Loans and Allowances for Credit Losses (Tables)

3 Months Ended

Mar. 31, 2022

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, 2022								December 31, 2021
	Fixed Rate		Variable Rate		Non-accrual		Total		Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	3,343,185	$	9,479,667	$	60,337	$	12,883,189	$	3,360,117	$	9,072,244	$	74,104	$	12,506,465
Commercial real estate	924,332		3,160,635		15,989		4,100,956		929,015		2,888,048		14,262		3,831,325
Paycheck protection program	137,365		—		—		137,365		276,341		—		—		276,341
Loans to individuals	2,006,029		1,498,970		47,920		3,552,919		2,037,792		1,508,064		45,693		3,591,549
Total	$	6,410,911	$	14,139,272	$	124,246	$	20,674,429	$	6,603,265	$	13,468,356	$	134,059	$	20,205,680

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, 2022
	Commercial		Commercial Real Estate		Paycheck Protection Program		Loans to Individuals		Total
Allowance for loan losses:
Beginning balance	$	162,056	$	58,553	$	—	$	35,812	$	256,421
Provision for loan losses	(5,118)		468		—		683		(3,967)
Loans charged off	(6,081)		(191)		—		(1,533)		(7,805)
Recoveries of loans previously charged off	591		144		—		1,089		1,824
Ending Balance	$	151,448	$	58,974	$	—	$	36,051	$	246,473
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	154		3,023		—		91		3,268
Ending Balance	$	13,966	$	20,465	$	—	$	1,814	$	36,245

	Three Months Ended
	March 31, 2021
	Commercial		Commercial Real Estate		Paycheck Protection Program		Loans to Individuals		Total
Allowance for loan losses:
Beginning balance	$	254,934	$	86,558	$	—	$	47,148	$	388,640
Provision for loan losses	(9,893)		(4,579)		—		(7,298)		(21,770)
Loans charged off	(15,345)		(263)		—		(1,297)		(16,905)
Recoveries of loans previously charged off	1,676		30		—		731		2,437
Ending Balance	$	231,372	$	81,746	$	—	$	39,284	$	352,402
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	(1,686)		(2,273)		—		(85)		(4,044)
Ending Balance	$	12,736	$	18,298	$	—	$	1,843	$	32,877

Changes in our reasonable and supportable forecasts of macroeconomic variables resulted in a $7.3 million negative provision for credit losses related to lending activities during the first quarter of 2022. Continued strength in commodity prices was partially offset by changes in our economic outlook. Changes in the loan portfolio characteristics, including specific impairment and losses, loan balances, risk grading and changes in payment profile resulted in a $6.6 million provision for credit losses related to lending activities.

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each measurement method at March 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	$	12,822,852	$	149,095	$	60,337	$	2,353	$	12,883,189	$	151,448
Commercial real estate	4,084,967		58,039		15,989		935		4,100,956		58,974
Paycheck protection program	137,365		—		—		—		137,365		—
Loans to individuals	3,504,999		36,051		47,920		—		3,552,919		36,051
Total	$	20,550,183	$	243,185	$	124,246	$	3,288	$	20,674,429	$	246,473

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

The following table summarizes the Company’s loan portfolio at March 31, 2022 by the risk grade categories and vintage (in thousands): 

	Origination Year
	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Commercial:
Energy
Pass	$	102,694	$	156,167	$	48,775	$	15,678	$	11,925	$	8,450	$	2,753,419	$	—	$	3,097,108
Special Mention	—		551		642		—		—		—		1,090		—		2,283
Accruing Substandard	—		—		—		1,139		693		705		60,863		9,900		73,300
Nonaccrual	—		—		19,404		—		—		602		4,970		—		24,976
Total energy	102,694		156,718		68,821		16,817		12,618		9,757		2,820,342		9,900		3,197,667
Healthcare
Pass	140,071		574,892		549,379		514,779		483,909		933,344		168,255		24		3,364,653
Special Mention	—		6,787		—		15,417		—		5,712		5		—		27,921
Accruing Substandard	—		—		—		26,973		—		7,109		—		—		34,082
Nonaccrual	—		—		—		—		6,542		8,534		—		—		15,076
Total healthcare	140,071		581,679		549,379		557,169		490,451		954,699		168,260		24		3,441,732
Services
Pass	54,992		634,506		361,724		266,054		246,336		933,399		779,824		567		3,277,402
Special Mention	—		415		6,326		1,989		1,006		95		22,419		182		32,432
Accruing Substandard	—		10		499		4,002		10,579		2,990		7,046		—		25,126
Nonaccrual	—		—		—		—		—		16,145		390		—		16,535
Total services	54,992		634,931		368,549		272,045		257,921		952,629		809,679		749		3,351,495
General business
Pass	209,407		547,777		220,861		250,546		167,570		356,548		1,102,054		1,981		2,856,744
Special Mention	—		—		137		—		1,374		2,975		8,100		—		12,586
Accruing Substandard	—		215		957		1,139		5,673		9,231		2,000		—		19,215
Nonaccrual	—		—		1,111		799		1,004		24		800		12		3,750
Total general business	209,407		547,992		223,066		252,484		175,621		368,778		1,112,954		1,993		2,892,295
Total commercial	507,164		1,921,320		1,209,815		1,098,515		936,611		2,285,863		4,911,235		12,666		12,883,189
Commercial real estate:
Pass	279,254		921,473		695,399		826,150		398,633		820,481		107,780		25		4,049,195
Special Mention	—		—		—		—		—		18,942		—		—		18,942
Accruing Substandard	—		—		—		—		13,501		3,329		—		—		16,830
Nonaccrual	—		—		—		7,908		—		8,081		—		—		15,989
Total commercial real estate	279,254		921,473		695,399		834,058		412,134		850,833		107,780		25		4,100,956

	Origination Year
	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Paycheck protection program:
Pass	—		113,697		23,668		—		—		—		—		—		137,365
Total paycheck protection program	—		113,697		23,668		—		—		—		—		—		137,365
Loans to individuals:
Residential mortgage
Pass	77,813		393,077		427,965		70,900		48,809		330,626		320,350		21,887		1,691,427
Special Mention	—		35		—		17		145		284		552		210		1,243
Accruing Substandard	—		—		—		—		—		53		26		—		79
Nonaccrual	35		1,517		2,571		356		2,057		21,653		1,903		665		30,757
Total residential mortgage	77,848		394,629		430,536		71,273		51,011		352,616		322,831		22,762		1,723,506
Residential mortgage guaranteed by U.S. government agencies
Pass	—		1,080		11,379		15,778		23,480		253,872		—		—		305,589
Nonaccrual	—		—		—		2,081		1,746		13,165		—		—		16,992
Total residential mortgage guaranteed by U.S. government agencies	—		1,080		11,379		17,859		25,226		267,037		—		—		322,581
Personal:
Pass	40,789		219,748		171,964		174,523		70,349		214,736		613,114		598		1,505,821
Special Mention	—		49		23		—		15		42		15		—		144
Accruing Substandard	—		524		—		165		—		—		7		—		696
Nonaccrual	—		14		19		10		22		42		64		—		171
Total personal	40,789		220,335		172,006		174,698		70,386		214,820		613,200		598		1,506,832
Total loans to individuals	118,637		616,044		613,921		263,830		146,623		834,473		936,031		23,360		3,552,919
Total loans	$	905,055	$	3,572,534	$	2,542,803	$	2,196,403	$	1,495,368	$	3,971,169	$	5,955,046	$	36,051	$	20,674,429

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:
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
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
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 at March 31, 2022 follows (in thousands): 

	As of March 31, 2022
	Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Energy	$	24,976	$	24,976	$	—	$	—
Healthcare	15,076		8,534		6,542		946
Services	16,535		13,290		3,245		1,407
General business	3,750		3,750		—		—
Total commercial	60,337		50,550		9,787		2,353
Commercial real estate	15,989		8,081		7,908		935
Loans to individuals:
Residential mortgage	30,757		30,757		—		—
Residential mortgage guaranteed by U.S. government agencies	16,992		16,992		—		—
Personal	171		171		—		—
Total loans to individuals	47,920		47,920		—		—
Total	$	124,246	$	106,551	$	17,695	$	3,288

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

	As of December 31, 2021
	Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Energy	$	31,091	$	31,091	$	—	$	—
Healthcare	15,762		9,679		6,083		53
Services	17,170		13,686		3,484		2,584
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 March 31, 2022 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:
Energy	$	3,197,667	$	—	$	—	$	—	$	3,197,667	$	—
Healthcare	3,433,749		1,300		141		6,542		3,441,732		—
Services	3,340,989		743		1,377		8,386		3,351,495		—
General business	2,891,472		691		—		132		2,892,295		—
Total commercial	12,863,877		2,734		1,518		15,060		12,883,189		—
Commercial real estate	4,089,135		4,473		4,270		3,078		4,100,956		—
Paycheck protection program	137,052		—		6		307		137,365		307
Loans to individuals:
Residential mortgage	1,707,772		9,334		364		6,036		1,723,506		—
Residential mortgage guaranteed by U.S. government agencies	147,883		51,165		—		123,533		322,581		109,283
Personal	1,506,538		114		107		73		1,506,832		—
Total loans to individuals	3,362,193		60,613		471		129,642		3,552,919		109,283
Total	$	20,452,257	$	67,820	$	6,265	$	148,087	$	20,674,429	$	109,590

A summary of loans currently performing and past due as of December 31, 2021 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:
Energy	$	3,002,623	$	545	$	3,716	$	—	$	3,006,884	$	—
Healthcare	3,412,072		2,359		—		509		3,414,940		—
Services	3,352,639		920		4,620		9,014		3,367,193		—
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:
Residential mortgage	1,707,654		6,263		1,556		6,697		1,722,170		—
Residential mortgage 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