Loans (Tables)

12 Months Ended

Dec. 31, 2015

Receivables [Abstract]

Loans

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

	2015		2014
Commercial and industrial	$	4,120,522	$	4,055,225
Energy:
Production	1,249,678		1,160,404
Service	272,934		319,618
Other	235,583		293,923
Total energy	1,758,195		1,773,945
Commercial real estate:
Commercial mortgages	3,285,041		2,999,082
Construction	720,695		624,888
Land	286,991		291,907
Total commercial real estate	4,292,727		3,915,877
Consumer real estate:
Home equity loans	340,528		342,725
Home equity lines of credit	233,525		220,128
Other	306,696		286,198
Total consumer real estate	880,749		849,051
Total real estate	5,173,476		4,764,928
Consumer and other	434,338		393,437
Total loans	$	11,486,531	$	10,987,535

Activities in Related Party Loans

Activity in related party loans during 2015 is presented in the following table. Other changes were primarily related to changes in related-party status.

Balance outstanding at December 31, 2014	$	38,700
Principal additions	230,806
Principal reductions	(200,867		)
Other changes	16,127
Balance outstanding at December 31, 2015	$	84,766

Non-Accrual Loans, Segregated by Class of Loans

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

	2015		2014
Commercial and industrial	$	25,111	$	34,108
Energy	21,180		636
Commercial real estate:
Buildings, land and other	34,519		19,639
Construction	569		2,792
Consumer real estate	1,862		2,212
Consumer and other	226		538
Total	$	83,467	$	59,925

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, 2015 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	$	27,777	$	20,668	$	48,445	$	4,072,077	$	4,120,522	$	4,091
Energy	3,463		15,504		18,967		1,739,228		1,758,195		580
Commercial real estate:
Buildings, land and other	43,090		5,307		48,397		3,523,635		3,572,032		1,642
Construction	1,149		569		1,718		718,977		720,695		—
Consumer real estate	5,202		1,652		6,854		873,895		880,749		1,476
Consumer and other	3,781		382		4,163		430,175		434,338		319
Total	$	84,462	$	44,082	$	128,544	$	11,357,987	$	11,486,531	$	8,108

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
2015
Commercial and industrial	$	26,067	$	18,776	$	4,084	$	22,860	$	2,378	$	27,338
Energy	25,240		8,689		12,450		21,139		2,000		7,235
Commercial real estate:
Buildings, land and other	37,126		32,425		—		32,425		—		18,211
Construction	793		569		—		569		—		1,320
Consumer real estate	755		485		—		485		—		664
Consumer and other	—		—		—		—		—		—
Total	$	89,981	$	60,944	$	16,534	$	77,478	$	4,378	$	54,768
2014
Commercial and industrial	$	42,212	$	29,007	$	2,853	$	31,860	$	1,613	$	27,154
Energy	706		636		—		636		—		571
Commercial real estate:
Buildings, land and other	22,919		17,441		265		17,706		67		20,339
Construction	3,007		2,793		—		2,793		—		739
Consumer real estate	812		596		—		596		—		674
Consumer and other	—		—		—		—		—		159
Total	$	69,656	$	50,473	$	3,118	$	53,591	$	1,680	$	49,636
2013
Commercial and industrial	$	31,429	$	15,337	$	7,004	$	22,341	$	4,140	$	34,894
Energy	545		531		—		531		—		428
Commercial real estate:
Buildings, land and other	27,792		15,697		8,870		24,567		2,786		34,633
Construction	—		—		—		—		—		634
Consumer real estate	907		745		—		745		—		804
Consumer and other	334		278		—		278		—		348
Total	$	61,007	$	32,588	$	15,874	$	48,462	$	6,926	$	71,741

Troubled Debt Restructurings

Troubled debt restructurings that occurred during 2015, 2014 and 2013 are set forth in the following table.

	2015				2014				2013
	Balance at Restructure		Balance at Year-end		Balance at Restructure		Balance at Year-end		Balance at Restructure		Balance at Year-end
Commercial and industrial	$	709	$	536	$	5,795	$	5,391	$	6,334	$	4,937
Energy	—		—		—		—		528		531
Commercial real estate:
Buildings, land and other	—		—		3,121		2,948		7,964		5,747
Consumer	—		—		—		—		7		—
	$	709	$	536	$	8,916	$	8,339	$	14,833	$	11,215

Weighted Average Risk Grades for All Commercial Loans by Class

The following table presents weighted average risk grades for all commercial loans by class.

	December 31, 2015			December 31, 2014
	Weighted Average Risk Grade	Loans		Weighted Average Risk Grade	Loans
Commercial and industrial
Risk grades 1-8	5.88	$	3,869,203	5.93	$	3,846,598
Risk grade 9	9.00	100,670		9.00	65,166
Risk grade 10	10.00	76,030		10.00	54,519
Risk grade 11	11.00	49,508		11.00	55,034
Risk grade 12	12.00	22,644		12.00	31,683
Risk grade 13	13.00	2,467		13.00	2,225
Total	6.13	$	4,120,522	6.16	$	4,055,225
Energy
Risk grades 1-8	6.12	$	1,385,749	5.37	$	1,740,455
Risk grade 9	9.00	212,250		9.00	27,313
Risk grade 10	10.00	62,163		10.00	161
Risk grade 11	11.00	76,853		11.00	5,380
Risk grade 12	12.00	19,180		12.00	636
Risk grade 13	13.00	2,000		13.00	—
Total	6.89	$	1,758,195	5.45	$	1,773,945
Commercial real estate:
Buildings, land and other
Risk grades 1-8	6.58	$	3,280,435	6.53	$	3,067,219
Risk grade 9	9.00	140,900		9.00	72,906
Risk grade 10	10.00	72,577		10.00	87,889
Risk grade 11	11.00	43,601		11.00	43,336
Risk grade 12	12.00	34,519		12.00	19,501
Risk grade 13	13.00	—		13.00	138
Total	6.85	$	3,572,032	6.76	$	3,290,989
Construction
Risk grades 1-8	6.91	$	696,229	6.91	$	612,705
Risk grade 9	9.00	13,074		9.00	8,003
Risk grade 10	10.00	2,757		10.00	1,323
Risk grade 11	11.00	8,066		11.00	64
Risk grade 12	12.00	569		12.00	2,793
Risk grade 13	13.00	—		13.00	—
Total	7.01	$	720,695	6.97	$	624,888

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

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

	2015			2014			2013
Commercial and industrial	$	(6,535	)	$	(2,911	)	$	(28,431	)
Energy	(5,997		)	(1,237		)	(913		)
Commercial real estate:
Buildings, land and other	314			(2,348		)	(381		)
Construction	18			348			256
Consumer real estate	(91		)	(733		)	(719		)
Consumer and other	(3,237		)	(2,329		)	(2,409		)
Total	$	(15,528	)	$	(9,210	)	$	(32,597	)

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, 2015
Historical valuation allowances	$	25,428	$	21,195	$	15,544	$	2,109	$	12,813		$	77,089
Specific valuation allowances	2,378		2,000		—		—		—			4,378
General valuation allowances	7,339		5,525		4,619		2,052		(6,932		)	12,603
Macroeconomic valuation allowances	7,848		25,976		4,150		498		3,317			41,789
Total	$	42,993	$	54,696	$	24,313	$	4,659	$	9,198		$	135,859
December 31, 2014
Historical valuation allowances	$	25,249	$	7,172	$	14,684	$	2,017	$	10,482		$	59,604
Specific valuation allowances	1,613		—		67		—		—			1,680
General valuation allowances	5,354		2,232		5,324		1,972		(6,263		)	8,619
Macroeconomic valuation allowances	12,057		5,515		7,088		1,189		3,790			29,639
Total	$	44,273	$	14,919	$	27,163	$	5,178	$	8,009		$	99,542

Activity in Allowance for Loan Losses by Portfolio Segment

The following table details activity in the allowance for loan losses by portfolio segment for 2015, 2014 and 2013. 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			Unallocated			Total
2015
Beginning balance	$	44,273		$	14,919		$	27,163		$	5,178		$	8,009		$	—		$	99,542
Provision for loan losses	5,255			45,774			(3,182		)	(428		)	4,426			—			51,845
Charge-offs	(11,092		)	(6,000		)	(657		)	(577		)	(11,246		)	—			(29,572		)
Recoveries	4,557			3			989			486			8,009			—			14,044
Net charge-offs	(6,535		)	(5,997		)	332			(91		)	(3,237		)	—			(15,528		)
Ending balance	$	42,993		$	54,696		$	24,313		$	4,659		$	9,198		$	—		$	135,859
Allocated to loans:
Individually evaluated for impairment	$	2,378		$	2,000		$	—		$	—		$	—		$	—		$	4,378
Collectively evaluated for impairment	40,615			52,696			24,313			4,659			9,198			—			131,481
Ending balance	$	42,993		$	54,696		$	24,313		$	4,659		$	9,198		$	—		$	135,859
2014
Beginning balance	$	46,700		$	6,090		$	22,590		$	5,230		$	5,010		$	6,818		$	92,438
Provision for loan losses	484			10,066			6,573			681			5,328			(6,818		)	16,314
Charge-offs	(12,073		)	(1,747		)	(3,800		)	(1,097		)	(9,768		)	—			(28,485		)
Recoveries	9,162			510			1,800			364			7,439			—			19,275
Net charge-offs	(2,911		)	(1,237		)	(2,000		)	(733		)	(2,329		)	—			(9,210		)
Ending balance	$	44,273		$	14,919		$	27,163		$	5,178		$	8,009		$	—		$	99,542
Allocated to loans:
Individually evaluated for impairment	$	1,613		$	67		$	—		$	—		$	—		$	—		$	1,680
Collectively evaluated for impairment	42,660			14,852			27,163			5,178			8,009			—			97,862
Ending balance	$	44,273		$	14,919		$	27,163		$	5,178		$	8,009		$	—		$	99,542
2013
Beginning balance	$	46,585		$	7,579		$	29,346		$	5,252		$	3,507		$	12,184		$	104,453
Provision for loan losses	28,546			(576		)	(6,631		)	697			3,912			(5,366		)	20,582
Charge-offs	(32,008		)	(924		)	(1,329		)	(1,047		)	(9,489		)	—			(44,797		)
Recoveries	3,577			11			1,204			328			7,080			—			12,200
Net charge-offs	(28,431		)	(913		)	(125		)	(719		)	(2,409		)	—			(32,597		)
Ending balance	$	46,700		$	6,090		$	22,590		$	5,230		$	5,010		$	6,818		$	92,438
Allocated to loans:
Individually evaluated for impairment	$	4,140		$	—		$	2,786		$	—		$	—		$	—		$	6,926
Collectively evaluated for impairment	42,560			6,090			19,804			5,230			5,010			6,818			85,512
Ending balance	$	46,700		$	6,090		$	22,590		$	5,230		$	5,010		$	6,818		$	92,438

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

The Corporation’s recorded investment in loans as of December 31, 2015 and 2014 related to each balance in the allowance for loan losses by portfolio segment and detailed on the basis of the impairment methodology used by the Corporation was as follows:

	Commercial and Industrial		Energy		Commercial Real Estate		Consumer Real Estate		Consumer and Other		Total
2015
Individually evaluated	$	22,860	$	21,139	$	32,994	$	485	$	—	$	77,478
Collectively evaluated	4,097,662		1,737,056		4,259,733		880,264		434,338		11,409,053
Total	$	4,120,522	$	1,758,195	$	4,292,727	$	880,749	$	434,338	$	11,486,531
2014
Individually evaluated	$	31,860	$	636	$	20,499	$	596	$	—	$	53,591
Collectively evaluated	4,023,365		1,773,309		3,895,378		848,455		393,437		10,933,944
Total	$	4,055,225	$	1,773,945	$	3,915,877	$	849,051	$	393,437	$	10,987,535