	March 31, 2019					December 31, 2018
	Amount		Percent			Amount		Percent
	(Dollars in thousands)
Commercial and financial:
Commercial and industrial	$	1,043,848		20.70	%	$	1,032,787		20.76	%
Oil & gas production and equipment		106,991		2.12			94,729		1.90
Agriculture		130,717		2.59			136,313		2.74
State and political subdivisions:
Taxable		73,051		1.45			76,211		1.53
Tax-exempt		49,833		0.99			48,415		0.97
Real estate:
Construction		469,826		9.32			451,224		9.07
Farmland		227,526		4.51			219,241		4.41
One to four family residences		982,605		19.49			979,170		19.68
Multifamily residential properties		68,412		1.36			65,949		1.33
Commercial		1,514,266		30.03			1,506,937		30.28
Consumer		326,002		6.46			328,069		6.59
Other (not classified above)		49,425		0.98			36,931		0.74
Total loans	$	5,042,502		100.00	%	$	4,975,976		100.00	%

The Company’s loans are mostly to customers within Oklahoma and approximately 65% of the loans are secured by real estate. Credit risk on loans is managed through limits on amounts loaned to individual and related borrowers, underwriting standards and loan monitoring procedures. The amounts and types of collateral obtained, if any, to secure loans are based upon the Company’s underwriting standards and management’s credit evaluation. Collateral varies, but may include real estate, equipment, accounts receivable, inventory, livestock and securities. The Company’s interest in collateral is secured through filing mortgages and liens, and in some cases, by possession of the collateral.

The Company’s commercial and industrial loan category includes a small percentage of loans to companies that provide ancillary services to the oil and gas industry, such as transportation, preparation contractors and equipment manufacturers. The balance of these loans was approximately $61 million at March 31, 2019 and approximately $60 million at December 31, 2018.

Accounting policies related to appraisals, nonaccruals and charge-offs are disclosed in Note (1) to the Company’s Annual Report on Form 10-K for the year ended December 31, 2018.

Had nonaccrual loans performed in accordance with their original contractual terms, the Company would have recognized additional interest income of approximately $544,000 for the three months ended March 31, 2019 and approximately $542,000 for the three months ended March 31, 2018.

The Company charges interest on principal balances outstanding on restructured loans during deferral periods. The current and future financial effects of the recorded balance of loans considered to be restructured were not considered to be material.

Loans are segregated into classes based upon the nature of the collateral and the borrower. These classes are used to estimate the allowance for loan losses. The following table is a summary of amounts included in nonaccrual loans, segregated by class of loans. Residential real estate refers to one-to-four family real estate.

Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due. The following table presents an age analysis of past due loans, segregated by class of loans:

	Age Analysis of Past Due Loans
	30-59 Days Past Due		60-89 Days Past Due		90 Days and Greater		Total Past Due Loans		Current Loans		Total Loans		Accruing Loans 90 Days or More Past Due
	(Dollars in thousands)
As of March 31, 2019
Real estate:
Non-residential real estate owner occupied	$	8,948	$	30	$	123	$	9,101	$	629,918	$	639,019	$	117
Non-residential real estate other		2,089		152		593		2,834		1,186,935		1,189,769		121
Residential real estate permanent mortgage		3,374		634		801		4,809		328,857		333,666		401
Residential real estate all other		2,239		4,002		2,327		8,568		832,865		841,433		247
Commercial and financial:
Non-consumer non-real estate		3,226		999		2,164		6,389		1,320,215		1,326,604		453
Consumer non-real estate		1,498		548		311		2,357		324,649		327,006		173
Other loans		1,485		156		92		1,733		140,687		142,420		—
Acquired loans		1,528		1,689		4,290		7,507		235,078		242,585		658
Total	$	24,387	$	8,210	$	10,701	$	43,298	$	4,999,204	$	5,042,502	$	2,170
As of December 31, 2018
Real estate:
Non-residential real estate owner occupied	$	5,114	$	810	$	43	$	5,967	$	620,654	$	626,621	$	—
Non-residential real estate other		2,772		32		114		2,918		1,143,210		1,146,128		—
Residential real estate permanent mortgage		2,448		653		693		3,794		324,908		328,702		430
Residential real estate all other		1,728		292		2,799		4,819		822,685		827,504		612
Commercial and financial:
Non-consumer non-real estate		3,620		702		833		5,155		1,278,499		1,283,654		282
Consumer non-real estate		1,991		565		559		3,115		323,747		326,862		325
Other loans		322		158		178		658		141,251		141,909		—
Acquired loans		5,240		1,669		4,936		11,845		282,751		294,596		267
Total	$	23,235	$	4,881	$	10,155	$	38,271	$	4,937,705	$	4,975,976	$	1,916

Loans are considered impaired when, based on current information and events, it is probable the Company will be unable to collect the full amount of scheduled principal and interest payments in accordance with the original contractual terms of the loan agreement. If a loan is impaired, a specific valuation allowance may be allocated, if necessary, so that the loan is reported, net of allowance for loss, at the present value of future cash flows using the loan’s existing rate, or the fair value of collateral if repayment is expected solely from the collateral.

The following table presents impaired loans, segregated by class of loans. During the period ended March 31, 2019 and March 31, 2018, no material amount of interest income was recognized on impaired loans subsequent to their classification as impaired.

	Impaired Loans
	Unpaid Principal Balance		Recorded Investment with Allowance		Related Allowance		Average Recorded Investment
	(Dollars in thousands)
As of March 31, 2019
Real estate:
Non-residential real estate owner occupied	$	7,730	$	7,619	$	228	$	7,362
Non-residential real estate other		1,976		1,722		212		1,247
Residential real estate permanent mortgage		1,871		1,619		143		1,618
Residential real estate all other		7,153		6,854		2,478		7,024
Commercial and financial:
Non-consumer non-real estate		18,769		11,120		857		10,976
Consumer non-real estate		767		660		133		724
Other loans		694		422		31		369
Acquired loans		12,764		10,228		2		11,078
Total	$	51,724	$	40,244	$	4,084	$	40,398

As of December 31, 2018
Real estate:
Non-residential real estate owner occupied	$	7,126	$	6,933	$	202	$	7,739
Non-residential real estate other		949		757		50		6,057
Residential real estate permanent mortgage		1,789		1,545		127		1,650
Residential real estate all other		7,177		6,862		2,433		7,154
Commercial and financial:
Non-consumer non-real estate		18,507		10,977		881		12,140
Consumer non-real estate		928		829		131		846
Other loans		710		490		35		481
Acquired loans		12,846		9,864		2		11,050
Total	$	50,032	$	38,257	$	3,861	$	47,117

The Company considers various factors to monitor the credit risk in the loan portfolio including volume and severity of loan delinquencies, nonaccrual loans, internal grading of loans, historical loan loss experience and economic conditions.

An internal risk grading system is used to indicate the credit risk of loans. The loan grades used by the Company are for internal risk identification purposes and do not directly correlate to regulatory classification categories or any financial reporting definitions.

The general characteristics of the risk grades are disclosed in Note (5) to the Company’s Annual Report on Form 10-K for the year ended December 31, 2018.

	Internal Loan Grading
	Grade
		1		2		3		4		5	Total
	(Dollars in thousands)
As of March 31, 2019
Real estate:
Non-residential real estate owner occupied	$	459,381	$	153,357	$	25,456	$	825	$	—	$	639,019
Non-residential real estate other		956,483		206,591		25,665		1,030		—		1,189,769
Residential real estate permanent mortgage		283,951		41,010		7,080		1,625		—		333,666
Residential real estate all other		659,846		159,703		15,943		5,941		—		841,433
Commercial and financial:
Non-consumer non-real estate		1,033,690		264,192		24,726		3,996		—		1,326,604
Consumer non-real estate		302,263		21,860		2,246		637		—		327,006
Other loans		136,737		4,317		1,348		18		—		142,420
Acquired loans		127,474		94,135		13,455		7,206		315		242,585
Total	$	3,959,825	$	945,165	$	115,919	$	21,278	$	315	$	5,042,502

As of December 31, 2018
Real estate:
Non-residential real estate owner occupied	$	451,059	$	157,715	$	16,949	$	898	$	—	$	626,621
Non-residential real estate other		932,454		188,341		25,146		187		—		1,146,128
Residential real estate permanent mortgage		279,870		39,806		7,401		1,625		—		328,702
Residential real estate all other		644,217		162,003		15,232		6,052		—		827,504
Commercial and financial:
Non-consumer non-real estate		1,000,089		264,134		15,128		4,303		—		1,283,654
Consumer non-real estate		302,217		21,600		2,255		790		—		326,862
Other loans		136,132		5,542		116		119		—		141,909
Acquired loans		156,008		109,075		20,884		8,284		345		294,596
Total	$	3,902,046	$	948,216	$	103,111	$	22,258	$	345	$	4,975,976

The allowance for loan losses (“ALL”) methodology is disclosed in Note (5) to the Company’s Annual Report on Form 10-K for the year ended December 31, 2018.

The following table details activity in the ALL by class of loans for the period presented. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.

	ALL
	Balance at beginning of period		Charge- offs			Recoveries		Net charge-offs			Provisions charged to operations			Balance at end of period
	(Dollars in thousands)
Three Months Ended March 31, 2019
Real estate:
Non-residential real estate owner occupied	$	6,328	$	(6	)	$	1	$	(5	)	$	332		$	6,655
Non-residential real estate other		11,027		(6	)		—		(6	)		341			11,362
Residential real estate permanent mortgage		3,261		(63	)		5		(58	)		58			3,261
Residential real estate all other		10,673		(52	)		2		(50	)		423			11,046
Commercial and financial:
Non-consumer non-real estate		13,151		(70	)		67		(3	)		1,261			14,409
Consumer non-real estate		3,065		(120	)		71		(49	)		56			3,072
Other loans		2,423		—			35		35			(50	)		2,408
Acquired loans		1,461		(26	)		4		(22	)		(737	)		702
Total	$	51,389	$	(343	)	$	185	$	(158	)	$	1,684		$	52,915

	ALL
	Balance at beginning of period		Charge- offs			Recoveries		Net charge-offs			Provisions charged to operations			Balance at end of period
	(Dollars in thousands)
Three Months Ended March 31, 2018
Real estate:
Non-residential real estate owner occupied	$	6,195	$	(19	)	$	1	$	(18	)	$	473		$	6,650
Non-residential real estate other		10,519		(1	)		39		38			(9	)		10,548
Residential real estate permanent mortgage		3,226		(56	)		3		(53	)		108			3,281
Residential real estate all other		9,672		(90	)		3		(87	)		246			9,831
Commercial and financial:
Non-consumer non-real estate		15,334		(156	)		13		(143	)		(406	)		14,785
Consumer non-real estate		2,793		(250	)		80		(170	)		76			2,699
Other loans		2,481		—			12		12			(157	)		2,336
Acquired loans		1,446		(27	)		18		(9	)		(17	)		1,420
Total	$	51,666	$	(599	)	$	169	$	(430	)	$	314		$	51,550

The following table details the amount of ALL by class of loans for the period presented, detailed on the basis of the impairment methodology used by the Company.

	ALL
	March 31, 2019				December 31, 2018

	Individually evaluated for impairment		Collectively evaluated for impairment		Individually evaluated for impairment		Collectively evaluated for impairment
	(Dollars in thousands)
Real estate:
Non-residential real estate owner occupied.	$	986	$	5,669	$	669	$	5,659
Non-residential real estate other		1,024		10,338		1,119		9,908
Residential real estate permanent mortgage		457		2,804		505		2,756
Residential real estate all other		3,691		7,355		3,413		7,260
Commercial and financial:
Non-consumer non-real estate		3,069		11,340		2,114		11,037
Consumer non-real estate		375		2,697		374		2,691
Other loans		26		2,382		65		2,358
Acquired loans		—		702		—		1,461
Total	$	9,628	$	43,287	$	8,259	$	43,130

The following table details the loans outstanding by class of loans for the period presented, on the basis of the impairment methodology used by the Company.

	Loans
	March 31, 2019						December 31, 2018
	Individually evaluated for impairment		Collectively evaluated for impairment		Loans acquired with deteriorated credit quality		Individually evaluated for impairment		Collectively evaluated for impairment		Loans acquired with deteriorated credit quality
	(Dollars in thousands)
Real estate:
Non-residential real estate owner occupied	$	26,281	$	612,738	$	—	$	17,846	$	608,775	$	—
Non-residential real estate other		26,695		1,163,074		—		25,333		1,120,795		—
Residential real estate permanent mortgage		8,705		324,961		—		9,026		319,676		—
Residential real estate all other		21,883		819,550		—		21,285		806,219		—
Commercial and financial:
Non-consumer non-real estate		28,722		1,297,882		—		19,432		1,264,222		—
Consumer non-real estate		2,875		324,131		—		3,093		323,769		—
Other loans		26		142,394		—		209		141,700		—
Acquired loans		14,057		221,608		6,920		22,132		265,084		7,380
Total	$	129,244	$	4,906,338	$	6,920	$	118,356	$	4,850,240	$	7,380

Transfers from loans and premises and equipment to other real estate owned and repossessed assets are non-cash transactions, and are not included in the statements of cash flow.

Transfers from loans and premises and equipment to other real estate owned and repossessed assets during the periods presented, are summarized as follows: