Loans (Tables)

9 Months Ended

Sep. 30, 2017

Loans were as follows:



	September 30, 2017		Percentage of Total		December 31, 2016		Percentage of Total
Commercial and industrial	$	4,677,923	36.8	%	$	4,344,000	36.3	%
Energy:
Production	1,094,927		8.6		971,767		8.1
Service	159,893		1.3		221,213		1.8
Other	132,240		1.0		193,081		1.7
Total energy	1,387,060		10.9		1,386,061		11.6
Commercial real estate:
Commercial mortgages	3,714,172		29.2		3,481,157		29.1
Construction	1,082,229		8.5		1,043,261		8.7
Land	307,701		2.4		311,030		2.6
Total commercial real estate	5,104,102		40.1		4,835,448		40.4
Consumer real estate:
Home equity loans	357,542		2.8		345,130		2.9
Home equity lines of credit	288,981		2.3		264,862		2.2
Other	367,948		2.9		326,793		2.7
Total consumer real estate	1,014,471		8.0		936,785		7.8
Total real estate	6,118,573		48.1		5,772,233		48.2
Consumer and other	522,748		4.2		473,098		3.9
Total loans	$	12,706,304	100.0	%	$	11,975,392	100.0	%

Non-Accrual Loans, Segregated by Class of Loans

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



	September 30, 2017		December 31, 2016
Commercial and industrial	$	37,239	$	31,475
Energy	96,717		57,571
Commercial real estate:
Buildings, land and other	6,773		8,550
Construction	—		—
Consumer real estate	2,167		2,130
Consumer and other	208		425
Total	$	143,104	$	100,151

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 September 30, 2017 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	$	26,415	$	30,740	$	57,155	$	4,620,768	$	4,677,923	$	20,614
Energy	12,585		46,097		58,682		1,328,378		1,387,060		634
Commercial real estate:
Buildings, land and other	9,065		4,065		13,130		4,008,743		4,021,873		2,229
Construction	—		2,331		2,331		1,079,898		1,082,229		2,331
Consumer real estate	7,671		2,107		9,778		1,004,693		1,014,471		835
Consumer and other	9,754		486		10,240		512,508		522,748		478
Total	$	65,490	$	85,826	$	151,316	$	12,554,988	$	12,706,304	$	27,121

Impaired Loans

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
September 30, 2017
Commercial and industrial	$	48,751	$	31,065	$	3,937	$	35,002	$	1,665
Energy	107,883		34,834		61,805		96,639		13,267
Commercial real estate:
Buildings, land and other	9,976		5,627		—		5,627		—
Construction	—		—		—		—		—
Consumer real estate	1,214		1,214		—		1,214		—
Consumer and other	—		—		—		—		—
Total	$	167,824	$	72,740	$	65,742	$	138,482	$	14,932



	Unpaid Contractual Principal Balance		Recorded Investment With No Allowance		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance
December 31, 2016
Commercial and industrial	$	40,288	$	19,862	$	9,047	$	28,909	$	5,436
Energy	60,522		27,759		29,804		57,563		3,750
Commercial real estate:
Buildings, land and other	11,369		6,866		—		6,866		—
Construction	—		—		—		—		—
Consumer real estate	977		655		—		655		—
Consumer and other	32		30		—		30		—
Total	$	113,188	$	55,172	$	38,851	$	94,023	$	9,186

Average Recorded Investment In Impaired Loans

The average recorded investment in impaired loans was as follows:



	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Commercial and industrial	$	26,910	$	26,921	$	26,651	$	25,365
Energy	76,008		47,003		72,055		57,309
Commercial real estate:
Buildings, land and other	5,553		8,904		6,106		20,444
Construction	—		326		—		548
Consumer real estate	1,209		545		1,155		508
Consumer and other	—		48		13		24
Total	$	109,680	$	83,747	$	105,980	$	104,198

Troubled Debt Restructurings

Troubled debt restructurings during the nine months ended September 30, 2017 and September 30, 2016 are set forth in the following table.



	Nine Months Ended September 30, 2017				Nine Months Ended September 30, 2016
	Balance at Restructure		Balance at Period-End		Balance at Restructure		Balance at Period-End
Commercial and industrial	$	4,026	$	3,875	$	510	$	505
Energy	56,097		55,023		73,977		31,918
Commercial real estate:
Buildings, land and other	—		—		1,455		1,455
Construction	—		—		243		221
	$	60,123	$	58,898	$	76,185	$	34,099

Weighted Average Risk Grades for All Commercial Loans by Class

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



	September 30, 2017			December 31, 2016
	Weighted Average Risk Grade	Loans		Weighted Average Risk Grade	Loans
Commercial and industrial:
Risk grades 1-8	6.01	$	4,236,670	6.01	$	3,989,722
Risk grade 9	9.00	201,635		9.00	106,988
Risk grade 10	10.00	89,126		10.00	115,420
Risk grade 11	11.00	113,253		11.00	100,245
Risk grade 12	12.00	35,574		12.00	25,939
Risk grade 13	13.00	1,665		13.00	5,686
Total	6.38	$	4,677,923	6.35	$	4,344,000
Energy
Risk grades 1-8	6.19	$	1,082,349	6.34	$	854,688
Risk grade 9	9.00	46,285		9.00	78,524
Risk grade 10	10.00	67,694		10.00	150,872
Risk grade 11	11.00	94,015		11.00	244,406
Risk grade 12	12.00	83,450		12.00	53,821
Risk grade 13	13.00	13,267		13.00	3,750
Total	7.21	$	1,387,060	7.95	$	1,386,061
Commercial real estate:
Buildings, land and other
Risk grades 1-8	6.69	$	3,720,068	6.67	$	3,463,064
Risk grade 9	9.00	115,196		9.00	109,110
Risk grade 10	10.00	110,647		10.00	145,067
Risk grade 11	11.00	69,189		11.00	66,396
Risk grade 12	12.00	6,773		12.00	8,550
Risk grade 13	13.00	—		13.00	—
Total	6.93	$	4,021,873	6.95	$	3,792,187
Construction
Risk grades 1-8	7.14	$	1,058,847	6.97	$	1,023,194
Risk grade 9	9.00	18,106		9.00	15,829
Risk grade 10	10.00	3,768		10.00	2,889
Risk grade 11	11.00	1,508		11.00	1,349
Risk grade 12	12.00	—		12.00	—
Risk grade 13	13.00	—		13.00	—
Total	7.19	$	1,082,229	7.01	$	1,043,261

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

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



	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Commercial and industrial	$	(4,565	)	$	(3,079	)	$	(12,155	)	$	(8,177	)
Energy	451			(865		)	(10,010		)	(18,623		)
Commercial real estate:
Buildings, land and other	266			259			768			801
Construction	2			9			8			18
Consumer real estate	(629		)	(195		)	(422		)	(22		)
Consumer and other	(1,760		)	(1,115		)	(4,289		)	(2,817		)
Total	$	(6,235	)	$	(4,986	)	$	(26,100	)	$	(28,820	)

Unallocated Portion of Allowance for Loan Losses

The following table presents details of the allowance for loan losses allocated to each portfolio segment as of September 30, 2017 and December 31, 2016 and detailed on the basis of the impairment evaluation methodology we used:



	Commercial and Industrial		Energy		Commercial Real Estate		Consumer Real Estate		Consumer and Other			Total
September 30, 2017
Historical valuation allowances	$	27,190	$	21,900	$	18,304	$	2,443	$	5,491		$	75,328
Specific valuation allowances	1,665		13,267		—		—		—			14,932
General valuation allowances	7,397		4,677		4,841		2,040		163			19,118
Macroeconomic valuation allowances	12,185		12,069		14,930		2,392		3,349			44,925
Total	$	48,437	$	51,913	$	38,075	$	6,875	$	9,003		$	154,303
Allocated to loans:
Individually evaluated	$	1,665	$	13,267	$	—	$	—	$	—		$	14,932
Collectively evaluated	46,772		38,646		38,075		6,875		9,003			139,371
Total	$	48,437	$	51,913	$	38,075	$	6,875	$	9,003		$	154,303
December 31, 2016
Historical valuation allowances	$	33,251	$	34,626	$	16,976	$	2,225	$	4,585		$	91,663
Specific valuation allowances	5,436		3,750		—		—		—			9,186
General valuation allowances	6,708		3,769		5,004		1,506		(144		)	16,843
Macroeconomic valuation allowances	7,520		18,508		8,233		507		585			35,353
Total	$	52,915	$	60,653	$	30,213	$	4,238	$	5,026		$	153,045
Allocated to loans:
Individually evaluated	$	5,436	$	3,750	$	—	$	—	$	—		$	9,186
Collectively evaluated	47,479		56,903		30,213		4,238		5,026			143,859
Total	$	52,915	$	60,653	$	30,213	$	4,238	$	5,026		$	153,045

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

Our recorded investment in loans as of September 30, 2017 and December 31, 2016 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
September 30, 2017
Individually evaluated	$	35,002	$	96,639	$	5,627	$	1,214	$	—	$	138,482
Collectively evaluated	4,642,921		1,290,421		5,098,475		1,013,257		522,748		12,567,822
Total	$	4,677,923	$	1,387,060	$	5,104,102	$	1,014,471	$	522,748	$	12,706,304
December 31, 2016
Individually evaluated	$	28,909	$	57,563	$	6,866	$	655	$	30	$	94,023
Collectively evaluated	4,315,091		1,328,498		4,828,582		936,130		473,068		11,881,369
Total	$	4,344,000	$	1,386,061	$	4,835,448	$	936,785	$	473,098	$	11,975,392

Activity in Allowance for Loan Losses by Portfolio Segment

The following table details activity in the allowance for loan losses by portfolio segment for the three and nine months ended September 30, 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
Three months ended:
September 30, 2017
Beginning balance	$	48,906		$	54,277		$	33,002		$	5,535		$	7,838		$	149,558
Provision for loan losses	4,096			(2,815		)	4,805			1,969			2,925			10,980
Charge-offs	(5,468		)	—			—			(766		)	(4,120		)	(10,354		)
Recoveries	903			451			268			137			2,360			4,119
Net charge-offs	(4,565		)	451			268			(629		)	(1,760		)	(6,235		)
Ending balance	$	48,437		$	51,913		$	38,075		$	6,875		$	9,003		$	154,303
September 30, 2016
Beginning balance	$	47,578		$	66,339		$	27,063		$	3,935		$	4,799		$	149,714
Provision for loan losses	4,632			(3,231		)	1,886			427			1,331			5,045
Charge-offs	(4,036		)	(884		)	(9		)	(287		)	(3,300		)	(8,516		)
Recoveries	957			19			277			92			2,185			3,530
Net charge-offs	(3,079		)	(865		)	268			(195		)	(1,115		)	(4,986		)
Ending balance	$	49,131		$	62,243		$	29,217		$	4,167		$	5,015		$	149,773

Nine months ended:
September 30, 2017
Beginning balance	$	52,915		$	60,653		$	30,213		$	4,238		$	5,026		$	153,045
Provision for loan losses	7,677			1,270			7,086			3,059			8,266			27,358
Charge-offs	(14,574		)	(10,595		)	(14		)	(779		)	(11,291		)	(37,253		)
Recoveries	2,419			585			790			357			7,002			11,153
Net charge-offs	(12,155		)	(10,010		)	776			(422		)	(4,289		)	(26,100		)
Ending balance	$	48,437		$	51,913		$	38,075		$	6,875		$	9,003		$	154,303
September 30, 2016
Beginning balance	$	42,993		$	54,696		$	24,313		$	4,659		$	9,198		$	135,859
Provision for loan losses	14,315			26,170			4,085			(470		)	(1,366		)	42,734
Charge-offs	(10,754		)	(18,644		)	(56		)	(464		)	(9,276		)	(39,194		)
Recoveries	2,577			21			875			442			6,459			10,374
Net charge-offs	(8,177		)	(18,623		)	819			(22		)	(2,817		)	(28,820		)
Ending balance	$	49,131		$	62,243		$	29,217		$	4,167		$	5,015		$	149,773