Loans (Tables)

3 Months Ended

Mar. 31, 2020

Receivables [Abstract]

Loans

Loans were as follows:

	March 31, 2020		Percentage of Total		December 31, 2019		Percentage of Total
Commercial and industrial	$	5,536,760	36.1	%	$	5,187,466	35.2	%
Energy:
Production	1,268,832		8.3		1,348,900		9.2
Service	185,210		1.2		192,996		1.3
Other	114,812		0.7		110,986		0.8
Total energy	1,568,854		10.2		1,652,882		11.2
Commercial real estate:
Commercial mortgages	4,920,882		32.1		4,594,113		31.1
Construction	1,265,441		8.3		1,312,659		8.9
Land	286,876		1.9		289,467		2.0
Total commercial real estate	6,473,199		42.3		6,196,239		42.0
Consumer real estate:
Home equity loans	389,844		2.5		375,596		2.6
Home equity lines of credit	350,330		2.3		354,671		2.4
Other	480,933		3.1		464,146		3.1
Total consumer real estate	1,221,107		7.9		1,194,413		8.1
Total real estate	7,694,306		50.2		7,390,652		50.1
Consumer and other	538,340		3.5		519,332		3.5
Total loans	$	15,338,260	100.0	%	$	14,750,332	100.0	%

Non-Accrual Loans, Segregated by Class of Loans

Non-accrual loans, segregated by class of loans, were as follows:

	March 31, 2020				December 31, 2019
	Total Non-Accrual		Non-Accrual with No Credit Loss Allowance		Total Non-Accrual		Non-Accrual with No Credit Loss Allowance
Commercial and industrial	$	23,913	$	11,085	$	26,038	$	13,266
Energy	28,702		28,702		65,761		3,281
Commercial real estate:
Buildings, land and other	8,224		5,922		8,912		6,558
Construction	3,774		683		665		665
Consumer real estate	2,094		2,094		922		922
Consumer and other	20		1		5		—
Total	$	66,727	$	48,487	$	102,303	$	24,692

Financing Receivable, Non-Accrual Loans, Segregated by Class of Loan and Year of Origination

The following table presents non-accrual loans as of March 31, 2020 by class and year of origination.

	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term		Total
Commercial and industrial	$	—	$	3,187	$	9,012	$	2,448	$	384	$	146	$	4,601	$	4,135	$	23,913
Energy	—		—		—		—		—		—		3,035		25,667		28,702
Commercial real estate:
Buildings, land and other	—		2,207		34		1,470		306		3,639		568		—		8,224
Construction	—		3,774		—		—		—		—		—		—		3,774
Consumer real estate	—		—		—		211		350		628		844		61		2,094
Consumer and other	—		1		—		—		—		—		19		—		20
Total	$	—	$	9,169	$	9,046	$	4,129	$	1,040	$	4,413	$	9,067	$	29,863	$	66,727

Age Analysis of Past Due Loans, Segregated by Class of Loans

An age analysis of past due loans (including both accruing and non-accruing loans), segregated by class of loans, as of March 31, 2020 was as follows:

	Loans 30-89 Days Past Due		Loans 90 or More Days Past Due		Total Past Due Loans		Current Loans		Total Loans		Accruing Loans 90 or More Days Past Due
Commercial and industrial	$	38,518	$	24,217	$	62,735	$	5,474,025	$	5,536,760	$	8,343
Energy	23,913		25,667		49,580		1,519,274		1,568,854		—
Commercial real estate:
Buildings, land and other	39,359		3,472		42,831		5,164,927		5,207,758		817
Construction	4,701		127		4,828		1,260,613		1,265,441		127
Consumer real estate	9,542		3,230		12,772		1,208,335		1,221,107		1,572
Consumer and other	6,134		1,013		7,147		531,193		538,340		1,013
Total	$	122,167	$	57,726	$	179,893	$	15,158,367	$	15,338,260	$	11,872

Troubled Debt Restructurings

Troubled debt restructurings during the three months ended March 31, 2020 and March 31, 2019 are set forth in the following table.

	Three Months Ended   March 31, 2020				Three Months Ended   March 31, 2019
	Balance at Restructure		Balance at Period-End		Balance at Restructure		Balance at Period-End
Commercial and industrial	$	2,191	$	2,198	$	307	$	293
Commercial real estate:
Buildings, land and other	—		—		5,901		5,898
	$	2,191	$	2,198	$	6,208	$	6,191

Restructured Loans Past Due in Excess of 90 Days on Financing Receivables

Additional information related to restructured loans as of or for the three months ended March 31, 2020 and March 31, 2019 is set forth in the following table.

	March 31, 2020		March 31, 2019
Restructured loans past due in excess of 90 days at period-end:
Number of loans	3		4
Dollar amount of loans	$	1,733	$	2,367
Restructured loans on non-accrual status at period end	2,198		2,162
Charge-offs of restructured loans:
Recognized in connection with restructuring	—		—
Recognized on previously restructured loans	1,533		—

Weighted Average Risk Grades for All Commercial Loans by Class and Year of Origination

The following tables present weighted-average risk grades for all commercial loans by class and year of origination/renewal as of March 31, 2020.

	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term		Total		W/A Risk Grade
Commercial and industrial
Risk grades 1-8	$	765,088	$	813,141	$	433,145	$	333,114	$	168,744	$	143,770	$	2,362,308	$	47,080	$	5,066,390	6.14
Risk grade 9	15,539		34,847		51,906		14,167		7,700		10,993		127,148		6,267		268,567		9.00
Risk grade 10	21,815		10,918		13,042		7,237		6,670		3,377		74,625		679		138,363		10.00
Risk grade 11	45		5,853		2,276		3,149		922		661		17,664		8,957		39,527		11.00
Risk grade 12	—		536		7,179		1,432		384		146		2,520		2,512		14,709		12.00
Risk grade 13	—		2,651		1,833		1,016		—		—		2,081		1,623		9,204		13.00
	$	802,487	$	867,946	$	509,381	$	360,115	$	184,420	$	158,947	$	2,586,346	$	67,118	$	5,536,760	6.44
W/A Risk grade	5.75		6.69		7.12		6.18		6.24		6.10		6.46		7.89		6.44
Energy
Risk grades 1-8	$	585,655	$	95,004	$	22,101	$	11,048	$	3,187	$	5,514	$	665,347	$	9,642	$	1,397,498	6.33
Risk grade 9	215		2,105		999		587		—		—		25,658		46		29,610		9.00
Risk grade 10	—		669		—		—		—		47		10,250		—		10,966		10.00
Risk grade 11	62,509		325		941		300		8		770		36,105		1,120		102,078		11.00
Risk grade 12	—		—		—		—		—		—		3,035		25,667		28,702		12.00
Risk grade 13	—		—		—		—		—		—		—		—		—		13.00
	$	648,379	$	98,103	$	24,041	$	11,935	$	3,195	$	6,331	$	740,395	$	36,475	$	1,568,854	6.81
W/A Risk grade	6.89		7.21		7.25		7.34		6.60		7.48		6.48		10.69		6.81
Commercial real estate:
Buildings, land, other
Risk grades 1-8	$	503,028	$	1,080,494	$	780,270	$	745,352	$	518,981	$	909,275	$	83,274	$	59,064	$	4,679,738	6.89
Risk grade 9	1,872		89,718		41,520		79,696		55,037		59,672		400		264		328,179		9.00
Risk grade 10	—		14,619		500		20,394		26,200		58,297		632		—		120,642		10.00
Risk grade 11	249		11,275		1,789		31,201		8,235		16,135		100		1,991		70,975		11.00
Risk grade 12	—		2,207		34		1,470		306		3,389		505		—		7,911		12.00
Risk grade 13	—		—		—		—		—		250		63		—		313		13.00
	$	505,149	$	1,198,313	$	824,113	$	878,113	$	608,759	$	1,047,018	$	84,974	$	61,319	$	5,207,758	7.16
W/A Risk grade	6.97		7.19		7.08		7.32		7.37		7.04		7.03		6.84		7.16
Construction
Risk grades 1-8	$	115,476	$	374,393	$	456,568	$	105,160	$	1,196	$	17,193	$	144,922	$	—	$	1,214,908	7.15
Risk grade 9	406		14,003		3,500		2,919		6,984		—		127		—		27,939		9.00
Risk grade 10	12,991		2,744		—		917		—		—		—		—		16,652		10.00
Risk grade 11	1,192		—		—		—		—		976		—		—		2,168		11.00
Risk grade 12	—		683		—		—		—		—		—		—		683		12.00
Risk grade 13	—		3,091		—		—		—		—		—		—		3,091		13.00
	$	130,065	$	394,914	$	460,068	$	108,996	$	8,180	$	18,169	$	145,049	$	—	$	1,265,441	7.25
W/A Risk grade	7.59		7.24		7.24		7.54		8.71		6.31		6.84		—		7.25
Total commercial real estate	$	635,214	$	1,593,227	$	1,284,181	$	987,109	$	616,939	$	1,065,187	$	230,023	$	61,319	$	6,473,199	7.18
W/A Risk grade	7.10		7.21		7.14		7.35		7.38		7.02		6.91		6.84		7.18

Weighted Average Risk Grades for All Commercial Loans by Class

The following tables present weighted average risk grades for all commercial loans by class as of December 31, 2019.

	Commercial and Industrial			Energy			Commercial Real Estate - Buildings, Land and Other			Commercial Real Estate - Construction			Total Commercial Real Estate
	W/A Risk Grade	Loans		W/A Risk Grade	Loans		W/A Risk Grade	Loans		W/A Risk Grade	Loans		W/A Risk Grade	Loans
Risk grades 1-8	6.17	$	4,788,857	5.90	$	1,488,301	6.78	$	4,523,271	7.25	$	1,274,098	6.88	$	5,797,369
Risk grade 9	9.00	247,212		9.00	32,163		9.00	163,714		9.00	21,509		9.00	185,223
Risk grade 10	10.00	71,472		10.00	51,898		10.00	103,626		10.00	15,243		10.00	118,869
Risk grade 11	11.00	53,887		11.00	14,760		11.00	84,057		11.00	1,144		11.00	85,201
Risk grade 12	12.00	18,189		12.00	45,514		12.00	8,529		12.00	665		12.00	9,194
Risk grade 13	13.00	7,849		13.00	20,246		13.00	383		13.00	—		13.00	383
Total	6.44	$	5,187,466	6.39	$	1,652,882	7.01	$	4,883,580	7.31	$	1,312,659	7.07	$	6,196,239

Age analysis of Past Due Consumer Loans by Class and Year of Origination

, segregated by portfolio segment and year of origination, as of March 31, 2020 was as follows:

	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term		Total
Consumer real estate:
Past due 30-89 days	$	—	$	623	$	771	$	1,490	$	763	$	3,575	$	1,206	$	1,114	$	9,542
Past due 90 or more days	—		—		512		108		386		1,000		1,224		—		3,230
Total past due	—		623		1,283		1,598		1,149		4,575		2,430		1,114		12,772
Current loans	65,082		217,726		142,566		122,282		93,385		180,883		367,149		19,262		1,208,335
Total	$	65,082	$	218,349	$	143,849	$	123,880	$	94,534	$	185,458	$	369,579	$	20,376	$	1,221,107
Consumer and other:
Past due 30-89 days	$	1,414	$	801	$	263	$	151	$	102	$	23	$	3,380	$	—	$	6,134
Past due 90 or more days	—		902		—		—		—		—		111		—		1,013
Total past due	1,414		1,703		263		151		102		23		3,491		—		7,147
Current loans	19,780		44,825		14,699		4,329		2,762		1,490		420,517		22,791		531,193
Total	$	21,194	$	46,528	$	14,962	$	4,480	$	2,864	$	1,513	$	424,008	$	22,791	$	538,340

Revolving Loans Converted to Term [Table Text Block]

Revolving loans that converted to term during the three months ended March 31, 2020 were as follows:

Commercial and industrial	$	11,346
Energy	15,353
Commercial real estate:
Buildings, land and other	7,639
Construction	—
Consumer real estate	1,071
Consumer and other	—
Total	$	35,409

Financing Receivable, Allowance for Credit Loss By Loan Class Calculated in Accordance With CECL Methodology

The following table presents details of the allowance for credit losses on loans segregated by loan portfolio segment as of March 31, 2020, calculated in accordance with the CECL methodology described above.

	Commercial and Industrial		Energy		Commercial Real Estate		Consumer Real Estate		Consumer and Other		Total
Modeled expected credit losses	$	69,446	$	15,425	$	34,941	$	6,974	$	6,950	$	133,736
Q-Factor adjustments	13,501		87,776		13,974		1,196		1,070		117,517
Specific allocations	9,205		—		3,404		—		19		12,628
Total	$	92,152	$	103,201	$	52,319	$	8,170	$	8,039	$	263,881

Allowance for Credit Losses By Loan Class in Accordance With Methodology Used Prior to CECL

The following table presents details of the allowance for credit losses on loans segregated by loan portfolio segment as of December 31, 2019, calculated in accordance with our prior incurred loss methodology described in our 2019 Form 10-K.

	Commercial and Industrial		Energy		Commercial Real Estate		Consumer Real Estate		Consumer and Other			Total
December 31, 2019
Historical valuation allowances	$	29,015	$	7,873	$	21,947	$	2,690	$	7,562		$	69,087
Specific valuation allowances	7,849		20,246		383		—		5			28,483
General valuation allowances	9,840		5,196		4,201		904		(409		)	19,732
Macroeconomic valuation allowances	4,889		4,067		4,506		519		884			14,865
Total	$	51,593	$	37,382	$	31,037	$	4,113	$	8,042		$	132,167

Activity in Allowance for Loan Losses by Portfolio Segment

The following table details activity in the allowance for credit losses on loans by portfolio segment for the three months ended March 31, 2020 and 2019. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.

	Commercial and Industrial			Energy			Commercial Real Estate			Consumer Real Estate			Consumer and Other			Total
March 31, 2020
Beginning balance	$	51,593		$	37,382		$	31,037		$	4,113		$	8,042		$	132,167
Impact of adopting ASC 326	21,263			(10,453		)	(13,519		)	2,392			(2,248		)	(2,565		)
Credit loss expense	21,950			110,006			34,761			1,570			4,638			172,925
Charge-offs	(4,369		)	(33,800		)	(73		)	(285		)	(5,005		)	(43,532		)
Recoveries	1,715			66			113			380			2,612			4,886
Net charge-offs	(2,654		)	(33,734		)	40			95			(2,393		)	(38,646		)
Ending balance	$	92,152		$	103,201		$	52,319		$	8,170		$	8,039		$	263,881
March 31, 2019
Beginning balance	$	48,580		$	29,052		$	38,777		$	6,103		$	9,620		$	132,132
Credit loss expense	11,929			(3,756		)	(2,352		)	1,247			3,935			11,003
Charge-offs	(2,688		)	—			(60		)	(1,778		)	(5,697		)	(10,223		)
Recoveries	750			47			90			89			2,462			3,438
Net charge-offs	(1,938		)	47			30			(1,689		)	(3,235		)	(6,785		)
Ending balance	$	58,571		$	25,343		$	36,455		$	5,661		$	10,320		$	136,350

Investment in Loans Related to Allowance for Loan Losses by Portfolio Segment Disaggregated Based on Impairment Methodology

The following table presents loans that were evaluated for expected credit losses on an individual basis and the related specific allocations, by loan portfolio segment as of March 31, 2020 and December 31, 2019.

	March 31, 2020				December 31, 2019
	Loan Balance		Specific Allocations		Loan Balance		Specific Allocations
Commercial and industrial	$	21,925	$	9,205	$	24,360	$	7,849
Energy	28,330		—		65,244		20,246
Commercial real estate	11,669		3,404		9,274		383
Consumer real estate	1,423		—		570		—
Consumer and other	20		19		5		5
Total	$	63,367	$	12,628	$	99,453	$	28,483