Loans and Allowances for Credit Losses (Tables)

12 Months Ended

Dec. 31, 2022

Dec. 31, 2021

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, 2022								December 31, 2021
	Fixed Rate		Variable Rate		Non-accrual		Total		Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	3,378,110	$	10,759,780	$	60,297	$	14,198,187	$	3,360,117	$	9,072,244	$	74,104	$	12,506,465
Commercial real estate	874,716		3,715,491		16,570		4,606,777		929,015		2,888,048		14,262		3,831,325
Paycheck protection program	14,312		—		—		14,312		276,341		—		—		276,341
Loans to individuals	2,099,165		1,593,779		44,930		3,737,874		2,037,792		1,508,064		45,693		3,591,549
Total	$	6,366,303	$	16,069,050	$	121,797	$	22,557,150	$	6,603,265	$	13,468,356	$	134,059	$	20,205,680
Foregone interest on nonaccrual loans							$	6,796							$	14,102

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, 2022 is summarized as follows (in thousands):

	Commercial		Commercial Real Estate		Paycheck Protection Program		Loans to Individuals		Nonspecific Allowance		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 risk	4,434		23,048		—		460		—		27,942
Ending balance	$	18,246	$	40,490	$	—	$	2,183	$	—	$	60,919

A $30.0 million provision for credit losses was recorded for the year ended December 31, 2022, primarily due to strong growth in loans and loan commitments, partially offset by improvement in credit quality metrics. The uncertainty in our economic forecast increased resulting in an increase in the probability weighting of the downside scenario. In addition, some key economic factors were less favorable to growth across all scenarios.

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, 2021 is summarized as follows (in thousands):

	Commercial		Commercial Real Estate		Paycheck Protection Program		Loans to Individuals		Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	254,934	$	86,558	$	—	$	47,148	$	—	$	388,640
Provision for loan losses	(59,326)		(26,522)		—		(9,354)		—		(95,202)
Loans charged off	(43,956)		(2,485)		—		(4,910)		—		(51,351)
Recoveries of loans previously charged off	10,404		1,002		—		2,928		—		14,334
Ending balance	$	162,056	$	58,553	$	—	$	35,812	$	—	$	256,421
Allowance for off-balance sheet credit risk from unfunded loan commitments:
Beginning balance	$	14,422	$	20,571	$	—	$	1,928	$	—	$	36,921
Provision for off-balance sheet credit risk	(610)		(3,129)		—		(205)		—		(3,944)
Ending balance	$	13,812	$	17,442	$	—	$	1,723	$	—	$	32,977

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, 2020 summarized as follows (in thousands):

	Commercial		Commercial Real Estate		Paycheck Protection Program		Loans to Individuals		Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	118,187	$	51,805	$	—	$	23,572	$	17,195	$	210,759
Transition adjustment	33,681		(4,620)		—		13,943		(17,195)		25,809
Beginning balance, adjusted	151,868		47,185		—		37,515		—		236,568
Provision for loan losses	171,800		40,407		—		10,253		—		222,460
Loans charged off	(73,370)		(1,300)		—		(4,729)		—		(79,399)
Recoveries	4,636		266		—		4,109		—		9,011
Ending balance	$	254,934	$	86,558	$	—	$	47,148	$	—	$	388,640
Allowance for off-balance sheet credit risk from unfunded loan commitments:
Beginning balance	1,434		107		—		44		—		1,585
Transition adjustment	10,144		11,660		—		1,748		—		23,552
Beginning balance, adjusted	11,578		11,767		—		1,792		—		25,137
Provision for off-balance sheet credit losses	2,844		8,804		—		136		—		11,784
Ending balance	$	14,422	$	20,571	$	—	$	1,928	$	—	$	36,921

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2022 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	$	14,137,890	$	127,566	$	60,297	$	4,020	$	14,198,187	$	131,586
Commercial real estate	4,590,207		56,098		16,570		1,550		4,606,777		57,648
Paycheck protection program	14,312		—		—		—		14,312		—
Loans to individuals	3,692,944		46,470		44,930		—		3,737,874		46,470
Total	$	22,435,353	$	230,134	$	121,797	$	5,570	$	22,557,150	$	235,704

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2021 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	$	12,432,361	$	158,063	$	74,104	$	3,993	$	12,506,465	$	162,056
Commercial real estate	3,817,063		56,204		14,262		2,349		3,831,325		58,553
Paycheck protection program	276,341		—		—		—		276,341		—
Loans to individuals	3,545,856		35,812		45,693		—		3,591,549		35,812
Total	$	20,071,621	$	250,079	$	134,059	$	6,342	$	20,205,680	$	256,421

Schedule of Credit Quality Indicators [Table Text Block]

	Origination Year
	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Commercial:
Healthcare
Pass	$	932,097	$	604,886	$	476,854	$	404,204	$	464,989	$	618,163	$	245,898	$	20	$	3,747,111
Special Mention	—		—		—		20,071		—		18,859		4		—		38,934
Accruing Substandard	—		—		—		—		—		14,304		3,634		—		17,938
Nonaccrual	—		—		—		26,480		6,373		8,181		—		—		41,034
Total healthcare	932,097		604,886		476,854		450,755		471,362		659,507		249,536		20		3,845,017
Energy
Pass	157,745		76,951		30,284		12,783		5,992		4,980		3,104,906		—		3,393,641
Accruing Substandard	—		—		—		664		385		683		28,018		—		29,750
Nonaccrual	—		—		—		—		—		159		1,240		—		1,399
Total energy	157,745		76,951		30,284		13,447		6,377		5,822		3,134,164		—		3,424,790
Services
Pass	821,785		496,510		286,085		193,481		156,736		696,300		722,371		639		3,373,907
Special Mention	502		5,139		989		771		894		1,345		8,668		—		18,308
Accruing Substandard	—		—		—		2,459		43		2,789		17,665		122		23,078
Nonaccrual	—		5,570		449		—		—		2,389		7,820		—		16,228
Total services	822,287		507,219		287,523		196,711		157,673		702,823		756,524		761		3,431,521
General business
Pass	725,894		358,383		187,418		172,878		139,140		283,694		1,570,536		2,329		3,440,272
Special Mention	17,759		13,065		208		71		7		2,291		7,094		26		40,521
Accruing Substandard	—		2,169		66		4,130		4,680		3,287		94		4		14,430
Nonaccrual	—		—		1,052		14		72		5		485		8		1,636
Total general business	743,653		373,617		188,744		177,093		143,899		289,277		1,578,209		2,367		3,496,859
Total commercial	2,655,782		1,562,673		983,405		838,006		779,311		1,657,429		5,718,433		3,148		14,198,187
Commercial real estate:
Pass	1,188,483		1,158,002		552,616		641,102		247,625		633,304		161,616		—		4,582,748
Accruing Substandard	—		—		—		7,459		—		—		—		—		7,459
Nonaccrual	—		—		—		—		—		16,570		—		—		16,570
Total commercial real estate	1,188,483		1,158,002		552,616		648,561		247,625		649,874		161,616		—		4,606,777

	Origination Year
	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Paycheck protection program:
Pass	—		3,456		10,856		—		—		—		—		—		14,312
Total paycheck protection program	—		3,456		10,856		—		—		—		—		—		14,312
Loans to individuals:
Residential mortgage
Pass	354,497		373,190		393,002		63,142		40,525		260,625		352,126		22,176		1,859,283
Special Mention	—		81		42		—		142		388		527		87		1,267
Accruing Substandard	—		—		187		—		—		138		117		1		443
Nonaccrual	32		1,656		2,717		362		1,904		20,139		2,216		765		29,791
Total residential mortgage	354,529		374,927		395,948		63,504		42,571		281,290		354,986		23,029		1,890,784
Residential mortgage guaranteed by U.S. government agencies
Pass	289		2,254		9,000		10,722		17,244		191,426		—		—		230,935
Nonaccrual	—		—		299		1,460		2,319		10,927		—		—		15,005
Total residential mortgage guaranteed by U.S. government agencies	289		2,254		9,299		12,182		19,563		202,353		—		—		245,940
Personal
Pass	254,497		193,095		154,887		172,114		68,871		201,278		549,187		332		1,594,261
Special Mention	47		28		40		12		17		—		6,003		4		6,151
Accruing Substandard	—		444		—		160		—		—		—		—		604
Nonaccrual	38		7		12		22		14		18		23		—		134
Total personal	254,582		193,574		154,939		172,308		68,902		201,296		555,213		336		1,601,150
Total loans to individuals	609,400		570,755		560,186		247,994		131,036		684,939		910,199		23,365		3,737,874
Total loans	$	4,453,665	$	3,294,886	$	2,107,063	$	1,734,561	$	1,157,972	$	2,992,242	$	6,790,248	$	26,513	$	22,557,150

The following table summarizes the Company's loan portfolio at December 31, 2021 by the risk grade categories and vintage (in thousands):

	Origination Year
	2021		2020		2019		2018		2017		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Commercial:
Healthcare
Pass	$	563,800	$	589,193	$	516,558	$	498,998	$	319,096	$	688,136	$	160,154	$	26	$	3,335,961
Special Mention	6,835		—		15,583		—		11,135		—		5		—		33,558
Accruing Substandard	—		—		27,135		543		—		1,981		—		—		29,659
Nonaccrual	—		—		—		6,542		—		8,711		509		—		15,762
Total healthcare	570,635		589,193		559,276		506,083		330,231		698,828		160,668		26		3,414,940
Energy
Pass	252,133		29,556		15,914		13,548		4,741		6,765		2,540,525		—		2,863,182
Special Mention	558		771		—		—		—		—		750		—		2,079
Accruing Substandard	10,650		22,611		1,185		814		—		716		74,556		—		110,532
Nonaccrual	—		20,487		—		—		—		714		9,890		—		31,091
Total energy	263,341		73,425		17,099		14,362		4,741		8,195		2,625,721		—		3,006,884
Services
Pass	696,149		405,057		289,375		275,010		225,404		795,029		607,958		375		3,294,357
Special Mention	434		405		1,830		1,047		3,290		47		17,210		192		24,455
Accruing Substandard	43		530		4,166		10,714		1,785		2,366		11,607		—		31,211
Nonaccrual	—		—		—		230		13,918		2,519		503		—		17,170
Total services	696,626		405,992		295,371		287,001		244,397		799,961		637,278		567		3,367,193
General business
Pass	584,438		211,892		264,462		177,384		168,977		215,014		1,047,420		2,284		2,671,871
Special Mention	218		223		60		1,435		3,842		—		5,875		—		11,653
Accruing Substandard	265		1,066		1,634		7,697		8,336		3,024		1,821		—		23,843
Nonaccrual	—		2,444		4,562		1,046		762		518		730		19		10,081
Total general business	584,921		215,625		270,718		187,562		181,917		218,556		1,055,846		2,303		2,717,448
Total commercial	2,115,523		1,284,235		1,142,464		995,008		761,286		1,725,540		4,479,513		2,896		12,506,465
Commercial real estate:
Pass	717,400		711,231		871,283		403,115		279,058		664,684		117,847		31		3,764,649
Special Mention	—		—		—		6,660		10,898		9,244		—		—		26,802
Accruing Substandard	—		—		—		13,352		4,480		7,780		—		—		25,612
Nonaccrual	—		—		8,076		—		—		6,186		—		—		14,262
Total commercial real estate	717,400		711,231		879,359		423,127		294,436		687,894		117,847		31		3,831,325

	Origination Year
	2021		2020		2019		2018		2017		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Paycheck protection program:
Pass	237,357		38,984		—		—		—		—		—		—		276,341
Total paycheck protection program	237,357		38,984		—		—		—		—		—		—		276,341
Loans to individuals:
Residential mortgage
Pass	386,092		452,537		84,001		60,390		68,150		295,632		320,638		21,463		1,688,903
Special Mention	—		—		156		—		19		411		282		159		1,027
Accruing Substandard	98		—		—		—		127		41		400		—		666
Nonaccrual	1,516		1,809		383		1,968		629		22,289		2,177		803		31,574
Total residential mortgage	387,706		454,346		84,540		62,358		68,925		318,373		323,497		22,425		1,722,170
Residential mortgage guaranteed by U.S. government agencies
Pass	699		11,380		20,650		27,970		32,742		246,871		—		—		340,312
Nonaccrual	—		—		1,259		821		635		11,146		—		—		13,861
Total residential mortgage guaranteed by U.S. government agencies	699		11,380		21,909		28,791		33,377		258,017		—		—		354,173
Personal
Pass	218,960		180,577		177,389		70,249		92,592		135,041		638,713		728		1,514,249
Special Mention	—		9		34		3		—		47		—		—		93
Accruing Substandard	435		5		165		—		—		1		—		—		606
Nonaccrual	110		14		10		24		35		40		25		—		258
Total personal	219,505		180,605		177,598		70,276		92,627		135,129		638,738		728		1,515,206
Total loans to individuals	607,910		646,331		284,047		161,425		194,929		711,519		962,235		23,153		3,591,549
Total loans	$	3,678,190	$	2,680,781	$	2,305,870	$	1,579,560	$	1,250,651	$	3,124,953	$	5,559,595	$	26,080	$	20,205,680

Financing Receivable, Nonaccrual [Table Text Block]

A summary of nonaccruing loans as of December 31, 2022 follows (in thousands): 

	Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Healthcare	$	41,034	$	34,661	$	6,373	$	946
Services	16,228		7,835		8,393		3,074
Energy	1,399		1,399		—		—
General business	1,636		1,636		—		—
Total commercial	60,297		45,531		14,766		4,020
Commercial real estate	16,570		393		16,177		1,550
Loans to individuals:
Residential mortgage	29,791		29,791		—		—
Residential mortgage guaranteed by U.S. government agencies	15,005		15,005		—		—
Personal	134		134		—		—
Total loans to individuals	44,930		44,930		—		—
Total	$	121,797	$	90,854	$	30,943	$	5,570

A summary of nonaccruing loans as of December 31, 2021 follows (in thousands):

	Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Energy	$	31,091	$	31,091	$	—	$	—
Services	17,170		13,686		3,484		2,584
Healthcare	15,762		9,679		6,083		53
General business	10,081		7,690		2,391		1,357
Total commercial	74,104		62,146		11,958		3,994
Commercial real estate	14,262		6,186		8,076		2,349
Loans to individuals:
Residential mortgage	31,574		31,574		—		—
Residential mortgage guaranteed by U.S. government agencies	13,861		13,861		—		—
Personal	258		258		—		—
Total loans to individuals	45,693		45,693		—		—
Total	$	134,059	$	114,025	$	20,034	$	6,343

Summary of Loans by Aging Status [Table Text Block]

A summary of loans currently performing and past due as of December 31, 2022 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	$	3,812,164	$	5,914	$	26,480	$	459	$	3,845,017	$	—
Energy	3,424,766		24		—		—		3,424,790		—
Services	3,423,042		1,060		2,461		4,958		3,431,521		—
General business	3,496,815		26		18		—		3,496,859		—
Total commercial	14,156,787		7,024		28,959		5,417		14,198,187		—
Commercial real estate	4,606,029		531		—		217		4,606,777		—
Paycheck protection program	12,279		231		1,406		396		14,312		396
Loans to individuals:
Permanent mortgage	1,872,155		10,632		1,828		6,169		1,890,784		114
Permanent mortgages guaranteed by U.S. government agencies	108,019		36,119		19,400		82,402		245,940		75,604
Personal	1,600,595		502		21		32		1,601,150		—
Total loans to individuals	3,580,769		47,253		21,249		88,603		3,737,874		75,718
Total	$	22,355,864	$	55,039	$	51,614	$	94,633	$	22,557,150	$	76,114

A summary of loans currently performing and past due as of December 31, 2021 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	$	3,412,072	$	2,359	$	—	$	509	$	3,414,940	$	—
Services	3,352,639		920		4,620		9,014		3,367,193		—
Energy	3,002,623		545		3,716		—		3,006,884		—
General business	2,705,596		6,080		997		4,775		2,717,448		199
Total commercial	12,472,930		9,904		9,333		14,298		12,506,465		199
Commercial real estate	3,827,962		—		206		3,157		3,831,325		—
Paycheck protection program	276,341		—		—		—		276,341		74
Loans to individuals:
Permanent mortgage	1,707,654		6,263		1,556		6,697		1,722,170		—
Permanent mortgages guaranteed by U.S. government agencies	181,022		26,869		16,751		129,531		354,173		118,819
Personal	1,514,938		66		24		178		1,515,206		40
Total loans to individuals	3,403,614		33,198		18,331		136,406		3,591,549		118,859
Total	$	19,980,847	$	43,102	$	27,870	$	153,861	$	20,205,680	$	119,132