Loans (Tables)

6 Months Ended

Jun. 30, 2017

Loans were as follows:



	June 30, 2017		Percentage of Total		December 31, 2016		Percentage of Total
Commercial and industrial	$	4,604,269	36.8	%	$	4,344,000	36.3	%
Energy:
Production	1,040,506		8.3		971,767		8.1
Service	183,543		1.5		221,213		1.8
Other	185,563		1.5		193,081		1.7
Total energy	1,409,612		11.3		1,386,061		11.6
Commercial real estate:
Commercial mortgages	3,620,885		28.9		3,481,157		29.1
Construction	1,050,837		8.4		1,043,261		8.7
Land	322,130		2.6		311,030		2.6
Total commercial real estate	4,993,852		39.9		4,835,448		40.4
Consumer real estate:
Home equity loans	355,744		2.8		345,130		2.9
Home equity lines of credit	283,344		2.3		264,862		2.2
Other	351,985		2.8		326,793		2.7
Total consumer real estate	991,073		7.9		936,785		7.8
Total real estate	5,984,925		47.8		5,772,233		48.2
Consumer and other	513,532		4.1		473,098		3.9
Total loans	$	12,512,338	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:



	June 30, 2017		December 31, 2016
Commercial and industrial	$	21,226	$	31,475
Energy	55,464		57,571
Commercial real estate:
Buildings, land and other	6,916		8,550
Construction	—		—
Consumer real estate	2,543		2,130
Consumer and other	264		425
Total	$	86,413	$	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 June 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	$	24,320	$	26,149	$	50,469	$	4,553,800	$	4,604,269	$	10,768
Energy	5,991		6,430		12,421		1,397,191		1,409,612		2,902
Commercial real estate:
Buildings, land and other	21,157		4,166		25,323		3,917,692		3,943,015		944
Construction	—		—		—		1,050,837		1,050,837		—
Consumer real estate	4,693		2,022		6,715		984,358		991,073		739
Consumer and other	3,508		740		4,248		509,284		513,532		650
Total	$	59,669	$	39,507	$	99,176	$	12,413,162	$	12,512,338	$	16,003

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
June 30, 2017
Commercial and industrial	$	27,709	$	14,777	$	4,040	$	18,817	$	1,780
Energy	59,771		36,162		19,215		55,377		350
Commercial real estate:
Buildings, land and other	9,729		5,478		—		5,478		—
Construction	—		—		—		—		—
Consumer real estate	1,203		1,203		—		1,203		—
Consumer and other	—		—		—		—		—
Total	$	98,412	$	57,620	$	23,255	$	80,875	$	2,130



	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 June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Commercial and industrial	$	21,347	$	24,866	$	23,867	$	24,197
Energy	67,008		78,359		63,860		59,286
Commercial real estate:
Buildings, land and other	5,966		20,533		6,266		24,497
Construction	—		648		—		622
Consumer real estate	1,376		443		1,135		457
Consumer and other	12		27		18		18
Total	$	95,709	$	124,876	$	95,146	$	109,077

Troubled Debt Restructurings

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



	Six Months Ended June 30, 2017				Six Months Ended June 30, 2016
	Balance at Restructure		Balance at Period-End		Balance at Restructure		Balance at Period-End
Commercial and industrial	$	784	$	643	$	510	$	505
Energy	12,959		12,458		62,546		20,795
Commercial real estate:
Buildings, land and other	—		—		1,456		1,456
Construction	—		—		243		224
	$	13,743	$	13,101	$	64,755	$	22,980

Weighted Average Risk Grades for All Commercial Loans by Class

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



	June 30, 2017			December 31, 2016
	Weighted Average Risk Grade	Loans		Weighted Average Risk Grade	Loans
Commercial and industrial:
Risk grades 1-8	6.00	$	4,146,261	6.01	$	3,989,722
Risk grade 9	9.00	222,108		9.00	106,988
Risk grade 10	10.00	78,696		10.00	115,420
Risk grade 11	11.00	135,978		11.00	100,245
Risk grade 12	12.00	19,446		12.00	25,939
Risk grade 13	13.00	1,780		13.00	5,686
Total	6.39	$	4,604,269	6.35	$	4,344,000
Energy
Risk grades 1-8	6.32	$	1,024,927	6.34	$	854,688
Risk grade 9	9.00	43,415		9.00	78,524
Risk grade 10	10.00	115,913		10.00	150,872
Risk grade 11	11.00	169,893		11.00	244,406
Risk grade 12	12.00	55,114		12.00	53,821
Risk grade 13	13.00	350		13.00	3,750
Total	7.49	$	1,409,612	7.95	$	1,386,061
Commercial real estate:
Buildings, land and other
Risk grades 1-8	6.69	$	3,590,525	6.67	$	3,463,064
Risk grade 9	9.00	123,492		9.00	109,110
Risk grade 10	10.00	148,718		10.00	145,067
Risk grade 11	11.00	73,364		11.00	66,396
Risk grade 12	12.00	6,916		12.00	8,550
Risk grade 13	13.00	—		13.00	—
Total	6.97	$	3,943,015	6.95	$	3,792,187
Construction
Risk grades 1-8	7.03	$	1,019,355	6.97	$	1,023,194
Risk grade 9	9.00	22,632		9.00	15,829
Risk grade 10	10.00	5,116		10.00	2,889
Risk grade 11	11.00	3,734		11.00	1,349
Risk grade 12	12.00	—		12.00	—
Risk grade 13	13.00	—		13.00	—
Total	7.10	$	1,050,837	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 June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Commercial and industrial	$	(4,861	)	$	(3,966	)	$	(7,590	)	$	(5,098	)
Energy	(6,236		)	(16,747		)	(10,461		)	(17,758		)
Commercial real estate:
Buildings, land and other	460			481			502			542
Construction	3			2			6			9
Consumer real estate	111			74			207			173
Consumer and other	(1,401		)	(1,199		)	(2,529		)	(1,702		)
Total	$	(11,924	)	$	(21,355	)	$	(19,865	)	$	(23,834	)

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 June 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
June 30, 2017
Historical valuation allowances	$	28,504	$	32,452	$	17,975	$	2,416	$	5,455		$	86,802
Specific valuation allowances	1,780		350		—		—		—			2,130
General valuation allowances	8,418		5,934		4,724		2,032		137			21,245
Macroeconomic valuation allowances	10,204		15,541		10,303		1,087		2,246			39,381
Total	$	48,906	$	54,277	$	33,002	$	5,535	$	7,838		$	149,558
Allocated to loans:
Individually evaluated	$	1,780	$	350	$	—	$	—	$	—		$	2,130
Collectively evaluated	47,126		53,927		33,002		5,535		7,838			147,428
Total	$	48,906	$	54,277	$	33,002	$	5,535	$	7,838		$	149,558
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 June 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
June 30, 2017
Individually evaluated	$	18,817	$	55,377	$	5,478	$	1,203	$	—	$	80,875
Collectively evaluated	4,585,452		1,354,235		4,988,374		989,870		513,532		12,431,463
Total	$	4,604,269	$	1,409,612	$	4,993,852	$	991,073	$	513,532	$	12,512,338
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 six months ended June 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:
June 30, 2017
Beginning balance	$	45,583		$	61,793		$	34,009		$	4,823		$	6,848		$	153,056
Provision for loan losses	8,184			(1,280		)	(1,470		)	601			2,391			8,426
Charge-offs	(5,579		)	(6,317		)	(14		)	(2		)	(3,623		)	(15,535		)
Recoveries	718			81			477			113			2,222			3,611
Net charge-offs	(4,861		)	(6,236		)	463			111			(1,401		)	(11,924		)
Ending balance	$	48,906		$	54,277		$	33,002		$	5,535		$	7,838		$	149,558
June 30, 2016
Beginning balance	$	45,084		$	84,973		$	23,587		$	3,786		$	4,450		$	161,880
Provision for loan losses	6,460			(1,887		)	2,993			75			1,548			9,189
Charge-offs	(4,857		)	(16,749		)	(19		)	(23		)	(3,252		)	(24,900		)
Recoveries	891			2			502			97			2,053			3,545
Net charge-offs	(3,966		)	(16,747		)	483			74			(1,199		)	(21,355		)
Ending balance	$	47,578		$	66,339		$	27,063		$	3,935		$	4,799		$	149,714

Six months ended:
June 30, 2017
Beginning balance	$	52,915		$	60,653		$	30,213		$	4,238		$	5,026		$	153,045
Provision for loan losses	3,581			4,085			2,281			1,090			5,341			16,378
Charge-offs	(9,106		)	(10,595		)	(14		)	(13		)	(7,171		)	(26,899		)
Recoveries	1,516			134			522			220			4,642			7,034
Net charge-offs	(7,590		)	(10,461		)	508			207			(2,529		)	(19,865		)
Ending balance	$	48,906		$	54,277		$	33,002		$	5,535		$	7,838		$	149,558
June 30, 2016
Beginning balance	$	42,993		$	54,696		$	24,313		$	4,659		$	9,198		$	135,859
Provision for loan losses	9,683			29,401			2,199			(897		)	(2,697		)	37,689
Charge-offs	(6,718		)	(17,760		)	(47		)	(177		)	(5,976		)	(30,678		)
Recoveries	1,620			2			598			350			4,274			6,844
Net charge-offs	(5,098		)	(17,758		)	551			173			(1,702		)	(23,834		)
Ending balance	$	47,578		$	66,339		$	27,063		$	3,935		$	4,799		$	149,714