
	2024		2023		2022		2021		2020		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Commercial:
Healthcare
Pass	$	165,523	$	638,346	$	924,230	$	573,778	$	382,923	$	1,095,684	$	288,056	$	14	$	4,068,554
Special Mention	—		15,000		—		1,254		—		20,027		855		—		37,136
Accruing Substandard	—		1,492		429		18,397		58,753		10,896		975		—		90,942
Nonaccrual	—		—		—		—		—		49,307		—		—		49,307
Total healthcare	165,523		654,838		924,659		593,429		441,676		1,175,914		289,886		14		4,245,939
Loans charged off, year-to-date	—		—		—		—		—		502		—		—		502
Services
Pass	183,565		786,684		514,841		380,227		219,684		725,856		677,588		534		3,488,979
Special Mention	—		—		1,042		1,305		1,321		9,243		31		—		12,942
Accruing Substandard	—		—		13,380		155		341		7,204		2,351		750		24,181
Nonaccrual	—		—		—		1,487		349		—		1,483		—		3,319
Total services	183,565		786,684		529,263		383,174		221,695		742,303		681,453		1,284		3,529,421
Loans charged off, year-to-date	—		—		—		—		—		—		—		—		—
Energy
Pass	58,061		141,197		90,222		13,033		7,447		20,635		3,067,570		—		3,398,165
Special Mention	—		—		—		—		—		—		13,950		—		13,950
Accruing Substandard	—		—		—		—		—		—		16,613		—		16,613
Nonaccrual	—		—		—		—		—		89		14,902		—		14,991
Total energy	58,061		141,197		90,222		13,033		7,447		20,724		3,113,035		—		3,443,719
Loans charged off, year-to-date	—		—		—		—		—		—		—		—		—
General business
Pass	285,096		845,326		383,429		215,106		134,121		378,163		1,569,156		1,945		3,812,342
Special Mention	—		6,110		8,244		8,594		—		1,602		10,611		6		35,167
Accruing Substandard	—		3,375		37,682		1,280		1,235		6,701		9,003		—		59,276
Nonaccrual	—		994		101		—		—		42		5,862		4		7,003
Total general business	285,096		855,805		429,456		224,980		135,356		386,508		1,594,632		1,955		3,913,788
Loans charged off, year-to-date	—		27		1,399		—		—		158		2,154		—		3,738
Total commercial	692,245		2,438,524		1,973,600		1,214,616		806,174		2,325,449		5,679,006		3,253		15,132,867
Commercial real estate:
Pass	18,763		418,504		2,059,848		1,061,396		386,041		1,127,922		119,823		—		5,192,297
Special Mention	—		440		—		—		—		16,527		—		—		16,967
Accruing Substandard	—		—		—		—		—		5,326		—		—		5,326
Nonaccrual	—		2,992		—		—		—		19,095		—		—		22,087
Total commercial real estate	18,763		421,936		2,059,848		1,061,396		386,041		1,168,870		119,823		—		5,236,677
Loans charged off, year-to-date	—		—		—		—		—		1,250		—		—		1,250

	Origination Year
	2024		2023		2022		2021		2020		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Loans to individuals:
Residential mortgage
Pass	96,002		405,724		319,050		336,878		343,246		284,962		367,761		21,386		2,175,009
Special Mention	—		225		167		3		—		161		3,290		—		3,846
Accruing Substandard	—		—		—		—		—		—		279		1		280
Nonaccrual	—		120		414		351		522		8,994		2,441		607		13,449
Total residential mortgage	96,002		406,069		319,631		337,232		343,768		294,117		373,771		21,994		2,192,584
Loans charged off, year-to-date	—		—		—		—		—		2		5		—		7
Residential mortgage guaranteed by U.S. government agencies
Pass	—		361		3,012		2,204		3,806		120,856		—		—		130,239
Nonaccrual	—		—		—		—		280		8,937		—		—		9,217
Total residential mortgage guaranteed by U.S. government agencies	—		361		3,012		2,204		4,086		129,793		—		—		139,456
Personal:
Pass	91,355		215,282		210,876		145,542		124,996		186,791		493,653		100		1,468,595
Special Mention	—		28		13		51		13		3		—		—		108
Accruing Substandard	—		—		24		—		1		144		1,962		—		2,131
Nonaccrual	—		31		29		12		9		12		32		17		142
Total personal	91,355		215,341		210,942		145,605		125,019		186,950		495,647		117		1,470,976
Loans charged off, year-to-date1	1,461		40		45		12		—		—		—		5		1,563
Total loans to individuals	187,357		621,771		533,585		485,041		472,873		610,860		869,418		22,111		3,803,016
Total loans	$	898,365	$	3,482,231	$	4,567,033	$	2,761,053	$	1,665,088	$	4,105,179	$	6,668,247	$	25,364	$	24,172,560

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
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
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
Loans charged off, year-to-date	—		—		—		—		—		—		—		—		—
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 at March 31, 2024 follows (in thousands): 

	As of March 31, 2024
	Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Healthcare	$	49,307	$	9,668	$	39,639	$	2,100
Services	3,319		1,542		1,777		460
Energy	14,991		14,991		—		—
General business	7,003		6,362		641		400
Total commercial	74,620		32,563		42,057		2,960
Commercial real estate	22,087		22,087		—		—
Loans to individuals:
Residential mortgage	13,449		13,449		—		—
Residential mortgage guaranteed by U.S. government agencies	9,217		9,217		—		—
Personal	142		142		—		—
Total loans to individuals	22,808		22,808		—		—
Total	$	119,515	$	77,458	$	42,057	$	2,960

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

	As of December 31, 2023
	Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Healthcare	$	81,529	$	40,372	$	41,157	$	1,478
Services	3,616		1,684		1,932		1,214
Energy	17,843		17,843		—		—
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 March 31, 2024 is as follows (in thousands):

			Past Due								Past Due 90 Days or More and Accruing
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Total
Commercial:
Healthcare	$	4,206,313	$	—	$	—	$	39,626	$	4,245,939	$	—
Services	3,528,567		485		20		349		3,529,421		—
Energy	3,443,719		—		—		—		3,443,719		—
General business	3,905,270		2,054		209		6,255		3,913,788		—
Total commercial	15,083,869		2,539		229		46,230		15,132,867		—
Commercial real estate	5,214,737		11,800		—		10,140		5,236,677		—
Loans to individuals:
Residential mortgage	2,183,027		7,139		737		1,681		2,192,584		—
Residential mortgage guaranteed by U.S. government agencies	55,886		22,873		15,080		45,617		139,456		41,364
Personal	1,469,874		1,055		24		23		1,470,976		—
Total loans to individuals	3,708,787		31,067		15,841		47,321		3,803,016		41,364
Total	$	24,007,393	$	45,406	$	16,070	$	103,691	$	24,172,560	$	41,364

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

			Past Due								Past Due 90 Days or More and Accruing
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Total
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:
Residential mortgage	2,149,927		6,340		1,494		2,879		2,160,640		36
Residential mortgage 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