Allegiance Bancshares (ABTX) 10-K 10 Mar 21 2020 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Mar. 08, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	Allegiance Bancshares, Inc.
Entity Central Index Key	0001642081
Trading Symbol	ABTX
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 480.2
Entity Common Stock Shares Outstanding		20,166,968
Title of 12(b) Security	Common Stock, par value $1.00 per share
Security Exchange Name	NASDAQ
Entity File Number	001-37585
Entity Incorporation, State or Country Code	TX
Entity Tax Identification Number	26-3564100
Entity Address, Address Line One	8847 West Sam Houston Parkway, N.
Entity Address, Address Line Two	Suite 200
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77040
City Area Code	281
Local Phone Number	894-3200
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	Documents Incorporated by Reference: Portions of the Proxy Statement relating to the 2021 Annual Meeting of Shareholders of Allegiance Bancshares, Inc., which will be filed within 120 days after December 31, 2020, are incorporated by reference into Part III, Items 10-14 of this Annual Report on Form 10-K.

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Cash and due from banks	$ 122,897	$ 213,347
Interest-bearing deposits at other financial institutions	299,869	132,901
Total cash and cash equivalents	422,766	346,248
Available for sale securities, at fair value	772,890	372,545
Loans held for investment	4,491,764	3,915,310
Less: allowance for credit losses on loans	(53,173)	(29,438)
Loans, net	4,438,591	3,885,872
Accrued interest receivable	40,053	15,468
Premises and equipment, net	70,685	66,790
Other real estate owned	9,196	8,337
Federal Home Loan Bank stock	7,756	6,242
Bank owned life insurance	27,686	27,104
Goodwill	223,642	223,642
Core deposit intangibles, net	17,954	21,876
Other assets	18,909	18,530
TOTAL ASSETS	6,050,128	4,992,654
Deposits:
Noninterest-bearing	1,704,567	1,252,232
Interest-bearing
Demand	437,328	367,278
Money market and savings	1,499,938	1,258,008
Certificates and other time	1,346,649	1,190,583
Total interest-bearing deposits	3,283,915	2,815,869
Total deposits	4,988,482	4,068,101
Accrued interest payable	2,701	4,326
Borrowed funds	155,515	75,503
Subordinated debt	108,322	107,799
Other liabilities	36,439	27,060
Total liabilities	5,291,459	4,282,789
COMMITMENTS AND CONTINGENCIES (See Note 17)
SHAREHOLDERS’ EQUITY:
Preferred stock, $1 par value; 1,000,000 shares authorized; no shares issued or outstanding
Common stock, $1 par value; 80,000,000 shares authorized; 20,208,323 shares issued and outstanding at December 31, 2020 and 20,523,816 shares issued and outstanding at December 31, 2019	20,208	20,524
Capital surplus	508,794	521,066
Retained earnings	195,236	163,375
Accumulated other comprehensive income	34,431	4,900
Total shareholders’ equity	758,669	709,865
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ 6,050,128	$ 4,992,654

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parentheticals) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Shares issued (in shares)	0	0
Shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	80,000,000	80,000,000
Common stock, shares issued (in shares)	20,208,323	20,523,816
Common stock, shares outstanding (in shares)	20,208,323	20,523,816

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
INTEREST INCOME:
Loans, including fees	$ 225,959	$ 221,363	$ 148,223
Securities:
Taxable	8,227	6,975	2,725
Tax-exempt	7,311	2,934	5,802
Deposits in other financial institutions	265	1,635	1,473
Total interest income	241,762	232,907	158,223
INTEREST EXPENSE:
Demand, money market and savings deposits	9,371	18,307	6,478
Certificates and other time deposits	21,675	26,656	15,478
Borrowed funds	2,183	4,675	4,788
Subordinated debt	5,850	3,732	2,900
Total interest expense	39,079	53,370	29,644
NET INTEREST INCOME	202,683	179,537	128,579
Provision for credit losses	27,374	5,939	4,248
Net interest income after provision for credit losses	175,309	173,598	124,331
NONINTEREST INCOME:
Gain on sale of securities	287	1,459
(Loss) gain on sale of other real estate and other repossessed assets	(258)	26	(428)
Bank owned life insurance income	582	624	579
Rebate from correspondent bank	876	3,580	2,609
Other	4,735	5,604	3,329
Total noninterest income	8,156	13,423	7,713
NONINTEREST EXPENSE:
Salaries and employee benefits	80,152	77,593	56,704
Net occupancy and equipment	7,969	8,179	5,845
Depreciation	3,716	3,192	2,132
Data processing and software amortization	7,992	7,464	5,120
Professional fees	3,128	2,333	2,009
Regulatory assessments and FDIC insurance	2,926	1,705	2,309
Core deposit intangibles amortization	3,922	4,711	1,815
Communications	1,387	1,839	1,185
Advertising	1,565	2,367	1,725
Other real estate expense	5,162	614	313
Acquisition and merger-related expenses		1,326	1,661
Other	9,575	9,312	5,969
Total noninterest expense	127,494	120,635	86,787
INCOME BEFORE INCOME TAXES	55,971	66,386	45,257
Provision for income taxes	10,437	13,427	7,948
NET INCOME	$ 45,534	$ 52,959	$ 37,309
EARNINGS PER SHARE:
Basic	$ 2.23	$ 2.50	$ 2.41
Diluted	2.22	$ 2.47	$ 2.37
DIVIDENDS PER SHARE	$ 0.40
Deposit Account, Nonsufficient Funds Fee
NONINTEREST INCOME:
Revenue from contract with customer	$ 404	$ 658	$ 755
Deposit Account, Service Charge Fee
NONINTEREST INCOME:
Revenue from contract with customer	$ 1,530	$ 1,472	$ 869

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 45,534	$ 52,959	$ 37,309
Unrealized gain (loss) on securities:
Change in unrealized holding gain (loss) on available for sale securities during the period, net of tax	30,747	8,941	(3,224)
Reclassification of gain realized through the sale of securities, net of tax	(227)	(1,153)
Change in fair value of cash flow hedge, net of tax	(989)
Total other comprehensive income (loss), net of tax	29,531	7,788	(3,224)
Comprehensive income	$ 75,065	$ 60,747	$ 34,085

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Capital Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2017	$ 306,865	$ 13,227	$ 218,408	$ 74,894	$ 336
Balance (in shares) at Dec. 31, 2017		13,226,826
Net income	37,309			37,309
Other comprehensive income (loss)	(3,224)				(3,224)
Reclassification of amounts within AOCI to retained earnings due to tax reform	(72)			(72)
Common stock issued in connection with the exercise of stock options, restricted stock awards and the ESPP	3,750	$ 378	3,372
Common stock issued in connection with the exercise of stock options, restricted stock awards and the ESPP (in shares)		378,293
Common stock issued in connection with the acquisition of Post Oak Bancshares, Inc., net of registration expenses	358,783	$ 8,402	350,381
Common stock issued in connection with the acquisition of Post Oak Bancshares, Inc., net of registration expenses (in shares)		8,402,010
Repurchase of common stock	(2,112)	$ (69)	(2,043)
Repurchase of common stock (in shares)		(69,389)
Stock based compensation expense	1,685		1,685
Balance at Dec. 31, 2018	702,984	$ 21,938	571,803	112,131	(2,888)
Balance (in shares) at Dec. 31, 2018		21,937,740
Cumulative effect of change in accounting principle (Accounting Standards Update 2017-08) at Dec. 31, 2018	(1,715)			(1,715)
Total shareholders' equity at beginning of period, as adjusted (See Note 1) at Dec. 31, 2018	701,269	$ 21,938	571,803	110,416	(2,888)
Net income	52,959			52,959
Other comprehensive income (loss)	7,788				7,788
Common stock issued in connection with the exercise of stock options, restricted stock awards and the ESPP	3,412	$ 272	3,140
Common stock issued in connection with the exercise of stock options, restricted stock awards and the ESPP (in shares)		272,353
Repurchase of common stock	(58,663)	$ (1,686)	(56,977)
Repurchase of common stock (in shares)		(1,686,277)
Stock based compensation expense	3,100		3,100
Balance at Dec. 31, 2019	709,865	$ 20,524	521,066	163,375	4,900
Balance (in shares) at Dec. 31, 2019		20,523,816
Cumulative effect of change in accounting principle (Accounting Standards Update 2016-13) at Dec. 31, 2019	(5,508)			(5,508)
Total shareholders' equity at beginning of period, as adjusted (See Note 1) at Dec. 31, 2019	704,357	$ 20,524	521,066	157,867	4,900
Net income	45,534			45,534
Other comprehensive income (loss)	29,531				29,531
Cash dividends declared	(8,165)			(8,165)
Common stock issued in connection with the exercise of stock options, restricted stock awards and the ESPP	2,569	$ 203	2,366
Common stock issued in connection with the exercise of stock options, restricted stock awards and the ESPP (in shares)		203,404
Repurchase of common stock	(18,582)	$ (519)	(18,063)
Repurchase of common stock (in shares)		(518,897)
Stock based compensation expense	3,425		3,425
Balance at Dec. 31, 2020	$ 758,669	$ 20,208	$ 508,794	$ 195,236	$ 34,431
Balance (in shares) at Dec. 31, 2020		20,208,323

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parentheticals)	12 Months Ended
	Dec. 31, 2020$ / shares
Retained Earnings
Per share amount of cash dividends declared	$ 0.40

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 45,534	$ 52,959	$ 37,309
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and core deposit intangibles amortization	7,638	7,903	3,947
Provision for credit losses	27,374	5,939	4,248
Deferred income tax benefit	(7,059)	(87)	(256)
Net amortization of premium on investments	3,731	4,051	3,533
Excess tax benefit from stock based compensation	(149)	(11)	(587)
Bank owned life insurance income	(582)	(624)	(579)
Net accretion of discount on loans	(2,508)	(8,853)	(2,702)
Net amortization of discount on subordinated debt	113	111	110
Net accretion of discount on certificates of deposit	(356)	(772)	(367)
Loss (gain) on sale or write-downs of other real estate and other repossessed assets	4,323	(26)	428
Net gain on sale of securities	(287)	(1,459)
Federal Home Loan Bank stock dividends	(192)	(403)	(396)
Stock based compensation expense	3,425	3,100	1,685
Net change in operating leases	2,627	2,097
Increase in accrued interest receivable and other assets	(24,964)	(111)	(2,136)
Increase in accrued interest payable and other liabilities	2,395	3,053	1,822
Net cash provided by operating activities	61,063	66,867	46,059
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities and principal paydowns of available for sale securities	3,959,259	3,462,495	2,328,864
Proceeds from sales and calls of available for sale securities	38,106	173,024	12,701
Purchase of available for sale securities	(4,362,521)	(3,663,770)	(2,334,149)
Net change in total loans	(591,471)	(165,984)	(270,314)
Purchase of bank premises and equipment	(7,182)	(13,385)	(3,419)
Proceeds from sale of bank premises, equipment and other real estate	4,027	1,871
Net (redemptions) purchases of Federal Home Loan Bank stock	(1,322)	5,102	4,746
Net cash paid for the LoweryBank branch acquisition		(32,867)
Net cash and cash equivalents acquired in the purchase of Post Oak Bancshares, Inc.			230,416
Net cash used in investing activities	(961,104)	(233,514)	(31,155)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in noninterest-bearing deposits	452,335	29,052	93,053
Net increase in interest-bearing deposits	468,402	361,536	64,566
Net change in other borrowed funds	65,000	(149,990)	(87,076)
Net increase in borrowings under credit agreement	15,000
Proceeds from subordinated notes issuance		58,601
Dividends paid to common shareholders	(8,165)
Proceeds from the issuance of common stock, stock option exercises and the ESPP	2,569	3,412	3,750
Cash paid for fractional shares related to the Post Oak acquisition			(21)
Registration expenses related to common stock issued in the Post Oak acquisition			(220)
Repurchase of common stock	(18,582)	(58,663)	(2,112)
Net cash provided by financing activities	976,559	243,948	71,940
NET CHANGE IN CASH AND CASH EQUIVALENTS	76,518	77,301	86,844
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	346,248	268,947	182,103
CASH AND CASH EQUIVALENTS, END OF PERIOD	422,766	346,248	268,947
SUPPLEMENTAL CASH FLOW INFORMATION:
Income taxes paid	15,100	15,400	6,650
Interest paid	40,704	51,856	27,442
Cash paid for operating lease liabilities	3,282	3,543
SUPPLEMENTAL NONCASH DISCLOSURE:
Lease right-of-use asset obtained in exchange for lessee operating lease liabilities	3,056	13,277
Loans transferred to other real estate	9,209	$ 7,707	$ 265
Other real estate transferred to loans	$ 2,379

NATURE OF OPERATIONS AND SUMMAR

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES	1. NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES Nature of Operations and Principles of Consolidation- The consolidated financial statements include Allegiance Bancshares, Inc. (“Allegiance”) and its wholly-owned subsidiary, Allegiance Bank (the “Bank”, and together with Allegiance, collectively referred to as the “Company”) provide commercial and retail loans and commercial banking services. Intercompany transactions and balances are eliminated in consolidation under U.S. generally accepted accounting principles (“GAAP”). The Company derives substantially all of its revenues and income from the operation of the Bank. Allegiance Bank is a Texas banking association which began operations in October 2007. The Company is focused on delivering a wide variety of relationship-driven commercial banking products and community-oriented services tailored to meet the needs of small to mid-sized businesses, professionals and individuals through its 28 offices, with 27 bank offices in the Houston metropolitan area and one office in Beaumont, just outside of the Houston metropolitan area, as of the year ended December 31, 2020. The Bank provides its customers with a variety of banking services including checking accounts, savings accounts and certificates of deposit and its primary lending products are commercial, personal, automobile, mortgage and home improvement loans. The Bank also offers safe deposit boxes, automated teller machines, drive-through services and 24-hour depository facilities. Use of Estimates— The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions based on available information. These estimates and assumptions affect the reporting of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Acquisitions – On October 1, 2018, Allegiance completed the acquisition of Post Oak Bancshares, Inc. On February 1, 2019, Allegiance completed the acquisition of the LoweryBank branch, the Sugar Land location of Huntington State Bank. See Note 2 – Acquisitions for additional information pertaining to the Post Oak and LoweryBank acquisitions and the impact of the Post Oak transaction on the Company’s consolidated financial statements. Cash and cash equivalents —Cash and cash equivalents include cash, deposits with other financial institutions with maturities not greater than one year. Net cash flows are reported for customer loan and deposit transactions. Securities —Debt securities are classified as available for sale when they might be sold before maturity. Securities available for sale are carried at fair value. Unrealized gains and losses are excluded from earnings and reported, net of tax, as a separate component of shareholders’ equity until realized. Securities within the available for sale portfolio may be used as part of the Company’s asset/liability strategy and may be sold in response to changes in interest rate risk, prepayment risk or other similar economic factors. Interest earned on these assets is included in interest income. Interest income includes amortization of purchase premium or discount. Premiums and discounts on securities are amortized on the level-yield method, except for mortgage backed securities where prepayments are anticipated. Gains and losses on sales are recorded on the trade date and determined using the specific identification method. Loans —Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at amortized cost net of the allowance for credit losses on loans. Amortized cost is the principal balance outstanding, net of purchase accounting adjustments and deferred fees and costs. Accrued interest receivable on loans totaled $34.5 million at December 31, 2020 and was reported in accrued interest receivable on the consolidated balance sheets. Interest income is accrued on the unpaid principal balance. Loan origination fees, net of origination costs, are deferred and recognized in interest income using the interest method without anticipating prepayments. Interest income on loans is discontinued and placed on nonaccrual status at the time the loan is 90 days delinquent. All interest accrued but not received for loans placed on nonaccrual is reversed against interest income. Loans are returned to accrual status when all the principal and interest amount contractually due are brought current and future payments are reasonably assured. Purchased Credit Deteriorated (PCD) Loans —Upon adoption of ASC 326, the allowance for credit losses was determined for each loan and added to the loan’s carrying amount to establish a new amortized cost basis. The difference between the unpaid principal balance of the loan and the new amortized cost basis was the noncredit premium or discount which was amortized into interest income over the remaining life of the loan. Changes to the allowance for credit losses after adoption are recorded through provision expense. Nonrefundable Fees and Costs Associated with Lending Activities —Loan commitment and loan origination fees, and certain direct origination costs, are deferred and recognized in interest income as an adjustment to yield without anticipating prepayments using the interest method over the related loan life or; if the commitment expires unexercised, balances are recognized in income upon expiration of the commitment. Nonperforming and Past Due Loans —The Company has several procedures in place to assist it in maintaining the overall quality of its loan portfolio. The Company has established underwriting guidelines to be followed by its officers, and monitors its delinquency levels for any negative or adverse trends. There can be no assurance, however, that the Company’s loan portfolio will not become subject to increasing pressures from deteriorating borrower credit due to general economic conditions or other factors. Past due status is based on the contractual terms of the loan. 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 Company generally classifies a loan as nonperforming, automatically places the loan on nonaccrual status, ceases accruing interest and reverses all unpaid accrued interest against interest income, when, in management’s opinion, the borrower may be unable to meet payment obligations, when the payment of principal or interest on a loan is delinquent for 90 days, as well as when required by regulatory provisions, unless the loan is in the process of collection and the underlying collateral fully supports the carrying value of the loan. Any payments received on nonaccrual loans are applied first to outstanding loan amounts. Interest income is subsequently recognized only to the extent cash payments are received in excess of principal due. Any excess is treated as recovery of lost interest. Loans are returned to accrual status when all of the principal and interest amounts contractually due are brought current and future payments are reasonably assured. In all cases, loans are placed on nonaccrual or charged-off at an earlier date if collection of principal or interest is considered doubtful. If the decision is made to continue accruing interest on the loan, periodic reviews are made to confirm the accruing status of the loan. Nonaccrual loans and loans past due 90 days include both smaller balance homogeneous loans that are collectively and individually evaluated. When available information confirms that specific loans, or portions thereof, are uncollectible, these amounts are charged-off against the allowance. All loan types are considered delinquent after 30 days past due and are typically charged-off or charged-down no later than 120 days past due, with consideration of, but not limited to, the following criteria in determining the need and timing of the charge-off or charge-down: (1) the Bank is in the process of repossession or foreclosure and there appears to be a likely deficiency; (2) the collateral securing the loan has been sold and there is an actual deficiency; (3) the Bank is proceeding with lengthy legal action to collect its balance; (4) the borrower is unable to be located; or (5) the borrower has filed bankruptcy. Charge-offs occur when the Company confirms a loss on a loan. Acquired Loans — Acquired loans are recorded at fair value at the date of acquisition with no initial valuation allowance based on a discounted cash flow methodology that considers various factors including the type of loan and related collateral, classification status, fixed or variable interest rate, term of loan and whether or not the loan was amortizing, and a discount rate reflecting the Company’s assessment of risk inherent in the cash flow estimates. Certain larger purchased loans are individually evaluated while certain purchased loans are grouped together according to similar risk characteristics and are treated in the aggregate when applying various valuation techniques. These cash flow evaluations are inherently subjective as they require material estimates, all of which may be susceptible to significant change. Prior to the adoption of ASC Topic 326 on January 1, 2020, loans acquired in a business combination that had evidence of deterioration of credit quality since origination and for which it was probable, at acquisition, that the Company would be unable to collect all contractually required payments receivable were considered purchased credit impaired (“PCI”). PCI loans were individually evaluated and recorded at fair value at the date of acquisition with no initial valuation allowance based on a discounted cash flow methodology that considers various factors including the type of loan and related collateral, classification status, fixed or variable interest rate, term of loan and whether or not the loan was amortizing, and a discount rate reflecting the Company’s assessment of risk inherent in the cash flow estimates. Increases in expected cash flows, including prepayments, subsequent to the initial investment were recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows were recognized as impairment. Valuation allowances on PCI loans reflected only losses incurred after the acquisition (meaning the present value of all cash flows expected at acquisition that ultimately are not to be received). Subsequent to January 1, 2020, loans acquired in a business combination that have experienced more-than-insignificant deterioration in credit quality since origination are considered purchased credit deteriorated (“PCD”) loans. At the acquisition date, an estimate of expected credit losses is made for groups of PCD loans with similar risk characteristics and individual PCD loans without similar risk characteristics. This initial allowance for credit losses is allocated to individual PCD loans and added to the purchase price or acquisition date fair values to establish the initial amortized cost basis of the PCD loans. As the initial allowance for credit losses is added to the purchase price, there is no credit loss expense recognized upon acquisition of a PCD loan. Any difference between the unpaid principal balance of PCD loans and the amortized cost basis is considered to relate to noncredit factors and results in a discount or premium. Discounts and premiums are recognized through interest income on a level-yield method over the life of the loans. All loans considered to be PCI prior to January 1, 2020 were converted to PCD on that date. For acquired loans not deemed purchased credit deteriorated at acquisition, the differences between the initial fair value and the unpaid principal balance are recognized as interest income on a level-yield basis over the lives of the related loans. At the acquisition date, an initial allowance for expected credit losses is estimated and recorded as a provision for credit losses expense. The subsequent measurement of expected credit losses for all acquired loans is the same as the subsequent measurement of expected credit losses for originated loans. A llowance for Credit Losses – Allowance for Credit Losses on Loans - Effective January 1, 2020, the Company adopted ASU 2016-13 Financial Instruments – Credit Losses (ASC Topic 326): Measurement of Credit Losses on Financial Instruments , which replaced the incurred loss methodology with an expected loss methodology that is referred to as the CECL methodology. The level of the allowance is based upon management's evaluation of historical default and loss experience, current and projected economic conditions, asset quality trends, known and inherent risks in the portfolio, adverse situations that may affect the borrowers' ability to repay a loan (including the timing of future payments), the estimated value of any underlying collateral, composition of the loan portfolio, industry and peer bank loan quality indications and other pertinent factors, including regulatory recommendations. The allowance for credit losses on loans maintained by management is believed adequate to absorb all expected future losses in the loan portfolio at the balance sheet date. The Company disaggregates the loan portfolio into pools for purposes of determining the allowance for credit losses. These pools are based on the level at which the Company develops, documents and applies a systematic methodology to determine the allowance for credit losses. Loans with similar risk characteristics are collectively evaluated resulting in loss estimates as determined by applying reserve factors, such as historical lifetime loan loss experience, concentration risk of specific loan types, the volume, growth and composition of the Company’s loan portfolio, current economic conditions and reasonable and supportable forecasted economic conditions that may affect the borrower’s ability to pay and the value of collateral, the evaluation of the Company’s loan portfolio through its internal loan review process, general economic conditions and other qualitative risk factors both internal and external to the Company and other relevant factors, designed to estimate current expected credit losses, to amortized cost balances over the remaining contractual life of the collectively evaluated portfolio. Loans with similar risk characteristics are aggregated into homogeneous pools for assessment. Historical lifetime loan loss experience is determined by utilizing an open-pool (“cumulative loss rate”) methodology. Adjustments to the historical lifetime loan loss experience are made for differences in current loan pool risk characteristics such as portfolio concentrations, delinquency, nonaccrual, and watch list levels, as well as changes in current and forecasted economic conditions such as unemployment rates, property and collateral values, and other indices relating to economic activity. Losses are predicted over a period of time determined to be reasonable and supportable, and at the end of the reasonable and supportable period losses are reverted to long term historical averages. The reasonable and supportable period and reversion period are re-evaluated each year by the Company and are dependent on the current economic environment among other factors. A reasonable and supportable period of twelve months was utilized for all loan pools, followed by an immediate reversion to long term averages. Based on a review of these factors for each loan type, the Company applies an estimated percentage to the outstanding balance of each loan type. Loans that no longer share risk characteristics with the collectively evaluated loan pools are evaluated on an individual basis and are excluded from the collectively evaluated pools. In order to assess which loans are to be individually evaluated, the Company follows a loan review program to evaluate the credit risk in the total loan portfolio and assigns risk grades to each loan. Individual credit loss estimates are typically performed for nonaccrual loans, modified loans classified as troubled debt restructurings and all other loans identified by management. All loans deemed as being individually evaluated are reviewed on a quarterly basis in order to determine whether a specific reserve is required. The Company considers certain loans to be collateral dependent if the borrower is experiencing financial difficulty and management expects repayment for the loan to be substantially through the operation or sale of the collateral. For collateral dependent loans, loss estimates are based on the fair value of collateral, less estimated cost to sell (if applicable). Collateral values supporting individually evaluated loans are assessed quarterly and appraisals are typically obtained at least annually. The Company allocates a specific loan loss reserve on an individual loan basis primarily based on the value of the collateral securing the individually evaluated loan. Through this loan review process, the Company assesses the overall quality of the loan portfolio and the adequacy of the allowance for credit losses on loans while considering risk elements attributable to particular loan types in assessing the quality of individual loans. In addition, for each category of loans, the Company considers secondary sources of income and the financial strength and credit history of the borrower and any guarantors. A change in the allowance for credit losses on loans can be attributable to several factors, most notably specific reserves for individually evaluated loans, historical lifetime loan loss information, and changes in economic factors and growth in the loan portfolio. Specific reserves that are calculated on an individual basis and the qualitative assessment of all other loans reflect current changes in the credit quality of the loan portfolio. Historical lifetime credit losses, on the other hand, are based on an open-pool (“cumulative loss rate”) methodology, which is then applied to estimate lifetime credit losses in the loan portfolio. The allowance for credit losses on loans is further determined by the size of the loan portfolio subject to the allowance methodology and factors that include Company-specific risk indicators and general economic conditions, both of which are constantly changing. The Company evaluates the economic and portfolio-specific factors on a quarterly basis to determine a qualitative component of the general valuation allowance. These factors include current economic metrics, reasonable and supportable forecasted economic metrics, delinquency trends, credit concentrations, nature and volume of the portfolio and other adjustments for items not covered by specific reserves and historical lifetime loss experience. Based on the Company’s actual historical lifetime loan loss experience relative to economic and loan portfolio-specific factors at the time the losses occurred, management is able to identify the probable level of lifetime losses as of the date of measurement. The Company’s analysis of qualitative, or economic, factors on pools of loans with common risk characteristics, in combination with the quantitative historical lifetime loss information and specific reserves, provides the Company with an estimate of lifetime losses. The calculation of current expected credit losses is inherently subjective, as it requires management to exercise judgment in determining appropriate factors used to determine the allowance. The estimated loan losses for all loan pools are adjusted for changes in qualitative factors not inherently considered in the quantitative analyses to bring the allowance to the level management believes is appropriate based on factors that have not otherwise been fully accounted for, including adjustments for foresight risk, input imprecision and model imprecision. The qualitative categories and the measurements used to quantify the risks within each of these categories are subjectively selected by management, but measured by objective measurements period over period. The data for each measurement may be obtained from internal or external sources. The current period measurements are evaluated and assigned a factor commensurate with the current level of risk relative to past measurements over time. The resulting qualitative adjustments are applied to the relevant collectively evaluated loan portfolios. These adjustments are based upon quarterly trend assessments in portfolio concentrations, changes in lending policies and procedures, policy exceptions, independent loan review results, internal risk ratings and peer group credit quality trends. The qualitative allowance allocation, as determined by the processes noted above, is increased or decreased for each loan pool based on the assessment of these various qualitative factors. The determination of the appropriate qualitative adjustment is based on management's analysis of current and expected economic conditions and their impact to the portfolio, as well as internal credit risk movements and a qualitative assessment of the lending environment, including underwriting standards. Management recognizes the sensitivity of various assumptions made in the quantitative modeling of expected losses and may adjust reserves depending upon the level of uncertainty that currently exists in one or more assumptions. While policies and procedures used to estimate the allowance for credit losses on loans, as well as the resultant provision for credit losses charged to income, are considered adequate by management and are reviewed periodically by regulators and internal audit, they are approximate and could materially change based on changes within the loan portfolio and effects from economic factors. There are factors beyond the Company’s control, such as changes in projected economic conditions, including political instability or global events affecting the U.S. economy, real estate markets or particular industry conditions which could cause changes to expectations for current conditions and economic forecasts that could result in an unanticipated increase in the allowance and may materially impact asset quality and the adequacy of the allowance for credit losses and thus the resulting provision for credit losses. In assessing the adequacy of the allowance for credit losses on loans, the Company considers the results of its ongoing independent loan review process. The Company undertakes this process both to ascertain those loans in the portfolio with elevated credit risk and to assist in its overall evaluation of the risk characteristics of the entire loan portfolio. Its loan review process includes the judgment of management, independent internal loan reviewers and reviews that may have been conducted by third-party reviewers including regulatory examiners. The Company incorporates relevant loan review results in the allowance. In accordance with CECL, losses are estimated over the remaining contractual terms of loans, adjusted for prepayments. The contractual term excludes expected extensions, renewals and modifications unless management has a reasonable expectation at the reporting date that a troubled debt restructuring will be executed or such renewals, extensions or modifications are included in the original loan agreement and are not unconditionally cancellable by the Company. Credit losses are estimated on the amortized cost basis of loans, which includes the principal balance outstanding, purchase discounts and premiums and deferred loan fees and costs. Loan losses are not estimated for accrued interest receivable as interest that is deemed uncollectible is written off through interest income in a timely manner. Accrued interest is presented separately on the balance sheets and as allowed under ASC Topic 326 is excluded from the tabular loan disclosures in Note 6 – Loans and Allowance for Credit Losses. Allowance for Credit Losses on Unfunded Commitments - The Company estimates expected credit losses over the contractual term in which the Company is exposed to credit risk through a contractual obligation to extend credit, unless the obligation is unconditionally cancellable by the Company. The allowance for credit losses on unfunded commitments is adjusted as a provision for credit loss expense. The estimates are determined based on the likelihood of funding during the contractual term and an estimate of credit losses subsequent to funding. Estimated credit losses on subsequently funded balances are based on the same assumptions as used to estimate credit losses on existing funded loans. Allowance for Credit Losses - Securities Available for Sale – For securities classified as available for sale that are in an unrealized loss position at the balance sheet date, the Company first assesses whether or not it intends to sell the security, or more likely than not will be required to sell the security, before recovery of its amortized cost basis. If either criteria is met, the security's amortized cost basis is written down to fair value through net income. If neither criteria is met, the Company evaluates whether any portion of the decline in fair value is the result of credit deterioration. Such evaluations consider the extent to which the amortized cost of the security exceeds its fair value, changes in credit ratings and any other known adverse conditions related to the specific security. If the evaluation indicates that a credit loss exists, an allowance for credit losses is recorded through provisions for credit losses for the amount by which the amortized cost basis of the security exceeds the present value of cash flows expected to be collected, limited by the amount by which the amortized cost exceeds fair value. Losses are charged against the allowance when management believes the uncollectibility of an available for sale security is confirmed or when either of the criteria regarding intent or requirement to sell is met. Any impairment not recognized in the allowance for credit losses is recognized in other comprehensive income. For certain types of debt securities, such as U.S. Treasuries and other securities with government guarantees, entities may expect zero credit losses. The zero-loss expectation applies to all of the Company’s securities and no allowance for credit losses was recorded on its available for sale securities portfolio at transition. Prior to the adoption of ASU 2016-13, declines in the fair value of available-for-sale securities below their cost that were deemed to be other than temporary were reflected in earnings as realized losses. In estimating other-than-temporary impairment losses prior to January 1, 2020, management considered, among other things, (i) the length of time and the extent to which the fair value had been less than cost, (ii) the financial condition and near-term prospects of the issuer and (iii) the intent and our ability to retain our investment in the issuer for a period of time sufficient to allow for any anticipated recovery in fair value. Accrued interest receivable on available for sale securities totaled $5.5 million at December 31, 2020 and is excluded from the estimate of credit losses. Troubled debt restructurings (TDRs) — Loans for which terms have been modified in a TDR are evaluated using these same individual evaluation methods. For troubled debt restructurings that subsequently default, the Company determines the amount of reserve in accordance with the accounting policy for the allowance for credit losses. The Company assesses the exposure for each modification, by collateral discounting and determines if a specific allocation to the allowance for credit losses is needed. Once an obligation has been restructured because of such credit problems, it continues to be considered a troubled debt restructuring until paid in full. The Company returns troubled debt restructurings to accrual status only if (1) all contractual amounts due can reasonably be expected to be repaid within a prudent period and (2) repayment has been in accordance with the contract for a sustained period, typically at least twelve months. Premises and Equipment —Premises and equipment are carried at cost less accumulated depreciation. Depreciation expense is calculated principally using the straight-line method over the estimated useful lives of the assets which range from 3 to 40 years. Leasehold improvements are amortized using the straight-line method over the periods of the leases or the estimated useful lives, whichever is shorter. Land is carried at cost. Leases — On January 1, 2019, the Company adopted Accounting Standards Update ("ASU") 2016-02, Leases (Topic 842) through the required modified retrospective approach by applying the allowed transition method whereby comparative periods were not restated. The Company elected to apply several of the available practical expedients provided by ASU 2016-12, including carryover of historical lease determination, carryover of historical initial direct cost balances for existing leases and accounting for lease and non-lease components in contracts in which the Company is a lease as a single lease component. Upon adoption of the new leasing standard on January 1, 2019, the Company recognized $15.3 million of right-of-use assets, and $15.7 million of related lease liabilities on the Consolidated Balance Sheet. The Company leases certain office facilities under operating leases. We also own certain office facilities which we lease to outside parties under operating lessor leases; however, such leases are not significant. Under the new standards, for operating leases other than those considered to be short-term, we recognize lease right-of-use assets and related lease liabilities. Such amounts are reported as components of premises and equipment and other liabilities, respectively, on our consolidated balance sheet. Other Real Estate Owned —Assets acquired through or instead of loan foreclosure are held for sale and are initially recorded at fair value less estimated selling costs when acquired, establishing a new cost basis. Costs after acquisition are generally expensed. If the fair value of the asset declines, a write-down is recorded through expense. The valuation of foreclosed assets is subjective in nature and may be adjusted in the future because of changes in economic conditions. At December 31, 2020, the $9.2 million balance of other real estate owned primarily consisted of foreclosed commercial real estate properties recorded as a result of obtaining physical possession of the property. Federal Home Loan Bank (“FHLB”) Stock— The Bank is a member of the FHLB system. Members are required to own a certain amount of stock based on the level of borrowings and other factors and may invest in additional amounts. FHLB stock is carried at cost, classified as a restricted security and periodically evaluated for impairment based on ultimate recovery of par value. Both cash and stock dividends are reported as income. Bank Owned Life Insurance— The Company purchased bank owned life insurance policies on certain key executives and acquired life insurance policies in conjunction with the acquisitions of F&M Bancshares and Post Oak. Bank owned life insurance is recorded at the amount that can be realized under the insurance contract at the balance sheet date, which is the cash surrender value, and the most reasonable estimate of fair value, adjusted for other charges or other amounts due that are probable at settlement. Goodwill —Goodwill resulting from business combinations is generally determined as the excess of the fair value of the consideration transferred, plus the fair value of any noncontrolling interests in the acquiree, over the fair value of the net assets acquired and liabilities assumed as of the acquisition date. Goodwill is assessed annually on October 1 for impairment or more frequently if events and circumstances exist that indicate that the carrying amount of the asset may not be recoverable and a goodwill impairment test should be performed. A significant amount of judgment is involved in determining if an indicator of impairment has occurred. Such indicators may include, among others: a significant decline in our expected future cash flows; a sustained, significant decline in our stock price and market capitalization; a significant adverse change in legal factors or in the business climate; adverse action or assessment by

ACQUISITIONS

ACQUISITIONS	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
ACQUISITIONS	2. ACQUISITIONS Acquisitions are accounted for using the acquisition method of accounting. Accordingly, the assets and liabilities of an acquired entity are recorded at their fair value at the acquisition date. The excess of the purchase price over the estimated fair value of the net assets is recorded as goodwill. The results of operations for an acquisition have been included in the Company’s consolidated financial results beginning on the respective acquisition date. The measurement period for the Company to determine the fair values of acquired identifiable assets and assumed liabilities will end at the earlier of (1) twelve months from the date of the acquisition or (2) as soon as the Company receives the information it was seeking about facts and circumstances that existed as of the acquisition date or learns that more information is not obtainable. The following acquisitions were completed on the dates indicated below: 2019 Acquisition Acquisition of LoweryBank Branch —On February 1, 2019, the Bank completed the acquisition of the LoweryBank branch, the Sugar Land location of Huntington State Bank. The Bank paid $32.9 million in cash to acquire certain assets which included approximately $45.0 million in loans and assumed approximately $16.0 million in customer deposits. The Bank consolidated its existing Sugar Land bank office into this new bank office location, which was less than one mile away. The acquisition of LoweryBank was accounted for under the acquisition method of accounting in accordance with ASC Topic 805, Business Combinations. The Company recognized goodwill of $578 thousand which is calculated as the excess of both the consideration exchanged and liabilities assumed as compared to the fair value of identifiable assets acquired, which was deductible for tax purposes. Income and expense generated from acquired assets and liabilities assumed would not have a material impact, therefore, proforma numbers are not presented 2018 Acquisition Acquisition of Post Oak Bancshares, Inc. —On October 1, 2018, the Company completed the acquisition of Post Oak Bancshares, Inc. (“Post Oak”) and its wholly-owned subsidiary Post Oak Bank, N.A. headquartered in Houston, Texas. Post Oak operated thirteen bank offices, twelve located throughout the greater Houston metropolitan area and one in Beaumont, just outside of the Houston metropolitan area. The Company acquired Post Oak to further expand its Houston, Texas area market. Goodwill resulted from a combination of expected operational synergies and an enhanced branching network and was not deductible for tax purposes. Pursuant to the merger agreement, the Company issued 8,402,010 shares of Company common stock for all outstanding shares of Post Oak common stock and paid $21 thousand in cash for any fractional shares held by Post Oak shareholders. Additionally, all outstanding Post Oak options were assumed by Allegiance and converted using the 0.7017 exchange ratio to 299,352 options at a weighted average exercise price of $12.83 per option. Based on the $41.70 per share closing price of Allegiance common stock on September 28, 2018, the total transaction value was approximately $359.0 million. The acquisition was accounted for under the acquisition method of accounting in accordance with ASC Topic 805, Business Combinations. The Company recognized goodwill of $183.7 million which is calculated as the excess of both the consideration exchanged and liabilities assumed as compared to the fair value of identifiable assets acquired, none of which is expected to be deductible for tax purposes. The intangible assets recognized in the transaction will be amortized utilizing an accelerated method over their ten year estimated useful lives. As of September 30, 2019, the Company finalized its valuation of all assets and liabilities acquired. A summary of the final purchase price allocation is as follows (dollars in thousands): Fair value of consideration paid: Common shares issued (8,402,010 shares) $ 350,364 Stock options issued (299,352) 8,639 Cash in lieu of fractional shares 21 Total consideration paid $ 359,024 Fair value of assets acquired: Cash and cash equivalents $ 230,416 Investment securities 42,779 Loans 1,164,281 Premises and equipment 21,988 Core deposit intangibles 25,128 Other assets 18,076 Total assets acquired $ 1,502,668 Fair value of liabilities assumed: Deposits $ 1,291,310 Other borrowed funds 30,000 Other liabilities 6,070 Total liabilities assumed 1,327,380 Fair value of net assets acquired $ 175,288 Goodwill resulting from acquisition $ 183,736 The fair value of net assets acquired includes fair value adjustments to certain acquired loans that were not considered impaired as of the acquisition date. The fair value adjustments were determined using discounted contractual cash flows. The following presents details of all loans acquired as of October 1, 2018: Contractual Balance Fair Value Discount (Dollars in thousands) Commercial and industrial $ 221,098 $ 217,204 $ (3,894 ) Real estate: Commercial real estate (including multi-family residential) 450,947 443,512 (7,435 ) Commercial real estate construction and land development 167,386 165,387 (1,999 ) 1-4 family residential (including home equity) 288,304 285,099 (3,205 ) Residential construction 23,812 23,812 — Consumer and other 29,684 29,267 (417 ) Total loans $ 1,181,231 $ 1,164,281 $ (16,950 ) In connection with the Post Oak acquisition, the Company acquired loans both with and without evidence of credit quality deterioration since origination. The acquired loans were initially recorded at fair value with no carryover of any allowance for loan losses. Acquired loans were segregated between those considered to be purchased credit impaired (“PCI”) loans and those without credit impairment at acquisition. PCI Loans. The following presents information at the acquisition date for PCI loans acquired in the transaction (dollars in thousands): Contractually required principal and interest payments $ 28,340 Contractual cash flows not expected to be collected (nonaccretable difference) (3,163 ) Expected cash flows at acquisition 25,177 Interest component of expected cash flows (accretable yield) (495 ) Fair value of loans acquired with deterioration of credit quality $ 25,672 Non-PCI Loans. The following table presents information at the acquisition date for non-PCI loans acquired in the transaction (dollars in thousands): Contractually required principal and interest payments $ 1,152,892 Accretable discount (13,293 ) Fair value at acquisition $ 1,166,185 The following table presents unaudited pro forma financial information as if the acquisition had occurred at the beginning of 2017. Post Oak’s results of operations were included in the Company’s results beginning October 1, 2018. The pro forma financial information is not necessarily indicative of the results of operations that would have occurred had the transaction been effected on the assumed dates. For the Years Ended December 31, 2018 2017 (Dollars in thousands, except per share data) Net interest income $ 170,801 $ 165,612 Noninterest income 10,060 9,543 Net income 41,807 35,107 Basic earnings per common share 2.70 1.63 Diluted earnings per common share 2.65 1.61 To determine pro forma information, the Company adjusted its year ended December 31, 2018 and 2017 historical results to include the historical results for Post Oak for the year ended December 31, 2017 and the year ended December 31, 2018. The pro forma information includes acquisition accounting adjustments to interest on loans, certificates of deposit and subordinated debt, difference in the rate of borrowed funds, amortization of intangibles arising from the transaction and the related income tax effects. Earnings of Post Oak since the acquisition date have not been disclosed as the acquired company was merged into the Company and separate financial information is not readily available. The Company incurred approximately $1.3 million and $1.7 million of pre-tax acquisition and merger-related expenses during the years ended December 31, 2019 and 2018, respectively, related to the Post Oak acquisition. The acquisition and merger-related expenses are reflected on the Company’s income statement for 2019 and 2018 but are excluded from the calculation of pro forma income above.

GOODWILL AND CORE DEPOSIT INTAN

GOODWILL AND CORE DEPOSIT INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
GOODWILL AND CORE DEPOSIT INTANGIBLE ASSETS	3. GOODWILL AND CORE DEPOSIT INTANGIBLE ASSETS Changes in the carrying amount of the Company’s goodwill and core deposit intangibles were as follows: Core Deposit Goodwill Intangibles (Dollars in thousands) Balance as of December 31, 2017 $ 39,389 $ 3,274 Acquisition of Post Oak Bancshares, Inc. 183,736 25,128 Amortization — (1,815 ) Balance as of December 31, 2018 223,125 26,587 Acquisition of LoweryBank branch 578 — Measurement period adjustment (61 ) — Amortization — (4,711 ) Balance as of December 31, 2019 223,642 21,876 Amortization — (3,922 ) Balance as of December 31, 2020 $ 223,642 $ 17,954 Goodwill is recorded on the acquisition date of an entity. During the measurement period, the Company may record subsequent adjustments to goodwill for provisional amounts recorded at the acquisition date. The Company performs its annual evaluation of goodwill impairment of Allegiance Bancshares, Inc., the sole reporting unit, on October 1 each year and on an interim basis if events or changes in circumstances between annual tests suggest additional testing may be warranted to determine if goodwill might be impaired. The Company has one reporting unit. Due to the effects that the COVID-19 pandemic continued to have on the economy and the movement of the Company’s stock price, the Company performed its annual quantitative goodwill impairment analysis as of September 30, 2020 and determined that goodwill was not impaired. If adverse economic conditions or declines in the Company’s stock price are sustained, further quantitative and qualitative analysis could result in an impairment charge being recorded for that period. In the event that the Company concludes that all or a portion of its goodwill is impaired, a non-cash charge for the amount of such impairment would be recorded to earnings. However, such a charge would not have an impact on the Company’s liquidity, operations or regulatory capital. No triggering event occurred during the fourth quarter of 2020 that required an updated goodwill impairment analysis at December 31, 2020. The estimated aggregate future amortization expense for core deposit intangibles remaining as of December 31, 2020 is as follows (dollars in thousands): 2021 $ 3,296 2022 3,003 2023 2,323 2024 2,188 2025 2,061 Thereafter 5,083 Total $ 17,954

CASH AND DUE FROM BANKS

CASH AND DUE FROM BANKS	12 Months Ended
	Dec. 31, 2020
Cash And Cash Equivalents [Abstract]
CASH AND DUE FROM BANKS	4. CASH AND DUE FROM BANKS The Bank can be required by the Federal Reserve Bank of Dallas to maintain average reserve balances. The Bank was not required to maintain reserve balances at December 31, 2020 and 2019.

SECURITIES

SECURITIES	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
SECURITIES	5. The amortized cost and fair value of investment securities were as follows: December 31, 2020 Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value (Dollars in thousands) Available for Sale U.S. government and agency securities $ 25,545 $ 654 $ — $ 26,199 Municipal securities 392,586 35,079 (60 ) 427,605 Agency mortgage-backed pass-through securities 167,606 3,829 (146 ) 171,289 Agency collateralized mortgage obligations 80,182 4,263 (75 ) 84,370 Corporate bonds and other 62,124 1,352 (49 ) 63,427 Total $ 728,043 $ 45,177 $ (330 ) $ 772,890 December 31, 2019 Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value (Dollars in thousands) Available for Sale U.S. government and agency securities $ 29,420 $ 298 $ (243 ) $ 29,475 Municipal securities 84,200 3,453 (116 ) 87,537 Agency mortgage-backed pass-through securities 104,669 1,713 (214 ) 106,168 Agency collateralized mortgage obligations 106,351 1,199 (208 ) 107,342 Corporate bonds and other 41,691 346 (14 ) 42,023 Total $ 366,331 $ 7,009 $ (795 ) $ 372,545 As of December 31, 2020, no The amortized cost and fair value of investment securities at December 31, 2020, by contractual maturity, are shown below. Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations at any time with or without call or prepayment penalties. Amortized Fair Cost Value (Dollars in thousands) Due in one year or less $ 110 $ 110 Due after one year through five years 12,849 13,412 Due after five years through ten years 105,239 109,238 Due after ten years 362,057 394,471 Subtotal 480,255 517,231 Agency mortgage-backed pass through and collateralized mortgage obligation securities 247,788 255,659 Total $ 728,043 $ 772,890 Securities with unrealized losses segregated by length of time such securities have been in a continuous loss position are as follows: December 31, 2020 Less than 12 Months More than 12 Months Total Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses (Dollars in thousands) Available for Sale Agency mortgage-backed pass-through securities $ 28,659 $ (146 ) $ — $ — $ 28,659 $ (146 ) Agency collateralized mortgage obligations 11,629 (39 ) 4,203 (36 ) 15,832 (75 ) Municipal securities 8,844 (60 ) — — 8,844 (60 ) Corporate bonds and other 15,951 (49 ) — — 15,951 (49 ) Total $ 65,083 $ (294 ) $ 4,203 $ (36 ) $ 69,286 $ (330 ) December 31, 2019 Less than 12 Months More than 12 Months Total Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses (Dollars in thousands) Available for Sale U.S. government and agency securities $ 22,295 $ (239 ) $ 436 $ (4 ) $ 22,731 $ (243 ) Agency mortgage-backed pass-through securities 20,792 (155 ) 4,369 (59 ) 25,161 (214 ) Agency collateralized mortgage obligations 22,340 (208 ) — — 22,340 (208 ) Municipal securities 9,514 (116 ) — — 9,514 (116 ) Corporate bonds and other 5,492 (14 ) — — 5,492 (14 ) Total $ 80,433 $ (732 ) $ 4,805 $ (63 ) $ 85,238 $ (795 ) During 2020, the Company sold $30.8 million and had calls of $7.3 million of securities recording gross gains of $391 thousand and gross losses of $104 thousand for a net gain of $287 thousand for the year ended December 31, 2020. The Company sold $173.0 million of securities recording gross gains of $2.1 million and gross losses of $596 thousand for a net gain of $1.5 million for the year ended December 31, 2019. At December 31, 2020 and 2019, the Company did not own securities of any one issuer, other than the U.S. government and its agencies, in an amount greater than 10% of the consolidated shareholders’ equity at such respective dates. The carrying value of pledged securities was $18.5 million and $24.3 million at December 31, 2020 and 2019, respectively. The majority of the securities were pledged to collateralize public fund deposits.

LOANS AND ALLOWANCE FOR CREDIT

LOANS AND ALLOWANCE FOR CREDIT LOSSES	12 Months Ended
	Dec. 31, 2020
Loans And Allowance For Credit Losses [Abstract]
LOANS AND ALLOWANCE FOR CREDIT LOSSES	6. LOANS AND ALLOWANCE FOR CREDIT LOSSES The loan portfolio balances, net of unearned income and fees, consist of various types of loans primarily all made to borrowers located within Texas and are classified by major type as follows: December 31, 2020 December 31, 2019 (Dollars in thousands) Commercial and industrial $ 667,079 $ 689,360 Mortgage warehouse — 8,304 Paycheck Protection Program (PPP) 569,901 — Real estate: Commercial real estate (including multi-family residential) 1,999,877 1,873,782 Commercial real estate construction and land development 367,213 410,471 1-4 family residential (including home equity) 737,605 698,957 Residential construction 127,522 192,515 Consumer and other 22,567 41,921 Total loans 4,491,764 3,915,310 Allowance for credit losses on loans (53,173 ) (29,438 ) Loans, net $ 4,438,591 $ 3,885,872 Loan Origination/Risk Management The Company has certain lending policies and procedures in place that are designed to maximize loan income within an acceptable level of risk. The Company maintains an independent loan review department that reviews and validates the credit risk program on a periodic basis. In addition, an independent third party loan review is performed on a semi-annual basis. In connection with the reviews of the loan portfolio, the Company considers risk elements attributable to particular loan types or categories in assessing the quality of individual loans. Some of the risk elements include: (i) Commercial and Industrial Loans. (ii) Commercial Real Estate. The Company’s nonowner-occupied and multi-family commercial real estate lending typically involves higher loan principal amounts and the repayment of these loans is generally dependent on sufficient income from the properties securing the loans to cover operating expenses and debt service. The Company generally requires the borrower to have had an existing relationship with the Company and have a proven record of success. In addition, these loans are generally guaranteed by individual owners of the borrower and have typically lower loan to value ratios. Loans secured by owner-occupied properties represented 54.6% of the outstanding principal balance of the Company’s commercial real estate loans at December 31, 2020. The Company is dependent on the cash flows of the business occupying the property and its owners and requires these loans generally to be secured by property with adequate margins and guaranteed by the individual owners. The Company’s owner-occupied commercial real estate loans collateralized by first liens on real estate typically have fixed interest rates and amortize over a 10 to 20 year period. Commercial real estate loans are viewed primarily as cash flow loans and secondarily as loans secured by real estate. Credit risk in these loans may be impacted by the creditworthiness of a borrower, property values and the local economies in the Company’s region. (iii) Construction and Land Development Loans. have floating interest rates. Construction and land development real estate loans are usually based upon estimates of costs and estimated value of the completed project and include independent appraisal reviews and a financial analysis of the developers and property owners. The Company generally conducts periodic inspections, either directly or through an agent, prior to approval of periodic draws on these loans. Underwriting guidelines similar to those described above are also used in the Company’s construction lending activities. The Company may be required to fund additional amounts to complete a project and may have to hold the property for an indeterminate period of time. Sources of repayment of these loans may include permanent loans, sales of developed property or an interim loan commitment from the Company until permanent financing is obtained. These loans are considered to be higher risk than other real estate loans due to their ultimate repayment being sensitive to interest rate changes, general economic conditions and the availability of long-term financing. Credit risk in these loans may be impacted by the creditworthiness of a borrower, property values and the local economies in the Company’s region . (iv) Residential Real Estate Loans. (v) Consumer and Other Loans. In addition, for each category, the Company considers secondary sources of income and the financial strength and credit history of the borrower and any guarantors. Acquired Loans The carrying amount of PCI loans included in the consolidated balance sheet and the related outstanding balance owed at December 31, 2019 are presented in the table below (dollars in thousands): As of December 31, 2019 Outstanding balance $ 16,589 Less: Discount (2,414 ) Less: Allowance (259 ) Recorded investment $ 13,916 Changes in the accretable yield for PCI loans for the year ended December 31, 2019 were deemed immaterial. Non-PCI Loans The recorded investment of Non-PCI loans included in the consolidated balance sheet and the related outstanding balance owed are presented in the table below (dollars in thousands). As of December 31, 2019 Outstanding balance $ 672,927 Less: Discount (3,069 ) Recorded investment $ 669,858 Changes in the discount accretion for Non-PCI loans were as follows (dollars in thousands): As of December 31, 2019 Balance at beginning of period $ 10,650 Additions 573 Accretion (8,154 ) Balance at end of period $ 3,069 Concentrations of Credit The vast majority of the Company’s lending activity occurs in and around the Houston, Texas area. The Company’s loans are primarily loans secured by real estate, including commercial and residential construction, owner-occupied and nonowner-occupied and multi-family commercial real estate, raw land and other real estate based loans. Related Party Loans As of December 31, 2020 and 2019, loans outstanding to directors, officers and their affiliates totaled $1.2 million and $6.8 million, respectively. An analysis of activity with respect to these related-party loans is as follows: 2020 (Dollars in thousands) Beginning balance on January 1 $ 6,782 New loans and reclassified related loans 90 Repayments and reclassified related loans (5,689 ) Ending balance on December 31 $ 1,183 Nonaccrual and Past Due Loans An aging analysis of the recorded investment in past due loans, segregated by class of loans, is included below. For purposes of this and future disclosures recorded investment has been defined as the outstanding loan balances including net deferred loan fees, and excluding accrued interest receivable of $34.5 million and $15.5 million as of December 31, 2020 and 2019, respectively, due to immateriality. December 31, 2020 Loans Past Due and Still Accruing 30-89 90 or More Total Past Nonaccrual Current Total Days Days Due Loans Loans Loans Loans (Dollars in thousands) Commercial and industrial $ 2,486 $ — $ 2,486 $ 10,747 $ 653,846 $ 667,079 Mortgage warehouse — — — — — — Paycheck Protection Program (PPP) — — — — 569,901 569,901 Real estate: Commercial real estate (including multi-family residential) 3,063 — 3,063 10,081 1,986,733 1,999,877 Commercial real estate construction and land development 2,930 — 2,930 3,011 361,272 367,213 1-4 family residential (including home equity) 3,000 — 3,000 4,525 730,080 737,605 Residential construction — — — — 127,522 127,522 Consumer and other 46 — 46 529 21,992 22,567 Total loans $ 11,525 $ — $ 11,525 $ 28,893 $ 4,451,346 $ 4,491,764 December 31, 2019 Loans Past Due and Still Accruing 30-89 90 or More Total Past Nonaccrual Current Total Days Days Due Loans Loans Loans Loans (Dollars in thousands) Commercial and industrial $ 3,098 $ — $ 3,098 $ 8,388 $ 677,874 $ 689,360 Mortgage warehouse — — — — 8,304 8,304 Real estate: Commercial real estate (including multi-family residential) 4,421 — 4,421 6,741 1,862,620 1,873,782 Commercial real estate construction and land development 66 — 66 9,050 401,355 410,471 1-4 family residential (including home equity) 1,598 — 1,598 3,294 694,065 698,957 Residential construction 564 — 564 746 191,205 192,515 Consumer and other 254 — 254 152 41,515 41,921 Total loans $ 10,001 $ — $ 10,001 $ 28,371 $ 3,876,938 $ 3,915,310 If interest on nonaccrual loans had been accrued under the original loan terms, approximately $902.5 thousand and $1.2 million would have been recorded as income for the years ended December 31, 2020 and 2019, respectively. Credit Quality Indicators The Company categorizes loans into risk categories based on relevant information about the ability of borrowers to service their debt. The Company utilizes a risk rating matrix to assign a risk rating to each of its loans. Loans are rated on a scale of 1 to 9. Risk ratings are updated on an ongoing basis and are subject to change by continuous loan monitoring processes including lending management monitoring, executive management and board committee oversight, and independent credit review. including trends related to (i) the weighted-average risk The following is a general description of the risk ratings used: Watch —Loans classified as watch loans may still be of high quality, but have an element of risk added to the credit such as declining payment history, deteriorating financial position of the borrower or a decrease in collateral value. Special Mention —Loans classified as special mention have a potential weakness that deserves management’s close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the loan or of the institution’s credit position at some future date. They are characterized by the distinct possibility that the institution will sustain some loss if the deficiencies are not corrected. Substandard —Loans classified as substandard have well-defined weaknesses on a continuing basis and are inadequately protected by the current net worth and paying capacity of the borrower, declining collateral values, or a continuing downturn in their industry which is reducing their profits to below zero and having a significantly negative impact on their cash flow. These loans so classified are characterized by the distinct possibility that the institution will sustain some loss if the deficiencies are not corrected. Doubtful —Loans classified as doubtful have all the weaknesses inherent in those classified as substandard with the added characteristic that the weaknesses make collection or liquidation in full on the basis of currently existing facts, conditions and values, highly questionable and improbable. Loss — Loans classified as loss are to be charged-off or charged-down when payment is acknowledged to be uncertain or when the timing or value of payments cannot be determined. “Loss” is not intended to imply that the loan or some portion of it will never be paid, nor does it in any way imply that there has been a forgiveness of debt. The following table presents risk ratings by category of loan as of December 31, 2020 and 2019: As of December 31, 2020 As of December 31, 2019 Term Loans Amortized Cost Basis by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Loans Total Total (Dollars in thousands) Commercial and industrial Pass $ 149,522 $ 81,526 $ 46,909 $ 17,610 $ 20,955 $ 6,951 $ 239,045 $ — $ 562,518 $ 637,388 Watch 12,755 6,956 6,600 2,436 1,446 1,067 9,766 — 41,026 14,797 Special Mention 758 2,746 3,740 1,860 2,756 — 13,150 — 25,010 10,871 Substandard 12,650 4,272 3,798 7,043 2,577 99 7,946 — 38,385 26,226 Doubtful 69 71 — — — — — — 140 78 Total commercial and industrial loans $ 175,754 $ 95,571 $ 61,047 $ 28,949 $ 27,734 $ 8,117 $ 269,907 $ — $ 667,079 $ 689,360 Mortgage warehouse Pass $ — $ — $ — $ — $ — $ — $ — $ — $ — $ 8,304 Watch — — — — — — — — — — Special Mention — — — — — — — — — — Substandard — — — — — — — — — — Doubtful — — — — — — — — — — Total mortgage warehouse loans $ — $ — $ — $ — $ — $ — $ — $ — $ — $ 8,304 Paycheck Protection Program (PPP) Pass $ 569,901 $ — $ — $ — $ — $ — $ — $ — $ 569,901 $ — Watch — — — — — — — — — — Special Mention — — — — — — — — — — Substandard — — — — — — — — — — Doubtful — — — — — — — — — — Total PPP loans $ 569,901 $ — $ — $ — $ — $ — $ — $ — $ 569,901 $ — Commercial real estate (including multi-family residential) Pass $ 587,089 $ 321,020 $ 220,554 $ 221,147 $ 156,671 $ 75,353 $ 47,189 $ — $ 1,629,023 $ 1,760,476 Watch 27,851 45,009 23,492 32,567 24,051 23,531 1,150 — 177,651 56,367 Special Mention 10,931 16,452 9,940 12,128 3,243 14,482 1,100 — 68,276 11,974 Substandard 17,391 27,265 18,926 20,688 27,595 10,896 2,166 — 124,927 44,965 Doubtful — — — — — — — — — — Total commercial real estate (including multi-family residential) loans $ 643,262 $ 409,746 $ 272,912 $ 286,530 $ 211,560 $ 124,262 $ 51,605 $ — $ 1,999,877 $ 1,873,782 Commercial real estate construction and land development Pass $ 172,389 $ 77,535 $ 31,392 $ 16,712 $ 5,098 $ 2,036 $ 14,971 $ — $ 320,133 $ 385,832 Watch 12,801 2,943 4,315 13,157 5,290 515 — — 39,021 9,583 Special Mention 615 1,620 378 — — 267 — — 2,880 639 Substandard 2,958 986 693 — — — 542 — 5,179 14,417 Doubtful — — — — — — — — — — Total commercial real estate construction and land development $ 188,763 $ 83,084 $ 36,778 $ 29,869 $ 10,388 $ 2,818 $ 15,513 $ — $ 367,213 $ 410,471 The following table presents risk ratings by category of loan as of December 31, 2020 and 2019: As of December 31, 2020 As of December 31, 2019 Term Loans Amortized Cost Basis by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Loans Total Total (Dollars in thousands) 1-4 family residential (including home equity) Pass $ 212,543 $ 128,835 $ 101,091 $ 67,257 $ 44,666 $ 27,846 $ 87,836 $ — $ 670,074 $ 669,288 Watch 14,153 3,565 4,406 5,994 2,099 3,138 4,312 — 37,667 15,798 Special Mention 6,237 728 4,312 674 2,379 2,006 2,454 — 18,790 5,844 Substandard 1,392 2,308 2,576 1,238 1,869 1,422 269 — 11,074 8,027 Doubtful — — — — — — — — — — Total 1-4 family residential (including home equity) $ 234,325 $ 135,436 $ 112,385 $ 75,163 $ 51,013 $ 34,412 $ 94,871 $ — $ 737,605 $ 698,957 Residential construction Pass $ 106,804 $ 10,330 $ 5,288 $ 742 $ 1,573 $ — $ — $ — $ 124,737 $ 188,636 Watch 2,036 749 — — — — — — 2,785 2,560 Special Mention — — — — — — — — — — Substandard — — — — — — — — — 1,319 Doubtful — — — — — — — — — — Total residential construction $ 108,840 $ 11,079 $ 5,288 $ 742 $ 1,573 $ — $ — $ — $ 127,522 $ 192,515 Consumer and other Pass (1) $ (6,193 ) $ 20,578 $ 1,537 $ 586 $ 25 $ 122 $ 4,704 $ — $ 21,359 $ 41,355 Watch 57 242 27 — — — 63 — 389 6 Special Mention 231 — 39 — — — — — 270 358 Substandard 491 33 25 — — — — — 549 202 Doubtful — — — — — — — — — — Total consumer and other $ (5,414 ) $ 20,853 $ 1,628 $ 586 $ 25 $ 122 $ 4,767 $ — $ 22,567 $ 41,921 Total loans Pass $ 1,792,055 $ 639,824 $ 406,771 $ 324,054 $ 228,988 $ 112,308 $ 393,745 $ — $ 3,897,745 $ 3,691,279 Watch 69,653 59,464 38,840 54,154 32,886 28,251 15,291 — 298,539 99,111 Special Mention 18,772 21,546 18,409 14,662 8,378 16,755 16,704 — 115,226 29,686 Substandard 34,882 34,864 26,018 28,969 32,041 12,417 10,923 — 180,114 95,156 Doubtful 69 71 — — — — — — 140 78 Total loans $ 1,915,431 $ 755,769 $ 490,038 $ 421,839 $ 302,293 $ 169,731 $ 436,663 $ — $ 4,491,764 $ 3,915,310 (1) Includes net deferred fees of $13.9 million on PPP loans. The following table presents the activity in the allowance for credit losses on loans by portfolio type for the years ended December 31, 2020, 2019 and 2018: Commercial and Mortgage warehouse Paycheck Protection Program (PPP) Commercial real estate (including multi-family residential) Commercial real estate construction and land development 1-4 family residential (including home equity) Residential construction Consumer and other Total (Dollars in thousands) Allowance for credit losses on loans: Balance December 31, 2019 $ 8,818 $ — $ — $ 11,170 $ 4,421 $ 3,852 $ 1,057 $ 120 $ 29,438 Impact of ASC 326 adoption 7,022 — — (5,163 ) 1,630 1,600 (1 ) 137 5,225 Provision for loan losses 4,363 — — 20,417 3,461 (1,822 ) (186 ) 310 26,543 Charge-offs (2,938 ) — — (2,562 ) (2,573 ) (351 ) — (159 ) (8,583 ) Recoveries 473 — — 72 — — — 5 550 Net charge-offs (2,465 ) — — (2,490 ) (2,573 ) (351 ) — (154 ) (8,033 ) Balance December 31, 2020 $ 17,738 $ — $ — $ 23,934 $ 6,939 $ 3,279 $ 870 $ 413 $ 53,173 Allowance for loan losses: Balance December 31, 2018 $ 8,351 $ — $ — $ 11,901 $ 2,724 $ 2,242 $ 1,040 $ 73 $ 26,331 Provision for loan losses 2,881 — — (654 ) 1,741 1,905 17 49 5,939 Charge-offs (2,688 ) — — (80 ) (44 ) (295 ) — (34 ) (3,141 ) Recoveries 274 — — 3 — — — 32 309 Net charge-offs (2,414 ) — — (77 ) (44 ) (295 ) — (2 ) (2,832 ) Balance December 31, 2019 $ 8,818 $ — $ — $ 11,170 $ 4,421 $ 3,852 $ 1,057 $ 120 $ 29,438 Allowance for loan losses: Balance December 31, 2017 $ 7,694 $ — $ — $ 10,253 $ 2,525 $ 2,140 $ 942 $ 95 $ 23,649 Provision for loan losses 2,234 — — 1,588 199 127 98 2 4,248 Charge-offs (2,424 ) — — (42 ) — (25 ) — (24 ) (2,515 ) Recoveries 847 — — 102 — — — — 949 Net charge-offs (1,577 ) — — 60 — (25 ) — (24 ) (1,566 ) Balance December 31, 2018 $ 8,351 $ — $ — $ 11,901 $ 2,724 $ 2,242 $ 1,040 $ 73 $ 26,331 Allowance for Credit Losses on Unfunded Commitments . In addition to the allowance for credit losses on loans, the Company has established an allowance for credit losses on unfunded commitments, classified in other liabilities and adjusted as a provision for credit loss expense. The allowance represents estimates of expected credit losses over the contractual period in which there is exposure to credit risk via a contractual obligation to extend credit, unless that obligation is unconditionally cancellable by the Company. The estimate includes consideration of the likelihood that funding will occur and an estimate of expected credit losses on the commitments expected to fund. The estimate of commitments expected to fund is informed by historical analysis looking at utilization rates. The expected credit loss rates applied to the commitments expected to fund is informed by the general valuation allowance utilized for outstanding balances with the same underlying assumptions and drivers. The allowance for credit losses on unfunded commitments as of December 31, 2020 was $4.7 million. There was no allowance recorded on unfunded commitments at December 31, 2019. The establishment of an allowance in 2020 was due to the adoption of CECL. This reserve is maintained at a level management believes to be sufficient to absorb losses arising from unfunded loan commitments. The following table details activity in the allowance for credit losses on unfunded commitments: As of December 31, 2020 (Dollars in thousands) Balance at beginning of period on January 1 $ 3,866 Provision for credit losses on off-balance sheet exposures 831 Balance at end of period on December 31 $ 4,697 Collateral dependent loans we re secured by commercial real estate assets, accounts receivable, inventory and equipment. For a collateral dependent loan, the Company’s evaluation process includes a valuation by appraisal or other collateral analysis adjusted for selling costs, when appropriate. This valuation is compared to the remaining outstanding principal balance of the loan. If a loss is determined to be probable, the loss is incl uded in the allowance for credit losses on loan s as a specific allocation. A t December 31, 2020, collateral dependent loans consisted primarily of com mercial loans. The following table presents the amortized cost basis of collateral dependent loans, which are individually evaluated to determine expected credit losses: As of December 31, 2020 Real Estate Business Assets Other Total (Dollars in thousands) Commercial and industrial $ — $ 5,157 $ — $ 5,157 Mortgage warehouse — — — — Paycheck Protection Program (PPP) — — — — Real estate: Commercial real estate (including multi-family residential) 425 — — 425 Commercial real estate construction and land development — — — — 1-4 family residential (including home equity) 3,101 — — 3,101 Residential construction — — — — Consumer and other — — — — Total $ 3,526 $ 5,157 $ — $ 8,683 The following table presents additional information regarding nonaccrual loans. No interest income was recognized on nonaccrual loans for the years ended December 31, 2020 and 2019, respectively. As of December 31, 2020 Nonaccrual Loans with No Related Allowance Nonaccrual Loans with Related Allowance Total Nonaccrual Loans (Dollars in thousands) Commercial and industrial $ 2,097 $ 8,650 $ 10,747 Mortgage warehouse — — — Paycheck Protection Program (PPP) — — — Real estate: Commercial real estate (including multi-family residential) 7,487 2,594 10,081 Commercial real estate construction and land development 2,958 53 3,011 1-4 family residential (including home equity) 2,652 1,873 4,525 Residential construction — — — Consumer and other — 529 529 Total loans $ 15,194 $ 13,699 $ 28,893 Impaired Loans. Prior to the adoption of ASC Topic 326 on January 1, 2020, loans were reported as impaired when, based on then current information and events, it was probable the Company would be unable to collect all amounts due in accordance with the original contractual terms of the loan agreement, including scheduled principal and interest payments. If a loan was impaired, a specific valuation allowance was allocated, if necessary, so that the loan was reported net, at the fair value of collateral if repayment was expected solely from the collateral. The following table presents impaired loans at December 31, 2019 as determined under ASC 310 prior to the adoption of ASC Topic 326 by class of loans. As of December 31, 2019 Unpaid Recorded Principal Related Investment Balance Allowance (Dollars in thousands) With no related allowance recorded: Commercial and industrial $ 5,721 $ 6,136 $ — Mortgage warehouse — — — Real estate: Commercial real estate (including multi-family residential) 19,478 19,558 — Commercial real estate construction and land development — — — 1-4 family residential (including home equity) 2,000 2,000 — Residential construction 208 208 — Consumer and other 38 38 — Total 27,445 27,940 — With an allowance recorded: Commercial and industrial 7,812 7,286 3,480 Mortgage warehouse — — — Real estate: Commercial real estate (including multi-family residential) 5,335 5,335 459 Commercial real estate construction and land development 12,142 12,142 2,085 1-4 family residential (including home equity) — — — Residential construction 537 537 66 Consumer and other 26 26 26 PCI 2,039 2,959 659 Total 27,891 28,285 6,775 Total: Commercial and industrial 13,533 13,422 3,480 Mortgage warehouse — — — Real estate: Commercial real estate (including multi-family residential) 24,813 24,893 459 Commercial real estate construction and land development 12,142 12,142 2,085 1-4 family residential (including home equity) 2,000 2,000 — Residential construction 745 745 66 Consumer and other 64 64 26 PCI 2,039 2,959 659 $ 55,336 $ 56,225 $ 6,775 The following table presents average impaired loans and interest recognized on impaired loans for the year ended December 31, 2019: For the Year Ended December 31, 2019 Average Interest Recorded Income Investment Recognized (Dollars in thousands) Commercial and industrial $ 13,376 $ 399 Mortgage warehouse — — Paycheck Protection Program (PPP) — — Real estate: Commercial real estate (including multi-family residential) 25,856 489 Commercial real estate construction and land development 10,251 185 1-4 family residential (including home equity) 2,058 6 Residential construction 594 — Consumer and other 75 1 PCI 3,133 8 Total $ 55,343 $ 1,088 Troubled Debt Restructurings As of December 31, 2020 and 2019, the Company had a recorded investment in troubled debt restructurings of $25.8 million and $28.9 million, respectively. The Company allocated $3.3 million and $3.2 million of specific reserves for these loans at December 31, 2020 and 2019, respectively, and did not commit to lend additional amounts on these loans. The following table presents information regarding loans modified in a troubled debt restructuring during the years ended December 31, 2020, 2019 and 2018: As of December 31, 2020 2019 2018 Number of Contracts Pre-Modification of Outstanding Recorded Investment Post Modification of Outstanding Recorded Investment Number of Contracts Pre-Modification of Outstanding Recorded Investment Post Modification of Outstanding Recorded Investment Number of Contracts Pre-Modification of Outstanding Recorded Investment Post Modification of Outstanding Recorded Investment (Dollars in thousands) Troubled Debt Restructurings Commercial and industrial 20 $ 4,333 $ 4,333 13 $ 4,358 $ 4,358 11 $ 2,770 $ 2,770 Mortgage warehouse — — — — — — — — — Real estate: Commercial real estate (including multi-family residential) 5 4,560 4,560 1 303 303 3 4,288 4,288 Commercial real estate construction and land development 1 830 830 — — — 1 3,114 3,114 1-4 family residential (including home equity) 5 2,051 2,051 1 396 396 — — — Residential construction — — — — — — — — — Consumer and other 1 30 30 2 43 43 — — — Total 32 $ 11,804 $ 11,804 17 $ 5,100 $ 5,100 15 $ 10,172 $ 10,172 Troubled debt restructurings resulted in charge-offs of $3.2 million, $251 thousand and $272 thousand during the years ended December 31, 2020, 2019 and 2018, respectively. As of December 31, 2020, there were four loans for a total of $2.6 million were modified under a troubled debt restructuring during the previous twelve-month period that subsequently defaulted during the year 2020. As of December 31, 2019, there were five loans for a total of $472 thousand were modified under a troubled debt restructuring during the previous twelve-month period that subsequently defaulted during the year 2019. Default is determined at 90 or more days past due. The modifications primarily related to extending the amortization periods of the loans. The Company did not grant principal reductions on any restructured loans. There were no commitments to lend additional amounts for the years 2020 and 2019. During the year ended December 31, 2020, the Company added $11.8 million in new troubled debt restructurings, of which $8.1 million was still outstanding on December 31, 2020. During the year ended December 31, 2019, the Company added $ 5.1 million in new troubled debt restructurings, of which $ 4.6 million was still outstanding on December 31, 2019. During the year ended December 31, 2020, the Company granted principal and interest deferrals on outstanding loan balances to customers affected by the COVID-19 pandemic. Additionally, upon request and after meeting certain conditions, borrowers could be granted additional payment deferrals subsequent to the first deferral. In addition to the short-term modification program implemented by the Company, Section 4013 of the CARES Act and bank regulatory interagency guidance gave entities temporary relief from the accounting and disclosure requirements for TDRs indicating that a lender could conclude that the modifications are not a TDR if the borrower was less than 30 days past due as of December 31, 2019. The following table presents information regarding principal and interest deferrals as of December 31, 2020 associated with loan modifications related to COVID-19: Initial Deferrals Additional Deferrals Remaining Deferrals Outstanding Loan Balance Deferred Loan Balance Percentage of Total Deferrals Deferred Loan Balance Percentage of Total Deferrals Deferred Loan Balance Percentage of Total Deferrals (Dollars in thousands) Commercial and industrial $ 667,079 $ 127,689 11.3 % $ 21,747 9.5 % $ 23,822 14.8 % Mortgage warehouse — — 0.0 % — 0.0 % — 0.0 % Paycheck Protection Program (PPP) 569,901 — 0.0 % — 0.0 % — 0.0 % Real estate: Commercial real estate (including multi-family residential) 1,999,877 790,468 69.9 % 171,945 75.5 % 129,067 80.0 % Commercial real estate construction and land development 367,213 88,446 7.8 % 20,032 8.8 % 5,860 3.6 % 1-4 family residential (including home equity) 737,605 118,595 10.5 % 12,922 5.7 % 2,489 1.6 % Residential construction 127,522 4,452 0.4 % 926 0.4 % — 0.0 % Consumer and other 22,567 1,015 0.1 % 172 0.1 % 59 0.0 % Total loans $ 4,491,764 $ 1,130,665 100.0 % $ 227,744 100.0 % $ 161,297 100.0 %

FAIR VALUE

FAIR VALUE	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE	7. FAIR VALUE The Company uses fair value measurements to record fair value adjustments to certain assets and to determine fair value disclosures. Fair value represents the estimated exchange price that would be received from selling an asset or paid to transfer a liability, otherwise known as an “exit price” in the principal or most advantageous market available to the entity in an orderly transaction between market participants on the measurement date. Fair Value Hierarchy Fair value is the exchange price that would be received for an asset or paid to transfer a liability (exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The Company groups financial assets and financial liabilities measured at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are: • Level 1—Quoted prices for identical assets or liabilities in active markets that the entity has the ability to access as of the measurement date. • Level 2—Significant other observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data. • Level 3—Significant unobservable inputs that reflect management’s judgment and assumptions that market participants would use in pricing an asset or liability that are supported by little or no market activity. The carrying amounts and estimated fair values of financial instruments that are reported on the balance sheet are as follows: As of December 31, 2020 Carrying Estimated Fair Value Amount Level 1 Level 2 Level 3 Total (Dollars in thousands) Financial assets Cash and cash equivalents $ 422,766 $ 422,766 $ — $ — $ 422,766 Available for sale securities 772,890 — 772,890 — 772,890 Loans held for investment, net of allowance 4,438,591 — — 4,431,816 4,431,816 Accrued interest receivable 40,053 2 5,531 34,520 40,053 Financial liabilities Deposits $ 4,988,482 $ — $ 5,003,594 $ — $ 5,003,594 Interest rate swap 1,252 — 1,252 — 1,252 Accrued interest payable 2,701 — 2,701 — 2,701 Borrowed funds 155,515 — 144,629 — 144,629 Subordinated debt 108,322 — 109,832 — 109,832 As of December 31, 2019 Carrying Estimated Fair Value Amount Level 1 Level 2 Level 3 Total (Dollars in thousands) Financial assets Cash and cash equivalents $ 346,248 $ 346,248 $ — $ — $ 346,248 Available for sale securities 372,545 — 372,545 — 372,545 Loans held for investment, net of allowance 3,885,872 — — 3,918,210 3,918,210 Accrued interest receivable 15,468 13 1,783 13,672 15,468 Financial liabilities Deposits $ 4,068,101 $ — $ 4,073,031 $ — $ 4,073,031 Accrued interest payable 4,326 — 4,326 — 4,326 Borrowed funds 75,503 — 83,302 — 83,302 Subordinated debt 107,799 — 109,607 — 109,607 The fair value estimates presented herein are based on pertinent information available to management as of the dates indicated. The following is a description of valuation methodologies used for assets and liabilities recorded at fair value, non-financial assets and non-financial liabilities and for estimating fair value for financial instruments not recorded at fair value: Cash and Cash Equivalents —For these short-term instruments, the carrying amount is a reasonable estimate of fair value. The Company classifies the estimated fair value of these instruments as Level 1. Available for Sale Securities —Fair values for investment securities are based upon quoted market prices, if available, and are considered Level 1 inputs. For all other available for sale securities, if quoted prices are not available, fair values are measured based on market prices for similar securities and are considered Level 2 inputs. For these securities, the Company generally obtains fair value measurements from an independent pricing service. The fair value measurements consider observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the bond’s terms and conditions, among other things. Available for sale securities are recorded at fair value on a recurring basis. Loans —The estimated fair value approximates carrying value for variable-rate loans that reprice frequently and that have no significant change in credit risk resulting in a Level 3 classification. Fair values for fixed-rate loans and variable rate loans which reprice infrequently are estimated by discounting future cash flows. In accordance with ASU 2016-01, which was adopted effective January 1, 2018, the discount rates used to determine the fair value of loans used interest rate spreads that reflect factors such as liquidity, credit and nonperformance risk of the loans. Deposits —The fair value of demand deposits (e.g., interest and noninterest checking, savings and certain types of money market deposits) is the amount payable on demand at the reporting date (i.e., their carrying amount) resulting in a Level 2 classification. The fair value of fixed rate certificates of deposit is estimated using a discounted cash flows calculation that applies interest rates currently offered on certificates of deposit to a schedule of aggregated expected monthly maturities on time deposits resulting in a Level 2 classification. Accrued Interest —The carrying amounts of accrued interest approximate their fair values resulting in a Level 1, 2 or 3 classification. Borrowed Funds —The fair value of the Company’s borrowed funds are estimated using discounted cash flow analyses based on the current borrowing rates for similar types of borrowing arrangements and are measured utilizing Level 2 inputs. Subordinated Debt —The fair values of subordinated debentures and notes are estimated using discounted cash flow analyses based on the Company’s current borrowing rates for similar types of borrowing arrangements and are measured utilizing Level 2 inputs. Off-balance sheet instruments —The fair values of off-balance sheet commitments to extend credit and standby letters of credit financial instruments are based on fees currently charged to enter into similar agreements, taking into account the remaining terms of the agreements and the counterparties’ credit standing. The Company has reviewed the unfunded portion of commitments to extend credit as well as standby and other letters of credit and has determined that the fair value of such financial instruments is not material. The following tables present fair values for assets measured at fair value on a recurring basis: December 31, 2020 Level 1 Level 2 Level 3 Total (Dollars in thousands) Financial assets Available for sale securities: U.S. government and agency securities $ — $ 26,199 $ — $ 26,199 Municipal securities — 427,605 — 427,605 Agency mortgage-backed pass-through securities — 171,289 — 171,289 Agency collateralized mortgage obligations — 84,370 — 84,370 Corporate bonds and other — 63,427 — 63,427 Total available for sale securities $ — $ 772,890 $ — $ 772,890 Financial liabilities Interest rate swap $ — $ 1,252 $ — $ 1,252 December 31, 2019 Level 1 Level 2 Level 3 Total (Dollars in thousands) Financial assets Available for sale securities: U.S. government and agency securities $ — $ 29,475 $ — $ 29,475 Municipal securities — 87,537 — 87,537 Agency mortgage-backed pass-through securities — 106,168 — 106,168 Agency collateralized mortgage obligations — 107,342 — 107,342 Corporate bonds and other — 42,023 — 42,023 Total available for sale securities $ — $ 372,545 $ — $ 372,545 There were no liabilities measured at fair value on a recurring basis as of December 31, 2019. There were no transfers between levels during 2020 or 2019. Assets measured at fair value on a nonrecurring basis are summarized in the table below. There were no liabilities measured at fair value on a nonrecurring basis at December 31, 2020 and 2019. As of December 31, 2020 Level 1 Level 2 Level 3 (Dollars in thousands) Collateral Dependent Loans: Commercial and industrial $ — $ — $ 8,650 Commercial real estate (including multi- family residential) — — 2,594 Commercial real estate construction and land development — — 53 1-4 family residential (including home equity) — — 1,873 Residential construction — — — Consumer and other — — 529 Other real estate owned — — 9,196 $ — $ — $ 22,895 As of December 31, 2019 Level 1 Level 2 Level 3 (Dollars in thousands) Impaired loans: Commercial and industrial $ — $ — $ 4,332 Commercial real estate (including multi- family residential) — — 4,876 Commercial real estate construction and land development — — 10,057 Residential construction — — 471 PCI — — 1,380 Other real estate owned — — 8,337 $ — $ — $ 29,453 Historically, the Company measures fair value for certain loans and other real estate owned on a nonrecurring basis as described below. Collateral Dependent Loans Specific Allocation of Allowance for Credit Losses on Loans A loan is considered to be a collateral dependent loan when, based on current information and events, the Company expects repayment of the financial assets to be provided substantially through the operation or sale of the collateral and the Company has determined that the borrower is experiencing financial difficulty as of the measurement date. The allowance for credit losses on loans is measured by estimating the fair value of the loan based on the present value of expected cash flows, the market price of the loan, or the underlying fair value of the loan’s collateral. For real estate loans, fair value of the loan’s collateral is generally determined by third-party appraisals or internal evaluations, which are then adjusted for the estimated selling and closing costs related to liquidation of the collateral. For this asset class, the actual valuation methods (income, sales comparable, or cost) vary based on the status of the project or property. For example, land is generally based on the sales comparable method while construction is based on the income and/or sales comparable methods. The unobservable inputs may vary depending on the individual assets with no one of the three methods being the predominant approach. The Company reviews the third-party appraisal for appropriateness and adjusts the value downward to consider selling and closing costs, which typically range from 5% to 10% of the appraised value. For non-real estate loans, fair value of the loan’s collateral may be determined using an appraisal, net book value per the borrower’s financial statements, or aging reports, adjusted or discounted based on management’s historical knowledge, changes in market conditions from the time of the valuation, and management’s expertise and knowledge of the client and client’s business. Other Real Estate Owned Other real estate owned is comprised of real estate acquired in partial or full satisfaction of loans. Other real estate owned is recorded at its estimated fair value less estimated selling and closing costs at the date of transfer. Any excess of the related loan balance over the fair value less expected selling costs is charged to the allowance. Subsequent declines in fair value are reported as adjustments to the carrying amount and are recorded against earnings. The fair value of other real estate owned is determined using appraisals or other indications of value based on recent comparable sales of similar properties or assumptions generally observable in the marketplace. For this asset class, the actual valuation methods (income, sales comparable or cost) vary based on the status of the project or property. For example, land is generally based on the sales comparable method while construction is based on the income and/or sales comparable methods. The unobservable inputs may vary depending on the individual assets with no one of the three methods being the predominant approach. The Company reviews the third party appraisal for appropriateness and adjusts the value downward to consider selling and closing costs, which typically range from 5 % to 10 % of the appraised value. At December 31, 2020, the balance of other real estate owned was $9.2 million consisting primarily of foreclosed commercial real estate properties recorded as a result of obtaining physical possession of the property. The Company had $8.3 million of other real estate owned at December 31, 2019. As of December 31, 2020 and 2019, no valuation allowance was recorded.

PREMISES AND EQUIPMENT

PREMISES AND EQUIPMENT	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
PREMISES AND EQUIPMENT	8. PREMISES AND EQUIPMENT Premises and equipment are summarized as follows: As of December 31, 2020 2019 (Dollars in thousands) Land $ 13,913 $ 13,913 Buildings 39,998 36,826 Lease right-of-use assets 11,610 11,180 Leasehold improvements 5,689 4,522 Furniture, fixtures and equipment 16,106 13,612 Construction in progress 2 250 Total 87,318 80,303 Less: accumulated depreciation 16,633 13,513 Premises and equipment, net $ 70,685 $ 66,790 Depreciation expense was $3.7 million for the year ended December 31, 2020 and $3.2 million for the year ended December 31, 2019.

LEASES

LEASES	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
LEASES	9. LEASES Lease payments over the expected term are discounted using the Company’s incremental borrowing rate for borrowings of similar terms. Generally, the Company cannot be reasonably certain about whether or not it will renew a lease until such time as the lease is within the last two years of the existing lease term. When the Company is reasonably certain that a renewal option will be exercised, it measures/remeasures the right-of-use asset and related lease liability using the lease payments specified for the renewal period or, if such amounts are unspecified, the Company generally assumes an increase (evaluated on a case-by-case basis in light of prevailing market conditions) in the lease payment over the final period of the existing lease term. There were no sale and leaseback transactions, leveraged leases or lease transactions with related parties during the years ended December 31, 2020 and 2019. At December 31, 2020, the Company had 14 leases consisting of branch locations and office space along with equipment. On the December 31, 2020 balance sheet, the right-of-use asset is classified within premises and equipment and the lease liability is included in other liabilities. The Company also owns certain office facilities which it leases to outside parties under operating lessor leases; however, such leases are not significant. All leases were classified as operating leases. Leases with an initial term of 12 months or less are not recorded on the balance sheet and the related lease expense is recognized on a straight-line basis over the lease term. During the year 2019, Allegiance Bank purchased two previously leased properties for a total of $10.7 million. Certain leases include options to renew, with renewal terms that can extend the lease term from one to five years. Lease assets and liabilities include related options that are reasonably certain of being exercised. The depreciable life of leased assets are limited by the expected lease term. Supplemental lease information at the dates indicated is as follows: December 31, 2020 December 31, 2019 (Dollars in thousands) Balance Sheet: Operating lease right of use asset classified as premises and equipment $ 11,610 $ 11,180 Operating lease liability classified as other liabilities $ 11,850 $ 11,477 Weighted average lease term, in years 5.56 5.53 Weighted average discount rate 2.86 % 3.19 % Lease costs for the dates indicated is as follows: For the Years Ended December 31, 2020 2019 (Dollars in thousands) Income Statement: Operating lease cost $ 3,270 $ 3,073 Short-term lease cost 78 553 Sublease income (66 ) (72 ) Total operating lease costs $ 3,282 $ 3,554 A maturity analysis of the Company’s lease liabilities is as follows: December 31, 2020 December 31, 2019 (Dollars in thousands) Lease payments due: Within one year $ 3,068 $ 2,867 After one but within two years 2,664 2,608 After two but within three years 2,056 2,204 After three but within four years 1,591 1,596 After four but within five years 1,057 1,131 After five years 2,355 2,162 Total lease payments 12,791 12,568 Discount on cash flows 941 1,091 Total lease liability $ 11,850 $ 11,477

DEPOSITS

DEPOSITS	12 Months Ended
	Dec. 31, 2020
Deposit Liabilities [Abstract]
DEPOSITS	10. DEPOSITS Time deposits that meet or exceed the Federal Deposit Insurance Corporation (the “FDIC”) insurance limit of $250 thousand at December 31, 2020 and December 31, 2019 were $726.8 million and $485.8 million, respectively. Scheduled maturities of time deposits for the next five years are as follows (dollars in thousands): Within one year $ 872,599 After one but within two years 313,154 After two but within three years 92,863 After three but within four years 39,782 After four but within five years 28,251 Total $ 1,346,649 The Company had $453.8 million and $263.5 million of brokered deposits as of December 31, 2020 and 2019, respectively. There were no concentrations of deposits with any one depositor at December 31, 2020 or 2019. Related party deposits from principal officers, directors and their affiliates at December 31, 2020 and 2019 were $9.2 million.

DERIVATIVE INSTRUMENTS

DERIVATIVE INSTRUMENTS	12 Months Ended
	Dec. 31, 2020
Derivative Instruments And Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS	11. DERIVATIVE INSTRUMENTS During 2020, the Company entered into a financial derivative. Financial derivatives are reported at fair value in other assets or other liabilities. The accounting for changes in the fair value of a derivative depends on whether it has been designated and qualifies as part of a hedging relationship. Derivatives designated as cash flow hedges For derivative instruments that are designated and qualify as a cash flow hedge, the aggregate fair value of the derivative instrum ent is recorded in other assets or other liabilities with any gain or loss related to changes in fair value recorded in accumulated other comprehensive income, net of tax. The gain or loss is reclassified into earnings in the same period during which the hedged asset or liability affects earnings and is presented in the same income statement line item as the earnings effect of the hedged asset or liability. The Company uses forward cash flow hedges in an effort to manage future interest rate exposure on liabilities. The hedging strategy converts the variable interest rate on liabilities to a fixed interest rate and is used in an effort to protect the Company from floating interest rate variability. A summary of the Company’s cash flow hedge relationship as of December 31, 2020 is as follows: Balance Sheet Location Weighted Average Maturity (In Years) Weighted Average Pay Rate Receive Rate Notional Amount Estimated Fair Value (Dollars in thousands) Liability derivatives Interest rate swaps Other liabilities 4.02 0.64% 3 month LIBOR $ 100,000 $ (1,252 ) The effects of the Company’s cash flow hedge relationship on the statement of comprehensive income during the years ended December Amount of Loss Recognized in Other Comprehensive Loss For the Years Ended December 31, 2020 2019 (Dollars in thousands) Liability derivatives Interest rate swaps $ (989 ) $ — The cash flow hedge was determined to be effective during the periods presented and as a result qualified for hedge accounting treatment. The hedge would no longer be considered effective if a portion of the hedge becomes ineffective, the item hedged is no longer in existence or the Company discontinues hedge accounting. The Company expects the hedge at December December Losses totaling $76 thousand, net of tax, were reclassified from accumulated other comprehensive income into net income during the year ended December 31, 2020.

BORROWINGS AND BORROWING CAPACI

BORROWINGS AND BORROWING CAPACITY	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
BORROWINGS AND BORROWING CAPACITY	12. BORROWINGS AND BORROWING CAPACITY The Company has an available line of credit with the FHLB of Dallas, which allows the Company to borrow on a collateralized basis. FHLB advances are used to manage liquidity as needed. The advances are secured by a blanket lien on certain loans. Maturing advances are replaced by drawing on available cash, making additional borrowings or through increased customer deposits. At December 31, 2020, the Company had total borrowing capacity of $1.99 billion, of which $1.44 billion was available under this agreement and $550.2 million was outstanding. FHLB advances of $140.0 million were outstanding at December 31, 2020, at a weighted average rate of 1.19%. Letters of credit were $410.2 million at December 31, 2020, of which $248.4 million will expire in 2021, $151.7 million will expire in 2022 and $10.1 million will expire in 2023. On December 28, 2018, the Company amended its revolving credit agreement to increase the maximum commitment to advance funds to $45.0 million which will reduce annually by $7.5 million beginning in December 2020 and on each December 22nd for the following years thereafter. The Company is required to repay any outstanding balance in excess of the then-current maximum commitment amount. The revised agreement will mature in December 2025 and is secured by 100% of the capital stock of the Bank. The credit agreement contains certain restrictive covenants. At December 31, 2020, the Company believes it was in compliance with all such debt covenants and had not been made aware of any noncompliance by the lender. The interest rate on the debt is the Prime Rate minus 25 basis points, or 3.00%, at December 31, 2020, and is paid quarterly. Scheduled principal maturities are as follows (dollars in thousands): 2021 $ — 2022 — 2023 — 2024 569 2025 and thereafter 15,000 Total $ 15,569

SUBORDINATED DEBT

SUBORDINATED DEBT	12 Months Ended
	Dec. 31, 2020
Subordinated Borrowings [Abstract]
SUBORDINATED DEBT	13. SUBORDINATED DEBT Junior Subordinated Debentures On January 1, 2015, the Company acquired F&M Bancshares and assumed Farmers & Merchants Capital Trust II and Farmers & Merchants Capital Trust III with an aggregate original principal amount of $11.3 million and a current carrying value of $9.6 million at December 31, 2020. At acquisition, the Company recorded a discount of $2.5 million on the debentures. The difference between the carrying value and contractual balance will be recognized as a yield adjustment over the remaining term for the debentures. Each of the trusts is a capital or statutory business trust organized for the sole purpose of issuing trust securities and investing the proceeds in the Company’s junior subordinated debentures. The preferred trust securities of each trust represent preferred beneficial interests in the assets of the respective trusts and are subject to mandatory redemption upon payment of the junior subordinated debentures held by the trust. The common securities of each trust are wholly owned by the Company. Each trust’s ability to pay amounts due on the trust preferred securities is solely dependent upon the Company making payment on the related junior subordinated debentures. The debentures, which are the only assets of each trust, are subordinate and junior in right of payment to all of the Company’s present and future senior indebtedness. The Company has fully and unconditionally guaranteed each trust’s obligations under the trust securities issued by such trust to the extent not paid or made by each trust, provided such trust has funds available for such obligations. The junior subordinated debentures are included in Tier 1 capital under current regulatory guidelines and interpretations. Under the provisions of each issue of the debentures, the Company has the right to defer payment of interest on the debentures at any time, or from time to time, for periods not exceeding five years. If interest payments on either issue of the debentures are deferred, the distributions on the applicable trust preferred securities and common securities will also be deferred. A summary of pertinent information related to the Company's issuances of junior subordinated debentures outstanding at December 31, 2020 is set forth in the table below: Description Issuance Date Trust Preferred Securities Outstanding Interest Rate (1) Junior Subordinated Debt Owed to Trusts Maturity Date (2) (Dollars in thousands) Farmers & Merchants Capital Trust II November 13, 2003 $ 7,500 3 month LIBOR + 3.00% $ 7,732 November 8, 2033 Farmers & Merchants Capital Trust III June 30, 2005 3,500 3 month LIBOR + 1.80% 3,609 July 7, 2035 $ 11,341 (1) The 3-month LIBOR in effect as of December 31, 2020 was 0.23364%. (2) All debentures are currently callable. Subordinated Notes In December 2017, the Bank completed the issuance, through a private placement, of $40.0 million aggregate principal amount of Fixed-to-Floating Rate Subordinated Notes (the "Notes") due December 15, 2027. The Notes were issued at a price equal to 100% of the principal amount, resulting in net proceeds to the Bank of $39.4 million. The Bank used the net proceeds from the offering to support its growth and for general corporate purposes. The Notes are intended to qualify as Tier 2 capital for bank regulatory purposes. The Notes bear a fixed interest rate of 5.25% per annum until (but excluding) December 15, 2022, payable semi-annually in arrears. From December 15, 2022, the Notes will bear a floating rate of interest equal to 3-Month LIBOR + 3.03% until the Notes mature on December 15, 2027, or such earlier redemption date, payable quarterly in arrears. The Notes will be redeemable by the Bank, in whole or in part, on or after December 15, 2022 or, in whole but not in part, upon the occurrence of certain specified tax events, capital events or investment company events. Any redemption will be at a redemption price equal to 100% of the principal amount of Notes being redeemed, plus accrued and unpaid interest, and will be subject to, and require, prior regulatory approval. The Notes are not subject to redemption at the option of the holders. In September 2019, the Company completed the issuance of $60.0 million aggregate principal amount of Fixed-to-Floating Rate Subordinated Notes (the "Company Notes") due October 1, 2029. The Company Notes were issued at a price equal to 100% of the principal amount, resulting in net proceeds to the Company of $58.6 million. The Company Notes bear a fixed interest rate of 4.70% per annum until (but excluding) October 1, 2024, payable semi-annually in arrears on April 1 and October 1, commencing on April 1, 2020. Thereafter, from October 1, 2024 through the maturity date, October 1, 2029, or earlier redemption date, the Company Notes will bear interest at a floating rate equal to the then-current three-month LIBOR, plus 313 basis points (3.13%) for each quarterly interest period (subject to certain provisions set forth under “Description of the Notes—Interest Rates and Interest Payment Dates” included in the Prospectus Supplement), payable quarterly in arrears on January 1, April 1, July 1 and October 1 of each year. Any redemption will be at a redemption price equal to 100% of the principal amount of Company Notes being redeemed, plus accrued and unpaid interest, and will be subject to, and require, prior regulatory approval. The Company Notes are not subject to redemption at the option of the holders.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
INCOME TAXES	14. INCOME TAXES The components of the provision for federal income taxes are as follows: For the Years Ended December 31, 2020 2019 2018 (Dollars in thousands) Current $ 17,527 $ 13,514 $ 8,204 Deferred (7,090 ) (87 ) (256 ) Total $ 10,437 $ 13,427 $ 7,948 Reported income tax expense differs from the amounts computed by applying the U.S. federal statutory income tax rate to income before income taxes for the years ended December 31, 2020, 2019 and 2018 due to the following: For the Years Ended December 31, 2020 2019 2018 (Dollars in thousands) Taxes calculated at statutory rate $ 11,754 $ 13,940 $ 9,504 Increase (decrease) resulting from: Stock based compensation 136 (11 ) (400 ) Effect of tax-exempt income (1,475 ) (698 ) (1,284 ) Other, net 22 196 128 Total $ 10,437 $ 13,427 $ 7,948 The Company recognized net tax shortfall related to stock based compensation totaling $136 thousand in 2020, compared to net tax benefits of $11 thousand in 2019 and $400 thousand in 2018. Year-end deferred taxes are presented in the table below. Deferred taxes as of December 31, 2020 and 2019 are based on the 21% Deferred tax assets and liabilities are as follows: As of December 31, 2020 2019 (Dollars in thousands) Deferred tax assets: Allowance for credit losses $ 12,590 $ 6,432 Deferred loan fees 3,164 — Deferred compensation 655 855 Cash flow hedge 263 — Other deferred assets 342 — Total deferred tax assets 17,014 7,287 Deferred tax liabilities: Core deposit intangible and other purchase accounting adjustments (3,964 ) (3,591 ) Net unrealized gain on available for sale securities (9,417 ) (1,307 ) Premises and equipment basis difference (2,573 ) (2,099 ) Total deferred tax liabilities (15,954 ) (6,997 ) Net deferred tax assets $ 1,060 $ 290 Interest and penalties related to tax positions are recognized in the period in which they begin accruing or when the entity claims the position that does not meet the minimum statutory thresholds. The Company does not have any uncertain tax positions and does not have any interest and penalties recorded in the income statement for the years ended December 31, 2020, 2019 and 2018. The Company is no longer subject to examination by the US Federal Tax Jurisdiction for the years prior to 2017.

STOCK BASED COMPENSATION

STOCK BASED COMPENSATION	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
STOCK BASED COMPENSATION	15. STOCK BASED COMPENSATION At December 31, 2020, the Company had two stock-based employee compensation plans with awards outstanding. In connection with the acquisition of Post Oak Bancshares, Inc., on October 1, 2018, the Company assumed the Post Oak Bancshares, Inc. Stock Option Plan, under which no additional awards will be issued. During 2019, the Company’s Board of Directors and shareholders approved the 2019 Amended and Restated Stock Awards and Incentive Plan (the “Plan”) covering certain awards of stock-based compensation to key employees and directors of the Company and its affiliates. Under the Plan, the Company is authorized to issue a maximum aggregate of 3,200,000 shares of stock, up to 1,800,000 of which may be issued through incentive stock options. The Company accounts for stock based employee compensation plans using the fair value-based method of accounting. The Company recognized total stock based compensation expense of $3.4 million, $3.1 million and $1.7 million for the years ended December 31, 2020, 2019 and 2018, respectively. Stock Options Options to purchase a total of 1,309,231 shares of Company stock have been granted as of December 31, 2020. There were no stock options granted during 2020 and 2019. Under the Plan, options are exercisable up to 10 years from the date of the grant and, dependent on the terms of the applicable award agreement generally vest 4 years after the date of grant. The fair value of stock options granted is estimated at the date of grant using the Black-Scholes model. A summary of the activity in the stock option plans during the years ended December 31, 2020 and 2019 is set forth below: Weighted Weighted Average Average Aggregate Number of Exercise Remaining Intrinsic Options Price Contractual Term Value (Shares in thousands) (In years) (Dollars in thousands) Options outstanding, January 1, 2019 802 $ 18.88 4.61 $ 10,830 Options granted — — Options exercised (179 ) 15.16 Options forfeited (7 ) 24.18 Options outstanding, December 31, 2019 616 $ 19.90 4.00 $ 10,904 Options granted — — Options exercised (141 ) 15.72 Options forfeited (6 ) 20.36 Options outstanding, December 31, 2020 469 $ 21.08 3.43 $ 6,118 Options vested and exercisable, December 31, 2020 455 $ 20.58 3.34 $ 6,164 The Company expects all outstanding options at December 31, 2020 to vest. Information related to the stock option plans during each year is as follows: 2020 2019 2018 (Dollars in thousands, except per share data) Intrinsic value of options exercised $ 734 $ 751 $ 3,254 Cash received from option exercises 2,221 2,709 3,393 Weighted average fair value of options granted $ — $ — $ 18.00 As of December 31, 2020, there was $110 thousand of total unrecognized compensation cost related to nonvested stock options granted under the plans. The cost is expected to be recognized over a weighted-average period of 0.53 years. Restricted Stock Awards The Company has issued 378,091 restricted stock awards under the Plan as of December 31, 2020. During 2019, the Company awarded 87,950 shares of restricted stock with a weighted average grant date fair value of $34.97. During 2020, the Company awarded 63,596 shares of restricted stock with a weighted average grant date fair value of $22.59. The shares of restricted stock generally vest over a period of 4 years and are considered outstanding at the date of issuance. The Company accounts for shares of restricted stock by recording the fair value of the grant on the award date as compensation expense over the vesting period. A summary of the activity of the nonvested shares of restricted stock as of December 31, 2020 and 2019 including changes during the years then ended is as follows: Weighted Average Grant Number of Date Fair Shares Value (Shares in thousands) Nonvested share awards outstanding, January 1, 2019 143 $ 37.48 Share awards granted 88 34.97 Share awards vested (45 ) 36.70 Unvested share awards forfeited or cancelled (19 ) 38.46 Nonvested share awards outstanding, December 31, 2019 167 $ 36.23 Share awards granted 64 22.59 Share awards vested (60 ) 33.97 Unvested share awards forfeited or cancelled (13 ) 37.92 Nonvested share awards outstanding, December 31, 2020 158 $ 30.78 At December 31, 2020, there was $4.3 million of unrecognized compensation expense related to the restricted stock awards which is expected to be recognized over a weighted-average period of 2.28 years. The total fair value of restricted stock awards that fully vested during the years ended December 31, 2020, 2019 and 2018 was approximately $2.0 million, $1.6 million and $621 thousand, respectively. Performance Share Units (“PSUs”) PSUs are earned subject to certain performance goals being met after the two-year one-year

OTHER EMPLOYEE BENEFITS

OTHER EMPLOYEE BENEFITS	12 Months Ended
	Dec. 31, 2020
Compensation And Retirement Disclosure [Abstract]
OTHER EMPLOYEE BENEFITS	16. OTHER EMPLOYEE BENEFITS 401(k) benefit plan The Company has a 401(k) benefit plan whereby participants may contribute a percentage of their compensation. The Company matches 50% of an employee's contributions up to 6% of the employee’s compensation, for a maximum match of 3% of compensation. Matching contribution expense as of December 31, 2020, 2019 and 2018 was $1.4 million, $1.4 million and $962 thousand, respectively. Profit sharing plan The financial statements include an accrual for $3.5 million, $3.7 million and $2.5 million for a contribution to the plan as a profit sharing contribution for the years ended December 31, 2020, 2019 and 2018, respectively. Employee Stock Purchase Plan The Company offers its employees an opportunity to purchase shares of Allegiance’s common stock, pursuant to the terms of the Allegiance Bancshares, Inc. 2019 Amended and Restated Employee Stock Purchase Plan (“ESPP”). The ESPP was adopted by the Board of Directors to provide employees with an opportunity to purchase shares of Allegiance in order to provide employees a more direct opportunity to participate in the Company’s growth. The Company allows employees to purchase shares at a 15% discount to market value and thus incurs stock based compensation expense for the fair value of the discount given. The Company recognized total stock based compensation expense of $ 142 thousand, $ 210 thousand and $ thousand for the years ended D ecember 31, 20 20 , 201 9 , and 201 8 respectively.

OFF-BALANCE SHEET ARRANGEMENTS,

OFF-BALANCE SHEET ARRANGEMENTS, COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
OFF-BALANCE SHEET ARRANGEMENTS, COMMITMENTS AND CONTINGENCIES	17. OFF-BALANCE SHEET ARRANGEMENTS, COMMITMENTS AND CONTINGENCIES In the normal course of business, the Company enters into various transactions, which, in accordance with accounting principles generally accepted in the United States are not included in the Company’s consolidated balance sheets. The Company enters into these transactions to meet the financing needs of its customers. These transactions include commitments to extend credit and standby and commercial letters of credit, which involve to varying degrees elements of credit risk and interest rate risk in excess of the amounts recognized in the consolidated balance sheets. The Company uses the same credit policies in making commitments and conditional obligations as it does for on balance sheet instruments. Commitments to Extend Credit Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many of the commitments are expected to expire without being fully drawn upon, the total commitment amounts disclosed do not necessarily represent future cash funding requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. The Company minimizes its exposure to loss under these commitments by subjecting them to credit approval and monitoring procedures. Management assesses the credit risk associated with certain commitments to extend credit in determining the level of the allowance for credit losses. The amount and type of collateral, if deemed necessary by the Company upon extension of credit, is based on management’s credit evaluation of the customer. Standby Letters of Credit Standby letters of credit are written conditional commitments issued by the Company to guarantee the performance of a customer to a third party. In the event of nonperformance by the customer, the Company has the rights to the underlying collateral. The credit risk to the Company in issuing letters of credit is essentially the same as that involved in extending loan facilities to its customers. The Company’s policy for obtaining collateral, and the nature of such collateral, is essentially the same as that involved in making commitments to extend credit. The contractual amounts of financial instruments with off-balance sheet risk are as follows: December 31, 2020 December 31, 2019 Fixed Variable Fixed Variable Rate Rate Rate Rate (Dollars in thousands) Commitments to extend credit $ 761,938 $ 480,067 $ 507,411 $ 531,470 Standby letters of credit 9,252 8,003 10,843 4,309 Total $ 771,190 $ 488,070 $ 518,254 $ 535,779 Commitments to make loans are generally made for periods of 120 days or less. As of December 31, 2020, the fixed rate loan commitments have interest rates ranging from 1.20% to 18.00% with a weighted average maturity and rate of 3.53 years and 5.13%, respectively.

REGULATORY CAPITAL MATTERS

REGULATORY CAPITAL MATTERS	12 Months Ended
	Dec. 31, 2020
Banking And Thrift [Abstract]
REGULATORY CAPITAL MATTERS	18. REGULATORY CAPITAL MATTERS The Company and the Bank are subject to various regulatory capital requirements administered by the federal banking agencies. Capital adequacy guidelines and, additionally for banks, prompt corrective action regulations involve quantitative measures of assets, liabilities and certain off balance sheet items calculated under regulatory accounting practices. Capital amounts and classifications are also subject to qualitative judgments by regulators about components, risk weightings and other factors. Failure to meet minimum capital requirements can initiate actions by regulators that, if undertaken, could have a direct material effect on the Company’s consolidated financial statements. Management believes as of December 31, 2020 and 2019, the Company and the Bank met all capital adequacy requirements to which they were subject. Prompt corrective action regulations provide five classifications: well capitalized, adequately capitalized, undercapitalized, significantly undercapitalized and critically undercapitalized, although these terms are not used to represent overall financial condition. If adequately capitalized, regulatory approval is required to accept brokered deposits. If undercapitalized, capital distributions are limited as is asset growth and expansion, and capital restoration plans are required. At year-end 20 20 and 201 9 , the most recent regulatory notifications categorized the Bank as well capitalized under the regulatory framework for prompt corrective action. There are no conditions or events since that notification that management believes have changed the institution’s category. The following is a summary of the Company’s and the Bank’s actual and required capital ratios at December 31, 2020 and 2019: Actual Minimum Required for Capital Adequacy Purposes Minimum Required Plus Capital Conservation Buffer To Be Categorized As Well Capitalized Under Prompt Corrective Action Provisions Amount Ratio Amount Ratio Amount Ratio Amount Ratio (Dollars in thousands) ALLEGIANCE BANCSHARES, INC. (Consolidated) As of December 31, 2020 Total Capital (to risk weighted assets) $ 642,155 15.71 % $ 327,084 8.00 % $ 429,298 10.50 % N/A N/A Common Equity Tier 1 Capital (to risk weighted assets) 482,643 11.80 % 183,985 4.50 % 286,199 7.00 % N/A N/A Tier 1 Capital (to risk weighted assets) 492,281 12.04 % 245,313 6.00 % 347,527 8.50 % N/A N/A Tier 1 Capital (to average tangible assets) 492,281 8.51 % 231,518 4.00 % 231,518 4.00 % N/A N/A As of December 31, 2019 Total Capital (to risk weighted assets) $ 596,684 14.83 % $ 321,775 8.00 % $ 422,330 10.50 % N/A N/A Common Equity Tier 1 Capital (to risk weighted assets) 459,447 11.42 % 180,999 4.50 % 281,553 7.00 % N/A N/A Tier 1 Capital (to risk weighted assets) 468,972 11.66 % 241,331 6.00 % 341,886 8.50 % N/A N/A Tier 1 Capital (to average tangible assets) 468,972 10.02 % 187,146 4.00 % 187,146 4.00 % N/A N/A ALLEGIANCE BANK As of December 31, 2020 Total Capital (to risk weighted assets) $ 635,223 15.55 % $ 326,804 8.00 % $ 428,931 10.50 % $ 408,506 10.00 % Common Equity Tier 1 Capital (to risk weighted assets) 544,331 13.32 % 183,828 4.50 % 285,954 7.00 % 265,529 6.50 % Tier 1 Capital (to risk weighted assets) 544,331 13.32 % 245,103 6.00 % 347,230 8.50 % 326,804 8.00 % Tier 1 Capital (to average tangible assets) 544,331 9.41 % 231,334 4.00 % 231,334 4.00 % 289,167 5.00 % As of December 31, 2019 Total Capital (to risk weighted assets) $ 578,425 14.39 % $ 321,556 8.00 % $ 422,043 10.50 % $ 401,945 10.00 % Common Equity Tier 1 Capital (to risk weighted assets) 509,372 12.67 % 180,875 4.50 % 281,362 7.00 % 261,265 6.50 % Tier 1 Capital (to risk weighted assets) 509,372 12.67 % 241,167 6.00 % 341,654 8.50 % 321,556 8.00 % Tier 1 Capital (to average tangible assets) 509,372 10.89 % 187,018 4.00 % 187,018 4.00 % 233,773 5.00 % Dividend Restrictions Allegiance's principal source of funds for dividend payments is dividends received from the Bank. Banking regulations limit the amount of dividends that may be paid without prior approval of regulatory agencies. In addition, Allegiance's credit agreement with another financial institution also limits its ability to pay dividends. Under applicable banking regulations, the amount of dividends that may be paid by the Bank in any calendar year is limited to the current year’s net profits combined with the retained net profits of the preceding two years, subject to the capital requirements described above.

EARNINGS PER COMMON SHARE

EARNINGS PER COMMON SHARE	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
EARNINGS PER COMMON SHARE	1 9 . EARNINGS PER COMMON SHARE Diluted earnings per common share is computed using the weighted-average number of common shares determined for the basic earnings per common share computation plus the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock using the treasury stock method. Outstanding stock options and PSUs issued by the Company represent the only dilutive effect reflected in diluted weighted average shares. Common shares issuable under restricted stock awards are considered outstanding at the date of grant and are accounted for as participating securities and included in basic and diluted weighted average common shares outstanding. For the Years Ended December 31, 2020 2019 2018 Per Share Per Share Per Share Amount Amount Amount Amount Amount Amount (Amounts in thousands, except per share data) Net income attributable to shareholders $ 45,534 $ 52,959 $ 37,309 Basic: Weighted average shares outstanding 20,415 $ 2.23 21,152 $ 2.50 15,485 $ 2.41 Diluted: Add incremental shares for: Dilutive effect of stock option exercises 131 272 288 Total 20,546 $ 2.22 21,424 $ 2.47 15,773 $ 2.37 Stock options for 39,050, 23,125 and 54,175 shares were not considered in computing diluted earnings per share as of December 31, 2020, 2019 and 2018, respectively, because they were antidilutive.

PARENT COMPANY ONLY FINANCIAL S

PARENT COMPANY ONLY FINANCIAL STATEMENTS	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
PARENT COMPANY ONLY FINANCIAL STATEMENTS	20. PARENT COMPANY ONLY FINANCIAL STATEMENTS ALLEGIANCE BANCSHARES, INC (PARENT COMPANY ONLY) CONDENSED BALANCE SHEETS December 31, 2020 2019 (Dollars in thousands) ASSETS Cash and due from banks $ 19,340 $ 17,775 Investment in subsidiary 820,699 760,131 Other assets 2,691 1,665 TOTAL $ 842,730 $ 779,571 LIABILITIES AND SHAREHOLDERS’ EQUITY LIABILITIES: Other borrowed funds $ 15,514 $ 504 Subordinated debentures 68,577 68,184 Accrued interest payable and other liabilities (30 ) 1,018 Total liabilities 84,061 69,706 SHAREHOLDERS’ EQUITY: Common stock 20,208 20,524 Capital surplus 508,794 521,066 Retained earnings 195,236 163,375 Accumulated other comprehensive income 34,431 4,900 Total shareholders’ equity 758,669 709,865 TOTAL $ 842,730 $ 779,571 ALLEGIANCE BANCSHARES, INC (PARENT COMPANY ONLY) CONDENSED STATEMENTS OF INCOME For the Years Ended December 31, 2020 2019 2018 (Dollars in thousands) OPERATING INCOME: Other income $ 16 $ 25 $ 16 Total income 16 25 16 OPERATING EXPENSE: Interest expense on borrowed funds 3,497 1,459 38 Other expenses 1,595 1,922 1,692 Total operating expense 5,092 3,381 1,730 Income before income tax benefit and equity in undistributed income of subsidiaries (5,076 ) (3,356 ) (1,714 ) Income tax benefit 1,066 705 360 Income before equity in undistributed income of subsidiaries (4,010 ) (2,651 ) (1,354 ) Dividends from subsidiary and equity in undistributed income of subsidiaries 49,544 55,610 38,663 Net income $ 45,534 $ 52,959 $ 37,309 ALLEGIANCE BANCSHARES, INC (PARENT COMPANY ONLY) CONDENSED STATEMENTS OF CASH FLOWS For the Years Ended December 31, 2020 2019 2018 (Dollars in thousands) CASH FLOWS FROM OPERATING ACTIVITIES: Net income $ 45,534 $ 52,959 $ 37,309 Adjustments to reconcile net income to net cash used in operating activities: Equity in undistributed earnings of subsidiaries (49,544 ) (55,610 ) (38,663 ) Net amortization of discount on subordinated debentures 392 169 110 Stock based compensation expense 3,425 3,100 1,685 Increase in other assets (1,026 ) (639 ) (236 ) (Decrease) increase in accrued interest payable and other liabilities (1,038 ) 166 279 Net cash (used in) provided by operating activities (2,257 ) 145 484 CASH FLOWS FROM INVESTING ACTIVITIES: Dividend from subsidiary 13,000 7,500 — Capital investment in bank subsidiary — — — Net cash provided by investing activities 13,000 7,500 — CASH FLOWS FROM FINANCING ACTIVITIES: Proceeds from the issuance of common stock, stock option exercises and the ESPP 2,569 3,412 3,552 Net increase in borrowings under credit agreement 15,000 — — Proceeds from subordinated notes issuance, net of offering expenses — 58,601 — Dividends paid to common shareholders (8,165 ) — — Repurchase of common stock (18,582 ) (58,663 ) (2,113 ) Net cash (used in) provided by financing activities (9,178 ) 3,350 1,439 NET CHANGE IN CASH AND CASH EQUIVALENTS 1,565 10,995 1,923 CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD 17,775 6,780 4,857 CASH AND CASH EQUIVALENTS, END OF PERIOD $ 19,340 $ 17,775 $ 6,780

QUARTERLY FINANCIAL DATA (UNAUD

QUARTERLY FINANCIAL DATA (UNAUDITED)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY FINANCIAL DATA (UNAUDITED)	21. QUARTERLY FINANCIAL DATA (UNAUDITED) Earnings Per Share (1) Interest Income Net Interest Income Net Income Attributable to Common Shareholders Basic Diluted (Dollars in thousands, except per share data) 2020 First quarter (2) $ 57,452 $ 45,025 $ 3,516 $ 0.17 $ 0.17 Second quarter (2) 60,452 50,847 9,907 0.49 0.48 Third quarter (2) 60,811 51,909 16,170 0.79 0.79 Fourth quarter 63,047 54,902 15,941 0.78 0.77 2019 First quarter $ 57,149 $ 44,603 $ 12,678 $ 0.58 $ 0.58 Second quarter 58,946 45,571 14,248 0.67 0.66 Third quarter 58,665 44,837 12,047 0.57 0.57 Fourth quarter 58,147 44,526 13,986 0.68 0.67 (1) Earnings per share are computed independently for each of the quarters presented and therefore may not total earnings per share for the year. (2) Does not reflect the adoption of ASC 326.

SUBSEQUENT EVENT

SUBSEQUENT EVENT	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
SUBSEQUENT EVENT	22. SUBSEQUENT EVENT Dividend Declaration On January 27, 2021, the Company declared a cash dividend of $0.12 per share of common stock to be paid on March 15, 2021 to all shareholders of record as of February 26, 2021.

NATURE OF OPERATIONS AND SUMM_2

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Nature of Operations and Principles of Consolidation	Nature of Operations and Principles of Consolidation- The consolidated financial statements include Allegiance Bancshares, Inc. (“Allegiance”) and its wholly-owned subsidiary, Allegiance Bank (the “Bank”, and together with Allegiance, collectively referred to as the “Company”) provide commercial and retail loans and commercial banking services. Intercompany transactions and balances are eliminated in consolidation under U.S. generally accepted accounting principles (“GAAP”). The Company derives substantially all of its revenues and income from the operation of the Bank. Allegiance Bank is a Texas banking association which began operations in October 2007. The Company is focused on delivering a wide variety of relationship-driven commercial banking products and community-oriented services tailored to meet the needs of small to mid-sized businesses, professionals and individuals through its 28 offices, with 27 bank offices in the Houston metropolitan area and one office in Beaumont, just outside of the Houston metropolitan area, as of the year ended December 31, 2020. The Bank provides its customers with a variety of banking services including checking accounts, savings accounts and certificates of deposit and its primary lending products are commercial, personal, automobile, mortgage and home improvement loans. The Bank also offers safe deposit boxes, automated teller machines, drive-through services and 24-hour depository facilities.
Use of Estimates	Use of Estimates— The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions based on available information. These estimates and assumptions affect the reporting of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Acquisitions	Acquisitions – On October 1, 2018, Allegiance completed the acquisition of Post Oak Bancshares, Inc. On February 1, 2019, Allegiance completed the acquisition of the LoweryBank branch, the Sugar Land location of Huntington State Bank. See Note 2 – Acquisitions for additional information pertaining to the Post Oak and LoweryBank acquisitions and the impact of the Post Oak transaction on the Company’s consolidated financial statements.
Cash and cash equivalents	Cash and cash equivalents —Cash and cash equivalents include cash, deposits with other financial institutions with maturities not greater than one year. Net cash flows are reported for customer loan and deposit transactions.
Securities	Securities —Debt securities are classified as available for sale when they might be sold before maturity. Securities available for sale are carried at fair value. Unrealized gains and losses are excluded from earnings and reported, net of tax, as a separate component of shareholders’ equity until realized. Securities within the available for sale portfolio may be used as part of the Company’s asset/liability strategy and may be sold in response to changes in interest rate risk, prepayment risk or other similar economic factors. Interest earned on these assets is included in interest income. Interest income includes amortization of purchase premium or discount. Premiums and discounts on securities are amortized on the level-yield method, except for mortgage backed securities where prepayments are anticipated. Gains and losses on sales are recorded on the trade date and determined using the specific identification method.
Loans	Loans —Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at amortized cost net of the allowance for credit losses on loans. Amortized cost is the principal balance outstanding, net of purchase accounting adjustments and deferred fees and costs. Accrued interest receivable on loans totaled $34.5 million at December 31, 2020 and was reported in accrued interest receivable on the consolidated balance sheets. Interest income is accrued on the unpaid principal balance. Loan origination fees, net of origination costs, are deferred and recognized in interest income using the interest method without anticipating prepayments. Interest income on loans is discontinued and placed on nonaccrual status at the time the loan is 90 days delinquent. All interest accrued but not received for loans placed on nonaccrual is reversed against interest income. Loans are returned to accrual status when all the principal and interest amount contractually due are brought current and future payments are reasonably assured.
Purchased Credit Deteriorated (PCD) Loans	Purchased Credit Deteriorated (PCD) Loans —Upon adoption of ASC 326, the allowance for credit losses was determined for each loan and added to the loan’s carrying amount to establish a new amortized cost basis. The difference between the unpaid principal balance of the loan and the new amortized cost basis was the noncredit premium or discount which was amortized into interest income over the remaining life of the loan. Changes to the allowance for credit losses after adoption are recorded through provision expense.
Nonrefundable Fees and Costs Associated with Lending Activities	Nonrefundable Fees and Costs Associated with Lending Activities —Loan commitment and loan origination fees, and certain direct origination costs, are deferred and recognized in interest income as an adjustment to yield without anticipating prepayments using the interest method over the related loan life or; if the commitment expires unexercised, balances are recognized in income upon expiration of the commitment.
Nonperforming and Past Due Loans	Nonperforming and Past Due Loans —The Company has several procedures in place to assist it in maintaining the overall quality of its loan portfolio. The Company has established underwriting guidelines to be followed by its officers, and monitors its delinquency levels for any negative or adverse trends. There can be no assurance, however, that the Company’s loan portfolio will not become subject to increasing pressures from deteriorating borrower credit due to general economic conditions or other factors. Past due status is based on the contractual terms of the loan. 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 Company generally classifies a loan as nonperforming, automatically places the loan on nonaccrual status, ceases accruing interest and reverses all unpaid accrued interest against interest income, when, in management’s opinion, the borrower may be unable to meet payment obligations, when the payment of principal or interest on a loan is delinquent for 90 days, as well as when required by regulatory provisions, unless the loan is in the process of collection and the underlying collateral fully supports the carrying value of the loan. Any payments received on nonaccrual loans are applied first to outstanding loan amounts. Interest income is subsequently recognized only to the extent cash payments are received in excess of principal due. Any excess is treated as recovery of lost interest. Loans are returned to accrual status when all of the principal and interest amounts contractually due are brought current and future payments are reasonably assured. In all cases, loans are placed on nonaccrual or charged-off at an earlier date if collection of principal or interest is considered doubtful. If the decision is made to continue accruing interest on the loan, periodic reviews are made to confirm the accruing status of the loan. Nonaccrual loans and loans past due 90 days include both smaller balance homogeneous loans that are collectively and individually evaluated. When available information confirms that specific loans, or portions thereof, are uncollectible, these amounts are charged-off against the allowance. All loan types are considered delinquent after 30 days past due and are typically charged-off or charged-down no later than 120 days past due, with consideration of, but not limited to, the following criteria in determining the need and timing of the charge-off or charge-down: (1) the Bank is in the process of repossession or foreclosure and there appears to be a likely deficiency; (2) the collateral securing the loan has been sold and there is an actual deficiency; (3) the Bank is proceeding with lengthy legal action to collect its balance; (4) the borrower is unable to be located; or (5) the borrower has filed bankruptcy. Charge-offs occur when the Company confirms a loss on a loan.
Acquired Loans	Acquired Loans — Acquired loans are recorded at fair value at the date of acquisition with no initial valuation allowance based on a discounted cash flow methodology that considers various factors including the type of loan and related collateral, classification status, fixed or variable interest rate, term of loan and whether or not the loan was amortizing, and a discount rate reflecting the Company’s assessment of risk inherent in the cash flow estimates. Certain larger purchased loans are individually evaluated while certain purchased loans are grouped together according to similar risk characteristics and are treated in the aggregate when applying various valuation techniques. These cash flow evaluations are inherently subjective as they require material estimates, all of which may be susceptible to significant change. Prior to the adoption of ASC Topic 326 on January 1, 2020, loans acquired in a business combination that had evidence of deterioration of credit quality since origination and for which it was probable, at acquisition, that the Company would be unable to collect all contractually required payments receivable were considered purchased credit impaired (“PCI”). PCI loans were individually evaluated and recorded at fair value at the date of acquisition with no initial valuation allowance based on a discounted cash flow methodology that considers various factors including the type of loan and related collateral, classification status, fixed or variable interest rate, term of loan and whether or not the loan was amortizing, and a discount rate reflecting the Company’s assessment of risk inherent in the cash flow estimates. Increases in expected cash flows, including prepayments, subsequent to the initial investment were recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows were recognized as impairment. Valuation allowances on PCI loans reflected only losses incurred after the acquisition (meaning the present value of all cash flows expected at acquisition that ultimately are not to be received). Subsequent to January 1, 2020, loans acquired in a business combination that have experienced more-than-insignificant deterioration in credit quality since origination are considered purchased credit deteriorated (“PCD”) loans. At the acquisition date, an estimate of expected credit losses is made for groups of PCD loans with similar risk characteristics and individual PCD loans without similar risk characteristics. This initial allowance for credit losses is allocated to individual PCD loans and added to the purchase price or acquisition date fair values to establish the initial amortized cost basis of the PCD loans. As the initial allowance for credit losses is added to the purchase price, there is no credit loss expense recognized upon acquisition of a PCD loan. Any difference between the unpaid principal balance of PCD loans and the amortized cost basis is considered to relate to noncredit factors and results in a discount or premium. Discounts and premiums are recognized through interest income on a level-yield method over the life of the loans. All loans considered to be PCI prior to January 1, 2020 were converted to PCD on that date. For acquired loans not deemed purchased credit deteriorated at acquisition, the differences between the initial fair value and the unpaid principal balance are recognized as interest income on a level-yield basis over the lives of the related loans. At the acquisition date, an initial allowance for expected credit losses is estimated and recorded as a provision for credit losses expense. The subsequent measurement of expected credit losses for all acquired loans is the same as the subsequent measurement of expected credit losses for originated loans.
Allowance for Credit Losses	A llowance for Credit Losses – Allowance for Credit Losses on Loans - Effective January 1, 2020, the Company adopted ASU 2016-13 Financial Instruments – Credit Losses (ASC Topic 326): Measurement of Credit Losses on Financial Instruments , which replaced the incurred loss methodology with an expected loss methodology that is referred to as the CECL methodology. The level of the allowance is based upon management's evaluation of historical default and loss experience, current and projected economic conditions, asset quality trends, known and inherent risks in the portfolio, adverse situations that may affect the borrowers' ability to repay a loan (including the timing of future payments), the estimated value of any underlying collateral, composition of the loan portfolio, industry and peer bank loan quality indications and other pertinent factors, including regulatory recommendations. The allowance for credit losses on loans maintained by management is believed adequate to absorb all expected future losses in the loan portfolio at the balance sheet date. The Company disaggregates the loan portfolio into pools for purposes of determining the allowance for credit losses. These pools are based on the level at which the Company develops, documents and applies a systematic methodology to determine the allowance for credit losses. Loans with similar risk characteristics are collectively evaluated resulting in loss estimates as determined by applying reserve factors, such as historical lifetime loan loss experience, concentration risk of specific loan types, the volume, growth and composition of the Company’s loan portfolio, current economic conditions and reasonable and supportable forecasted economic conditions that may affect the borrower’s ability to pay and the value of collateral, the evaluation of the Company’s loan portfolio through its internal loan review process, general economic conditions and other qualitative risk factors both internal and external to the Company and other relevant factors, designed to estimate current expected credit losses, to amortized cost balances over the remaining contractual life of the collectively evaluated portfolio. Loans with similar risk characteristics are aggregated into homogeneous pools for assessment. Historical lifetime loan loss experience is determined by utilizing an open-pool (“cumulative loss rate”) methodology. Adjustments to the historical lifetime loan loss experience are made for differences in current loan pool risk characteristics such as portfolio concentrations, delinquency, nonaccrual, and watch list levels, as well as changes in current and forecasted economic conditions such as unemployment rates, property and collateral values, and other indices relating to economic activity. Losses are predicted over a period of time determined to be reasonable and supportable, and at the end of the reasonable and supportable period losses are reverted to long term historical averages. The reasonable and supportable period and reversion period are re-evaluated each year by the Company and are dependent on the current economic environment among other factors. A reasonable and supportable period of twelve months was utilized for all loan pools, followed by an immediate reversion to long term averages. Based on a review of these factors for each loan type, the Company applies an estimated percentage to the outstanding balance of each loan type. Loans that no longer share risk characteristics with the collectively evaluated loan pools are evaluated on an individual basis and are excluded from the collectively evaluated pools. In order to assess which loans are to be individually evaluated, the Company follows a loan review program to evaluate the credit risk in the total loan portfolio and assigns risk grades to each loan. Individual credit loss estimates are typically performed for nonaccrual loans, modified loans classified as troubled debt restructurings and all other loans identified by management. All loans deemed as being individually evaluated are reviewed on a quarterly basis in order to determine whether a specific reserve is required. The Company considers certain loans to be collateral dependent if the borrower is experiencing financial difficulty and management expects repayment for the loan to be substantially through the operation or sale of the collateral. For collateral dependent loans, loss estimates are based on the fair value of collateral, less estimated cost to sell (if applicable). Collateral values supporting individually evaluated loans are assessed quarterly and appraisals are typically obtained at least annually. The Company allocates a specific loan loss reserve on an individual loan basis primarily based on the value of the collateral securing the individually evaluated loan. Through this loan review process, the Company assesses the overall quality of the loan portfolio and the adequacy of the allowance for credit losses on loans while considering risk elements attributable to particular loan types in assessing the quality of individual loans. In addition, for each category of loans, the Company considers secondary sources of income and the financial strength and credit history of the borrower and any guarantors. A change in the allowance for credit losses on loans can be attributable to several factors, most notably specific reserves for individually evaluated loans, historical lifetime loan loss information, and changes in economic factors and growth in the loan portfolio. Specific reserves that are calculated on an individual basis and the qualitative assessment of all other loans reflect current changes in the credit quality of the loan portfolio. Historical lifetime credit losses, on the other hand, are based on an open-pool (“cumulative loss rate”) methodology, which is then applied to estimate lifetime credit losses in the loan portfolio. The allowance for credit losses on loans is further determined by the size of the loan portfolio subject to the allowance methodology and factors that include Company-specific risk indicators and general economic conditions, both of which are constantly changing. The Company evaluates the economic and portfolio-specific factors on a quarterly basis to determine a qualitative component of the general valuation allowance. These factors include current economic metrics, reasonable and supportable forecasted economic metrics, delinquency trends, credit concentrations, nature and volume of the portfolio and other adjustments for items not covered by specific reserves and historical lifetime loss experience. Based on the Company’s actual historical lifetime loan loss experience relative to economic and loan portfolio-specific factors at the time the losses occurred, management is able to identify the probable level of lifetime losses as of the date of measurement. The Company’s analysis of qualitative, or economic, factors on pools of loans with common risk characteristics, in combination with the quantitative historical lifetime loss information and specific reserves, provides the Company with an estimate of lifetime losses. The calculation of current expected credit losses is inherently subjective, as it requires management to exercise judgment in determining appropriate factors used to determine the allowance. The estimated loan losses for all loan pools are adjusted for changes in qualitative factors not inherently considered in the quantitative analyses to bring the allowance to the level management believes is appropriate based on factors that have not otherwise been fully accounted for, including adjustments for foresight risk, input imprecision and model imprecision. The qualitative categories and the measurements used to quantify the risks within each of these categories are subjectively selected by management, but measured by objective measurements period over period. The data for each measurement may be obtained from internal or external sources. The current period measurements are evaluated and assigned a factor commensurate with the current level of risk relative to past measurements over time. The resulting qualitative adjustments are applied to the relevant collectively evaluated loan portfolios. These adjustments are based upon quarterly trend assessments in portfolio concentrations, changes in lending policies and procedures, policy exceptions, independent loan review results, internal risk ratings and peer group credit quality trends. The qualitative allowance allocation, as determined by the processes noted above, is increased or decreased for each loan pool based on the assessment of these various qualitative factors. The determination of the appropriate qualitative adjustment is based on management's analysis of current and expected economic conditions and their impact to the portfolio, as well as internal credit risk movements and a qualitative assessment of the lending environment, including underwriting standards. Management recognizes the sensitivity of various assumptions made in the quantitative modeling of expected losses and may adjust reserves depending upon the level of uncertainty that currently exists in one or more assumptions. While policies and procedures used to estimate the allowance for credit losses on loans, as well as the resultant provision for credit losses charged to income, are considered adequate by management and are reviewed periodically by regulators and internal audit, they are approximate and could materially change based on changes within the loan portfolio and effects from economic factors. There are factors beyond the Company’s control, such as changes in projected economic conditions, including political instability or global events affecting the U.S. economy, real estate markets or particular industry conditions which could cause changes to expectations for current conditions and economic forecasts that could result in an unanticipated increase in the allowance and may materially impact asset quality and the adequacy of the allowance for credit losses and thus the resulting provision for credit losses. In assessing the adequacy of the allowance for credit losses on loans, the Company considers the results of its ongoing independent loan review process. The Company undertakes this process both to ascertain those loans in the portfolio with elevated credit risk and to assist in its overall evaluation of the risk characteristics of the entire loan portfolio. Its loan review process includes the judgment of management, independent internal loan reviewers and reviews that may have been conducted by third-party reviewers including regulatory examiners. The Company incorporates relevant loan review results in the allowance. In accordance with CECL, losses are estimated over the remaining contractual terms of loans, adjusted for prepayments. The contractual term excludes expected extensions, renewals and modifications unless management has a reasonable expectation at the reporting date that a troubled debt restructuring will be executed or such renewals, extensions or modifications are included in the original loan agreement and are not unconditionally cancellable by the Company. Credit losses are estimated on the amortized cost basis of loans, which includes the principal balance outstanding, purchase discounts and premiums and deferred loan fees and costs. Loan losses are not estimated for accrued interest receivable as interest that is deemed uncollectible is written off through interest income in a timely manner. Accrued interest is presented separately on the balance sheets and as allowed under ASC Topic 326 is excluded from the tabular loan disclosures in Note 6 – Loans and Allowance for Credit Losses. Allowance for Credit Losses on Unfunded Commitments - The Company estimates expected credit losses over the contractual term in which the Company is exposed to credit risk through a contractual obligation to extend credit, unless the obligation is unconditionally cancellable by the Company. The allowance for credit losses on unfunded commitments is adjusted as a provision for credit loss expense. The estimates are determined based on the likelihood of funding during the contractual term and an estimate of credit losses subsequent to funding. Estimated credit losses on subsequently funded balances are based on the same assumptions as used to estimate credit losses on existing funded loans. Allowance for Credit Losses - Securities Available for Sale – For securities classified as available for sale that are in an unrealized loss position at the balance sheet date, the Company first assesses whether or not it intends to sell the security, or more likely than not will be required to sell the security, before recovery of its amortized cost basis. If either criteria is met, the security's amortized cost basis is written down to fair value through net income. If neither criteria is met, the Company evaluates whether any portion of the decline in fair value is the result of credit deterioration. Such evaluations consider the extent to which the amortized cost of the security exceeds its fair value, changes in credit ratings and any other known adverse conditions related to the specific security. If the evaluation indicates that a credit loss exists, an allowance for credit losses is recorded through provisions for credit losses for the amount by which the amortized cost basis of the security exceeds the present value of cash flows expected to be collected, limited by the amount by which the amortized cost exceeds fair value. Losses are charged against the allowance when management believes the uncollectibility of an available for sale security is confirmed or when either of the criteria regarding intent or requirement to sell is met. Any impairment not recognized in the allowance for credit losses is recognized in other comprehensive income. For certain types of debt securities, such as U.S. Treasuries and other securities with government guarantees, entities may expect zero credit losses. The zero-loss expectation applies to all of the Company’s securities and no allowance for credit losses was recorded on its available for sale securities portfolio at transition. Prior to the adoption of ASU 2016-13, declines in the fair value of available-for-sale securities below their cost that were deemed to be other than temporary were reflected in earnings as realized losses. In estimating other-than-temporary impairment losses prior to January 1, 2020, management considered, among other things, (i) the length of time and the extent to which the fair value had been less than cost, (ii) the financial condition and near-term prospects of the issuer and (iii) the intent and our ability to retain our investment in the issuer for a period of time sufficient to allow for any anticipated recovery in fair value. Accrued interest receivable on available for sale securities totaled $5.5 million at December 31, 2020 and is excluded from the estimate of credit losses.
Troubled debt restructurings (TDRs)	Troubled debt restructurings (TDRs) — Loans for which terms have been modified in a TDR are evaluated using these same individual evaluation methods. For troubled debt restructurings that subsequently default, the Company determines the amount of reserve in accordance with the accounting policy for the allowance for credit losses. The Company assesses the exposure for each modification, by collateral discounting and determines if a specific allocation to the allowance for credit losses is needed. Once an obligation has been restructured because of such credit problems, it continues to be considered a troubled debt restructuring until paid in full. The Company returns troubled debt restructurings to accrual status only if (1) all contractual amounts due can reasonably be expected to be repaid within a prudent period and (2) repayment has been in accordance with the contract for a sustained period, typically at least twelve months.
Premises and Equipment	Premises and Equipment —Premises and equipment are carried at cost less accumulated depreciation. Depreciation expense is calculated principally using the straight-line method over the estimated useful lives of the assets which range from 3 to 40 years. Leasehold improvements are amortized using the straight-line method over the periods of the leases or the estimated useful lives, whichever is shorter. Land is carried at cost.
Leases	Leases — On January 1, 2019, the Company adopted Accounting Standards Update ("ASU") 2016-02, Leases (Topic 842) through the required modified retrospective approach by applying the allowed transition method whereby comparative periods were not restated. The Company elected to apply several of the available practical expedients provided by ASU 2016-12, including carryover of historical lease determination, carryover of historical initial direct cost balances for existing leases and accounting for lease and non-lease components in contracts in which the Company is a lease as a single lease component. Upon adoption of the new leasing standard on January 1, 2019, the Company recognized $15.3 million of right-of-use assets, and $15.7 million of related lease liabilities on the Consolidated Balance Sheet. The Company leases certain office facilities under operating leases. We also own certain office facilities which we lease to outside parties under operating lessor leases; however, such leases are not significant. Under the new standards, for operating leases other than those considered to be short-term, we recognize lease right-of-use assets and related lease liabilities. Such amounts are reported as components of premises and equipment and other liabilities, respectively, on our consolidated balance sheet.
Other Real Estate Owned	Other Real Estate Owned —Assets acquired through or instead of loan foreclosure are held for sale and are initially recorded at fair value less estimated selling costs when acquired, establishing a new cost basis. Costs after acquisition are generally expensed. If the fair value of the asset declines, a write-down is recorded through expense. The valuation of foreclosed assets is subjective in nature and may be adjusted in the future because of changes in economic conditions. At December 31, 2020, the $9.2 million balance of other real estate owned primarily consisted of foreclosed commercial real estate properties recorded as a result of obtaining physical possession of the property.
Federal Home Loan Bank ("FHLB") Stock	Federal Home Loan Bank (“FHLB”) Stock— The Bank is a member of the FHLB system. Members are required to own a certain amount of stock based on the level of borrowings and other factors and may invest in additional amounts. FHLB stock is carried at cost, classified as a restricted security and periodically evaluated for impairment based on ultimate recovery of par value. Both cash and stock dividends are reported as income.
Bank Owned Life Insurance	Bank Owned Life Insurance— The Company purchased bank owned life insurance policies on certain key executives and acquired life insurance policies in conjunction with the acquisitions of F&M Bancshares and Post Oak. Bank owned life insurance is recorded at the amount that can be realized under the insurance contract at the balance sheet date, which is the cash surrender value, and the most reasonable estimate of fair value, adjusted for other charges or other amounts due that are probable at settlement.
Goodwill	Goodwill —Goodwill resulting from business combinations is generally determined as the excess of the fair value of the consideration transferred, plus the fair value of any noncontrolling interests in the acquiree, over the fair value of the net assets acquired and liabilities assumed as of the acquisition date. Goodwill is assessed annually on October 1 for impairment or more frequently if events and circumstances exist that indicate that the carrying amount of the asset may not be recoverable and a goodwill impairment test should be performed. A significant amount of judgment is involved in determining if an indicator of impairment has occurred. Such indicators may include, among others: a significant decline in our expected future cash flows; a sustained, significant decline in our stock price and market capitalization; a significant adverse change in legal factors or in the business climate; adverse action or assessment by a regulator; and unanticipated competition. Any adverse change in these factors could have a significant impact on the recoverability of these assets and could have a material impact on the Company’s consolidated financial statements. Goodwill is the only intangible asset with an indefinite life on the Company’s balance sheet.
Core Deposit Intangibles	Core Deposit Intangibles —Core deposit and acquired customer relationship intangibles arising from acquisitions are amortized using a straight-line amortization method over their estimated useful lives, which is seven to ten years.
Borrowed Funds	Borrowed Funds —The Company has a credit agreement with another financial institution. The Company pledged its shares in the Bank’s stock as collateral for the borrowing.
Loan Commitments and Related Financial Instruments	Loan Commitments and Related Financial Instruments —Financial instruments include off-balance sheet credit instruments, such as commitments to extend credit, issued to meet customer financing needs. The face amount for these items represents a promise to lend before considering customer collateral or ability to repay. Such financial instruments are recorded when they are funded.
Stock Based Compensation	Stock Based Compensation —Compensation cost is recognized for stock options, restricted stock awards and performance share units (“PSUs”) issued to employees and directors, based on the fair value of these awards at the date of grant. The expense associated with stock based compensation is recognized over the required service period, generally defined as the vesting period of each individual arrangement. The fair value of stock options granted are estimated at the date of grant using the Black-Scholes model. The fair value of restricted stock awards is generally the market price of our stock on the date of grant. The grant date fair value of the PSUs is based on the probable outcome of the applicable performance conditions and is calculated at target based on a combination of the closing market price of our common stock on the grant date and a Monte Carlo simulated fair value in accordance with ASC 718. The impact of forfeitures of share-based payment awards on compensation expense is recognized as forfeitures occur. PSUs are contingent upon performance and service conditions, which affect the number of shares ultimately issued. The Company periodically evaluates the probable outcome of the performance conditions and makes cumulative adjustments to compensation expense as appropriate.
Employee Stock Purchase Plan	Employee Stock Purchase Plan —The cost of shares issued in the ESPP, but not allocated to participants, is shown as a reduction of shareholder’s equity. Compensation expense is based on the market price of the shares as they are committed to be released to participant accounts.The fair value of shares purchased in the plan are estimated at the date of grant using the Black-Scholes model.
Income Taxes	Income Taxes —Income tax expense is the total of the current year income tax due and the change in deferred tax assets or liabilities. Deferred tax assets and liabilities are recognized for the estimated tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and are recorded in other assets on the Company’s consolidated balance sheets. The Company records uncertain tax positions on the basis of a two-step process whereby (1) the Company determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more likely than not recognition threshold, the Company recognizes the largest amount of tax benefit that is greater than 50 percent likely of being realized upon ultimate settlement with the related tax authority. For tax positions not meeting the more likely than not test, no tax benefit is recorded. Any interest and/or penalties related to income taxes are reported as a component of income tax expense. The Company files a consolidated federal income tax return.
Comprehensive Income	Comprehensive income —Comprehensive income consists of net income and other comprehensive income which includes unrealized gains and losses on securities available for sale which are also recognized as separate components of equity.
Fair Value of Financial Instruments	Fair Value of Financial Instruments —Fair values of financial instruments are estimated using relevant market information and other assumptions, as more fully disclosed in a separate note. Fair value estimates involve uncertainties and matters of significant judgment regarding interest rates, credit risk, prepayments and other factors, especially in the absence of broad markets for particular items. Changes in assumptions or in market conditions could significantly affect these estimates.
Operating Segments	Operating Segments— While management monitors the revenue streams of the various products and services, operations are managed and financial performance is evaluated on a Company-wide basis. All of the financial service operations are considered by management to be aggregated in one reportable operating segment.
Reclassification	Reclassifications —Some items in the prior year financial statements were reclassified to conform to the current presentation. Reclassifications had no effect on prior year net income or shareholders’ equity.
Earnings per Common Share	Earnings per Common Share —Basic earnings per common share is calculated as net income divided by the weighted average number of common shares outstanding during the period. Diluted earnings per common share includes the dilutive effect of additional potential common shares issuable under stock options, performance share unit awards and the Employee Stock Purchase Plan.
Loss Contingencies	Loss Contingencies —Loss contingencies, including claims and legal actions arising in the ordinary course of business, are recorded as liabilities when the likelihood of loss is probable and an amount or range of loss can be reasonably estimated. Management does not believe there are such matters that will have a material effect on the financial statements.
Dividend Restrictions	Dividend Restrictions —Banking regulations require maintaining certain capital levels and may limit the dividends paid by the Bank to Allegiance or by Allegiance to its shareholders. In addition, Allegiance's credit agreement with another financial institution also limits its ability to pay dividends.
Revenue from Contracts with Customers	Revenue from Contracts with Customers —The Company records revenue from contracts with customers in accordance with Accounting Standards Codification Topic 606, “Revenue from Contracts with Customers” (“Topic 606”). Under Topic 606, the Company must identify the contract with a customer, identify the performance obligations in the contract, determine the transaction price, allocate the transaction price to the performance obligations in the contract, and recognize revenue when (or as) the Company satisfies a performance obligation. Significant revenue has not been recognized in the current reporting period that results from performance obligations satisfied in previous periods. The Company’s primary sources of revenue are derived from interest and dividends earned on loans, investment securities, and other financial instruments that are not within the scope of Topic 606. The Company has evaluated the nature of its contracts with customers and determined that further disaggregation of revenue from contracts with customers into more granular categories beyond what is presented in the Consolidated Statements of Income was not necessary. The Company generally fully satisfies its performance obligations on its contracts with customers as services are rendered and the transaction prices are typically fixed; charged either on a periodic basis or based on activity. Because performance obligations are satisfied as services are rendered and the transaction prices are fixed, the Company has made no significant judgments in applying the revenue guidance prescribed in ASC 606 that affect the determination of the amount and timing of revenue from contracts with customers.
New Accounting Standards	New Accounting Standards Adoption of New Accounting Standards ASU 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASC Topic 326”) , was issued by the FASB in June 2016 along with subsequent amendments thereto, which introduce the current expected credit losses (“CECL”) methodology. The measurement of expected credit losses under the CECL methodology utilizes a lifetime “expected credit loss” measurement objective for the recognition of credit losses for loans, held-to-maturity debt securities measured at amortized cost. ASC Topic 326 also applies to off-balance sheet credit exposures. This methodology replaces the multiple existing impairment methods in current guidance, which generally require that a loss be incurred before it is recognized. Within the life cycle of a loan or other financial asset, this new guidance will generally result in the earlier recognition of the provision for credit losses and the related allowance for credit losses than previous practice. For available for sale debt securities that the Company intends to hold and where fair value is less than cost, credit-related impairment, if any, will be recognized through an allowance for credit losses and adjusted each period for changes in credit risk. CECL became effective for the Company on January 1, 2020 using the modified retrospective approach; however, o n March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) was signed in to law by the President of the United States and allowed the option to temporarily defer or suspend the adoption of AS C Topic 326 . The Company elected to temporarily defer the adoption of CECL due to the uncertainty of the impact of COVID-19 and the volatility of crude oil prices, which can be impactful to the Houston market. During th e deferral, t he Company calculated and recorded its provision for loan losses under the incurred loss model that existed prior to ASC Topic 326. The Company adopted the new standard as of January 1, 2020 during the fourth quarter of 2020. Upon adoption of ASC Topic 326, the Company recognized an increase in allowance for credit losses on loans of $3.1 million and the establishment of an allowance for credit losses for off-balance sheet exposure of $3.9 million and a corresponding decrease in retained earnings of $5.5 million, after-tax. The Company adopted ASC Topic 326 using the prospective transition approach for purchased credit deteriorated (“PCD”) loans, which did not require re-evaluation of whether loans previously classified as purchased credit impaired (“PCI”) loans met the criteria of PCD assets at the date of adoption. The Company recognized an increase in the allowance for credit losses for loans of $2.1 million, due to the reclass of PCD discounts previously classified as PCI with a corresponding adjustment to the gross carrying amount of the loans. The remaining noncredit discount was accreted into interest income at the effective interest rate as of January 1, 2020. See Note 6 “Loans and Allowance for Credit Losses” for additional information. The following table illustrates the impact of adopting ASC Topic 326: As of January 1, 2020 As Reported Under ASC Topic 326 Pre-ASC Topic 326 Adoption Impact of ASC Topic 326 Adoption (Dollars in thousands) Assets: Allowance for credit losses on loans: Commercial and industrial $ 15,840 $ 8,818 $ 7,022 Mortgage warehouse — — — Paycheck Protection Program (PPP) — — — Real estate: Commercial real estate (including multi-family residential) 6,007 11,170 (5,163 ) Commercial real estate construction and land development 6,051 4,421 1,630 1-4 family residential (including home equity) 5,452 3,852 1,600 Residential construction 1,056 1,057 (1 ) Consumer and other 257 120 137 Allowance for credit losses on loans $ 34,663 $ 29,438 $ 5,225 Liabilities: Allowance for credit losses on off-balance sheet exposures $ 3,866 $ — $ 3,866 ASC Topic 326 also requires expected credit losses on available for sale (AFS) debt securities to be recorded as an allowance for credit losses. For certain types of debt securities, such as U.S. Treasuries and other securities with government guarantees, entities may expect zero credit losses. The zero-loss expectation generally applies to the Company’s securities and no allowance for credit losses were recorded on its AFS securities portfolio at transition. See Note 5 “Securities” for additional information. ASU No. 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” ASU 2017-04 eliminates Step 2 from the goodwill impairment test which required entities to compute the implied fair value of goodwill. Under ASU 2017-04, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. ASU 2017-04 became effective for the Company on January 1, 2020 and did not have a significant impact on the Company's financial statements. ASU 2016-02, “Leases (Topic 842)." ASU 2016-02 requires lessees to recognize a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. ASU 2016-02 does not significantly change lease accounting requirements applicable to lessors; however, certain changes were made to align, where necessary, lessor accounting with the lessee accounting model and ASC Topic 606, “Revenue from Contracts with Customers.” ASU 2016-02 became effective for the Company on January 1, 2019. The Company adopted the standard through the required modified retrospective approach by applying the allowed transition method whereby comparative periods were not restated and a cumulative effect adjustment to the opening balance of retained earnings was recognized as of January 1, 2019. Topic 842 requires the recognition of a lease liability measured as the present value of unpaid lease payments for operating leases where the Company is the lessee, and a corresponding right-of-use (ROU) asset for the right to use the leased properties. The Company elected not to reassess whether contracts are or contain leases, lease classification or initial direct costs for existing leases, a set of practical expedients for transition provided by ASU 2016-12. Further, the Company elected the practical expedient to use hindsight in determining the lease term and assessing impairment. The election of the hindsight practical expedient resulted in longer lease terms for a limited number of strategic locations based on relevant factors as of the adoption date. The Company implemented a lease management system to assist in centralizing, maintaining and accounting for all leases to ensure the Company meets the ASU’s reporting and disclosure requirements. Prior comparable periods are presented in accordance with previous guidance under Accounting Standards Codification (ASC) 840, “Leases.” As of January 1, 2019, right-of-use assets and related lease liabilities totaled $15.3 million and $15.7 million, respectively. See Note 9 – Leases for further information regarding the Company’s leases on certain properties and equipment under operating leases. ASU 2017-08, “Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20) - Premium Amortization on Purchased Callable Debt Securities.” ASU 2017-08 shortens the amortization period for certain callable debt securities held at a premium to require such premiums to be amortized to the earliest call date unless applicable guidance related to certain pools of securities is applied to consider estimated prepayments. Under prior guidance, entities were generally required to amortize premiums on individual, non-pooled callable debt securities as a yield adjustment over the contractual life of the security. ASU 2017-08 does not change the accounting for callable debt securities held at a discount. ASU 2017-08 became effective for the Company on January 1, 2019. Upon adoption, the Company recognized a cumulative effect reduction in retained earnings totaling $1.7 million. Newly Issued But Not Yet Effective Accounting Standards ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), that removes certain exceptions for investments, intraperiod allocations and interim calculations, and adds guidance to reduce complexity in accounting for income taxes. ASU 2019-12 introduces the following new guidance: i) guidance to evaluate whether a step-up in tax basis of goodwill relates to a business combination in which book goodwill was recognized or a separate transaction and ii) a policy election to not allocate consolidated income taxes when a member of a consolidated tax return is not subject to income tax. Additionally, ASU 2019-12 changes the following current guidance: i) making an intraperiod allocation, if there is a loss in continuing operations and gains outside of continuing operations, ii) determining when a deferred tax liability is recognized after an investor in a foreign entity transitions to or from the equity method of accounting, iii) accounting for tax law changes and year-to-date losses in interim periods, and iv) determining how to apply the income tax guidance to franchise taxes that are partially based on income. ASU 2019-12 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, with early adoption permitted. ASU 2019-12 is not expected to have a material impact on the Company’s results of operations, financial position or disclosures. ASU 2020-04, "Reference Rate Reform: Facilitation of the Effects of Reference Rate Reform on Financial Reporting - Accounting Standards Codification (“ASC”) Topic 848." ASU 2020-04 provides optional expedients and exceptions for applying GAAP to loan and lease agreements, derivative contracts, and other transactions affected by the anticipated transition away from LIBOR toward new interest rate benchmarks. The guidance allows for companies to: (i) account for certain contract modifications as a continuation of the existing contract without additional analysis; (ii) continue hedge accounting when certain critical terms of a hedging relationship change and assess effectiveness in ways that disregard certain potential sources of ineffectiveness; and (iii) make a one-time sale and/or transfer of certain debt securities from held-to-maturity to available for sale or trading. This ASU is available for adoption effective March 12, 2020 through December 31, 2022. An entity may elect to apply ASU 2020-04 for contract modifications as of January 1, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic within ASU 2020-04, the amendments must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The one-time election to sell and/or transfer debt securities classified as held-to-maturity may be made at any time after March 12, 2020. The Company anticipates this ASU will simplify any modifications it executes between the selected start date (yet to be determined) and December 31, 2022 that are directly related to the LIBOR transition by allowing prospective recognition of the continuation of the contract, rather than extinguishment of the old contract resulting in writing off unamortized fees and costs. ASU 2020-04 is not expected to have a significant impact on the Company’s financial statements.

NATURE OF OPERATIONS AND SUMM_3

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Schedule of Impact of Adopting ASC Topic 326	The following table illustrates the impact of adopting ASC Topic 326: As of January 1, 2020 As Reported Under ASC Topic 326 Pre-ASC Topic 326 Adoption Impact of ASC Topic 326 Adoption (Dollars in thousands) Assets: Allowance for credit losses on loans: Commercial and industrial $ 15,840 $ 8,818 $ 7,022 Mortgage warehouse — — — Paycheck Protection Program (PPP) — — — Real estate: Commercial real estate (including multi-family residential) 6,007 11,170 (5,163 ) Commercial real estate construction and land development 6,051 4,421 1,630 1-4 family residential (including home equity) 5,452 3,852 1,600 Residential construction 1,056 1,057 (1 ) Consumer and other 257 120 137 Allowance for credit losses on loans $ 34,663 $ 29,438 $ 5,225 Liabilities: Allowance for credit losses on off-balance sheet exposures $ 3,866 $ — $ 3,866

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	12 Months Ended
	Dec. 31, 2020
Business Acquisition [Line Items]
Schedule of Purchase Price Allocation	As of September 30, 2019, the Company finalized its valuation of all assets and liabilities acquired. A summary of the final purchase price allocation is as follows (dollars in thousands): Fair value of consideration paid: Common shares issued (8,402,010 shares) $ 350,364 Stock options issued (299,352) 8,639 Cash in lieu of fractional shares 21 Total consideration paid $ 359,024 Fair value of assets acquired: Cash and cash equivalents $ 230,416 Investment securities 42,779 Loans 1,164,281 Premises and equipment 21,988 Core deposit intangibles 25,128 Other assets 18,076 Total assets acquired $ 1,502,668 Fair value of liabilities assumed: Deposits $ 1,291,310 Other borrowed funds 30,000 Other liabilities 6,070 Total liabilities assumed 1,327,380 Fair value of net assets acquired $ 175,288 Goodwill resulting from acquisition $ 183,736
Schedule of Details of Loans Acquired	The following presents details of all loans acquired as of October 1, 2018: Contractual Balance Fair Value Discount (Dollars in thousands) Commercial and industrial $ 221,098 $ 217,204 $ (3,894 ) Real estate: Commercial real estate (including multi-family residential) 450,947 443,512 (7,435 ) Commercial real estate construction and land development 167,386 165,387 (1,999 ) 1-4 family residential (including home equity) 288,304 285,099 (3,205 ) Residential construction 23,812 23,812 — Consumer and other 29,684 29,267 (417 ) Total loans $ 1,181,231 $ 1,164,281 $ (16,950 )
Schedule of Pro Forma Information	The following table presents unaudited pro forma financial information as if the acquisition had occurred at the beginning of 2017. Post Oak’s results of operations were included in the Company’s results beginning October 1, 2018. The pro forma financial information is not necessarily indicative of the results of operations that would have occurred had the transaction been effected on the assumed dates. For the Years Ended December 31, 2018 2017 (Dollars in thousands, except per share data) Net interest income $ 170,801 $ 165,612 Noninterest income 10,060 9,543 Net income 41,807 35,107 Basic earnings per common share 2.70 1.63 Diluted earnings per common share 2.65 1.61
PCI Loans
Business Acquisition [Line Items]
Schedule of PCI Loans and Non-PCI Loans Acquired in Transactions	The following presents information at the acquisition date for PCI loans acquired in the transaction (dollars in thousands): Contractually required principal and interest payments $ 28,340 Contractual cash flows not expected to be collected (nonaccretable difference) (3,163 ) Expected cash flows at acquisition 25,177 Interest component of expected cash flows (accretable yield) (495 ) Fair value of loans acquired with deterioration of credit quality $ 25,672
Non-PCI Loans
Business Acquisition [Line Items]
Schedule of PCI Loans and Non-PCI Loans Acquired in Transactions	The following table presents information at the acquisition date for non-PCI loans acquired in the transaction (dollars in thousands): Contractually required principal and interest payments $ 1,152,892 Accretable discount (13,293 ) Fair value at acquisition $ 1,166,185

GOODWILL AND CORE DEPOSIT INT_2

GOODWILL AND CORE DEPOSIT INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets and Goodwill	Changes in the carrying amount of the Company’s goodwill and core deposit intangibles were as follows: Core Deposit Goodwill Intangibles (Dollars in thousands) Balance as of December 31, 2017 $ 39,389 $ 3,274 Acquisition of Post Oak Bancshares, Inc. 183,736 25,128 Amortization — (1,815 ) Balance as of December 31, 2018 223,125 26,587 Acquisition of LoweryBank branch 578 — Measurement period adjustment (61 ) — Amortization — (4,711 ) Balance as of December 31, 2019 223,642 21,876 Amortization — (3,922 ) Balance as of December 31, 2020 $ 223,642 $ 17,954
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The estimated aggregate future amortization expense for core deposit intangibles remaining as of December 31, 2020 is as follows (dollars in thousands): 2021 $ 3,296 2022 3,003 2023 2,323 2024 2,188 2025 2,061 Thereafter 5,083 Total $ 17,954

SECURITIES (Tables)

SECURITIES (Tables)	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Available-for-sale Securities	The amortized cost and fair value of investment securities were as follows: December 31, 2020 Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value (Dollars in thousands) Available for Sale U.S. government and agency securities $ 25,545 $ 654 $ — $ 26,199 Municipal securities 392,586 35,079 (60 ) 427,605 Agency mortgage-backed pass-through securities 167,606 3,829 (146 ) 171,289 Agency collateralized mortgage obligations 80,182 4,263 (75 ) 84,370 Corporate bonds and other 62,124 1,352 (49 ) 63,427 Total $ 728,043 $ 45,177 $ (330 ) $ 772,890 December 31, 2019 Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value (Dollars in thousands) Available for Sale U.S. government and agency securities $ 29,420 $ 298 $ (243 ) $ 29,475 Municipal securities 84,200 3,453 (116 ) 87,537 Agency mortgage-backed pass-through securities 104,669 1,713 (214 ) 106,168 Agency collateralized mortgage obligations 106,351 1,199 (208 ) 107,342 Corporate bonds and other 41,691 346 (14 ) 42,023 Total $ 366,331 $ 7,009 $ (795 ) $ 372,545
Investments Classified by Contractual Maturity Date	The amortized cost and fair value of investment securities at December 31, 2020, by contractual maturity, are shown below. Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations at any time with or without call or prepayment penalties. Amortized Fair Cost Value (Dollars in thousands) Due in one year or less $ 110 $ 110 Due after one year through five years 12,849 13,412 Due after five years through ten years 105,239 109,238 Due after ten years 362,057 394,471 Subtotal 480,255 517,231 Agency mortgage-backed pass through and collateralized mortgage obligation securities 247,788 255,659 Total $ 728,043 $ 772,890
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	Securities with unrealized losses segregated by length of time such securities have been in a continuous loss position are as follows: December 31, 2020 Less than 12 Months More than 12 Months Total Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses (Dollars in thousands) Available for Sale Agency mortgage-backed pass-through securities $ 28,659 $ (146 ) $ — $ — $ 28,659 $ (146 ) Agency collateralized mortgage obligations 11,629 (39 ) 4,203 (36 ) 15,832 (75 ) Municipal securities 8,844 (60 ) — — 8,844 (60 ) Corporate bonds and other 15,951 (49 ) — — 15,951 (49 ) Total $ 65,083 $ (294 ) $ 4,203 $ (36 ) $ 69,286 $ (330 ) December 31, 2019 Less than 12 Months More than 12 Months Total Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses (Dollars in thousands) Available for Sale U.S. government and agency securities $ 22,295 $ (239 ) $ 436 $ (4 ) $ 22,731 $ (243 ) Agency mortgage-backed pass-through securities 20,792 (155 ) 4,369 (59 ) 25,161 (214 ) Agency collateralized mortgage obligations 22,340 (208 ) — — 22,340 (208 ) Municipal securities 9,514 (116 ) — — 9,514 (116 ) Corporate bonds and other 5,492 (14 ) — — 5,492 (14 ) Total $ 80,433 $ (732 ) $ 4,805 $ (63 ) $ 85,238 $ (795 )

LOANS AND ALLOWANCE FOR CREDI_2

LOANS AND ALLOWANCE FOR CREDIT LOSSES (Tables)	12 Months Ended
	Dec. 31, 2020
Accounts Notes And Loans Receivable [Line Items]
Schedule of Accounts, Notes, Loans and Financing Receivable	The loan portfolio balances, net of unearned income and fees, consist of various types of loans primarily all made to borrowers located within Texas and are classified by major type as follows: December 31, 2020 December 31, 2019 (Dollars in thousands) Commercial and industrial $ 667,079 $ 689,360 Mortgage warehouse — 8,304 Paycheck Protection Program (PPP) 569,901 — Real estate: Commercial real estate (including multi-family residential) 1,999,877 1,873,782 Commercial real estate construction and land development 367,213 410,471 1-4 family residential (including home equity) 737,605 698,957 Residential construction 127,522 192,515 Consumer and other 22,567 41,921 Total loans 4,491,764 3,915,310 Allowance for credit losses on loans (53,173 ) (29,438 ) Loans, net $ 4,438,591 $ 3,885,872
Schedule of Related Party Transactions	An analysis of activity with respect to these related-party loans is as follows: 2020 (Dollars in thousands) Beginning balance on January 1 $ 6,782 New loans and reclassified related loans 90 Repayments and reclassified related loans (5,689 ) Ending balance on December 31 $ 1,183
Past Due Financing Receivables	An aging analysis of the recorded investment in past due loans, segregated by class of loans, is included below. For purposes of this and future disclosures recorded investment has been defined as the outstanding loan balances including net deferred loan fees, and excluding accrued interest receivable of $34.5 million and $15.5 million as of December 31, 2020 and 2019, respectively, due to immateriality. December 31, 2020 Loans Past Due and Still Accruing 30-89 90 or More Total Past Nonaccrual Current Total Days Days Due Loans Loans Loans Loans (Dollars in thousands) Commercial and industrial $ 2,486 $ — $ 2,486 $ 10,747 $ 653,846 $ 667,079 Mortgage warehouse — — — — — — Paycheck Protection Program (PPP) — — — — 569,901 569,901 Real estate: Commercial real estate (including multi-family residential) 3,063 — 3,063 10,081 1,986,733 1,999,877 Commercial real estate construction and land development 2,930 — 2,930 3,011 361,272 367,213 1-4 family residential (including home equity) 3,000 — 3,000 4,525 730,080 737,605 Residential construction — — — — 127,522 127,522 Consumer and other 46 — 46 529 21,992 22,567 Total loans $ 11,525 $ — $ 11,525 $ 28,893 $ 4,451,346 $ 4,491,764 December 31, 2019 Loans Past Due and Still Accruing 30-89 90 or More Total Past Nonaccrual Current Total Days Days Due Loans Loans Loans Loans (Dollars in thousands) Commercial and industrial $ 3,098 $ — $ 3,098 $ 8,388 $ 677,874 $ 689,360 Mortgage warehouse — — — — 8,304 8,304 Real estate: Commercial real estate (including multi-family residential) 4,421 — 4,421 6,741 1,862,620 1,873,782 Commercial real estate construction and land development 66 — 66 9,050 401,355 410,471 1-4 family residential (including home equity) 1,598 — 1,598 3,294 694,065 698,957 Residential construction 564 — 564 746 191,205 192,515 Consumer and other 254 — 254 152 41,515 41,921 Total loans $ 10,001 $ — $ 10,001 $ 28,371 $ 3,876,938 $ 3,915,310
Risk Ratings by Category of Loans	The following table presents risk ratings by category of loan as of December 31, 2020 and 2019: As of December 31, 2020 As of December 31, 2019 Term Loans Amortized Cost Basis by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Loans Total Total (Dollars in thousands) Commercial and industrial Pass $ 149,522 $ 81,526 $ 46,909 $ 17,610 $ 20,955 $ 6,951 $ 239,045 $ — $ 562,518 $ 637,388 Watch 12,755 6,956 6,600 2,436 1,446 1,067 9,766 — 41,026 14,797 Special Mention 758 2,746 3,740 1,860 2,756 — 13,150 — 25,010 10,871 Substandard 12,650 4,272 3,798 7,043 2,577 99 7,946 — 38,385 26,226 Doubtful 69 71 — — — — — — 140 78 Total commercial and industrial loans $ 175,754 $ 95,571 $ 61,047 $ 28,949 $ 27,734 $ 8,117 $ 269,907 $ — $ 667,079 $ 689,360 Mortgage warehouse Pass $ — $ — $ — $ — $ — $ — $ — $ — $ — $ 8,304 Watch — — — — — — — — — — Special Mention — — — — — — — — — — Substandard — — — — — — — — — — Doubtful — — — — — — — — — — Total mortgage warehouse loans $ — $ — $ — $ — $ — $ — $ — $ — $ — $ 8,304 Paycheck Protection Program (PPP) Pass $ 569,901 $ — $ — $ — $ — $ — $ — $ — $ 569,901 $ — Watch — — — — — — — — — — Special Mention — — — — — — — — — — Substandard — — — — — — — — — — Doubtful — — — — — — — — — — Total PPP loans $ 569,901 $ — $ — $ — $ — $ — $ — $ — $ 569,901 $ — Commercial real estate (including multi-family residential) Pass $ 587,089 $ 321,020 $ 220,554 $ 221,147 $ 156,671 $ 75,353 $ 47,189 $ — $ 1,629,023 $ 1,760,476 Watch 27,851 45,009 23,492 32,567 24,051 23,531 1,150 — 177,651 56,367 Special Mention 10,931 16,452 9,940 12,128 3,243 14,482 1,100 — 68,276 11,974 Substandard 17,391 27,265 18,926 20,688 27,595 10,896 2,166 — 124,927 44,965 Doubtful — — — — — — — — — — Total commercial real estate (including multi-family residential) loans $ 643,262 $ 409,746 $ 272,912 $ 286,530 $ 211,560 $ 124,262 $ 51,605 $ — $ 1,999,877 $ 1,873,782 Commercial real estate construction and land development Pass $ 172,389 $ 77,535 $ 31,392 $ 16,712 $ 5,098 $ 2,036 $ 14,971 $ — $ 320,133 $ 385,832 Watch 12,801 2,943 4,315 13,157 5,290 515 — — 39,021 9,583 Special Mention 615 1,620 378 — — 267 — — 2,880 639 Substandard 2,958 986 693 — — — 542 — 5,179 14,417 Doubtful — — — — — — — — — — Total commercial real estate construction and land development $ 188,763 $ 83,084 $ 36,778 $ 29,869 $ 10,388 $ 2,818 $ 15,513 $ — $ 367,213 $ 410,471 The following table presents risk ratings by category of loan as of December 31, 2020 and 2019: As of December 31, 2020 As of December 31, 2019 Term Loans Amortized Cost Basis by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Loans Total Total (Dollars in thousands) 1-4 family residential (including home equity) Pass $ 212,543 $ 128,835 $ 101,091 $ 67,257 $ 44,666 $ 27,846 $ 87,836 $ — $ 670,074 $ 669,288 Watch 14,153 3,565 4,406 5,994 2,099 3,138 4,312 — 37,667 15,798 Special Mention 6,237 728 4,312 674 2,379 2,006 2,454 — 18,790 5,844 Substandard 1,392 2,308 2,576 1,238 1,869 1,422 269 — 11,074 8,027 Doubtful — — — — — — — — — — Total 1-4 family residential (including home equity) $ 234,325 $ 135,436 $ 112,385 $ 75,163 $ 51,013 $ 34,412 $ 94,871 $ — $ 737,605 $ 698,957 Residential construction Pass $ 106,804 $ 10,330 $ 5,288 $ 742 $ 1,573 $ — $ — $ — $ 124,737 $ 188,636 Watch 2,036 749 — — — — — — 2,785 2,560 Special Mention — — — — — — — — — — Substandard — — — — — — — — — 1,319 Doubtful — — — — — — — — — — Total residential construction $ 108,840 $ 11,079 $ 5,288 $ 742 $ 1,573 $ — $ — $ — $ 127,522 $ 192,515 Consumer and other Pass (1) $ (6,193 ) $ 20,578 $ 1,537 $ 586 $ 25 $ 122 $ 4,704 $ — $ 21,359 $ 41,355 Watch 57 242 27 — — — 63 — 389 6 Special Mention 231 — 39 — — — — — 270 358 Substandard 491 33 25 — — — — — 549 202 Doubtful — — — — — — — — — — Total consumer and other $ (5,414 ) $ 20,853 $ 1,628 $ 586 $ 25 $ 122 $ 4,767 $ — $ 22,567 $ 41,921 Total loans Pass $ 1,792,055 $ 639,824 $ 406,771 $ 324,054 $ 228,988 $ 112,308 $ 393,745 $ — $ 3,897,745 $ 3,691,279 Watch 69,653 59,464 38,840 54,154 32,886 28,251 15,291 — 298,539 99,111 Special Mention 18,772 21,546 18,409 14,662 8,378 16,755 16,704 — 115,226 29,686 Substandard 34,882 34,864 26,018 28,969 32,041 12,417 10,923 — 180,114 95,156 Doubtful 69 71 — — — — — — 140 78 Total loans $ 1,915,431 $ 755,769 $ 490,038 $ 421,839 $ 302,293 $ 169,731 $ 436,663 $ — $ 4,491,764 $ 3,915,310 (1) Includes net deferred fees of $13.9 million on PPP loans.
Allowance for Credit Losses on Financing Receivables	The following table presents the activity in the allowance for credit losses on loans by portfolio type for the years ended December 31, 2020, 2019 and 2018: Commercial and Mortgage warehouse Paycheck Protection Program (PPP) Commercial real estate (including multi-family residential) Commercial real estate construction and land development 1-4 family residential (including home equity) Residential construction Consumer and other Total (Dollars in thousands) Allowance for credit losses on loans: Balance December 31, 2019 $ 8,818 $ — $ — $ 11,170 $ 4,421 $ 3,852 $ 1,057 $ 120 $ 29,438 Impact of ASC 326 adoption 7,022 — — (5,163 ) 1,630 1,600 (1 ) 137 5,225 Provision for loan losses 4,363 — — 20,417 3,461 (1,822 ) (186 ) 310 26,543 Charge-offs (2,938 ) — — (2,562 ) (2,573 ) (351 ) — (159 ) (8,583 ) Recoveries 473 — — 72 — — — 5 550 Net charge-offs (2,465 ) — — (2,490 ) (2,573 ) (351 ) — (154 ) (8,033 ) Balance December 31, 2020 $ 17,738 $ — $ — $ 23,934 $ 6,939 $ 3,279 $ 870 $ 413 $ 53,173 Allowance for loan losses: Balance December 31, 2018 $ 8,351 $ — $ — $ 11,901 $ 2,724 $ 2,242 $ 1,040 $ 73 $ 26,331 Provision for loan losses 2,881 — — (654 ) 1,741 1,905 17 49 5,939 Charge-offs (2,688 ) — — (80 ) (44 ) (295 ) — (34 ) (3,141 ) Recoveries 274 — — 3 — — — 32 309 Net charge-offs (2,414 ) — — (77 ) (44 ) (295 ) — (2 ) (2,832 ) Balance December 31, 2019 $ 8,818 $ — $ — $ 11,170 $ 4,421 $ 3,852 $ 1,057 $ 120 $ 29,438 Allowance for loan losses: Balance December 31, 2017 $ 7,694 $ — $ — $ 10,253 $ 2,525 $ 2,140 $ 942 $ 95 $ 23,649 Provision for loan losses 2,234 — — 1,588 199 127 98 2 4,248 Charge-offs (2,424 ) — — (42 ) — (25 ) — (24 ) (2,515 ) Recoveries 847 — — 102 — — — — 949 Net charge-offs (1,577 ) — — 60 — (25 ) — (24 ) (1,566 ) Balance December 31, 2018 $ 8,351 $ — $ — $ 11,901 $ 2,724 $ 2,242 $ 1,040 $ 73 $ 26,331
Summary of Activity in Allowance for Credit Losses on Unfunded Commitments	The following table details activity in the allowance for credit losses on unfunded commitments: As of December 31, 2020 (Dollars in thousands) Balance at beginning of period on January 1 $ 3,866 Provision for credit losses on off-balance sheet exposures 831 Balance at end of period on December 31 $ 4,697
Summary of Amortized Cost Basis of Collateral Dependent Loans Individually Evaluated to Determine Expected Credit Losses	The following table presents the amortized cost basis of collateral dependent loans, which are individually evaluated to determine expected credit losses: As of December 31, 2020 Real Estate Business Assets Other Total (Dollars in thousands) Commercial and industrial $ — $ 5,157 $ — $ 5,157 Mortgage warehouse — — — — Paycheck Protection Program (PPP) — — — — Real estate: Commercial real estate (including multi-family residential) 425 — — 425 Commercial real estate construction and land development — — — — 1-4 family residential (including home equity) 3,101 — — 3,101 Residential construction — — — — Consumer and other — — — — Total $ 3,526 $ 5,157 $ — $ 8,683
Summary of Nonaccrual Loans	The following table presents additional information regarding nonaccrual loans. No interest income was recognized on nonaccrual loans for the years ended December 31, 2020 and 2019, respectively. As of December 31, 2020 Nonaccrual Loans with No Related Allowance Nonaccrual Loans with Related Allowance Total Nonaccrual Loans (Dollars in thousands) Commercial and industrial $ 2,097 $ 8,650 $ 10,747 Mortgage warehouse — — — Paycheck Protection Program (PPP) — — — Real estate: Commercial real estate (including multi-family residential) 7,487 2,594 10,081 Commercial real estate construction and land development 2,958 53 3,011 1-4 family residential (including home equity) 2,652 1,873 4,525 Residential construction — — — Consumer and other — 529 529 Total loans $ 15,194 $ 13,699 $ 28,893
Impaired Financing Receivables	The following table presents impaired loans at December 31, 2019 as determined under ASC 310 prior to the adoption of ASC Topic 326 by class of loans. As of December 31, 2019 Unpaid Recorded Principal Related Investment Balance Allowance (Dollars in thousands) With no related allowance recorded: Commercial and industrial $ 5,721 $ 6,136 $ — Mortgage warehouse — — — Real estate: Commercial real estate (including multi-family residential) 19,478 19,558 — Commercial real estate construction and land development — — — 1-4 family residential (including home equity) 2,000 2,000 — Residential construction 208 208 — Consumer and other 38 38 — Total 27,445 27,940 — With an allowance recorded: Commercial and industrial 7,812 7,286 3,480 Mortgage warehouse — — — Real estate: Commercial real estate (including multi-family residential) 5,335 5,335 459 Commercial real estate construction and land development 12,142 12,142 2,085 1-4 family residential (including home equity) — — — Residential construction 537 537 66 Consumer and other 26 26 26 PCI 2,039 2,959 659 Total 27,891 28,285 6,775 Total: Commercial and industrial 13,533 13,422 3,480 Mortgage warehouse — — — Real estate: Commercial real estate (including multi-family residential) 24,813 24,893 459 Commercial real estate construction and land development 12,142 12,142 2,085 1-4 family residential (including home equity) 2,000 2,000 — Residential construction 745 745 66 Consumer and other 64 64 26 PCI 2,039 2,959 659 $ 55,336 $ 56,225 $ 6,775 The following table presents average impaired loans and interest recognized on impaired loans for the year ended December 31, 2019: For the Year Ended December 31, 2019 Average Interest Recorded Income Investment Recognized (Dollars in thousands) Commercial and industrial $ 13,376 $ 399 Mortgage warehouse — — Paycheck Protection Program (PPP) — — Real estate: Commercial real estate (including multi-family residential) 25,856 489 Commercial real estate construction and land development 10,251 185 1-4 family residential (including home equity) 2,058 6 Residential construction 594 — Consumer and other 75 1 PCI 3,133 8 Total $ 55,343 $ 1,088
Troubled Debt Restructurings on Financing Receivables	The following table presents information regarding loans modified in a troubled debt restructuring during the years ended December 31, 2020, 2019 and 2018: As of December 31, 2020 2019 2018 Number of Contracts Pre-Modification of Outstanding Recorded Investment Post Modification of Outstanding Recorded Investment Number of Contracts Pre-Modification of Outstanding Recorded Investment Post Modification of Outstanding Recorded Investment Number of Contracts Pre-Modification of Outstanding Recorded Investment Post Modification of Outstanding Recorded Investment (Dollars in thousands) Troubled Debt Restructurings Commercial and industrial 20 $ 4,333 $ 4,333 13 $ 4,358 $ 4,358 11 $ 2,770 $ 2,770 Mortgage warehouse — — — — — — — — — Real estate: Commercial real estate (including multi-family residential) 5 4,560 4,560 1 303 303 3 4,288 4,288 Commercial real estate construction and land development 1 830 830 — — — 1 3,114 3,114 1-4 family residential (including home equity) 5 2,051 2,051 1 396 396 — — — Residential construction — — — — — — — — — Consumer and other 1 30 30 2 43 43 — — — Total 32 $ 11,804 $ 11,804 17 $ 5,100 $ 5,100 15 $ 10,172 $ 10,172
Schedule of Principal and Interest Deferrals Associated with Loan Modifications Related to COVID 19	The following table presents information regarding principal and interest deferrals as of December 31, 2020 associated with loan modifications related to COVID-19: Initial Deferrals Additional Deferrals Remaining Deferrals Outstanding Loan Balance Deferred Loan Balance Percentage of Total Deferrals Deferred Loan Balance Percentage of Total Deferrals Deferred Loan Balance Percentage of Total Deferrals (Dollars in thousands) Commercial and industrial $ 667,079 $ 127,689 11.3 % $ 21,747 9.5 % $ 23,822 14.8 % Mortgage warehouse — — 0.0 % — 0.0 % — 0.0 % Paycheck Protection Program (PPP) 569,901 — 0.0 % — 0.0 % — 0.0 % Real estate: Commercial real estate (including multi-family residential) 1,999,877 790,468 69.9 % 171,945 75.5 % 129,067 80.0 % Commercial real estate construction and land development 367,213 88,446 7.8 % 20,032 8.8 % 5,860 3.6 % 1-4 family residential (including home equity) 737,605 118,595 10.5 % 12,922 5.7 % 2,489 1.6 % Residential construction 127,522 4,452 0.4 % 926 0.4 % — 0.0 % Consumer and other 22,567 1,015 0.1 % 172 0.1 % 59 0.0 % Total loans $ 4,491,764 $ 1,130,665 100.0 % $ 227,744 100.0 % $ 161,297 100.0 %
PCI Loans
Accounts Notes And Loans Receivable [Line Items]
Carrying Amount of PCI Loans	The carrying amount of PCI loans included in the consolidated balance sheet and the related outstanding balance owed at December 31, 2019 are presented in the table below (dollars in thousands): As of December 31, 2019 Outstanding balance $ 16,589 Less: Discount (2,414 ) Less: Allowance (259 ) Recorded investment $ 13,916
Non-PCI Loans
Accounts Notes And Loans Receivable [Line Items]
Recorded Investment of Non-PCI Loans	The recorded investment of Non-PCI loans included in the consolidated balance sheet and the related outstanding balance owed are presented in the table below (dollars in thousands). As of December 31, 2019 Outstanding balance $ 672,927 Less: Discount (3,069 ) Recorded investment $ 669,858
Changes in or Discount Accretion for Non-PCI Loans	Changes in the discount accretion for Non-PCI loans were as follows (dollars in thousands): As of December 31, 2019 Balance at beginning of period $ 10,650 Additions 573 Accretion (8,154 ) Balance at end of period $ 3,069

FAIR VALUE (Tables)

FAIR VALUE (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value, by Balance Sheet Grouping	The carrying amounts and estimated fair values of financial instruments that are reported on the balance sheet are as follows: As of December 31, 2020 Carrying Estimated Fair Value Amount Level 1 Level 2 Level 3 Total (Dollars in thousands) Financial assets Cash and cash equivalents $ 422,766 $ 422,766 $ — $ — $ 422,766 Available for sale securities 772,890 — 772,890 — 772,890 Loans held for investment, net of allowance 4,438,591 — — 4,431,816 4,431,816 Accrued interest receivable 40,053 2 5,531 34,520 40,053 Financial liabilities Deposits $ 4,988,482 $ — $ 5,003,594 $ — $ 5,003,594 Interest rate swap 1,252 — 1,252 — 1,252 Accrued interest payable 2,701 — 2,701 — 2,701 Borrowed funds 155,515 — 144,629 — 144,629 Subordinated debt 108,322 — 109,832 — 109,832 As of December 31, 2019 Carrying Estimated Fair Value Amount Level 1 Level 2 Level 3 Total (Dollars in thousands) Financial assets Cash and cash equivalents $ 346,248 $ 346,248 $ — $ — $ 346,248 Available for sale securities 372,545 — 372,545 — 372,545 Loans held for investment, net of allowance 3,885,872 — — 3,918,210 3,918,210 Accrued interest receivable 15,468 13 1,783 13,672 15,468 Financial liabilities Deposits $ 4,068,101 $ — $ 4,073,031 $ — $ 4,073,031 Accrued interest payable 4,326 — 4,326 — 4,326 Borrowed funds 75,503 — 83,302 — 83,302 Subordinated debt 107,799 — 109,607 — 109,607
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables present fair values for assets measured at fair value on a recurring basis: December 31, 2020 Level 1 Level 2 Level 3 Total (Dollars in thousands) Financial assets Available for sale securities: U.S. government and agency securities $ — $ 26,199 $ — $ 26,199 Municipal securities — 427,605 — 427,605 Agency mortgage-backed pass-through securities — 171,289 — 171,289 Agency collateralized mortgage obligations — 84,370 — 84,370 Corporate bonds and other — 63,427 — 63,427 Total available for sale securities $ — $ 772,890 $ — $ 772,890 Financial liabilities Interest rate swap $ — $ 1,252 $ — $ 1,252 December 31, 2019 Level 1 Level 2 Level 3 Total (Dollars in thousands) Financial assets Available for sale securities: U.S. government and agency securities $ — $ 29,475 $ — $ 29,475 Municipal securities — 87,537 — 87,537 Agency mortgage-backed pass-through securities — 106,168 — 106,168 Agency collateralized mortgage obligations — 107,342 — 107,342 Corporate bonds and other — 42,023 — 42,023 Total available for sale securities $ — $ 372,545 $ — $ 372,545
Fair Value Measurements, Nonrecurring	Assets measured at fair value on a nonrecurring basis are summarized in the table below. As of December 31, 2020 Level 1 Level 2 Level 3 (Dollars in thousands) Collateral Dependent Loans: Commercial and industrial $ — $ — $ 8,650 Commercial real estate (including multi- family residential) — — 2,594 Commercial real estate construction and land development — — 53 1-4 family residential (including home equity) — — 1,873 Residential construction — — — Consumer and other — — 529 Other real estate owned — — 9,196 $ — $ — $ 22,895 As of December 31, 2019 Level 1 Level 2 Level 3 (Dollars in thousands) Impaired loans: Commercial and industrial $ — $ — $ 4,332 Commercial real estate (including multi- family residential) — — 4,876 Commercial real estate construction and land development — — 10,057 Residential construction — — 471 PCI — — 1,380 Other real estate owned — — 8,337 $ — $ — $ 29,453

PREMISES AND EQUIPMENT (Tables)

PREMISES AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Schedule of Premises and Equipment	Premises and equipment are summarized as follows: As of December 31, 2020 2019 (Dollars in thousands) Land $ 13,913 $ 13,913 Buildings 39,998 36,826 Lease right-of-use assets 11,610 11,180 Leasehold improvements 5,689 4,522 Furniture, fixtures and equipment 16,106 13,612 Construction in progress 2 250 Total 87,318 80,303 Less: accumulated depreciation 16,633 13,513 Premises and equipment, net $ 70,685 $ 66,790

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Supplemental Lease Information	Supplemental lease information at the dates indicated is as follows: December 31, 2020 December 31, 2019 (Dollars in thousands) Balance Sheet: Operating lease right of use asset classified as premises and equipment $ 11,610 $ 11,180 Operating lease liability classified as other liabilities $ 11,850 $ 11,477 Weighted average lease term, in years 5.56 5.53 Weighted average discount rate 2.86 % 3.19 %
Summary of Lease Costs	Lease costs for the dates indicated is as follows: For the Years Ended December 31, 2020 2019 (Dollars in thousands) Income Statement: Operating lease cost $ 3,270 $ 3,073 Short-term lease cost 78 553 Sublease income (66 ) (72 ) Total operating lease costs $ 3,282 $ 3,554
Maturity Analysis of Lease Liabilities	A maturity analysis of the Company’s lease liabilities is as follows: December 31, 2020 December 31, 2019 (Dollars in thousands) Lease payments due: Within one year $ 3,068 $ 2,867 After one but within two years 2,664 2,608 After two but within three years 2,056 2,204 After three but within four years 1,591 1,596 After four but within five years 1,057 1,131 After five years 2,355 2,162 Total lease payments 12,791 12,568 Discount on cash flows 941 1,091 Total lease liability $ 11,850 $ 11,477

DEPOSITS (Tables)

DEPOSITS (Tables)	12 Months Ended
	Dec. 31, 2020
Deposit Liabilities [Abstract]
Schedule of Maturities of Time Deposits	Scheduled maturities of time deposits for the next five years are as follows (dollars in thousands): Within one year $ 872,599 After one but within two years 313,154 After two but within three years 92,863 After three but within four years 39,782 After four but within five years 28,251 Total $ 1,346,649

DERIVATIVE INSTRUMENTS (Tables)

DERIVATIVE INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Summary of Cash Flow Hedge Relationships	A summary of the Company’s cash flow hedge relationship as of December 31, 2020 is as follows: Balance Sheet Location Weighted Average Maturity (In Years) Weighted Average Pay Rate Receive Rate Notional Amount Estimated Fair Value (Dollars in thousands) Liability derivatives Interest rate swaps Other liabilities 4.02 0.64% 3 month LIBOR $ 100,000 $ (1,252 )
Effect of Cash Flow Hedge Relationship on Statement of Comprehensive Income	The effects of the Company’s cash flow hedge relationship on the statement of comprehensive income during the years ended December Amount of Loss Recognized in Other Comprehensive Loss For the Years Ended December 31, 2020 2019 (Dollars in thousands) Liability derivatives Interest rate swaps $ (989 ) $ —

BORROWINGS AND BORROWING CAPA_2

BORROWINGS AND BORROWING CAPACITY (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of Maturities of Long-term Debt	Scheduled principal maturities are as follows (dollars in thousands): 2021 $ — 2022 — 2023 — 2024 569 2025 and thereafter 15,000 Total $ 15,569

SUBORDINATED DEBT (Tables)

SUBORDINATED DEBT (Tables)	12 Months Ended
	Dec. 31, 2020
Subordinated Borrowings [Abstract]
Schedule of Subordinated Borrowing	A summary of pertinent information related to the Company's issuances of junior subordinated debentures outstanding at December 31, 2020 is set forth in the table below: Description Issuance Date Trust Preferred Securities Outstanding Interest Rate (1) Junior Subordinated Debt Owed to Trusts Maturity Date (2) (Dollars in thousands) Farmers & Merchants Capital Trust II November 13, 2003 $ 7,500 3 month LIBOR + 3.00% $ 7,732 November 8, 2033 Farmers & Merchants Capital Trust III June 30, 2005 3,500 3 month LIBOR + 1.80% 3,609 July 7, 2035 $ 11,341 (1) The 3-month LIBOR in effect as of December 31, 2020 was 0.23364%. (2) All debentures are currently callable.

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Components of Provision for Federal Income Taxes	The components of the provision for federal income taxes are as follows: For the Years Ended December 31, 2020 2019 2018 (Dollars in thousands) Current $ 17,527 $ 13,514 $ 8,204 Deferred (7,090 ) (87 ) (256 ) Total $ 10,437 $ 13,427 $ 7,948
Schedule of Effective Income Tax Rate Reconciliation	Reported income tax expense differs from the amounts computed by applying the U.S. federal statutory income tax rate to income before income taxes for the years ended December 31, 2020, 2019 and 2018 due to the following: For the Years Ended December 31, 2020 2019 2018 (Dollars in thousands) Taxes calculated at statutory rate $ 11,754 $ 13,940 $ 9,504 Increase (decrease) resulting from: Stock based compensation 136 (11 ) (400 ) Effect of tax-exempt income (1,475 ) (698 ) (1,284 ) Other, net 22 196 128 Total $ 10,437 $ 13,427 $ 7,948
Schedule of Deferred Tax Assets and Liabilities	Deferred tax assets and liabilities are as follows: As of December 31, 2020 2019 (Dollars in thousands) Deferred tax assets: Allowance for credit losses $ 12,590 $ 6,432 Deferred loan fees 3,164 — Deferred compensation 655 855 Cash flow hedge 263 — Other deferred assets 342 — Total deferred tax assets 17,014 7,287 Deferred tax liabilities: Core deposit intangible and other purchase accounting adjustments (3,964 ) (3,591 ) Net unrealized gain on available for sale securities (9,417 ) (1,307 ) Premises and equipment basis difference (2,573 ) (2,099 ) Total deferred tax liabilities (15,954 ) (6,997 ) Net deferred tax assets $ 1,060 $ 290

STOCK BASED COMPENSATION (Table

STOCK BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Share-based Compensation, Stock Options, Activity	A summary of the activity in the stock option plans during the years ended December 31, 2020 and 2019 is set forth below: Weighted Weighted Average Average Aggregate Number of Exercise Remaining Intrinsic Options Price Contractual Term Value (Shares in thousands) (In years) (Dollars in thousands) Options outstanding, January 1, 2019 802 $ 18.88 4.61 $ 10,830 Options granted — — Options exercised (179 ) 15.16 Options forfeited (7 ) 24.18 Options outstanding, December 31, 2019 616 $ 19.90 4.00 $ 10,904 Options granted — — Options exercised (141 ) 15.72 Options forfeited (6 ) 20.36 Options outstanding, December 31, 2020 469 $ 21.08 3.43 $ 6,118 Options vested and exercisable, December 31, 2020 455 $ 20.58 3.34 $ 6,164
Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Grant Date Intrinsic Value	Information related to the stock option plans during each year is as follows: 2020 2019 2018 (Dollars in thousands, except per share data) Intrinsic value of options exercised $ 734 $ 751 $ 3,254 Cash received from option exercises 2,221 2,709 3,393 Weighted average fair value of options granted $ — $ — $ 18.00
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	A summary of the activity of the nonvested shares of restricted stock as of December 31, 2020 and 2019 including changes during the years then ended is as follows: Weighted Average Grant Number of Date Fair Shares Value (Shares in thousands) Nonvested share awards outstanding, January 1, 2019 143 $ 37.48 Share awards granted 88 34.97 Share awards vested (45 ) 36.70 Unvested share awards forfeited or cancelled (19 ) 38.46 Nonvested share awards outstanding, December 31, 2019 167 $ 36.23 Share awards granted 64 22.59 Share awards vested (60 ) 33.97 Unvested share awards forfeited or cancelled (13 ) 37.92 Nonvested share awards outstanding, December 31, 2020 158 $ 30.78

OFF-BALANCE SHEET ARRANGEMENT_2

OFF-BALANCE SHEET ARRANGEMENTS, COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Schedule of Fair Value, Off-balance Sheet Risks	The contractual amounts of financial instruments with off-balance sheet risk are as follows: December 31, 2020 December 31, 2019 Fixed Variable Fixed Variable Rate Rate Rate Rate (Dollars in thousands) Commitments to extend credit $ 761,938 $ 480,067 $ 507,411 $ 531,470 Standby letters of credit 9,252 8,003 10,843 4,309 Total $ 771,190 $ 488,070 $ 518,254 $ 535,779

REGULATORY CAPITAL MATTERS (Tab

REGULATORY CAPITAL MATTERS (Tables)	12 Months Ended
	Dec. 31, 2020
Banking And Thrift [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations	The following is a summary of the Company’s and the Bank’s actual and required capital ratios at December 31, 2020 and 2019: Actual Minimum Required for Capital Adequacy Purposes Minimum Required Plus Capital Conservation Buffer To Be Categorized As Well Capitalized Under Prompt Corrective Action Provisions Amount Ratio Amount Ratio Amount Ratio Amount Ratio (Dollars in thousands) ALLEGIANCE BANCSHARES, INC. (Consolidated) As of December 31, 2020 Total Capital (to risk weighted assets) $ 642,155 15.71 % $ 327,084 8.00 % $ 429,298 10.50 % N/A N/A Common Equity Tier 1 Capital (to risk weighted assets) 482,643 11.80 % 183,985 4.50 % 286,199 7.00 % N/A N/A Tier 1 Capital (to risk weighted assets) 492,281 12.04 % 245,313 6.00 % 347,527 8.50 % N/A N/A Tier 1 Capital (to average tangible assets) 492,281 8.51 % 231,518 4.00 % 231,518 4.00 % N/A N/A As of December 31, 2019 Total Capital (to risk weighted assets) $ 596,684 14.83 % $ 321,775 8.00 % $ 422,330 10.50 % N/A N/A Common Equity Tier 1 Capital (to risk weighted assets) 459,447 11.42 % 180,999 4.50 % 281,553 7.00 % N/A N/A Tier 1 Capital (to risk weighted assets) 468,972 11.66 % 241,331 6.00 % 341,886 8.50 % N/A N/A Tier 1 Capital (to average tangible assets) 468,972 10.02 % 187,146 4.00 % 187,146 4.00 % N/A N/A ALLEGIANCE BANK As of December 31, 2020 Total Capital (to risk weighted assets) $ 635,223 15.55 % $ 326,804 8.00 % $ 428,931 10.50 % $ 408,506 10.00 % Common Equity Tier 1 Capital (to risk weighted assets) 544,331 13.32 % 183,828 4.50 % 285,954 7.00 % 265,529 6.50 % Tier 1 Capital (to risk weighted assets) 544,331 13.32 % 245,103 6.00 % 347,230 8.50 % 326,804 8.00 % Tier 1 Capital (to average tangible assets) 544,331 9.41 % 231,334 4.00 % 231,334 4.00 % 289,167 5.00 % As of December 31, 2019 Total Capital (to risk weighted assets) $ 578,425 14.39 % $ 321,556 8.00 % $ 422,043 10.50 % $ 401,945 10.00 % Common Equity Tier 1 Capital (to risk weighted assets) 509,372 12.67 % 180,875 4.50 % 281,362 7.00 % 261,265 6.50 % Tier 1 Capital (to risk weighted assets) 509,372 12.67 % 241,167 6.00 % 341,654 8.50 % 321,556 8.00 % Tier 1 Capital (to average tangible assets) 509,372 10.89 % 187,018 4.00 % 187,018 4.00 % 233,773 5.00 %

EARNINGS PER COMMON SHARE (Tabl

EARNINGS PER COMMON SHARE (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Common shares issuable under restricted stock awards are considered outstanding at the date of grant and are accounted for as participating securities and included in basic and diluted weighted average common shares outstanding For the Years Ended December 31, 2020 2019 2018 Per Share Per Share Per Share Amount Amount Amount Amount Amount Amount (Amounts in thousands, except per share data) Net income attributable to shareholders $ 45,534 $ 52,959 $ 37,309 Basic: Weighted average shares outstanding 20,415 $ 2.23 21,152 $ 2.50 15,485 $ 2.41 Diluted: Add incremental shares for: Dilutive effect of stock option exercises 131 272 288 Total 20,546 $ 2.22 21,424 $ 2.47 15,773 $ 2.37

PARENT COMPANY ONLY FINANCIAL_2

PARENT COMPANY ONLY FINANCIAL STATEMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Schedule of Condensed Balance Sheet	ALLEGIANCE BANCSHARES, INC (PARENT COMPANY ONLY) CONDENSED BALANCE SHEETS December 31, 2020 2019 (Dollars in thousands) ASSETS Cash and due from banks $ 19,340 $ 17,775 Investment in subsidiary 820,699 760,131 Other assets 2,691 1,665 TOTAL $ 842,730 $ 779,571 LIABILITIES AND SHAREHOLDERS’ EQUITY LIABILITIES: Other borrowed funds $ 15,514 $ 504 Subordinated debentures 68,577 68,184 Accrued interest payable and other liabilities (30 ) 1,018 Total liabilities 84,061 69,706 SHAREHOLDERS’ EQUITY: Common stock 20,208 20,524 Capital surplus 508,794 521,066 Retained earnings 195,236 163,375 Accumulated other comprehensive income 34,431 4,900 Total shareholders’ equity 758,669 709,865 TOTAL $ 842,730 $ 779,571
Schedule of Condensed Income Statement	ALLEGIANCE BANCSHARES, INC (PARENT COMPANY ONLY) CONDENSED STATEMENTS OF INCOME For the Years Ended December 31, 2020 2019 2018 (Dollars in thousands) OPERATING INCOME: Other income $ 16 $ 25 $ 16 Total income 16 25 16 OPERATING EXPENSE: Interest expense on borrowed funds 3,497 1,459 38 Other expenses 1,595 1,922 1,692 Total operating expense 5,092 3,381 1,730 Income before income tax benefit and equity in undistributed income of subsidiaries (5,076 ) (3,356 ) (1,714 ) Income tax benefit 1,066 705 360 Income before equity in undistributed income of subsidiaries (4,010 ) (2,651 ) (1,354 ) Dividends from subsidiary and equity in undistributed income of subsidiaries 49,544 55,610 38,663 Net income $ 45,534 $ 52,959 $ 37,309
Schedule of Condensed Cash Flow Statement	ALLEGIANCE BANCSHARES, INC (PARENT COMPANY ONLY) CONDENSED STATEMENTS OF CASH FLOWS For the Years Ended December 31, 2020 2019 2018 (Dollars in thousands) CASH FLOWS FROM OPERATING ACTIVITIES: Net income $ 45,534 $ 52,959 $ 37,309 Adjustments to reconcile net income to net cash used in operating activities: Equity in undistributed earnings of subsidiaries (49,544 ) (55,610 ) (38,663 ) Net amortization of discount on subordinated debentures 392 169 110 Stock based compensation expense 3,425 3,100 1,685 Increase in other assets (1,026 ) (639 ) (236 ) (Decrease) increase in accrued interest payable and other liabilities (1,038 ) 166 279 Net cash (used in) provided by operating activities (2,257 ) 145 484 CASH FLOWS FROM INVESTING ACTIVITIES: Dividend from subsidiary 13,000 7,500 — Capital investment in bank subsidiary — — — Net cash provided by investing activities 13,000 7,500 — CASH FLOWS FROM FINANCING ACTIVITIES: Proceeds from the issuance of common stock, stock option exercises and the ESPP 2,569 3,412 3,552 Net increase in borrowings under credit agreement 15,000 — — Proceeds from subordinated notes issuance, net of offering expenses — 58,601 — Dividends paid to common shareholders (8,165 ) — — Repurchase of common stock (18,582 ) (58,663 ) (2,113 ) Net cash (used in) provided by financing activities (9,178 ) 3,350 1,439 NET CHANGE IN CASH AND CASH EQUIVALENTS 1,565 10,995 1,923 CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD 17,775 6,780 4,857 CASH AND CASH EQUIVALENTS, END OF PERIOD $ 19,340 $ 17,775 $ 6,780

QUARTERLY FINANCIAL DATA (UNA_2

QUARTERLY FINANCIAL DATA (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	Earnings Per Share (1) Interest Income Net Interest Income Net Income Attributable to Common Shareholders Basic Diluted (Dollars in thousands, except per share data) 2020 First quarter (2) $ 57,452 $ 45,025 $ 3,516 $ 0.17 $ 0.17 Second quarter (2) 60,452 50,847 9,907 0.49 0.48 Third quarter (2) 60,811 51,909 16,170 0.79 0.79 Fourth quarter 63,047 54,902 15,941 0.78 0.77 2019 First quarter $ 57,149 $ 44,603 $ 12,678 $ 0.58 $ 0.58 Second quarter 58,946 45,571 14,248 0.67 0.66 Third quarter 58,665 44,837 12,047 0.57 0.57 Fourth quarter 58,147 44,526 13,986 0.68 0.67 (1) Earnings per share are computed independently for each of the quarters presented and therefore may not total earnings per share for the year. (2) Does not reflect the adoption of ASC 326.

NATURE OF OPERATIONS AND SUMM_4

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES (Details) $ in Thousands	Jan. 01, 2020USD ($)	Feb. 01, 2019	Oct. 01, 2018	Dec. 31, 2020USD ($)officeBankSegment	Dec. 31, 2019USD ($)	Jan. 01, 2019USD ($)	Dec. 31, 2018USD ($)
New Accounting Pronouncement Early Adoption [Line Items]
Number of offices in which entity operates | office				28
Accrued interest receivable for loans outstanding				$ 34,500	$ 15,500
Debt securities available for Sale accrued interest receivable				5,500
Right-of-use assets				11,610	11,180
Lease liabilities				11,850	11,477
Other real estate owned				$ 9,200
Percentage of recognition threshold for which the largest amount of tax benefit is realized upon ultimate settlement with the related tax authority				50.00%
Number of reportable segments | Segment				1
Off-balance sheet exposure for allowance for credit losses	$ 3,866
ASU 2016-02
New Accounting Pronouncement Early Adoption [Line Items]
Right-of-use assets						$ 15,300
Lease liabilities						$ 15,700
Accounting Standards Update 2016-13
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans	3,100
Off-balance sheet exposure for allowance for credit losses	3,866
Cumulative effect of adopting new accounting principle in period of adoption					5,508
Increase in allowance for credit losses for loans	2,100
Accounting Standards Update 2016-13 | Retained Earnings
New Accounting Pronouncement Early Adoption [Line Items]
Cumulative effect of adopting new accounting principle in period of adoption	$ 5,500				$ 5,508
ASU 2017-08
New Accounting Pronouncement Early Adoption [Line Items]
Cumulative effect of adopting new accounting principle in period of adoption							$ 1,715
ASU 2017-08 | Retained Earnings
New Accounting Pronouncement Early Adoption [Line Items]
Cumulative effect of adopting new accounting principle in period of adoption				$ 1,700			$ 1,715
Minimum
New Accounting Pronouncement Early Adoption [Line Items]
Premises and equipment, useful life				3 years
Minimum | Core Deposits
New Accounting Pronouncement Early Adoption [Line Items]
Intangibles, useful life				7 years
Maximum
New Accounting Pronouncement Early Adoption [Line Items]
Premises and equipment, useful life				40 years
Maximum | Core Deposits
New Accounting Pronouncement Early Adoption [Line Items]
Intangibles, useful life				10 years
Post Oak Bancshares, Inc.
New Accounting Pronouncement Early Adoption [Line Items]
Effective date of acquisition			Oct. 1, 2018	Oct. 1, 2018
Post Oak Bancshares, Inc. | Minimum
New Accounting Pronouncement Early Adoption [Line Items]
Intangibles, useful life			10 years
Lowery Bank
New Accounting Pronouncement Early Adoption [Line Items]
Effective date of acquisition		Feb. 1, 2019		Feb. 1, 2019
Houston
New Accounting Pronouncement Early Adoption [Line Items]
Number of banks in which entity operates | Bank				27
Beaumont
New Accounting Pronouncement Early Adoption [Line Items]
Number of offices in which entity operates | office				1

NATURE OF OPERATIONS AND SUMM_5

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES - Schedule of Impact of Adopting ASC Topic 326 (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans	$ 53,173	$ 34,663	$ 29,438	$ 26,331	$ 23,649
Liabilities:
Off-balance sheet exposure for allowance for credit losses		3,866
Impact of ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		5,225	$ 5,225
Liabilities:
Off-balance sheet exposure for allowance for credit losses		3,866
Pre-ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		29,438
Commercial and industrial
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		15,840
Commercial and industrial | Impact of ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		7,022
Commercial and industrial | Pre-ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		8,818
Commercial real estate (including multi-family residential)
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		6,007
Commercial real estate (including multi-family residential) | Impact of ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		(5,163)
Commercial real estate (including multi-family residential) | Pre-ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		11,170
Commercial real estate construction and land development
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		6,051
Commercial real estate construction and land development | Impact of ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		1,630
Commercial real estate construction and land development | Pre-ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		4,421
1-4 family residential (including home equity)
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		5,452
1-4 family residential (including home equity) | Impact of ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		1,600
1-4 family residential (including home equity) | Pre-ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		3,852
Residential construction
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		1,056
Residential construction | Impact of ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		(1)
Residential construction | Pre-ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		1,057
Consumer and other
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		257
Consumer and other | Impact of ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		137
Consumer and other | Pre-ASC Topic 326 Adoption
New Accounting Pronouncement Early Adoption [Line Items]
Allowance for credit losses on loans		$ 120

ACQUISITIONS - Narrative (Detai

ACQUISITIONS - Narrative (Details) $ / shares in Units, $ in Thousands	Feb. 01, 2019USD ($)	Oct. 01, 2018USD ($)branch$ / sharesshares	Sep. 30, 2019USD ($)shares	Dec. 31, 2020$ / shares	Dec. 31, 2019USD ($)$ / shares	Dec. 31, 2018USD ($)	Sep. 28, 2018USD ($)$ / shares
Business Acquisition [Line Items]
Options exercised | $ / shares				$ 15.72	$ 15.16
Lowery Bank
Business Acquisition [Line Items]
Effective date of acquisition	Feb. 1, 2019			Feb. 1, 2019
Business acquisition, customer deposits balances	$ 16,000
Business acquisition, loans	45,000
Goodwill, acquired during period	578				$ 578
Lowery Bank | Minimum
Business Acquisition [Line Items]
Cash paid for acquisition	$ 32,900
Post Oak Bancshares, Inc.
Business Acquisition [Line Items]
Effective date of acquisition		Oct. 1, 2018		Oct. 1, 2018
Business acquisition, loans			$ 1,164,281
Goodwill, acquired during period		$ 183,700				$ 183,736
Cash paid for acquisition		$ 21
Number of branches | branch		13
Number of shares issued in acquisition | shares		8,402,010	8,402,010
Number of shares per common share or option to purchase common shares		0.7017
Option issued in acquisition to purchase common shares | shares		299,352	299,352
Options exercised | $ / shares		$ 12.83
Business acquisition, share price | $ / shares							$ 41.70
Business acquisition, equity transaction value							$ 359,000
Pre-tax acquisition and merger-related expenses					$ 1,300	$ 1,700
Post Oak Bancshares, Inc. | Houston, Texas
Business Acquisition [Line Items]
Number of branches | branch		12
Post Oak Bancshares, Inc. | Beaumont, TX
Business Acquisition [Line Items]
Number of branches | branch		1
Post Oak Bancshares, Inc. | Minimum
Business Acquisition [Line Items]
Intangibles, useful life		10 years

ACQUISITIONS - Allocation of th

ACQUISITIONS - Allocation of the Purchase Price to Assets and Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill		$ 223,642	$ 223,642	$ 223,125	$ 39,389
Post Oak Bancshares, Inc.
Business Acquisition [Line Items]
Stock options issued (299,352)	$ 8,639
Cash in lieu of fractional shares	21
Total consideration paid	359,024
Cash and cash equivalents	230,416
Investment securities	42,779
Loans	1,164,281
Premises and equipment	21,988
Core deposit intangibles	25,128
Other assets	18,076
Total assets acquired	1,502,668
Deposits	1,291,310
Other borrowed funds	30,000
Other liabilities	6,070
Total liabilities assumed	1,327,380
Fair value of net assets acquired	175,288
Goodwill	183,736
Post Oak Bancshares, Inc. | Common Stock
Business Acquisition [Line Items]
Common shares issued (8,402,010 shares)	$ 350,364

ACQUISITIONS - Allocation of _2

ACQUISITIONS - Allocation of the Purchase Price to Assets and Liabilities - Narrative (Details) - Post Oak Bancshares, Inc. - shares	Oct. 01, 2018	Sep. 30, 2019
Business Acquisition [Line Items]
Number of shares issued in acquisition	8,402,010	8,402,010
Option issued in acquisition to purchase common shares	299,352	299,352

ACQUISITIONS - Details of Loans

ACQUISITIONS - Details of Loans Acquired (Details) $ in Thousands	Oct. 01, 2018USD ($)
Business Acquisition [Line Items]
Discount	$ (16,950)
Contractual Balance
Business Acquisition [Line Items]
Acquired loans receivable	1,181,231
Fair Value
Business Acquisition [Line Items]
Acquired loans receivable	1,164,281
Commercial and industrial
Business Acquisition [Line Items]
Discount	(3,894)
Commercial and industrial | Contractual Balance
Business Acquisition [Line Items]
Acquired loans receivable	221,098
Commercial and industrial | Fair Value
Business Acquisition [Line Items]
Acquired loans receivable	217,204
Real estate | Commercial real estate (including multi-family residential)
Business Acquisition [Line Items]
Discount	(7,435)
Real estate | Commercial real estate (including multi-family residential) | Contractual Balance
Business Acquisition [Line Items]
Acquired loans receivable	450,947
Real estate | Commercial real estate (including multi-family residential) | Fair Value
Business Acquisition [Line Items]
Acquired loans receivable	443,512
Real estate | Commercial real estate construction and land development
Business Acquisition [Line Items]
Discount	(1,999)
Real estate | Commercial real estate construction and land development | Contractual Balance
Business Acquisition [Line Items]
Acquired loans receivable	167,386
Real estate | Commercial real estate construction and land development | Fair Value
Business Acquisition [Line Items]
Acquired loans receivable	165,387
Real estate | 1-4 family residential (including home equity)
Business Acquisition [Line Items]
Discount	(3,205)
Real estate | 1-4 family residential (including home equity) | Contractual Balance
Business Acquisition [Line Items]
Acquired loans receivable	288,304
Real estate | 1-4 family residential (including home equity) | Fair Value
Business Acquisition [Line Items]
Acquired loans receivable	285,099
Real estate | Residential construction | Contractual Balance
Business Acquisition [Line Items]
Acquired loans receivable	23,812
Real estate | Residential construction | Fair Value
Business Acquisition [Line Items]
Acquired loans receivable	23,812
Consumer and other
Business Acquisition [Line Items]
Discount	(417)
Consumer and other | Contractual Balance
Business Acquisition [Line Items]
Acquired loans receivable	29,684
Consumer and other | Fair Value
Business Acquisition [Line Items]
Acquired loans receivable	$ 29,267

ACQUISITIONS - Schedule of PCI

ACQUISITIONS - Schedule of PCI Loans and Non-PCI Loans Acquired in Transaction (Details) $ in Thousands	Oct. 01, 2018USD ($)
PCI Loans
Business Acquisition [Line Items]
Contractually required principal and interest payments	$ 28,340
Contractual cash flows not expected to be collected (nonaccretable difference)	(3,163)
Expected cash flows at acquisition	25,177
Interest component of expected cash flows (accretable yield)	(495)
Fair value of loans acquired with deterioration of credit quality	25,672
Non-PCI Loans
Business Acquisition [Line Items]
Contractually required principal and interest payments	1,152,892
Accretable discount	(13,293)
Fair value at acquisition	$ 1,166,185

ACQUISITIONS - Business Acquisi

ACQUISITIONS - Business Acquisition, Pro Forma Information (Details) - Post Oak Bancshares, Inc. - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Net interest income	$ 170,801	$ 165,612
Noninterest income	10,060	9,543
Net income	$ 41,807	$ 35,107
Basic earnings per common share	$ 2.70	$ 1.63
Diluted earnings per common share	$ 2.65	$ 1.61

GOODWILL AND CORE DEPOSIT INT_3

GOODWILL AND CORE DEPOSIT INTANGIBLE ASSETS - Changes in Carrying Amount of Goodwill and Intangibles (Details) - USD ($) $ in Thousands	Feb. 01, 2019	Oct. 01, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill
Balance, beginning			$ 223,642	$ 223,125	$ 39,389
Measurement period adjustment				(61)
Balance, ending			223,642	223,642	223,125
Core Deposit Intangible Assets
Balance, beginning			21,876
Amortization			(3,922)	(4,711)	(1,815)
Balance, ending			17,954	21,876
Core Deposit Intangible Assets
Core Deposit Intangible Assets
Balance, beginning			21,876	26,587	3,274
Amortization			(3,922)	(4,711)	(1,815)
Balance, ending			$ 17,954	21,876	26,587
Post Oak Bancshares, Inc.
Goodwill
Goodwill, acquired during period		$ 183,700			183,736
Post Oak Bancshares, Inc. | Core Deposit Intangible Assets
Core Deposit Intangible Assets
Acquisition					$ 25,128
Lowery Bank
Goodwill
Goodwill, acquired during period	$ 578			$ 578

GOODWILL AND CORE DEPOSIT INT_4

GOODWILL AND CORE DEPOSIT INTANGIBLE ASSETS - Narrative (Details)	12 Months Ended
	Dec. 31, 2020ReportingUnit	Sep. 30, 2020USD ($)
Finite Lived Intangible Assets [Line Items]
Number of reporting units | ReportingUnit	1
Goodwill impairment, triggering event	No triggering event occurred during the fourth quarter of 2020 that required an updated goodwill impairment analysis at December 31, 2020.
Acquisition of F&M
Finite Lived Intangible Assets [Line Items]
Goodwill impairment | $		$ 0

GOODWILL AND CORE DEPOSIT INT_5

GOODWILL AND CORE DEPOSIT INTANGIBLE ASSETS - Estimated Aggregate Future Amortization Expense for Core Deposit Intangibles (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
2021	$ 3,296
2022	3,003
2023	2,323
2024	2,188
2025	2,061
Thereafter	5,083
Total	$ 17,954	$ 21,876

SECURITIES - Amortized Cost and

SECURITIES - Amortized Cost and Fair Value of Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 728,043	$ 366,331
Gross Unrealized Gains	45,177	7,009
Gross Unrealized Losses	(330)	(795)
Fair Value	772,890	372,545
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	25,545	29,420
Gross Unrealized Gains	654	298
Gross Unrealized Losses		(243)
Fair Value	26,199	29,475
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	392,586	84,200
Gross Unrealized Gains	35,079	3,453
Gross Unrealized Losses	(60)	(116)
Fair Value	427,605	87,537
Agency mortgage-backed pass-through securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	167,606	104,669
Gross Unrealized Gains	3,829	1,713
Gross Unrealized Losses	(146)	(214)
Fair Value	171,289	106,168
Agency collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	80,182	106,351
Gross Unrealized Gains	4,263	1,199
Gross Unrealized Losses	(75)	(208)
Fair Value	84,370	107,342
Corporate bonds and other
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	62,124	41,691
Gross Unrealized Gains	1,352	346
Gross Unrealized Losses	(49)	(14)
Fair Value	$ 63,427	$ 42,023

SECURITIES - Narrative (Details

SECURITIES - Narrative (Details) - USD ($)	1 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Investments Debt And Equity Securities [Abstract]
Allowance for credit losses for available for sale securities	$ 0	$ 0
Proceeds from sales of available for sale securities	30,800,000	173,000,000
Calls of available for sale securities	7,300,000
Gross realized gains	391,000	2,100,000
Gross realized losses	104,000	596,000
Net realized gain (loss)	287,000	1,500,000
Security owned and pledged as collateral	$ 18,500,000	$ 18,500,000	$ 24,300,000

SECURITIES - Amortized Cost a_2

SECURITIES - Amortized Cost and Fair Value of Investment Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Amortized Cost
Due in one year or less	$ 110
Due after one year through five years	12,849
Due after five years through ten years	105,239
Due after ten years	362,057
Subtotal	480,255
Agency mortgage-backed pass through and collateralized mortgage obligation securities	247,788
Amortized Cost	728,043	$ 366,331
Fair Value
Due in one year or less	110
Due after one year through five years	13,412
Due after five years through ten years	109,238
Due after ten years	394,471
Subtotal	517,231
Agency mortgage-backed pass through and collateralized mortgage obligation securities	255,659
Total	$ 772,890	$ 372,545

SECURITIES - Securities in a Co

SECURITIES - Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Securities in a Continuous Unrealized Loss Position, Less than 12 months, Estimated Fair Value	$ 65,083	$ 80,433
Securities in a Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(294)	(732)
Securities in a Continuous Unrealized Loss Position, More than 12 Months, Estimated Fair Value	4,203	4,805
Securities in a Continuous Unrealized Loss Position, More than 12 Months Unrealized Losses	(36)	(63)
Securities in a Continuous Unrealized Loss Position, Total Estimated Fair Value	69,286	85,238
Securities in a Continuous Unrealized Loss Position, Total Unrealized Losses	(330)	(795)
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Securities in a Continuous Unrealized Loss Position, Less than 12 months, Estimated Fair Value		22,295
Securities in a Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses		(239)
Securities in a Continuous Unrealized Loss Position, More than 12 Months, Estimated Fair Value		436
Securities in a Continuous Unrealized Loss Position, More than 12 Months Unrealized Losses		(4)
Securities in a Continuous Unrealized Loss Position, Total Estimated Fair Value		22,731
Securities in a Continuous Unrealized Loss Position, Total Unrealized Losses		(243)
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Securities in a Continuous Unrealized Loss Position, Less than 12 months, Estimated Fair Value	8,844	9,514
Securities in a Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(60)	(116)
Securities in a Continuous Unrealized Loss Position, Total Estimated Fair Value	8,844	9,514
Securities in a Continuous Unrealized Loss Position, Total Unrealized Losses	(60)	(116)
Agency mortgage-backed pass-through securities
Debt Securities, Available-for-sale [Line Items]
Securities in a Continuous Unrealized Loss Position, Less than 12 months, Estimated Fair Value	28,659	20,792
Securities in a Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(146)	(155)
Securities in a Continuous Unrealized Loss Position, More than 12 Months, Estimated Fair Value		4,369
Securities in a Continuous Unrealized Loss Position, More than 12 Months Unrealized Losses		(59)
Securities in a Continuous Unrealized Loss Position, Total Estimated Fair Value	28,659	25,161
Securities in a Continuous Unrealized Loss Position, Total Unrealized Losses	(146)	(214)
Agency collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Securities in a Continuous Unrealized Loss Position, Less than 12 months, Estimated Fair Value	11,629	22,340
Securities in a Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(39)	(208)
Securities in a Continuous Unrealized Loss Position, More than 12 Months, Estimated Fair Value	4,203
Securities in a Continuous Unrealized Loss Position, More than 12 Months Unrealized Losses	(36)
Securities in a Continuous Unrealized Loss Position, Total Estimated Fair Value	15,832	22,340
Securities in a Continuous Unrealized Loss Position, Total Unrealized Losses	(75)	(208)
Corporate bonds and other
Debt Securities, Available-for-sale [Line Items]
Securities in a Continuous Unrealized Loss Position, Less than 12 months, Estimated Fair Value	15,951	5,492
Securities in a Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(49)	(14)
Securities in a Continuous Unrealized Loss Position, Total Estimated Fair Value	15,951	5,492
Securities in a Continuous Unrealized Loss Position, Total Unrealized Losses	$ (49)	$ (14)

LOANS AND ALLOWANCE FOR CREDI_3

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Loan Portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	$ 4,491,764		$ 3,915,310
Allowance for credit losses on loans	(53,173)	$ (34,663)	(29,438)	$ (26,331)	$ (23,649)
Loans, net	4,438,591		3,885,872
Commercial real estate construction and land development
Accounts Notes And Loans Receivable [Line Items]
Allowance for credit losses on loans		(6,051)
1-4 family residential (including home equity)
Accounts Notes And Loans Receivable [Line Items]
Allowance for credit losses on loans		(5,452)
Residential construction
Accounts Notes And Loans Receivable [Line Items]
Allowance for credit losses on loans		$ (1,056)
Commercial and industrial
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	667,079		689,360
Allowance for credit losses on loans	(17,738)		(8,818)	(8,351)	(7,694)
Mortgage warehouse
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment			8,304
Paycheck Protection Program (PPP)
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	569,901
Real estate | Commercial real estate (including multi-family residential)
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	1,999,877		1,873,782
Real estate | Commercial real estate construction and land development
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	367,213		410,471
Real estate | 1-4 family residential (including home equity)
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	737,605		698,957
Real estate | Residential construction
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	127,522		192,515
Consumer and other
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	22,567		41,921
Allowance for credit losses on loans	$ (413)		$ (120)	$ (73)	$ (95)

LOANS AND ALLOWANCE FOR CREDI_4

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Narrative (Details)	12 Months Ended
	Dec. 31, 2020USD ($)contractLoan	Dec. 31, 2019USD ($)contract	Dec. 31, 2018USD ($)	Jan. 01, 2020USD ($)	Dec. 31, 2017USD ($)
Accounts Notes And Loans Receivable [Line Items]
Owner-occupied loans to commercial real estate loans	54.60%
Maximum loans amount to appraised value	90.00%
Loans outstanding	$ 1,183,000	$ 6,782,000
Accrued interest receivable for loans outstanding	34,500,000	15,500,000
Impaired, interest lost on nonaccrual loans		902,500,000	$ 1,200,000
Allowance for credit losses on loans	53,173,000	29,438,000	26,331,000	$ 34,663,000	$ 23,649,000
Recorded investment	25,800,000	28,900,000
Change in method of calculating impairment	3,300,000	3,200,000
Troubled debt restructuring, write-down	3,200	251,000	272,000
Troubled debt restructuring, addition	2,600,000	472,000
Modification of outstanding recorded investment	$ 11,804,000	$ 5,100,000	$ 10,172,000
Number of defaults on loan that were modified as troubled debt restructurings during the preceding 12 months | contract	4	5
COVID-19
Accounts Notes And Loans Receivable [Line Items]
Number of loans deferral due to CARES Act | Loan	164
Outstanding loan balances deferrals due to CARES Act	$ 161,300,000
Troubled debt restructurings added in reporting period
Accounts Notes And Loans Receivable [Line Items]
Recorded investment	8,100,000	$ 4,600,000
Unfunded Loan Commitment
Accounts Notes And Loans Receivable [Line Items]
Allowance for credit losses on loans	4,697,000	0		$ 3,866,000
Non accrual loans interest income	$ 0	$ 0
Minimum
Accounts Notes And Loans Receivable [Line Items]
Owner-occupied commercial real estate loans, amortization period	10 years
Mortgage loan, term	5 years
Mortgage loan, amortization period	10 years
Consumer and other loans, term	12 months
Maximum
Accounts Notes And Loans Receivable [Line Items]
Owner-occupied commercial real estate loans, amortization period	20 years
Mortgage loan, term	7 years
Mortgage loan, amortization period	30 years
Consumer and other loans, term	60 months

LOANS AND ALLOWANCE FOR CREDI_5

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Carrying Amount of PCI Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Recorded investment	$ 4,491,764	$ 3,915,310
PCI Loans
Accounts Notes And Loans Receivable [Line Items]
Outstanding balance		16,589
Less: Discount		(2,414)
Less: Allowance		(259)
Recorded investment		$ 13,916

LOANS AND ALLOWANCE FOR CREDI_6

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Recorded Investment of Non-PCI Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Recorded investment	$ 4,491,764	$ 3,915,310
Non-PCI Loans
Accounts Notes And Loans Receivable [Line Items]
Outstanding balance		672,927
Less: Discount		(3,069)
Recorded investment		$ 669,858

LOANS AND ALLOWANCE FOR CREDI_7

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Changes in the Discount Accretion for Non-PCI Loans (Details) - Non-PCI Loans $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Accounts Notes And Loans Receivable [Line Items]
Balance at beginning of period	$ 10,650
Additions	573
Accretion	(8,154)
Balance at end of period	$ 3,069

LOANS AND ALLOWANCE FOR CREDI_8

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Analysis Of Activity with Related-party Loans (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Loans and Leases Receivable, Related Parties [Roll Forward]
Beginning balance on January 1	$ 6,782
New loans and reclassified related loans	90
Repayments and reclassified related loans	(5,689)
Ending balance on December 31	$ 1,183

LOANS AND ALLOWANCE FOR CREDI_9

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Aging Analysis of the Recorded Investment in Past Due Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing	$ 11,525	$ 10,001
Nonaccrual Loans	28,893	28,371
Current Loans	4,451,346	3,876,938
Total loans evaluated for impairment	4,491,764	3,915,310
Financing Receivables, 30 to 89 Days Past Due
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing	11,525	10,001
Commercial and industrial
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing	2,486	3,098
Nonaccrual Loans	10,747	8,388
Current Loans	653,846	677,874
Total loans evaluated for impairment	667,079	689,360
Commercial and industrial | Financing Receivables, 30 to 89 Days Past Due
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing	2,486	3,098
Mortgage warehouse
Accounts Notes And Loans Receivable [Line Items]
Current Loans		8,304
Total loans evaluated for impairment		8,304
Paycheck Protection Program (PPP)
Accounts Notes And Loans Receivable [Line Items]
Current Loans	569,901
Total loans evaluated for impairment	569,901
Real estate | Commercial real estate (including multi-family residential)
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing	3,063	4,421
Nonaccrual Loans	10,081	6,741
Current Loans	1,986,733	1,862,620
Total loans evaluated for impairment	1,999,877	1,873,782
Real estate | Commercial real estate (including multi-family residential) | Financing Receivables, 30 to 89 Days Past Due
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing	3,063	4,421
Real estate | Commercial real estate construction and land development
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing	2,930	66
Nonaccrual Loans	3,011	9,050
Current Loans	361,272	401,355
Total loans evaluated for impairment	367,213	410,471
Real estate | Commercial real estate construction and land development | Financing Receivables, 30 to 89 Days Past Due
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing	2,930	66
Real estate | 1-4 family residential (including home equity)
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing	3,000	1,598
Nonaccrual Loans	4,525	3,294
Current Loans	730,080	694,065
Total loans evaluated for impairment	737,605	698,957
Real estate | 1-4 family residential (including home equity) | Financing Receivables, 30 to 89 Days Past Due
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing	3,000	1,598
Real estate | Residential construction
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing		564
Nonaccrual Loans		746
Current Loans	127,522	191,205
Total loans evaluated for impairment	127,522	192,515
Real estate | Residential construction | Financing Receivables, 30 to 89 Days Past Due
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing		564
Consumer and other
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing	46	254
Nonaccrual Loans	529	152
Current Loans	21,992	41,515
Total loans evaluated for impairment	22,567	41,921
Consumer and other | Financing Receivables, 30 to 89 Days Past Due
Accounts Notes And Loans Receivable [Line Items]
Loans Past Due and Still Accruing	$ 46	$ 254

LOANS AND ALLOWANCE FOR CRED_10

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Risk Ratings by Category of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	$ 1,915,431
Term Loans Amortized Cost Basis by Origination Year, 2019	755,769
Term Loans Amortized Cost Basis by Origination Year, 2018	490,038
Term Loans Amortized Cost Basis by Origination Year, 2017	421,839
Term Loans Amortized Cost Basis by Origination Year, 2016	302,293
Term Loans Amortized Cost Basis by Origination Year, Prior	169,731
Revolving Loans	436,663
Total	4,491,764	$ 3,915,310
Commercial and industrial
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	175,754
Term Loans Amortized Cost Basis by Origination Year, 2019	95,571
Term Loans Amortized Cost Basis by Origination Year, 2018	61,047
Term Loans Amortized Cost Basis by Origination Year, 2017	28,949
Term Loans Amortized Cost Basis by Origination Year, 2016	27,734
Term Loans Amortized Cost Basis by Origination Year, Prior	8,117
Revolving Loans	269,907
Total	667,079	689,360
Mortgage warehouse
Accounts Notes And Loans Receivable [Line Items]
Total		8,304
Paycheck Protection Program (PPP)
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	569,901
Total	569,901
Paycheck Protection Program (PPP)
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	(5,414)
Term Loans Amortized Cost Basis by Origination Year, 2019	20,853
Term Loans Amortized Cost Basis by Origination Year, 2018	1,628
Term Loans Amortized Cost Basis by Origination Year, 2017	586
Term Loans Amortized Cost Basis by Origination Year, 2016	25
Term Loans Amortized Cost Basis by Origination Year, Prior	122
Revolving Loans	4,767
Total	22,567	41,921
Pass
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	1,792,055
Term Loans Amortized Cost Basis by Origination Year, 2019	639,824
Term Loans Amortized Cost Basis by Origination Year, 2018	406,771
Term Loans Amortized Cost Basis by Origination Year, 2017	324,054
Term Loans Amortized Cost Basis by Origination Year, 2016	228,988
Term Loans Amortized Cost Basis by Origination Year, Prior	112,308
Revolving Loans	393,745
Total	3,897,745	3,691,279
Pass | Commercial and industrial
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	149,522
Term Loans Amortized Cost Basis by Origination Year, 2019	81,526
Term Loans Amortized Cost Basis by Origination Year, 2018	46,909
Term Loans Amortized Cost Basis by Origination Year, 2017	17,610
Term Loans Amortized Cost Basis by Origination Year, 2016	20,955
Term Loans Amortized Cost Basis by Origination Year, Prior	6,951
Revolving Loans	239,045
Total	562,518	637,388
Pass | Mortgage warehouse
Accounts Notes And Loans Receivable [Line Items]
Total		8,304
Pass | Paycheck Protection Program (PPP)
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	569,901
Total	569,901
Pass | Paycheck Protection Program (PPP)
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	(6,193)
Term Loans Amortized Cost Basis by Origination Year, 2019	20,578
Term Loans Amortized Cost Basis by Origination Year, 2018	1,537
Term Loans Amortized Cost Basis by Origination Year, 2017	586
Term Loans Amortized Cost Basis by Origination Year, 2016	25
Term Loans Amortized Cost Basis by Origination Year, Prior	122
Revolving Loans	4,704
Total	21,359	41,355
Watch
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	69,653
Term Loans Amortized Cost Basis by Origination Year, 2019	59,464
Term Loans Amortized Cost Basis by Origination Year, 2018	38,840
Term Loans Amortized Cost Basis by Origination Year, 2017	54,154
Term Loans Amortized Cost Basis by Origination Year, 2016	32,886
Term Loans Amortized Cost Basis by Origination Year, Prior	28,251
Revolving Loans	15,291
Total	298,539	99,111
Watch | Commercial and industrial
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	12,755
Term Loans Amortized Cost Basis by Origination Year, 2019	6,956
Term Loans Amortized Cost Basis by Origination Year, 2018	6,600
Term Loans Amortized Cost Basis by Origination Year, 2017	2,436
Term Loans Amortized Cost Basis by Origination Year, 2016	1,446
Term Loans Amortized Cost Basis by Origination Year, Prior	1,067
Revolving Loans	9,766
Total	41,026	14,797
Watch | Paycheck Protection Program (PPP)
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	57
Term Loans Amortized Cost Basis by Origination Year, 2019	242
Term Loans Amortized Cost Basis by Origination Year, 2018	27
Revolving Loans	63
Total	389	6
Special Mention
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	18,772
Term Loans Amortized Cost Basis by Origination Year, 2019	21,546
Term Loans Amortized Cost Basis by Origination Year, 2018	18,409
Term Loans Amortized Cost Basis by Origination Year, 2017	14,662
Term Loans Amortized Cost Basis by Origination Year, 2016	8,378
Term Loans Amortized Cost Basis by Origination Year, Prior	16,755
Revolving Loans	16,704
Total	115,226	29,686
Special Mention | Commercial and industrial
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	758
Term Loans Amortized Cost Basis by Origination Year, 2019	2,746
Term Loans Amortized Cost Basis by Origination Year, 2018	3,740
Term Loans Amortized Cost Basis by Origination Year, 2017	1,860
Term Loans Amortized Cost Basis by Origination Year, 2016	2,756
Revolving Loans	13,150
Total	25,010	10,871
Special Mention | Paycheck Protection Program (PPP)
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	231
Term Loans Amortized Cost Basis by Origination Year, 2018	39
Total	270	358
Substandard
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	34,882
Term Loans Amortized Cost Basis by Origination Year, 2019	34,864
Term Loans Amortized Cost Basis by Origination Year, 2018	26,018
Term Loans Amortized Cost Basis by Origination Year, 2017	28,969
Term Loans Amortized Cost Basis by Origination Year, 2016	32,041
Term Loans Amortized Cost Basis by Origination Year, Prior	12,417
Revolving Loans	10,923
Total	180,114	95,156
Substandard | Commercial and industrial
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	12,650
Term Loans Amortized Cost Basis by Origination Year, 2019	4,272
Term Loans Amortized Cost Basis by Origination Year, 2018	3,798
Term Loans Amortized Cost Basis by Origination Year, 2017	7,043
Term Loans Amortized Cost Basis by Origination Year, 2016	2,577
Term Loans Amortized Cost Basis by Origination Year, Prior	99
Revolving Loans	7,946
Total	38,385	26,226
Substandard | Paycheck Protection Program (PPP)
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	491
Term Loans Amortized Cost Basis by Origination Year, 2019	33
Term Loans Amortized Cost Basis by Origination Year, 2018	25
Total	549	202
Doubtful
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	69
Term Loans Amortized Cost Basis by Origination Year, 2019	71
Total	140	78
Doubtful | Commercial and industrial
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	69
Term Loans Amortized Cost Basis by Origination Year, 2019	71
Total	140	78
Commercial real estate (including multi-family residential)
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	643,262
Term Loans Amortized Cost Basis by Origination Year, 2019	409,746
Term Loans Amortized Cost Basis by Origination Year, 2018	272,912
Term Loans Amortized Cost Basis by Origination Year, 2017	286,530
Term Loans Amortized Cost Basis by Origination Year, 2016	211,560
Term Loans Amortized Cost Basis by Origination Year, Prior	124,262
Revolving Loans	51,605
Total	1,999,877	1,873,782
Commercial real estate (including multi-family residential) | Pass
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	587,089
Term Loans Amortized Cost Basis by Origination Year, 2019	321,020
Term Loans Amortized Cost Basis by Origination Year, 2018	220,554
Term Loans Amortized Cost Basis by Origination Year, 2017	221,147
Term Loans Amortized Cost Basis by Origination Year, 2016	156,671
Term Loans Amortized Cost Basis by Origination Year, Prior	75,353
Revolving Loans	47,189
Total	1,629,023	1,760,476
Commercial real estate (including multi-family residential) | Watch
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	27,851
Term Loans Amortized Cost Basis by Origination Year, 2019	45,009
Term Loans Amortized Cost Basis by Origination Year, 2018	23,492
Term Loans Amortized Cost Basis by Origination Year, 2017	32,567
Term Loans Amortized Cost Basis by Origination Year, 2016	24,051
Term Loans Amortized Cost Basis by Origination Year, Prior	23,531
Revolving Loans	1,150
Total	177,651	56,367
Commercial real estate (including multi-family residential) | Special Mention
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	10,931
Term Loans Amortized Cost Basis by Origination Year, 2019	16,452
Term Loans Amortized Cost Basis by Origination Year, 2018	9,940
Term Loans Amortized Cost Basis by Origination Year, 2017	12,128
Term Loans Amortized Cost Basis by Origination Year, 2016	3,243
Term Loans Amortized Cost Basis by Origination Year, Prior	14,482
Revolving Loans	1,100
Total	68,276	11,974
Commercial real estate (including multi-family residential) | Substandard
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	17,391
Term Loans Amortized Cost Basis by Origination Year, 2019	27,265
Term Loans Amortized Cost Basis by Origination Year, 2018	18,926
Term Loans Amortized Cost Basis by Origination Year, 2017	20,688
Term Loans Amortized Cost Basis by Origination Year, 2016	27,595
Term Loans Amortized Cost Basis by Origination Year, Prior	10,896
Revolving Loans	2,166
Total	124,927	44,965
Commercial real estate construction and land development
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	188,763
Term Loans Amortized Cost Basis by Origination Year, 2019	83,084
Term Loans Amortized Cost Basis by Origination Year, 2018	36,778
Term Loans Amortized Cost Basis by Origination Year, 2017	29,869
Term Loans Amortized Cost Basis by Origination Year, 2016	10,388
Term Loans Amortized Cost Basis by Origination Year, Prior	2,818
Revolving Loans	15,513
Total	367,213	410,471
Commercial real estate construction and land development | Pass
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	172,389
Term Loans Amortized Cost Basis by Origination Year, 2019	77,535
Term Loans Amortized Cost Basis by Origination Year, 2018	31,392
Term Loans Amortized Cost Basis by Origination Year, 2017	16,712
Term Loans Amortized Cost Basis by Origination Year, 2016	5,098
Term Loans Amortized Cost Basis by Origination Year, Prior	2,036
Revolving Loans	14,971
Total	320,133	385,832
Commercial real estate construction and land development | Watch
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	12,801
Term Loans Amortized Cost Basis by Origination Year, 2019	2,943
Term Loans Amortized Cost Basis by Origination Year, 2018	4,315
Term Loans Amortized Cost Basis by Origination Year, 2017	13,157
Term Loans Amortized Cost Basis by Origination Year, 2016	5,290
Term Loans Amortized Cost Basis by Origination Year, Prior	515
Total	39,021	9,583
Commercial real estate construction and land development | Special Mention
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	615
Term Loans Amortized Cost Basis by Origination Year, 2019	1,620
Term Loans Amortized Cost Basis by Origination Year, 2018	378
Term Loans Amortized Cost Basis by Origination Year, Prior	267
Total	2,880	639
Commercial real estate construction and land development | Substandard
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	2,958
Term Loans Amortized Cost Basis by Origination Year, 2019	986
Term Loans Amortized Cost Basis by Origination Year, 2018	693
Revolving Loans	542
Total	5,179	14,417
1-4 family residential (including home equity)
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	234,325
Term Loans Amortized Cost Basis by Origination Year, 2019	135,436
Term Loans Amortized Cost Basis by Origination Year, 2018	112,385
Term Loans Amortized Cost Basis by Origination Year, 2017	75,163
Term Loans Amortized Cost Basis by Origination Year, 2016	51,013
Term Loans Amortized Cost Basis by Origination Year, Prior	34,412
Revolving Loans	94,871
Total	737,605	698,957
1-4 family residential (including home equity) | Pass
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	212,543
Term Loans Amortized Cost Basis by Origination Year, 2019	128,835
Term Loans Amortized Cost Basis by Origination Year, 2018	101,091
Term Loans Amortized Cost Basis by Origination Year, 2017	67,257
Term Loans Amortized Cost Basis by Origination Year, 2016	44,666
Term Loans Amortized Cost Basis by Origination Year, Prior	27,846
Revolving Loans	87,836
Total	670,074	669,288
1-4 family residential (including home equity) | Watch
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	14,153
Term Loans Amortized Cost Basis by Origination Year, 2019	3,565
Term Loans Amortized Cost Basis by Origination Year, 2018	4,406
Term Loans Amortized Cost Basis by Origination Year, 2017	5,994
Term Loans Amortized Cost Basis by Origination Year, 2016	2,099
Term Loans Amortized Cost Basis by Origination Year, Prior	3,138
Revolving Loans	4,312
Total	37,667	15,798
1-4 family residential (including home equity) | Special Mention
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	6,237
Term Loans Amortized Cost Basis by Origination Year, 2019	728
Term Loans Amortized Cost Basis by Origination Year, 2018	4,312
Term Loans Amortized Cost Basis by Origination Year, 2017	674
Term Loans Amortized Cost Basis by Origination Year, 2016	2,379
Term Loans Amortized Cost Basis by Origination Year, Prior	2,006
Revolving Loans	2,454
Total	18,790	5,844
1-4 family residential (including home equity) | Substandard
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	1,392
Term Loans Amortized Cost Basis by Origination Year, 2019	2,308
Term Loans Amortized Cost Basis by Origination Year, 2018	2,576
Term Loans Amortized Cost Basis by Origination Year, 2017	1,238
Term Loans Amortized Cost Basis by Origination Year, 2016	1,869
Term Loans Amortized Cost Basis by Origination Year, Prior	1,422
Revolving Loans	269
Total	11,074	8,027
Residential construction
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	108,840
Term Loans Amortized Cost Basis by Origination Year, 2019	11,079
Term Loans Amortized Cost Basis by Origination Year, 2018	5,288
Term Loans Amortized Cost Basis by Origination Year, 2017	742
Term Loans Amortized Cost Basis by Origination Year, 2016	1,573
Total	127,522	192,515
Residential construction | Pass
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	106,804
Term Loans Amortized Cost Basis by Origination Year, 2019	10,330
Term Loans Amortized Cost Basis by Origination Year, 2018	5,288
Term Loans Amortized Cost Basis by Origination Year, 2017	742
Term Loans Amortized Cost Basis by Origination Year, 2016	1,573
Total	124,737	188,636
Residential construction | Watch
Accounts Notes And Loans Receivable [Line Items]
Term Loans Amortized Cost Basis by Origination Year, 2020	2,036
Term Loans Amortized Cost Basis by Origination Year, 2019	749
Total	$ 2,785	2,560
Residential construction | Substandard
Accounts Notes And Loans Receivable [Line Items]
Total		$ 1,319

LOANS AND ALLOWANCE FOR CRED_11

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Risk Ratings by Category of Loans (Parenthetical) (Details) $ in Millions	Dec. 31, 2020USD ($)
Paycheck Protection Program (PPP)
Accounts Notes And Loans Receivable [Line Items]
Net deferred fees	$ 13.9

LOANS AND ALLOWANCE FOR CRED_12

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Losses on Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for credit losses on loans:
Balance, beginning of period	$ 29,438	$ 26,331	$ 23,649
Provision for loan losses	26,543	5,939	4,248
Charge-offs	(8,583)	(3,141)	(2,515)
Recoveries	550	309	949
Net charge-offs	(8,033)	(2,832)	(1,566)
Balance, end of period	53,173	29,438	26,331
Accounting Standards Update 2016-13
Allowance for credit losses on loans:
Balance, beginning of period	5,225
Balance, end of period		5,225
Commercial and industrial
Allowance for credit losses on loans:
Balance, beginning of period	8,818	8,351	7,694
Provision for loan losses	4,363	2,881	2,234
Charge-offs	(2,938)	(2,688)	(2,424)
Recoveries	473	274	847
Net charge-offs	(2,465)	(2,414)	(1,577)
Balance, end of period	17,738	8,818	8,351
Commercial and industrial | Accounting Standards Update 2016-13
Allowance for credit losses on loans:
Balance, beginning of period	7,022
Balance, end of period		7,022
Commercial Real Estate Portfolio Segment | Commercial real estate (including multi-family residential)
Allowance for credit losses on loans:
Balance, beginning of period	11,170	11,901	10,253
Provision for loan losses	20,417	(654)	1,588
Charge-offs	(2,562)	(80)	(42)
Recoveries	72	3	102
Net charge-offs	(2,490)	(77)	60
Balance, end of period	23,934	11,170	11,901
Commercial Real Estate Portfolio Segment | Commercial real estate (including multi-family residential) | Accounting Standards Update 2016-13
Allowance for credit losses on loans:
Balance, beginning of period	(5,163)
Balance, end of period		(5,163)
Commercial Real Estate Portfolio Segment | Commercial real estate construction and land development
Allowance for credit losses on loans:
Balance, beginning of period	4,421	2,724	2,525
Provision for loan losses	3,461	1,741	199
Charge-offs	(2,573)	(44)
Net charge-offs	(2,573)	(44)
Balance, end of period	6,939	4,421	2,724
Commercial Real Estate Portfolio Segment | Commercial real estate construction and land development | Accounting Standards Update 2016-13
Allowance for credit losses on loans:
Balance, beginning of period	1,630
Balance, end of period		1,630
Commercial Real Estate Portfolio Segment | 1-4 family residential (including home equity)
Allowance for credit losses on loans:
Balance, beginning of period	3,852	2,242	2,140
Provision for loan losses	(1,822)	1,905	127
Charge-offs	(351)	(295)	(25)
Net charge-offs	(351)	(295)	(25)
Balance, end of period	3,279	3,852	2,242
Commercial Real Estate Portfolio Segment | 1-4 family residential (including home equity) | Accounting Standards Update 2016-13
Allowance for credit losses on loans:
Balance, beginning of period	1,600
Balance, end of period		1,600
Commercial Real Estate Portfolio Segment | Residential construction
Allowance for credit losses on loans:
Balance, beginning of period	1,057	1,040	942
Provision for loan losses	(186)	17	98
Balance, end of period	870	1,057	1,040
Commercial Real Estate Portfolio Segment | Residential construction | Accounting Standards Update 2016-13
Allowance for credit losses on loans:
Balance, beginning of period	(1)
Balance, end of period		(1)
Consumer and other
Allowance for credit losses on loans:
Balance, beginning of period	120	73	95
Provision for loan losses	310	49	2
Charge-offs	(159)	(34)	(24)
Recoveries	5	32
Net charge-offs	(154)	(2)	(24)
Balance, end of period	413	120	$ 73
Consumer and other | Accounting Standards Update 2016-13
Allowance for credit losses on loans:
Balance, beginning of period	$ 137
Balance, end of period		$ 137

LOANS AND ALLOWANCE FOR CRED_13

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Summary of Activity in Allowance for Credit Losses on Unfunded Commitments (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance For Loan Commitments [Line Items]
Allowance for credit losses on loans	$ 53,173,000	$ 34,663,000	$ 29,438,000	$ 26,331,000	$ 23,649,000
Unfunded Loan Commitment
Allowance For Loan Commitments [Line Items]
Allowance for credit losses on loans	4,697,000	$ 3,866,000	$ 0
Provision for credit losses on off-balance sheet exposures	$ 831,000

LOANS AND ALLOWANCE FOR CRED_14

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Summary of Amortized Cost Basis of Collateral Dependent Loans Individually Evaluated to Determine Expected Credit Losses (Details) $ in Thousands	Dec. 31, 2020USD ($)
Financing Receivable Allowance For Credit Losses [Line Items]
Finance receivables allowance of credit losses	$ 8,683
Real Estate
Financing Receivable Allowance For Credit Losses [Line Items]
Finance receivables allowance of credit losses	3,526
Business Assets
Financing Receivable Allowance For Credit Losses [Line Items]
Finance receivables allowance of credit losses	5,157
Commercial and industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Finance receivables allowance of credit losses	5,157
Commercial and industrial | Business Assets
Financing Receivable Allowance For Credit Losses [Line Items]
Finance receivables allowance of credit losses	5,157
Real estate | Commercial real estate (including multi-family residential)
Financing Receivable Allowance For Credit Losses [Line Items]
Finance receivables allowance of credit losses	425
Real estate | 1-4 family residential (including home equity)
Financing Receivable Allowance For Credit Losses [Line Items]
Finance receivables allowance of credit losses	3,101
Real estate | Real Estate | Commercial real estate (including multi-family residential)
Financing Receivable Allowance For Credit Losses [Line Items]
Finance receivables allowance of credit losses	425
Real estate | Real Estate | 1-4 family residential (including home equity)
Financing Receivable Allowance For Credit Losses [Line Items]
Finance receivables allowance of credit losses	$ 3,101

LOANS AND ALLOWANCE FOR CRED_15

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Summary of Nonaccrual Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans with No Related Allowance	$ 15,194
Nonaccrual Loans with Related Allowance	13,699
Nonaccrual Loans	28,893	$ 28,371
Commercial and industrial
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans with No Related Allowance	2,097
Nonaccrual Loans with Related Allowance	8,650
Nonaccrual Loans	10,747	8,388
Real estate | Commercial real estate (including multi-family residential)
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans with No Related Allowance	7,487
Nonaccrual Loans with Related Allowance	2,594
Nonaccrual Loans	10,081	6,741
Real estate | Commercial real estate construction and land development
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans with No Related Allowance	2,958
Nonaccrual Loans with Related Allowance	53
Nonaccrual Loans	3,011	9,050
Real estate | 1-4 family residential (including home equity)
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans with No Related Allowance	2,652
Nonaccrual Loans with Related Allowance	1,873
Nonaccrual Loans	4,525	3,294
Real estate | Residential construction
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans		746
Consumer and other
Financing Receivable Nonaccrual Status [Line Items]
Nonaccrual Loans with Related Allowance	529
Nonaccrual Loans	$ 529	$ 152

LOANS AND ALLOWANCE FOR CRED_16

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Impaired Loans by Loan Class (Details) $ in Thousands	Dec. 31, 2019USD ($)
With no related allowance recorded:
Recorded investment with no related allowance recorded	$ 27,445
Unpaid principal balance with no related allowance recorded	27,940
With an allowance recorded:
Impaired financing receivable, with related allowance, recorded investment	27,891
Impaired financing receivable, with related allowance, unpaid principal balance	28,285
Related Allowance	6,775
Total:
Recorded Investment	55,336
Unpaid Principal Balance	56,225
Related Allowance	6,775
PCI Loans
With an allowance recorded:
Impaired financing receivable, with related allowance, recorded investment	2,039
Impaired financing receivable, with related allowance, unpaid principal balance	2,959
Related Allowance	659
Total:
Recorded Investment	2,039
Unpaid Principal Balance	2,959
Related Allowance	659
Commercial and industrial
With no related allowance recorded:
Recorded investment with no related allowance recorded	5,721
Unpaid principal balance with no related allowance recorded	6,136
With an allowance recorded:
Impaired financing receivable, with related allowance, recorded investment	7,812
Impaired financing receivable, with related allowance, unpaid principal balance	7,286
Related Allowance	3,480
Total:
Recorded Investment	13,533
Unpaid Principal Balance	13,422
Related Allowance	3,480
Mortgage warehouse
With no related allowance recorded:
Recorded investment with no related allowance recorded	0
Unpaid principal balance with no related allowance recorded	0
With an allowance recorded:
Impaired financing receivable, with related allowance, recorded investment	0
Impaired financing receivable, with related allowance, unpaid principal balance	0
Related Allowance	0
Total:
Recorded Investment	0
Unpaid Principal Balance	0
Related Allowance	0
Real estate | Commercial real estate (including multi-family residential)
With no related allowance recorded:
Recorded investment with no related allowance recorded	19,478
Unpaid principal balance with no related allowance recorded	19,558
With an allowance recorded:
Impaired financing receivable, with related allowance, recorded investment	5,335
Impaired financing receivable, with related allowance, unpaid principal balance	5,335
Related Allowance	459
Total:
Recorded Investment	24,813
Unpaid Principal Balance	24,893
Related Allowance	459
Real estate | Commercial real estate construction and land development
With no related allowance recorded:
Recorded investment with no related allowance recorded	0
Unpaid principal balance with no related allowance recorded	0
With an allowance recorded:
Impaired financing receivable, with related allowance, recorded investment	12,142
Impaired financing receivable, with related allowance, unpaid principal balance	12,142
Related Allowance	2,085
Total:
Recorded Investment	12,142
Unpaid Principal Balance	12,142
Related Allowance	2,085
Real estate | 1-4 family residential (including home equity)
With no related allowance recorded:
Recorded investment with no related allowance recorded	2,000
Unpaid principal balance with no related allowance recorded	2,000
With an allowance recorded:
Impaired financing receivable, with related allowance, recorded investment	0
Impaired financing receivable, with related allowance, unpaid principal balance	0
Related Allowance	0
Total:
Recorded Investment	2,000
Unpaid Principal Balance	2,000
Related Allowance	0
Real estate | Residential construction
With no related allowance recorded:
Recorded investment with no related allowance recorded	208
Unpaid principal balance with no related allowance recorded	208
With an allowance recorded:
Impaired financing receivable, with related allowance, recorded investment	537
Impaired financing receivable, with related allowance, unpaid principal balance	537
Related Allowance	66
Total:
Recorded Investment	745
Unpaid Principal Balance	745
Related Allowance	66
Consumer and other
With no related allowance recorded:
Recorded investment with no related allowance recorded	38
Unpaid principal balance with no related allowance recorded	38
With an allowance recorded:
Impaired financing receivable, with related allowance, recorded investment	26
Impaired financing receivable, with related allowance, unpaid principal balance	26
Related Allowance	26
Total:
Recorded Investment	64
Unpaid Principal Balance	64
Related Allowance	$ 26

LOANS AND ALLOWANCE FOR CRED_17

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Average Impaired Loans and Interest Recognized (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Accounts Notes And Loans Receivable [Line Items]
Investment	$ 55,343
Recognized	1,088
PCI Loans
Accounts Notes And Loans Receivable [Line Items]
Investment	3,133
Recognized	8
Commercial and industrial
Accounts Notes And Loans Receivable [Line Items]
Investment	13,376
Recognized	399
Real estate | Commercial real estate (including multi-family residential)
Accounts Notes And Loans Receivable [Line Items]
Investment	25,856
Recognized	489
Real estate | Commercial real estate construction and land development
Accounts Notes And Loans Receivable [Line Items]
Investment	10,251
Recognized	185
Real estate | 1-4 family residential (including home equity)
Accounts Notes And Loans Receivable [Line Items]
Investment	2,058
Recognized	6
Real estate | Residential construction
Accounts Notes And Loans Receivable [Line Items]
Investment	594
Consumer and other
Accounts Notes And Loans Receivable [Line Items]
Investment	75
Recognized	$ 1

LOANS AND ALLOWANCE FOR CRED_18

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Loans Modified in a Troubled Debt Restructuring (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)contract	Dec. 31, 2019USD ($)contract	Dec. 31, 2018USD ($)contract
Accounts Notes And Loans Receivable [Line Items]
Number of Contracts | contract	32	17	15
Pre-Modification of Outstanding Recorded Investment	$ 11,804	$ 5,100	$ 10,172
Post Modification of Outstanding Recorded Investment	$ 11,804	$ 5,100	$ 10,172
Commercial and industrial
Accounts Notes And Loans Receivable [Line Items]
Number of Contracts | contract	20	13	11
Pre-Modification of Outstanding Recorded Investment	$ 4,333	$ 4,358	$ 2,770
Post Modification of Outstanding Recorded Investment	$ 4,333	$ 4,358	$ 2,770
Mortgage warehouse
Accounts Notes And Loans Receivable [Line Items]
Number of Contracts | contract	0	0	0
Pre-Modification of Outstanding Recorded Investment	$ 0	$ 0	$ 0
Post Modification of Outstanding Recorded Investment	$ 0	$ 0	$ 0
Real estate | Commercial real estate (including multi-family residential)
Accounts Notes And Loans Receivable [Line Items]
Number of Contracts | contract	5	1	3
Pre-Modification of Outstanding Recorded Investment	$ 4,560	$ 303	$ 4,288
Post Modification of Outstanding Recorded Investment	$ 4,560	$ 303	$ 4,288
Real estate | Commercial real estate construction and land development
Accounts Notes And Loans Receivable [Line Items]
Number of Contracts | contract	1	0	1
Pre-Modification of Outstanding Recorded Investment	$ 830	$ 0	$ 3,114
Post Modification of Outstanding Recorded Investment	$ 830	$ 0	$ 3,114
Real estate | 1-4 family residential (including home equity)
Accounts Notes And Loans Receivable [Line Items]
Number of Contracts | contract	5	1	0
Pre-Modification of Outstanding Recorded Investment	$ 2,051	$ 396	$ 0
Post Modification of Outstanding Recorded Investment	$ 2,051	$ 396	$ 0
Real estate | Residential construction
Accounts Notes And Loans Receivable [Line Items]
Number of Contracts | contract	0	0	0
Pre-Modification of Outstanding Recorded Investment	$ 0	$ 0	$ 0
Post Modification of Outstanding Recorded Investment	$ 0	$ 0	$ 0
Consumer and other
Accounts Notes And Loans Receivable [Line Items]
Number of Contracts | contract	1	2	0
Pre-Modification of Outstanding Recorded Investment	$ 30	$ 43	$ 0
Post Modification of Outstanding Recorded Investment	$ 30	$ 43	$ 0

LOANS AND ALLOWANCE FOR CRED_19

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Schedule of Principal and Interest Deferrals Associated with Loan Modifications Related to COVID 19 (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	$ 4,491,764	$ 3,915,310
Initial Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 1,130,665
Percentage of Total Deferrals	100.00%
Additional Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 227,744
Percentage of Total Deferrals	100.00%
Remaining Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 161,297
Percentage of Total Deferrals	100.00%
Commercial and industrial
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	$ 667,079	689,360
Commercial and industrial | Initial Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 127,689
Percentage of Total Deferrals	11.30%
Commercial and industrial | Additional Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 21,747
Percentage of Total Deferrals	9.50%
Commercial and industrial | Remaining Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 23,822
Percentage of Total Deferrals	14.80%
Mortgage warehouse
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		8,304
Mortgage warehouse | Initial Deferrals
Accounts Notes And Loans Receivable [Line Items]
Percentage of Total Deferrals	0.00%
Mortgage warehouse | Additional Deferrals
Accounts Notes And Loans Receivable [Line Items]
Percentage of Total Deferrals	0.00%
Mortgage warehouse | Remaining Deferrals
Accounts Notes And Loans Receivable [Line Items]
Percentage of Total Deferrals	0.00%
Paycheck Protection Program (PPP)
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	$ 569,901
Paycheck Protection Program (PPP) | Initial Deferrals
Accounts Notes And Loans Receivable [Line Items]
Percentage of Total Deferrals	0.00%
Paycheck Protection Program (PPP) | Additional Deferrals
Accounts Notes And Loans Receivable [Line Items]
Percentage of Total Deferrals	0.00%
Paycheck Protection Program (PPP) | Remaining Deferrals
Accounts Notes And Loans Receivable [Line Items]
Percentage of Total Deferrals	0.00%
Consumer and other
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	$ 22,567	41,921
Consumer and other | Initial Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 1,015
Percentage of Total Deferrals	0.10%
Consumer and other | Additional Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 172
Percentage of Total Deferrals	0.10%
Consumer and other | Remaining Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 59
Percentage of Total Deferrals	0.00%
Commercial real estate (including multi-family residential) | Real estate
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	$ 1,999,877	1,873,782
Commercial real estate (including multi-family residential) | Real estate | Initial Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 790,468
Percentage of Total Deferrals	69.90%
Commercial real estate (including multi-family residential) | Real estate | Additional Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 171,945
Percentage of Total Deferrals	75.50%
Commercial real estate (including multi-family residential) | Real estate | Remaining Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 129,067
Percentage of Total Deferrals	80.00%
Commercial real estate construction and land development | Real estate
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	$ 367,213	410,471
Commercial real estate construction and land development | Real estate | Initial Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 88,446
Percentage of Total Deferrals	7.80%
Commercial real estate construction and land development | Real estate | Additional Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 20,032
Percentage of Total Deferrals	8.80%
Commercial real estate construction and land development | Real estate | Remaining Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 5,860
Percentage of Total Deferrals	3.60%
1-4 family residential (including home equity) | Real estate
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	$ 737,605	698,957
1-4 family residential (including home equity) | Real estate | Initial Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 118,595
Percentage of Total Deferrals	10.50%
1-4 family residential (including home equity) | Real estate | Additional Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 12,922
Percentage of Total Deferrals	5.70%
1-4 family residential (including home equity) | Real estate | Remaining Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 2,489
Percentage of Total Deferrals	1.60%
Residential construction | Real estate
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	$ 127,522	$ 192,515
Residential construction | Real estate | Initial Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 4,452
Percentage of Total Deferrals	0.40%
Residential construction | Real estate | Additional Deferrals
Accounts Notes And Loans Receivable [Line Items]
Deferred Loan Balance	$ 926
Percentage of Total Deferrals	0.40%
Residential construction | Real estate | Remaining Deferrals
Accounts Notes And Loans Receivable [Line Items]
Percentage of Total Deferrals	0.00%

FAIR VALUE - Carrying Amounts a

FAIR VALUE - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	$ 772,890	$ 372,545
Contractual Balance
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	422,766	346,248
Available for sale securities	772,890	372,545
Loans held for investment, net of allowance	4,438,591	3,885,872
Accrued interest receivable	40,053	15,468
Deposits	4,988,482	4,068,101
Interest rate swap	1,252
Accrued interest payable	2,701	4,326
Borrowed funds	155,515	75,503
Subordinated debt	108,322	107,799
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	422,766	346,248
Available for sale securities	772,890	372,545
Loans held for investment, net of allowance	4,431,816	3,918,210
Accrued interest receivable	40,053	15,468
Deposits	5,003,594	4,073,031
Interest rate swap	1,252
Accrued interest payable	2,701	4,326
Borrowed funds	144,629	83,302
Subordinated debt	109,832	109,607
Fair Value | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	422,766	346,248
Available for sale securities	0	0
Loans held for investment, net of allowance	0	0
Accrued interest receivable	2	13
Deposits	0	0
Accrued interest payable	0	0
Borrowed funds	0	0
Subordinated debt	0	0
Fair Value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Available for sale securities	772,890	372,545
Loans held for investment, net of allowance	0	0
Accrued interest receivable	5,531	1,783
Deposits	5,003,594	4,073,031
Interest rate swap	1,252
Accrued interest payable	2,701	4,326
Borrowed funds	144,629	83,302
Subordinated debt	109,832	109,607
Fair Value | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Available for sale securities	0	0
Loans held for investment, net of allowance	4,431,816	3,918,210
Accrued interest receivable	34,520	13,672
Deposits	0	0
Accrued interest payable	0	0
Borrowed funds	0	0
Subordinated debt	$ 0	$ 0

FAIR VALUE - Fair Values for As

FAIR VALUE - Fair Values for Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	$ 772,890,000	$ 372,545,000
U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	26,199,000	29,475,000
Municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	427,605,000	87,537,000
Agency mortgage-backed pass-through securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	171,289,000	106,168,000
Agency collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	84,370,000	107,342,000
Corporate bonds and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	63,427,000	42,023,000
Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	772,890,000	372,545,000
Financial liabilities		0
Recurring Basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Recurring Basis | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	772,890,000	372,545,000
Recurring Basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Recurring Basis | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	26,199,000	29,475,000
Recurring Basis | U.S. government and agency securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Recurring Basis | U.S. government and agency securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	26,199,000	29,475,000
Recurring Basis | U.S. government and agency securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Recurring Basis | Municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	427,605,000	87,537,000
Recurring Basis | Municipal securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Recurring Basis | Municipal securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	427,605,000	87,537,000
Recurring Basis | Municipal securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Recurring Basis | Agency mortgage-backed pass-through securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	171,289,000	106,168,000
Recurring Basis | Agency mortgage-backed pass-through securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Recurring Basis | Agency mortgage-backed pass-through securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	171,289,000	106,168,000
Recurring Basis | Agency mortgage-backed pass-through securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Recurring Basis | Agency collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	84,370,000	107,342,000
Recurring Basis | Agency collateralized mortgage obligations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Recurring Basis | Agency collateralized mortgage obligations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	84,370,000	107,342,000
Recurring Basis | Agency collateralized mortgage obligations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Recurring Basis | Corporate bonds and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	63,427,000	42,023,000
Recurring Basis | Corporate bonds and other | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Recurring Basis | Corporate bonds and other | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	63,427,000	42,023,000
Recurring Basis | Corporate bonds and other | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	$ 0
Recurring Basis | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial liabilities	1,252,000
Recurring Basis | Interest rate swap | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial liabilities	0
Recurring Basis | Interest rate swap | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial liabilities	1,252,000
Recurring Basis | Interest rate swap | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial liabilities	$ 0

FAIR VALUE - Narrative (Details

FAIR VALUE - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate acquired through foreclosure	$ 9,196,000	$ 8,337,000
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate acquired through foreclosure	9,200,000	8,300,000
Valuation allowance for other real estate owned	$ 0	0
Collateral Dependent Loans Specific Allocation of Allowance for Credit Losses on Loans | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of estimated selling and closing costs of collateral	5.00%
Collateral Dependent Loans Specific Allocation of Allowance for Credit Losses on Loans | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of estimated selling and closing costs of collateral	10.00%
Other Real Estate Owned | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of estimated selling and closing costs of collateral	5.00%
Other Real Estate Owned | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of estimated selling and closing costs of collateral	10.00%
Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial liabilities		0
Transfers of assets between Level 1 and Level 2	$ 0	0
Transfers of assets between Level 2 and Level 1	0	0
Transfers of assets into Level 3	0	0
Transfers of assets out of Level 3	0	0
Transfers of liabilities between Level 1 and Level 2	0	0
Transfers of liabilities between Level 2 and Level 3	0	0
Transfers of liabilities into Level 3	0	0
Transfers of liabilities out of Level 3	0	0
Nonrecurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial liabilities	$ 0	$ 0

FAIR VALUE - Assets Measured at

FAIR VALUE - Assets Measured at Fair Value on a Nonrecurring Basis (Details) - Nonrecurring Basis - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	$ 0	$ 0
Assets are measured at fair value, nonrecurring basis	0	0
Level 1 | PCI Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans:		0
Level 1 | Commercial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	0
Impaired loans:		0
Level 1 | Commercial real estate (including multi-family residential)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	0
Impaired loans:		0
Level 1 | Consumer and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	0
Level 1 | Commercial real estate construction and land development
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	0
Impaired loans:		0
Level 1 | 1-4 family residential (including home equity)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	0
Level 1 | Residential construction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	0
Impaired loans:		0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	0	0
Assets are measured at fair value, nonrecurring basis	0	0
Level 2 | PCI Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans:		0
Level 2 | Commercial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	0
Impaired loans:		0
Level 2 | Commercial real estate (including multi-family residential)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	0
Impaired loans:		0
Level 2 | Consumer and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	0
Level 2 | Commercial real estate construction and land development
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	0
Impaired loans:		0
Level 2 | 1-4 family residential (including home equity)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	0
Level 2 | Residential construction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	0
Impaired loans:		0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	9,196	8,337
Assets are measured at fair value, nonrecurring basis	22,895	29,453
Level 3 | PCI Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans:		1,380
Level 3 | Commercial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	8,650
Impaired loans:		4,332
Level 3 | Commercial real estate (including multi-family residential)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	2,594
Impaired loans:		4,876
Level 3 | Consumer and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	529
Level 3 | Commercial real estate construction and land development
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	53
Impaired loans:		10,057
Level 3 | 1-4 family residential (including home equity)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	1,873
Level 3 | Residential construction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Dependent Loans:	$ 0
Impaired loans:		$ 471

PREMISES AND EQUIPMENT - Premis

PREMISES AND EQUIPMENT - Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 87,318	$ 80,303
Less: accumulated depreciation	16,633	13,513
Premises and equipment, net	70,685	66,790
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	13,913	13,913
Buildings
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	39,998	36,826
Lease right-of-use assets
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	11,610	11,180
Leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	5,689	4,522
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	16,106	13,612
Construction in progress
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 2	$ 250

PREMISES AND EQUIPMENT - Narrat

PREMISES AND EQUIPMENT - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Abstract]
Depreciation	$ 3.7	$ 3.2

LEASES - Narrative (Details)

LEASES - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)BranchLocationandOfficeSpaceProperty	Dec. 31, 2019USD ($)
Lessee Lease Description [Line Items]
Number of leased branch locations and office space along with equipment | BranchLocationandOfficeSpace	14
Operating lease, cost	$ 3,270	$ 3,073
Operating lease, existence of option to extend	true
Allegiance Bank
Lessee Lease Description [Line Items]
Number of leased properties | Property	2
Operating lease, cost	$ 10,700
Maximum
Lessee Lease Description [Line Items]
Lessee, operating Lease, term of contract	12 months
Operating lease renewal term	5 years
Minimum
Lessee Lease Description [Line Items]
Operating lease renewal term	1 year

LEASES - Supplemental Lease Inf

LEASES - Supplemental Lease Information (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet:
Operating lease right of use asset classified as premises and equipment	$ 11,610	$ 11,180
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentNet
Operating lease liability classified as other liabilities	$ 11,850	$ 11,477
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilities
Weighted average lease term, in years	5 years 6 months 21 days	5 years 6 months 10 days
Weighted average discount rate	2.86%	3.19%

LEASES - Summary of Lease Costs

LEASES - Summary of Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Statement:
Operating lease cost	$ 3,270	$ 3,073
Short-term lease cost	78	553
Sublease income	(66)	(72)
Total operating lease costs	$ 3,282	$ 3,554

LEASES - Maturity Analysis of L

LEASES - Maturity Analysis of Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Lease payments due:
Within one year	$ 3,068	$ 2,867
After one but within two years	2,664	2,608
After two but within three years	2,056	2,204
After three but within four years	1,591	1,596
After four but within five years	1,057	1,131
After five years	2,355	2,162
Total lease payments	12,791	12,568
Discount on cash flows	941	1,091
Total lease liability	$ 11,850	$ 11,477

DEPOSITS - Narrative (Details)

DEPOSITS - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deposit Liabilities [Abstract]
Time deposits, at or above FDIC insurance limit	$ 250
Time deposits 250,000 or more	726,800	$ 485,800
Brokered deposits	453,800	263,500
Related party deposit liabilities	$ 9,200	$ 9,200

DEPOSITS - Time Deposits by Mat

DEPOSITS - Time Deposits by Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deposit Liabilities [Abstract]
Within one year	$ 872,599
After one but within two years	313,154
After two but within three years	92,863
After three but within four years	39,782
After four but within five years	28,251
Total	$ 1,346,649	$ 1,190,583

DERIVATIVE INSTRUMENTS - Summar

DERIVATIVE INSTRUMENTS - Summary of Cash Flow Hedge Relationships (Detail) - Interest rate swaps - Other Liabilities - Cash Flow Hedging - Designated as Hedging Instrument	12 Months Ended
	Dec. 31, 2020USD ($)
Derivatives Fair Value [Line Items]
Weighted Average Maturity (In Years)	4 years 7 days
Weighted Average Pay Rate	0.64%
Receive Rate	3 month LIBOR
Notional Amount	$ 100,000,000
Estimated Fair Value	$ (1,252,000)

DERIVATIVE INSTRUMENTS - Effect

DERIVATIVE INSTRUMENTS - Effect of Cash Flow Hedge Relationship on Statement of Comprehensive Income (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Derivative Instruments Gain Loss [Line Items]
Amount of Loss Recognized in Other Comprehensive Loss	$ (989)
Cash Flow Hedging | Designated as Hedging Instrument | Interest rate swaps
Derivative Instruments Gain Loss [Line Items]
Amount of Loss Recognized in Other Comprehensive Loss	$ (989)

DERIVATIVE INSTRUMENTS - Narrat

DERIVATIVE INSTRUMENTS - Narrative (Details) - Cash Flow Hedging - Designated as Hedging Instrument $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Derivative Instruments Gain Loss [Line Items]
Unrealized loss reclassified as interest expense during the next twelve months	$ 96
Losses, net of tax reclassified from accumulated other comprehensive income into net income	$ 76

BORROWINGS AND BORROWING CAPA_3

BORROWINGS AND BORROWING CAPACITY - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 28, 2018
Amended Revolving Credit Agreement
Debt Instrument [Line Items]
Debt instrument maturity, month and year	2025-12
Percentage of debt secured by capital stock	100.00%
Borrowing Agreement | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.25%
Interest rate, effective percentage	3.00%
Credit Facility With Another Financial Institution | Amended Revolving Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 45,000,000
Annual reduction in borrowing capacity		$ 7,500,000
Federal Home Loan Bank of Dallas
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 1,990,000,000
Remaining borrowing capacity	1,440,000,000
Outstanding amount	550,200,000
Letters of credit, outstanding amount	410,200,000
Federal Home Loan Bank of Dallas | Expire in 2021
Debt Instrument [Line Items]
Letters of credit, outstanding amount	248,400,000
Federal Home Loan Bank of Dallas | Expire in 2022
Debt Instrument [Line Items]
Letters of credit, outstanding amount	151,700,000
Federal Home Loan Bank of Dallas | Expire in 2023
Debt Instrument [Line Items]
Letters of credit, outstanding amount	10,100,000
Federal Home Loan Bank of Dallas | Short-term Debt
Debt Instrument [Line Items]
Federal Home Loan Bank, advances	$ 140,000,000
Federal Home Loan Bank of Dallas | Short-term Debt | Weighted Average
Debt Instrument [Line Items]
Federal Home Loan Bank, advances, interest rate	1.19%

BORROWINGS AND BORROWING CAPA_4

BORROWINGS AND BORROWING CAPACITY - Scheduled Principal Maturities (Details) $ in Thousands	Dec. 31, 2020USD ($)
Debt Disclosure [Abstract]
2021	$ 0
2022	0
2023	0
2024	569
2025 and thereafter	15,000
Total	$ 15,569

SUBORDINATED DEBT - Narrative (

SUBORDINATED DEBT - Narrative (Details) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Sep. 30, 2019	Dec. 31, 2017	Dec. 31, 2020	Jan. 01, 2015
Subordinated Notes | Fixed-to-Floating Rate Subordinated Notes
Subordinated Borrowing [Line Items]
Debt instrument, face amount	$ 60	$ 40
Issuance price, percentage	100.00%	100.00%
Proceeds from issuance of debt	$ 58.6	$ 39.4
Stated percentage	4.70%	5.25%
Redemption price, percentage	100.00%	100.00%
Subordinated Notes | Fixed-to-Floating Rate Subordinated Notes | 3 month LIBOR
Subordinated Borrowing [Line Items]
Basis spread on variable rate	3.13%	3.03%
F&M Bancshares. Inc. | Junior Subordinated Debt
Subordinated Borrowing [Line Items]
Debt instrument, face amount			$ 11.3
Debt instrument, carrying value			$ 9.6
Debt instrument, unamortized discount				$ 2.5
Debentures, period over which company may defer interest payments			5 years

SUBORDINATED DEBT - Summary of

SUBORDINATED DEBT - Summary of Pertinent Information Related to Junior Subordinated Debentures (Details)	12 Months Ended
	Dec. 31, 2020USD ($)
Subordinated Borrowing [Line Items]
Junior Subordinated Debt Owed to Trusts	$ 11,341,000
Junior Subordinated Debt | 3 month LIBOR
Subordinated Borrowing [Line Items]
Interest rate, period end	0.23364%
Junior Subordinated Debt | Farmers & Merchants Capital Trust II
Subordinated Borrowing [Line Items]
Issuance Date	Nov. 13, 2003
Trust Preferred Securities Outstanding	$ 7,500,000
Junior Subordinated Debt Owed to Trusts	$ 7,732,000
Maturity Date	Nov. 8, 2033	[1]
Junior Subordinated Debt | Farmers & Merchants Capital Trust II | 3 month LIBOR
Subordinated Borrowing [Line Items]
Basis spread on variable rate	3.00%	[2]
Junior Subordinated Debt | Farmers & Merchants Capital Trust III
Subordinated Borrowing [Line Items]
Issuance Date	Jun. 30, 2005
Trust Preferred Securities Outstanding	$ 3,500,000
Junior Subordinated Debt Owed to Trusts	$ 3,609,000
Maturity Date	Jul. 7, 2035	[1]
Junior Subordinated Debt | Farmers & Merchants Capital Trust III | 3 month LIBOR
Subordinated Borrowing [Line Items]
Basis spread on variable rate	1.80%	[2]
[1]	All debentures are currently callable.
[2]	The 3-month LIBOR in effect as of December 31, 2020 was 0.23364%.

INCOME TAXES - Components of th

INCOME TAXES - Components of the Provision for Federal Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Current	$ 17,527	$ 13,514	$ 8,204
Deferred	(7,090)	(87)	(256)
Total	$ 10,437	$ 13,427	$ 7,948

INCOME TAXES - Effective Income

INCOME TAXES - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Taxes calculated at statutory rate	$ 11,754	$ 13,940	$ 9,504
Increase (decrease) resulting from:
Stock based compensation	136	(11)	(400)
Effect of tax-exempt income	(1,475)	(698)	(1,284)
Other, net	22	196	128
Total	$ 10,437	$ 13,427	$ 7,948

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Net shortfall (benefits), share-based compensation	$ (136,000)	$ 11,000	$ 400,000
U.S. maximum federal statutory tax rate	21.00%	21.00%
Unrecognized tax benefits, income tax penalties and interest expense	$ 0	$ 0	$ 0

INCOME TAXES - Deferred Tax Ass

INCOME TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Allowance for credit losses	$ 12,590	$ 6,432
Deferred loan fees	3,164
Deferred compensation	655	855
Cash flow hedge	263
Other deferred assets	342
Total deferred tax assets	17,014	7,287
Deferred tax liabilities:
Core deposit intangible and other purchase accounting adjustments	(3,964)	(3,591)
Net unrealized gain on available for sale securities	(9,417)	(1,307)
Premises and equipment basis difference	(2,573)	(2,099)
Total deferred tax liabilities	(15,954)	(6,997)
Net deferred tax assets	$ 1,060	$ 290

STOCK BASED COMPENSATION - Narr

STOCK BASED COMPENSATION - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	3,200,000
Share-based compensation expense	$ 3,400	$ 3,100	$ 1,700
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	1,800,000
Option, cumulative options granted since inception (in shares)	1,309,231
Stock options granted	0	0
Expiration period	10 years
Award vesting period	4 years
Unrecognized compensation cost	$ 110
Weighted average period over which unrecognized compensation	6 months 10 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	$ 4,300
Weighted average period over which unrecognized compensation	2 years 3 months 10 days
Share awards granted (in shares)	64,000	88,000
Share awards granted (in dollars per share)	$ 22.59	$ 34.97
Restricted Stock | Share Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option, cumulative options granted since inception (in shares)	378,091
Award vesting period	4 years
Share awards granted (in shares)	63,596	87,950
Share awards granted (in dollars per share)	$ 22.59	$ 34.97
Award vested in period, fair value	$ 2,000	$ 1,600	$ 621
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	2 years
Weighted average period over which unrecognized compensation	1 year 10 months 17 days
Share awards granted (in shares)	46,243	34,628
Service period	1 year
Unrecognized compensation expense	$ 1,200

STOCK BASED COMPENSATION - Stoc

STOCK BASED COMPENSATION - Stock Option Plans Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Options
Options outstanding, beginning balance (in shares)	616	802
Options exercised (in shares)	(141)	(179)
Options forfeited (in shares)	(6)	(7)
Options outstanding, ending balance (in shares)	469	616	802
Number of options vested and exercisable (in shares)	455
Weighted Average Exercise Price
Options outstanding, beginning balance (in dollars per share)	$ 19.90	$ 18.88
Options exercised (in dollars per share)	15.72	15.16
Options forfeited (in dollars per share)	20.36	24.18
Options outstanding, ending balance (in dollars per share)	21.08	$ 19.90	$ 18.88
Weighted Average Exercise Price, Options vested and exercisable (in dollars per share)	$ 20.58
Weighted Average Remaining Contractual Term, Options outstanding	3 years 5 months 4 days	4 years	4 years 7 months 9 days
Weighted Average Remaining Contractual Term, Options vested and exercisable	3 years 4 months 2 days
Aggregate Intrinsic Value, Options outstanding	$ 6,118	$ 10,904	$ 10,830
Aggregate Intrinsic Value, Options vested and exercisable	$ 6,164

STOCK BASED COMPENSATION - Info

STOCK BASED COMPENSATION - Information Related To The Stock Option Plan (Details) - Stock Option Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of options exercised	$ 734	$ 751	$ 3,254
Cash received from option exercises	$ 2,221	$ 2,709	$ 3,393
Weighted average fair value of options granted			$ 18

STOCK BASED COMPENSATION - Summ

STOCK BASED COMPENSATION - Summary of Restricted Stock Activity (Details) - Restricted Stock - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Number of Shares
Nonvested share awards outstanding, beginning balance (in shares)	167	143
Share awards granted (in shares)	64	88
Share awards vested (in shares)	(60)	(45)
Unvested share awards forfeited or cancelled (in shares)	(13)	(19)
Nonvested share awards outstanding, ending balance (in shares)	158	167
Weighted Average Grant Date Fair Value
Nonvested share awards outstanding, beginning balance (in dollars per share)	$ 36.23	$ 37.48
Share awards granted (in dollars per share)	22.59	34.97
Share awards vested (in dollars per share)	33.97	36.70
Unvested share awards forfeited or cancelled (in dollars per share)	37.92	38.46
Nonvested share awards outstanding, ending balance	$ 30.78	$ 36.23

OTHER EMPLOYEE BENEFITS (Detail

OTHER EMPLOYEE BENEFITS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Contribution Plan Disclosure [Line Items]
Share-based compensation expense	$ 3,400	$ 3,100	$ 1,700
401 (k) Benefit Plan
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent of match	50.00%
Employer matching contribution, percent of employee's gross pay	6.00%
Maximum annual contributions per employee, percent	3.00%
Employer contribution amount	$ 1,400	1,400	962
Profit Sharing Plan
Defined Contribution Plan Disclosure [Line Items]
Employer contribution amount	$ 3,500	3,700	2,500
Employee Stock Purchase Plan
Defined Contribution Plan Disclosure [Line Items]
Employee purchase price for share as percent of discount to market value	15.00%
Share-based compensation expense	$ 142	$ 210	$ 48

OFF-BALANCE SHEET ARRANGEMENT_3

OFF-BALANCE SHEET ARRANGEMENTS, COMMITMENTS AND CONTINGENCIES - Contractual Amounts of Financial Instruments With Off-balance Sheet Risk (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	$ 771,190	$ 518,254
Variable Rate	488,070	535,779
Commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	761,938	507,411
Variable Rate	480,067	531,470
Standby letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	9,252	10,843
Variable Rate	$ 8,003	$ 4,309

OFF-BALANCE SHEET ARRANGEMENT_4

OFF-BALANCE SHEET ARRANGEMENTS, COMMITMENTS AND CONTINGENCIES - Narrative (Details)	12 Months Ended
	Dec. 31, 2020
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to make loans, period	120 days
Off-balance-sheet fixed rate loan commitments, weighted average maturity	3 years 6 months 10 days
Minimum
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet fixed rate loan commitments, interest rate	1.20%
Maximum
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet fixed rate loan commitments, interest rate	18.00%
Weighted Average
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet fixed rate loan commitments, interest rate	5.13%

REGULATORY CAPITAL MATTERS - Ac

REGULATORY CAPITAL MATTERS - Actual and Required Capital (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Total Capital
Capital	$ 642,155	$ 596,684
Capital to Risk Weighted Assets	15.71%	14.83%
Capital Required for Capital Adequacy	$ 327,084	$ 321,775
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Plus Capital Conservation Buffer	$ 429,298	$ 422,330
Plus Capital Conservation Buffer to Risk Weighted Assets	10.50%	10.50%
Common Equity Tier 1 Capital
Common Equity Tier 1 Risk Based Capital	$ 482,643	$ 459,447
Common Equity Tier 1 Risk Based Capital to Risk Weighted Assets	11.80%	11.42%
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy	$ 183,985	$ 180,999
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Plus Common Equity Tier 1 Risk Based Capital	$ 286,199	$ 281,553
Plus Common Equity Tier 1 Risk Based Capital to Risk Weighted Assets	7.00%	7.00%
Tier 1 Capital
Tier 1 Risk Based Capital	$ 492,281	$ 468,972
Tier 1 Risk Based Capital to Risk Weighted Assets	12.04%	11.66%
Tier 1 Risk Based Capital Required for Capital Adequacy	$ 245,313	$ 241,331
Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	6.00%
Plus Tier 1 Risk Based Capital	$ 347,527	$ 341,886
Plus Tier 1 Risk Based Capital to Risk Weighted Assets	8.50%	8.50%
Tier 1 Capital
Tier 1 Leverage Capital	$ 492,281	$ 468,972
Tier 1 Leverage Capital to Average Assets	8.51%	10.02%
Tier 1 Leverage Capital Required for Capital Adequacy	$ 231,518	$ 187,146
Tier 1 Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Plus Tier 1 Leverage Capital	$ 231,518	$ 187,146
Plus Tier 1 Leverage Capital to Average Assets	4.00%	4.00%
Allegiance Bank
Total Capital
Capital	$ 635,223	$ 578,425
Capital to Risk Weighted Assets	15.55%	14.39%
Capital Required for Capital Adequacy	$ 326,804	$ 321,556
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Plus Capital Conservation Buffer	$ 428,931	$ 422,043
Plus Capital Conservation Buffer to Risk Weighted Assets	10.50%	10.50%
Capital Required to be Well Capitalized	$ 408,506	$ 401,945
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Common Equity Tier 1 Capital
Common Equity Tier 1 Risk Based Capital	$ 544,331	$ 509,372
Common Equity Tier 1 Risk Based Capital to Risk Weighted Assets	13.32%	12.67%
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy	$ 183,828	$ 180,875
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Plus Common Equity Tier 1 Risk Based Capital	$ 285,954	$ 281,362
Plus Common Equity Tier 1 Risk Based Capital to Risk Weighted Assets	7.00%	7.00%
Common Equity Tier 1 Risk Based Capital Required to be Well Capitalized	$ 265,529	$ 261,265
Common Equity Tier 1 Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.50%	6.50%
Tier 1 Capital
Tier 1 Risk Based Capital	$ 544,331	$ 509,372
Tier 1 Risk Based Capital to Risk Weighted Assets	13.32%	12.67%
Tier 1 Risk Based Capital Required for Capital Adequacy	$ 245,103	$ 241,167
Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	6.00%
Plus Tier 1 Risk Based Capital	$ 347,230	$ 341,654
Plus Tier 1 Risk Based Capital to Risk Weighted Assets	8.50%	8.50%
Tier 1 Risk Based Capital Required to be Well Capitalized	$ 326,804	$ 321,556
Tier 1 Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Tier 1 Capital
Tier 1 Leverage Capital	$ 544,331	$ 509,372
Tier 1 Leverage Capital to Average Assets	9.41%	10.89%
Tier 1 Leverage Capital Required for Capital Adequacy	$ 231,334	$ 187,018
Tier 1 Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Plus Tier 1 Leverage Capital	$ 231,334	$ 187,018
Plus Tier 1 Leverage Capital to Average Assets	4.00%	4.00%
Tier 1 Leverage Capital Required to be Well Capitalized	$ 289,167	$ 233,773
Tier 1 Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%

EARNINGS PER COMMON SHARE - Sum

EARNINGS PER COMMON SHARE - Summary of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income attributable to shareholders									$ 45,534	$ 52,959	$ 37,309
Basic:
Weighted average shares outstanding (in shares)									20,415	21,152	15,485
Weighted average shares outstanding (in dollars per share)	$ 0.78	$ 0.79	$ 0.49	$ 0.17	$ 0.68	$ 0.57	$ 0.67	$ 0.58	$ 2.23	$ 2.50	$ 2.41
Diluted:
Dilutive effect of stock option exercises (in shares)									131	272	288
Total (in shares)									20,546	21,424	15,773
Total (in dollars per share)	$ 0.77	$ 0.79	$ 0.48	$ 0.17	$ 0.67	$ 0.57	$ 0.66	$ 0.58	$ 2.22	$ 2.47	$ 2.37

EARNINGS PER COMMON SHARE - Nar

EARNINGS PER COMMON SHARE - Narrative (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	39,050	23,125	54,175

PARENT COMPANY ONLY FINANCIAL_3

PARENT COMPANY ONLY FINANCIAL STATEMENTS - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
ASSETS
Cash and due from banks	$ 122,897	$ 213,347
Other assets	18,909	18,530
TOTAL ASSETS	6,050,128	4,992,654
LIABILITIES:
Subordinated debt	108,322	107,799
Total liabilities	5,291,459	4,282,789
SHAREHOLDERS’ EQUITY:
Common stock	20,208	20,524
Capital surplus	508,794	521,066
Retained earnings	195,236	163,375
Accumulated other comprehensive income	34,431	4,900
Total shareholders’ equity	758,669	709,865	$ 702,984	$ 306,865
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	6,050,128	4,992,654
Parent Company
ASSETS
Cash and due from banks	19,340	17,775
Investment in subsidiary	820,699	760,131
Other assets	2,691	1,665
TOTAL ASSETS	842,730	779,571
LIABILITIES:
Other borrowed funds	15,514	504
Subordinated debt	68,577	68,184
Accrued interest payable and other liabilities	(30)	1,018
Total liabilities	84,061	69,706
SHAREHOLDERS’ EQUITY:
Common stock	20,208	20,524
Capital surplus	508,794	521,066
Retained earnings	195,236	163,375
Accumulated other comprehensive income	34,431	4,900
Total shareholders’ equity	758,669	709,865
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ 842,730	$ 779,571

PARENT COMPANY ONLY FINANCIAL_4

PARENT COMPANY ONLY FINANCIAL STATEMENTS - Condensed Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
OPERATING EXPENSE:
Interest expense on borrowed funds	$ 39,079	$ 53,370	$ 29,644
Income tax benefit	(10,437)	(13,427)	(7,948)
Net income	45,534	52,959	37,309
Parent Company
OPERATING INCOME:
Other income	16	25	16
Total income	16	25	16
OPERATING EXPENSE:
Interest expense on borrowed funds	3,497	1,459	38
Other expenses	1,595	1,922	1,692
Total operating expense	5,092	3,381	1,730
Income before income tax benefit and equity in undistributed income of subsidiaries	(5,076)	(3,356)	(1,714)
Income tax benefit	1,066	705	360
Income before equity in undistributed income of subsidiaries	(4,010)	(2,651)	(1,354)
Dividends from subsidiary and equity in undistributed income of subsidiaries	49,544	55,610	38,663
Net income	$ 45,534	$ 52,959	$ 37,309

PARENT COMPANY ONLY FINANCIAL_5

PARENT COMPANY ONLY FINANCIAL STATEMENTS - Condensed Cash Flow Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 45,534	$ 52,959	$ 37,309
Adjustments to reconcile net income to net cash provided by operating activities:
Net amortization of discount on subordinated debentures	113	111	110
Stock based compensation expense	3,425	3,100	1,685
(Decrease) increase in accrued interest payable and other liabilities	2,395	3,053	1,822
Net cash provided by operating activities	61,063	66,867	46,059
CASH FLOWS FROM INVESTING ACTIVITIES:
Net cash used in investing activities	(961,104)	(233,514)	(31,155)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from the issuance of common stock, stock option exercises and the ESPP	2,569	3,412	3,750
Net increase in borrowings under credit agreement	15,000
Proceeds from subordinated notes issuance, net of offering expenses		58,601
Dividends paid to common shareholders	(8,165)
Repurchase of common stock	(18,582)	(58,663)	(2,112)
Net cash provided by financing activities	976,559	243,948	71,940
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	346,248
CASH AND CASH EQUIVALENTS, END OF PERIOD	422,766	346,248
Parent Company
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	45,534	52,959	37,309
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings of subsidiaries	(49,544)	(55,610)	(38,663)
Net amortization of discount on subordinated debentures	392	169	110
Stock based compensation expense	3,425	3,100	1,685
Increase in other assets	(1,026)	(639)	(236)
(Decrease) increase in accrued interest payable and other liabilities	(1,038)	166	279
Net cash provided by operating activities	(2,257)	145	484
CASH FLOWS FROM INVESTING ACTIVITIES:
Dividend from subsidiary	13,000	7,500
Net cash used in investing activities	13,000	7,500
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from the issuance of common stock, stock option exercises and the ESPP	2,569	3,412	3,552
Net increase in borrowings under credit agreement	15,000
Proceeds from subordinated notes issuance, net of offering expenses		58,601
Dividends paid to common shareholders	(8,165)
Repurchase of common stock	(18,582)	(58,663)	(2,113)
Net cash provided by financing activities	(9,178)	3,350	1,439
NET CHANGE IN CASH AND CASH EQUIVALENTS	1,565	10,995	1,923
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	17,775	6,780	4,857
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 19,340	$ 17,775	$ 6,780

QUARTERLY FINANCIAL DATA (UNA_3

QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Interest Income	$ 63,047	$ 60,811	$ 60,452	$ 57,452	$ 58,147	$ 58,665	$ 58,946	$ 57,149	$ 241,762	$ 232,907	$ 158,223
Net Interest Income	54,902	51,909	50,847	45,025	44,526	44,837	45,571	44,603	202,683	179,537	128,579
Net Income Attributable to Common Shareholders	$ 15,941	$ 16,170	$ 9,907	$ 3,516	$ 13,986	$ 12,047	$ 14,248	$ 12,678	$ 45,534	$ 52,959	$ 37,309
Earnings Per Share, Basic (in dollars per share)	$ 0.78	$ 0.79	$ 0.49	$ 0.17	$ 0.68	$ 0.57	$ 0.67	$ 0.58	$ 2.23	$ 2.50	$ 2.41
Earnings Per Share, Diluted (in dollars per share)	$ 0.77	$ 0.79	$ 0.48	$ 0.17	$ 0.67	$ 0.57	$ 0.66	$ 0.58	$ 2.22	$ 2.47	$ 2.37

SUBSEQUENT EVENT - Narrative (D

SUBSEQUENT EVENT - Narrative (Details) - Subsequent Event	Jan. 27, 2021$ / shares
Subsequent Event [Line Items]
Quarterly cash dividend, date declared	Jan. 27, 2021
Quarterly cash dividend, amount per share	$ 0.12
Quarterly cash dividend, date to be paid	Mar. 15, 2021
Quarterly cash dividend, date of record	Feb. 26, 2021