Loans (Tables)

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Loans

Year-end loans, including leases net of unearned discounts, consisted of the following:

	2018		2017
Commercial and industrial	$	5,111,957	$	4,792,388
Energy:
Production	1,309,314		1,182,326
Service	168,775		171,795
Other	124,509		144,972
Total energy	1,602,598		1,499,093
Commercial real estate:
Commercial mortgages	4,121,966		3,887,742
Construction	1,267,717		1,066,696
Land	306,755		331,986
Total commercial real estate	5,696,438		5,286,424
Consumer real estate:
Home equity loans	353,924		355,342
Home equity lines of credit	337,168		291,950
Other	427,898		376,002
Total consumer real estate	1,118,990		1,023,294
Total real estate	6,815,428		6,309,718
Consumer and other	569,750		544,466
Total loans	$	14,099,733	$	13,145,665

Activities in Related Party Loans

Activity in related party loans during 2018 is presented in the following table. Other changes were primarily related to changes in related-party status.

Balance outstanding at December 31, 2017	$	166,403
Principal additions	316,584
Principal reductions	(226,718		)
Other changes	(213		)
Balance outstanding at December 31, 2018	$	256,056

Non-Accrual Loans, Segregated by Class of Loans

Year-end non-accrual loans, segregated by class of loans, were as follows:

	2018		2017
Commercial and industrial	$	9,239	$	46,186
Energy	46,932		94,302
Commercial real estate:
Buildings, land and other	15,268		7,589
Construction	—		—
Consumer real estate	892		2,109
Consumer and other	1,408		128
Total	$	73,739	$	150,314

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 December 31, 2018 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	$	22,577	$	16,556	$	39,133	$	5,072,824	$	5,111,957	$	11,912
Energy	4,395		1,717		6,112		1,596,486		1,602,598		513
Commercial real estate:
Buildings, land and other	18,390		4,393		22,783		4,405,938		4,428,721		4,321
Construction	760		—		760		1,266,957		1,267,717		—
Consumer real estate	9,105		2,608		11,713		1,107,277		1,118,990		2,608
Consumer and other	7,019		1,114		8,133		561,617		569,750		1,114
Total	$	62,246	$	26,388	$	88,634	$	14,011,099	$	14,099,733	$	20,468

Impaired Loans

Year-end impaired loans are set forth in the following table. No interest income was recognized on impaired loans subsequent to their classification as impaired.

	Unpaid Contractual Principal Balance		Recorded Investment With No Allowance		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance		Average Recorded Investment
2018
Commercial and industrial	$	9,094	$	2,842	$	4,287	$	7,129	$	2,558	$	18,246
Energy	67,900		6,817		39,890		46,707		9,671		75,453
Commercial real estate:
Buildings, land and other	15,774		2,168		12,517		14,685		2,599		12,799
Construction	—		—		—		—		—		—
Consumer real estate	293		293		—		293		—		704
Consumer and other	1,475		—		1,407		1,407		1,407		925
Total	$	94,536	$	12,120	$	58,101	$	70,221	$	16,235	$	108,127
2017
Commercial and industrial	$	60,781	$	28,038	$	15,722	$	43,760	$	7,553	$	30,073
Energy	99,606		33,080		61,162		94,242		13,267		76,492
Commercial real estate:
Buildings, land and other	10,795		6,394		—		6,394		—		6,164
Construction	—		—		—		—		—		—
Consumer real estate	1,214		1,214		—		1,214		—		1,167
Consumer and other	—		—		—		—		—		11
Total	$	172,396	$	68,726	$	76,884	$	145,610	$	20,820	$	113,907
2016
Commercial and industrial	$	40,288	$	19,862	$	9,047	$	28,909	$	5,436	$	26,074
Energy	60,522		27,759		29,804		57,563		3,750		57,360
Commercial real estate:
Buildings, land and other	11,369		6,866		—		6,866		—		17,729
Construction	—		—		—		—		—		438
Consumer real estate	977		655		—		655		—		537
Consumer and other	32		30		—		30		—		25
Total	$	113,188	$	55,172	$	38,851	$	94,023	$	9,186	$	102,163

Troubled Debt Restructurings

Troubled debt restructurings that occurred during 2018, 2017 and 2016 are set forth in the following table.

	2018				2017				2016
	Balance at Restructure		Balance at Year-end		Balance at Restructure		Balance at Year-end		Balance at Restructure		Balance at Year-end
Commercial and industrial	$	2,203	$	—	$	4,026	$	3,766	$	2,148	$	1,022
Energy	13,708		—		56,096		54,330		87,572		43,841
Commercial real estate:
Buildings, land and other	—		—		—		—		1,455		—
Construction	—		—		388		388		243		—
	$	15,911	$	—	$	60,510	$	58,484	$	91,418	$	44,863

Restructured Loans Past Due in Excess of 90 Days on Financing Receivables [Table Text Block]

Additional information related to restructured loans was as follows:

	2018		2017		2016
Restructured loans past due in excess of 90 days at period-end:
Number of loans	—		1		2
Dollar amount of loans	$	—	$	43,137	$	3,230
Restructured loans on non-accrual status at period end	—		53,622		44,863
Charge-offs of restructured loans:
Recognized in connection with restructuring	—		—		4,115
Recognized on previously restructured loans	7,650		9,951		9,490
Proceeds from sale of restructured loans	15,750		—		30,470

Weighted Average Risk Grades for All Commercial Loans by Class

The following tables present weighted average risk grades for all commercial loans by class.

	December 31, 2018			December 31, 2017
	Weighted Average Risk Grade	Loans		Weighted Average Risk Grade	Loans
Commercial and industrial
Risk grades 1-8	6.12	$	4,862,275	6.06	$	4,378,839
Risk grade 9	9.00	112,431		9.00	170,285
Risk grade 10	10.00	58,328		10.00	99,260
Risk grade 11	11.00	69,684		11.00	97,818
Risk grade 12	12.00	6,681		12.00	38,633
Risk grade 13	13.00	2,558		13.00	7,553
Total	6.30	$	5,111,957	6.41	$	4,792,388
Energy
Risk grades 1-8	5.76	$	1,451,673	6.01	$	1,199,207
Risk grade 9	9.00	35,565		9.00	50,427
Risk grade 10	10.00	43,001		10.00	64,282
Risk grade 11	11.00	25,427		11.00	90,875
Risk grade 12	12.00	37,261		12.00	81,035
Risk grade 13	13.00	9,671		13.00	13,267
Total	6.22	$	1,602,598	6.97	$	1,499,093

	December 31, 2018			December 31, 2017
	Weighted Average Risk Grade	Loans		Weighted Average Risk Grade	Loans
Commercial real estate:
Buildings, land and other
Risk grades 1-8	6.76	$	4,143,264	6.75	$	3,868,659
Risk grade 9	9.00	109,660		9.00	151,487
Risk grade 10	10.00	62,353		10.00	129,391
Risk grade 11	11.00	98,176		11.00	62,602
Risk grade 12	12.00	12,669		12.00	7,589
Risk grade 13	13.00	2,599		13.00	—
Total	6.98	$	4,428,721	7.00	$	4,219,728
Construction
Risk grades 1-8	7.13	$	1,177,260	7.11	$	1,019,635
Risk grade 9	9.00	60,754		9.00	18,042
Risk grade 10	10.00	24,877		10.00	23,393
Risk grade 11	11.00	4,826		11.00	5,626
Risk grade 12	12.00	—		12.00	—
Risk grade 13	13.00	—		13.00	—
Total	7.29	$	1,267,717	7.23	$	1,066,696

Net (Charge-Offs)/Recoveries, Segregated by Class of Loans

Net (charge-offs)/recoveries, segregated by class of loan, were as follows:

	2018			2017			2016
Commercial and industrial	$	(22,388	)	$	(17,453	)	$	(12,259	)
Energy	(13,121		)	(10,009		)	(18,588		)
Commercial real estate:
Buildings, land and other	(263		)	735			813
Construction	13			11			23
Consumer real estate	(1,538		)	(506		)	(257		)
Consumer and other	(7,548		)	(5,919		)	(4,219		)
Total	$	(44,845	)	$	(33,141	)	$	(34,487	)

Unallocated Portion of the Allowance for Loan Losses

The following table presents details of the allowance for loan losses, segregated by loan portfolio segment.

	Commercial and Industrial		Energy		Commercial Real Estate		Consumer Real Estate		Consumer and Other			Total
December 31, 2018
Historical valuation allowances	$	25,351	$	9,697	$	20,817	$	2,688	$	6,845		$	65,398
Specific valuation allowances	2,558		9,671		2,599		—		1,407			16,235
General valuation allowances	10,062		6,014		4,366		1,671		(13		)	22,100
Macroeconomic valuation allowances	10,609		3,670		10,995		1,744		1,381			28,399
Total	$	48,580	$	29,052	$	38,777	$	6,103	$	9,620		$	132,132
December 31, 2017
Historical valuation allowances	$	26,401	$	22,073	$	18,931	$	2,473	$	5,603		$	75,481
Specific valuation allowances	7,553		13,267		—		—		—			20,820
General valuation allowances	9,112		7,964		4,165		2,133		(91		)	23,283
Macroeconomic valuation allowances	16,548		8,224		7,852		1,051		2,105			35,780
Total	$	59,614	$	51,528	$	30,948	$	5,657	$	7,617		$	155,364

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

Our recorded investment in loans related to each balance in the allowance for loan losses by portfolio segment and detailed on the basis of the impairment methodology we used was as follows:

	Commercial and Industrial		Energy		Commercial Real Estate		Consumer Real Estate		Consumer and Other		Total
December 31, 2018
Individually evaluated	$	7,129	$	46,707	$	14,685	$	293	$	1,407	$	70,221
Collectively evaluated	5,104,828		1,555,891		5,681,753		1,118,697		568,343		14,029,512
Total	$	5,111,957	$	1,602,598	$	5,696,438	$	1,118,990	$	569,750	$	14,099,733
December 31, 2017
Individually evaluated	$	43,760	$	94,242	$	6,394	$	1,214	$	—	$	145,610
Collectively evaluated	4,748,628		1,404,851		5,280,030		1,022,080		544,466		13,000,055
Total	$	4,792,388	$	1,499,093	$	5,286,424	$	1,023,294	$	544,466	$	13,145,665

Activity in Allowance for Loan Losses by Portfolio Segment

The following table details activity in the allowance for loan losses by portfolio segment for 2018, 2017 and 2016. 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
2018
Beginning balance	$	59,614		$	51,528		$	30,948		$	5,657		$	7,617		$	155,364
Provision for loan losses	11,354			(9,355		)	8,079			1,984			9,551			21,613
Charge-offs	(26,076		)	(13,940		)	(619		)	(2,143		)	(17,197		)	(59,975		)
Recoveries	3,688			819			369			605			9,649			15,130
Net charge-offs	(22,388		)	(13,121		)	(250		)	(1,538		)	(7,548		)	(44,845		)
Ending balance	$	48,580		$	29,052		$	38,777		$	6,103		$	9,620		$	132,132
Allocated to loans:
Individually evaluated for impairment	$	2,558		$	9,671		$	2,599		$	—		$	1,407		$	16,235
Collectively evaluated for impairment	46,022			19,381			36,178			6,103			8,213			115,897
Ending balance	$	48,580		$	29,052		$	38,777		$	6,103		$	9,620		$	132,132
2017
Beginning balance	$	52,915		$	60,653		$	30,213		$	4,238		$	5,026		$	153,045
Provision for loan losses	24,152			884			(11		)	1,925			8,510			35,460
Charge-offs	(20,619		)	(10,595		)	(86		)	(925		)	(15,579		)	(47,804		)
Recoveries	3,166			586			832			419			9,660			14,663
Net charge-offs	(17,453		)	(10,009		)	746			(506		)	(5,919		)	(33,141		)
Ending balance	$	59,614		$	51,528		$	30,948		$	5,657		$	7,617		$	155,364
Allocated to loans:
Individually evaluated for impairment	$	7,553		$	13,267		$	—		$	—		$	—		$	20,820
Collectively evaluated for impairment	52,061			38,261			30,948			5,657			7,617			134,544
Ending balance	$	59,614		$	51,528		$	30,948		$	5,657		$	7,617		$	155,364

	Commercial and Industrial			Energy			Commercial Real Estate			Consumer Real Estate			Consumer and Other			Total
2016
Beginning balance	$	42,993		$	54,696		$	24,313		$	4,659		$	9,198		$	135,859
Provision for loan losses	22,181			24,545			5,064			(164		)	47			51,673
Charge-offs	(15,910		)	(18,644		)	(82		)	(814		)	(12,878		)	(48,328		)
Recoveries	3,651			56			918			557			8,659			13,841
Net charge-offs	(12,259		)	(18,588		)	836			(257		)	(4,219		)	(34,487		)
Ending balance	$	52,915		$	60,653		$	30,213		$	4,238		$	5,026		$	153,045
Allocated to loans:
Individually evaluated for impairment	$	5,436		$	3,750		$	—		$	—		$	—		$	9,186
Collectively evaluated for impairment	47,479			56,903			30,213			4,238			5,026			143,859
Ending balance	$	52,915		$	60,653		$	30,213		$	4,238		$	5,026		$	153,045