Spirit of Texas Bancshares (STXB) 10-Q 8 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 04, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	STXB
Entity Registrant Name	Spirit of Texas Bancshares, Inc.
Entity Central Index Key	0001499453
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		16,140,422
Entity Shell Company	false
Title of 12(b) Security	Common Stock, no par value
Security Exchange Name	NASDAQ
Entity File Number	001-38484
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	TX
Entity Tax Identification Number	90-0499552
Entity Address, Address Line One	1836 Spirit of Texas Way
Entity Address, City or Town	Conroe
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77301
City Area Code	936
Local Phone Number	521-1836
Document Quarterly Report	true
Document Transition Report	false

CONSOLIDATED BALANCE SHEETS (Un

CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Assets:
Cash and due from banks		$ 28,822	$ 22,664
Interest-bearing deposits in other banks		122,721	66,351
Total cash and cash equivalents		151,543	89,015
Time deposits in other banks		1,225
Investment securities:
Available for sale securities, at fair value		166,669	179,461
Total investment securities		166,669	179,461
Loans held for sale		2,784	3,945
Loans:
Loans held for investment	[1]	1,487,602	1,102,808
Less: allowance for loan and lease losses		(6,565)	(6,286)
Loans, net		1,481,037	1,096,522
Premises and equipment, net		65,144	53,877
Accrued interest receivable		6,319	4,934
Other real estate owned and repossessed assets		1,042	782
Goodwill		43,086	18,253
Core deposit intangible		11,628	8,558
SBA servicing asset		3,548	3,965
Deferred tax asset, net			328
Bank-owned life insurance		15,521	7,401
Federal Home Loan Bank and other bank stock, at cost		6,233	5,304
Other assets		4,005	4,276
Total assets		1,959,784	1,476,621
Transaction accounts:
Noninterest-bearing		366,209	256,784
Interest-bearing		593,064	378,822
Total transaction accounts		959,273	635,606
Time deposits		625,940	547,042
Total deposits		1,585,213	1,182,648
Accrued interest payable		1,002	702
Short-term borrowings			12,500
Long-term borrowings		74,165	77,784
Deferred tax liability, net		215
Other liabilities		2,451	4,191
Total liabilities		1,663,046	1,277,825
Commitments and contingencies (Note 13)
Stockholders' Equity:
Preferred stock, $1 par value; 5 million shares authorized; 0 shares issued and outstanding
Common stock, no par value; 50 million shares authorized; 16,121,479 and 12,103,753 shares issued and outstanding		251,875	169,939
Retained earnings		41,970	27,003
Accumulated other comprehensive income (loss)		3,091	1,854
Treasury stock		(198)
Total stockholders' equity		296,738	198,796
Total liabilities and stockholders' equity		$ 1,959,784	$ 1,476,621
[1]	Balance includes $(7.1) million and $(4.9) million of deferred fees, cost, premium and discount as of September 30, 2019 and December 31, 2018, respectively.

CONSOLIDATED BALANCE SHEETS (_2

CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares, issued	16,121,479	12,103,753
Common stock, shares, outstanding	16,121,479	12,103,753

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Interest income:
Interest and fees on loans	$ 23,064	$ 13,901	$ 62,386	$ 39,270
Interest and dividends on investment securities	1,143	202	3,627	611
Other interest income	794	173	2,172	536
Total interest income	25,001	14,276	68,185	40,417
Interest expense:
Interest on deposits	4,097	2,197	11,106	5,869
Interest on FHLB advances and other borrowings	425	389	1,414	1,395
Total interest expense	4,522	2,586	12,520	7,264
Net interest income	20,479	11,690	55,665	33,153
Provision for loan losses	900	486	2,081	1,460
Net interest income after provision for loan losses	19,579	11,204	53,584	31,693
Noninterest income:
Service charges and fees	866	462	2,564	1,238
SBA loan servicing fees	234	529	538	1,701
Mortgage referral fees	173	160	481	524
Gain on sales of loans, net	1,151	1,369	3,339	3,884
Gain on sales of investment securities			2,134
Other noninterest income	257	47	457	111
Total noninterest income	2,681	2,567	9,513	7,458
Noninterest expense:
Salaries and employee benefits	9,502	6,623	25,391	19,524
Occupancy and equipment expenses	1,710	1,279	4,662	3,736
Professional services	791	624	2,854	1,249
Data processing and network	884	302	2,100	936
Regulatory assessments and insurance	(256)	266	157	787
Amortization of intangibles	1,015	176	2,624	527
Advertising	134	83	398	300
Marketing	136	115	407	354
Telephone expense	289	120	767	332
Conversion expense	314		1,918
Other operating expenses	1,037	693	3,107	2,043
Total noninterest expense	15,556	10,281	44,385	29,788
Income before income tax expense	6,704	3,490	18,712	9,363
Income tax expense	1,374	719	3,745	1,898
Net income	$ 5,330	$ 2,771	$ 14,967	$ 7,465
Earnings per common share:
Basic	$ 0.35	$ 0.28	$ 1.09	$ 0.86
Diluted	$ 0.34	$ 0.27	$ 1.05	$ 0.82
Weighted average common shares outstanding:
Basic	15,370,480	9,792,032	13,774,776	8,673,106
Diluted	15,771,249	10,360,301	14,198,926	9,094,691

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 5,330	$ 2,771	$ 14,967	$ 7,465
Other comprehensive income (loss):
Unrealized net holding gains (losses) on investment securities available for sale, net of (tax) and benefit of $(158), $16, $(857) and $169, respectively	595	(61)	3,225	(637)
Reclassification adjustment for realized (gains) losses on investment securities available for sale included in net income, net of taxes of $0, $0, $529 and $0, respectively			(1,988)
Total other comprehensive income (loss)	595	(61)	1,237	(637)
Total comprehensive income	$ 5,925	$ 2,710	$ 16,204	$ 6,828

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Unrealized net holding gains (losses) on investment securities available for sale, (tax) and benefit	$ (158)	$ 16	$ (857)	$ 169
Reclassification adjustment for realized (gains) losses on investment securities available for sale included in net income, tax	$ 0	$ 0	$ 529	$ 0

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2017	$ 99,139	$ 82,615	$ 17,025		$ (501)
Balance (in shares) at Dec. 31, 2017		7,280,183
Net income	7,465		7,465
Shares issued in offering, net adjustment	42,058	$ 42,058
Shares issued in offering, net adjustment (in shares)		2,300,000
Exercise of stock options and warrants	2,362	$ 2,362
Exercise of stock options and warrants (in shares)		232,298
Stock-based compensation	506	$ 506
Other comprehensive income (loss)	(637)				(637)
Balance at Sep. 30, 2018	150,893	$ 127,541	24,490		(1,138)
Balance (in shares) at Sep. 30, 2018		9,812,481
Balance at Jun. 30, 2018	147,986	$ 127,344	21,719		(1,077)
Balance (in shares) at Jun. 30, 2018		9,786,611
Net income	2,771		2,771
Shares issued in offering, net adjustment	(161)	$ (161)
Exercise of stock options and warrants	177	$ 177
Exercise of stock options and warrants (in shares)		25,870
Stock-based compensation	181	$ 181
Other comprehensive income (loss)	(61)				(61)
Balance at Sep. 30, 2018	150,893	$ 127,541	24,490		(1,138)
Balance (in shares) at Sep. 30, 2018		9,812,481
Balance at Dec. 31, 2018	198,796	$ 169,939	27,003		1,854
Balance (in shares) at Dec. 31, 2018		12,103,753
Net income	14,967		14,967
Shares issued in business combination	33,479	$ 33,479
Shares issued in business combination (in shares)		1,579,191
Shares issued in offering, net adjustment	46,542	$ 46,542
Shares issued in offering, net adjustment (in shares)		2,300,000
Exercise of stock options and warrants	1,463	$ 1,463
Exercise of stock options and warrants (in shares)		148,125
Stock-based compensation	452	$ 452
Treasury stock purchases	(198)			$ (198)
Treasury stock purchases (in shares)		(9,590)
Other comprehensive income (loss)	1,237				1,237
Balance at Sep. 30, 2019	296,738	$ 251,875	41,970	(198)	3,091
Balance (in shares) at Sep. 30, 2019		16,121,479
Balance at Jun. 30, 2019	244,110	$ 204,974	36,640		2,496
Balance (in shares) at Jun. 30, 2019		13,790,332
Net income	5,330		5,330
Shares issued in offering, net adjustment	46,542	$ 46,542
Shares issued in offering, net adjustment (in shares)		2,300,000
Exercise of stock options and warrants	175	$ 175
Exercise of stock options and warrants (in shares)		40,737
Stock-based compensation	184	$ 184
Treasury stock purchases	(198)			(198)
Treasury stock purchases (in shares)		(9,590)
Other comprehensive income (loss)	595				595
Balance at Sep. 30, 2019	$ 296,738	$ 251,875	$ 41,970	$ (198)	$ 3,091
Balance (in shares) at Sep. 30, 2019		16,121,479

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash Flows From Operating Activities:
Net income	$ 14,967	$ 7,465
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for loan losses	2,081	1,460
Depreciation and amortization	2,212	1,410
Net amortization (accretion) of premium (discount) on investment securities	294	234
Amortization of core deposit intangible	2,624	527
Accretion of discount on retained SBA loans	(941)	(672)
Deferred tax expense (benefit)	2,765	(18)
Originations of loans held for sale	(38,692)	(50,963)
Proceeds from loans held for sale	43,351	53,152
Net gains on sale of loans held for sale	(3,339)	(3,884)
(Gain) loss on sale of investment securities	(2,134)
(Gain) loss on sale of other real estate owned	(90)	11
Fair value adjustment on SBA servicing asset	1,201	805
Stock-based compensation	452	506
Increase in cash surrender value of BOLI	(217)	(4)
Net change in operating assets and liabilities:
Net change in accrued interest receivable	(235)	(249)
Net change in accrued interest payable	(40)	68
Net change in other assets	995	945
Net change in other liabilities	(1,943)	(701)
Net cash provided by (used in) operating activities	23,311	10,092
Cash Flows From Investing Activities:
Purchases of investment securities available for sale	(32,536)
Sales of investment securities available for sale	79,920
Paydown and maturities of investment securities available for sale	24,134	2,754
Purchase of FHLB and other bank stock	(124)	(49)
Sale of FHLB and other bank stock	378
Proceeds from the sale of loans held for investment		1,451
Net change in loans	(89,661)	(85,969)
Proceeds from the sale of other real estate owned	1,123	22
Purchase of premises and equipment	(7,410)	(5,356)
Net cash received in business combination	28,126
Net cash provided by (used in) investing activities	3,950	(87,147)
Cash Flows From Financing Activities:
Net change in deposits	3,503	37,242
Redemption of trust preferred securities	77
Proceeds from long-term borrowings	25,598
Repayment of long-term borrowings	(37,915)	(11,450)
Proceeds from short-term borrowings		10,000
Repayment of short-term borrowings	(12,500)	(15,000)
Net change in secured borrowings	8,697	(1,968)
Shares issued in offering, net	46,542	42,058
Purchase of treasury stock	(198)
Exercise of stock options and warrants	1,463	2,362
Net cash provided by (used in) financing activities	35,267	63,244
Net Change in Cash and Cash Equivalents	62,528	(13,811)
Cash and Cash Equivalents at Beginning of Period	89,015	57,949
Cash and Cash Equivalents at End of Period	151,543	44,138
Supplemental Disclosures of Cash Flow Information:
Interest paid	12,220	5,802
Income taxes paid	2,000	2,850
Supplemental disclosure of noncash investing and financing activities:
Transfer of loans to other real estate owned and repossessed assets	98	$ 301
Fair value of assets acquired in business combination, excluding cash	404,970
Goodwill recorded	24,843
Liabilities assumed in business combination	399,605
Stock issued in business combination	$ 33,479

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	NOTE 1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Nature of Operations Spirit of Texas Bancshares, Inc. (“Spirit,” “STXB,” the “Holding Company” or “Company”) is a bank holding company headquartered in Conroe, Texas that provides, through its bank subsidiary, a variety of financial services to individuals and corporate customers located largely in the State of Texas, and which customers are primarily involved in agricultural, light industrial and commercial arenas. The Company consummated the underwritten initial public offering of its common stock in May 2018. In connection with the initial public offering, the Company issued and sold 2,300,000 shares of its common stock, including 300,000 shares of common stock sold pursuant to the underwriters’ full exercise of their option to purchase additional shares, at an offering price of $21.00 per share, for aggregate gross proceeds of $48.3 million before deducting underwriting discounts and offering expenses, and aggregate net proceeds of $42.1 million after deducting underwriting discounts and offering expenses. In addition, the Company consummated an underwritten public offering of its common stock on July 25, 2019 (the “2019 Offering”). In connection with the 2019 Offering, the Company issued and sold 2,300,000 shares of its common stock, including 300,000 shares sold pursuant to the Underwriters’ full exercise of their option to purchase additional shares, at a public offering price of $21.50 per share for net proceeds of approximately $46.5 million after deducting underwriting discounts and commissions and estimated offering expenses. The Company used $21.0 million of the net proceeds from the Offering to pay off a line of credit with a third-party lender and approximately $17.9 million of the net proceeds from the Offering to fund the cash portion of the merger consideration paid to the sole shareholder of Chandler Bancorp, Inc. (“Chandler”) in the Company’s acquisition of Chandler and its subsidiary, Citizens State Bank. The remaining net proceeds will be used by the Company for other general corporate purposes in order to support its continued growth, including investments in its bank subsidiary and future strategic acquisitions. Basis of Presentation The consolidated financial statements include the accounts of the Holding Company and the accounts of its wholly-owned subsidiary, Spirit of Texas Bank, SSB (the “Bank”). All significant intercompany balances and transactions have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and Article 8 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. Operating results for the period ended September 30, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 and should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2018 previously filed with the Securities and Exchange Commission in the Company’s Annual Report on Form 10-K In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for the fair presentation of these consolidated financial statements have been included. The preparation of financial statements in conformity with these accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and income and expense during the reporting periods and the related disclosures. Although management’s estimates and assumptions are based on current expectations, estimates, forecasts and projections about future performance of the Company, such estimates and assumptions are not guarantees of future performance and involve certain risks, uncertainties and assumptions that are difficult for the Company to assess. Operating results for the interim periods disclosed herein are not necessarily indicative of the results that may be expected for a full year or any future period. Correction of an Immaterial Error on the Consolidated Balance Sheet and Cash Flow The Company identified an immaterial error pertaining to the accounting of certain loan participations sold impacting its consolidated balance sheet and its consolidated statement of cash flows. Due to the rights retained on certain loan participations sold, the Company is deemed to have retained effective control over these loans under Financial Accounting Standards Board (“FASB”)’s Accounting Standards Codification (“ASC”) Topic 860, “Transfers and Servicing”, and therefore these participations sold must be accounted for as a secured borrowing. The Company reviewed the impact of this error on the prior periods and determined that the error was not material to the prior period consolidated financial statements. The Company has corrected the immaterial error in the consolidated balance sheet as of December 31, 2018 by revising the previously reported loans held for investment and long-term borrowings. The impact of the immaterial error correction increased loans held for investment and long-term borrowings by $ 9.9 million. The Company has also made revisions to correct the immaterial errors in the consolidated statement of cash flows for the nine months ended September 30, 2018 by increasing investing cash flows by $ 2.0 million an d decreasing financing cash flows by $ 2.0 million from amounts previously reported . Accounting Policies Recently Adopted and Pending Accounting Pronouncements ASU 2019-04, “Codification Improvements to Topic 326, Financial Instruments-Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments” – Issued in April 2019, Accounting Standards Update (“ASU”) No. 2019-04 clarifies a number of issues discussed at the June 2018 and November 2018 Credit Losses Transition Resource Group meetings. The clarifications address a variety of identified issues including but not limited to the treatment of accrued interest receivable as it relates to the allowance for credit losses, transfers between loan classifications and categories, recoveries, and using projections of future interest rate environments in expected cash flow calculations. Management is evaluating these clarifications concurrently with our assessment of ASU 2016-13. ASU 2018-13, “Fair Value Measurement Disclosure Framework” – Issued in August 2018, ASU No. 2018-13 modifies the disclosure requirements on fair value measurements outlined in Topic 820, Fair Value Measurements. Specifically the amendments in the ASU remove the requirements to disclose the amount and reasons for transfers between fair value hierarchy levels, the policy for timing of transfers between levels, the valuation processes for Level 3 fair value measurements, and for nonpublic entities, disclosure of the changes in unrealized gains and losses for the period included in earnings for recurring Level 3 fair value measurements. Additionally, the ASU adds disclosure requirements regarding changes in unrealized gains and losses for the period included in other comprehensive income related to Level 3 fair value measurements, and disclosure of the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. The amendments of ASU 2018-13 are effective for all entities for interim and annual periods beginning after December 15, 2019. Management adopted the provisions of this ASU removing fair value disclosure requirements as of December 31, 2018 as early adoption of the removal provisions was allowed and will adopt the remaining provisions of the ASU as of the effective date. ASU 2018-09, “Codification Improvements.” - Issued in July 2018, ASU No. 2018-09 makes changes to a variety of topics to clarify, correct errors in, or make minor improvements to the Accounting Standards Codification. The majority of the amendments in ASU 2018-09 will be effective in annual periods beginning after December 15, 2018. ASU 2018-09 is not expected to have a material impact on the Company’s consolidated financial statements. ASU 2017-04, “Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” Issued in January 2017, ASU 2017-04 simplifies the manner in which an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. In computing the implied fair value of goodwill under Step 2, an entity, prior to the amendments in ASU 2017-04, had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities, including unrecognized assets and liabilities, in accordance with the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. However, under the amendments in ASU 2017-04, an entity should (1) perform its annual or interim goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount, and (2) recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, with the understanding that the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, ASU 2017-04 removes the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails such qualitative test, to perform Step 2 of the goodwill impairment test. ASU 2017-04 is effective prospectively for public entities for annual, or any interim, goodwill impairment tests in fiscal years beginning after December 15, 2019 and for all other entities for impairment tests in fiscal years beginning after December 15, 2021. Management will adopt this ASU using the public company effective date as early adoption is permitted and will continue to evaluate the impact this ASU will have on the consolidated financial statements through its effective date; however, the adoption of ASU 2017-04 is not expected to have a material impact on the Company’s consolidated financial statements. ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” Issued in June 2016, ASU 2016-13 will add FASB ASC Topic 326, “Financial Instruments-Credit Losses,” and finalizes amendments to FASB ASC Subtopic 825-15, “Financial Instruments-Credit Losses.” The amendments of ASU 2016-13 are intended to provide financial statement users with more decision-useful information related to expected credit losses on financial instruments and other commitments to extend credit by replacing the current incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. The amendments of ASU 2016-13 eliminate the probable initial recognition threshold and, in turn, reflect an entity’s current estimate of all expected credit losses. ASU 2016-13 does not specify the method for measuring expected credit losses, and an entity is allowed to apply methods that reasonably reflect its expectations of the credit loss estimate. Additionally, the amendments of ASU 2016-13 require that credit losses on available for sale debt securities be presented as an allowance rather than as a write-down. The amendments of ASU 2016-13 were originally effective for public entities for interim and annual periods beginning after December 15, 2019 and for all other entities for periods beginning after December 15, 2020. Issued in November 2018, ASU 2018-19 , “ Codification Improvements to Topic 326, Financial Instruments-Credit Losses , ” alters the effective date of ASU 2016-13 for private companies. Under the provisions of ASU 2018-19, ASU 2016-13 is now effective for fiscal years beginning after December 15, 2021 including interim periods within those years for non-public business entities. Earlier application is permitted for interim and annual periods beginning after December 15, 2018. Management has elected to adopt this ASU using the updated private company effective date and is currently evaluating the impact this ASU will have on the consolidated financial statements and that evaluation will depend on economic conditions and the composition of the Company’s loan and lease portfolio at the time of adoption. ASU 2016-02, “Leases (Topic 842).” Issued in February 2016, ASU 2016-02 was issued by the FASB to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and by disclosing key information about leasing arrangements. ASU 2016-02 will, among other things, require 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, the ASU contains some targeted improvements that are intended to align, where necessary, lessor accounting with the lessee accounting model and with the updated revenue recognition guidance issued in 2014. The amendments of ASU 2016-02 are effective for public entities for interim and annual periods beginning after December 15, 2018 and for other entities for periods beginning after December 15, 2019. The adoption of this ASU will result in an increase to the Consolidated Balance Sheets for right-of-use assets and associated lease liabilities for operating leases in which the Company is the lessee. Under current accounting standards, all of the Company's leases are classified as operating leases and, as such, are not recognized on the Company's Consolidated Balance Sheet. Additionally, in July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases and ASU No. 2018-11, Leases, Targeted Improvements. The amendments in these updates provide additional clarification and implementation guidance on certain aspects of ASU 2016-02 and have the same effective and transition requirements as ASU 2016-02. Specifically, ASU 2018-11 creates an additional transition method option allowing entities to record a cumulative effect adjustment to opening retained earnings in the year of adoption. In December 2018, the FASB further issued ASU 2018-20, . The amendments in this update permits lessors to make an accounting policy election to not evaluate whether certain sales taxes and other similar taxes are lessor costs or lessee costs and instead account for the costs as if they were lessee costs. Additionally, the amendment requires lessors to exclude from variable payments, and therefore revenue, lessor costs paid by lessees directly to third parties. The amendments also require lessors to account for costs excluded from the consideration of a contract that are paid by the lessor and reimbursed by the lessee as variable payments. In March 2019, the FASB also issued ASU 2019-01, to further clarify certain identified issues regarding implementation of ASU 2016-02. Specifically, the amendments in ASU 2019-01 clarify the determination of fair value of underlying assets by lessors that are not manufacturers or dealers, the cash flow presentation of sales-type or direct financing leases, and transition disclosures for interim periods. Management will adopt these ASUs using the private company effective date of January 1, 2020 and is currently evaluating the impact to the consolidated financial statements and related method of adoption, specifically, management is in the process of determining an appropriate discount rate to record identified right-of-use assets.

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2019
Revenue From Contract With Customer [Abstract]
Revenue Recognition	NOTE 2. REVENUE RECOGNITION On January 1, 2019, the Company adopted ASU No. 2014-09, “ Revenue from Contracts with Customers (Topic 606) Topic 606 does not apply to revenue associated with financial instruments, including revenue from loans and securities. In addition, certain non-interest income streams such as fees associated with mortgage servicing rights, financial guarantees, derivatives, and certain credit card fees are also not in scope of the new guidance. Topic 606 is applicable to non-interest revenue streams, such as deposit related fees, interchange fees, merchant income, and brokerage and investment advisory service commissions. However, the recognition of these revenue streams did not change significantly upon adoption of Topic 606. Substantially all of the Company’s revenue is generated from contracts with customers. Non-interest revenue streams in-scope of Topic 606 are discussed below. Core Service Charges on Deposit Accounts Core service charges on deposit accounts consist of account analysis fees (i.e., net fees earned on analyzed business and public checking accounts) and monthly service fees. The Company’s performance obligation for account analysis fees and monthly service fees is generally satisfied, and the related revenue recognized, over the period in which the service is provided. Payment for service charges on deposit accounts is primarily received immediately or in the following month through a direct charge to customers’ accounts. Transaction Based Fee Income on Deposit Accounts Transaction based fee income on deposit accounts consists of variable revenue streams associated with activities which a deposit account holder may initiate on a transaction by transaction basis. The majority of transaction based fee income arises from interchange revenue received when deposit customers use a debit card for a point of sale transaction over a third party card payment network. Interchange revenue is recorded net of related interchange expenses in the month in which the transaction occurs. Merchant services income is realized through a third party service provider who is contracted by the Bank under a referral arrangement. Such fees represent fees charged to merchants to process their debit card transactions, in addition to account management fees. The third party service provider also issues credit cards as private label in the Company's name in exchange for a referral fee. Fees are earned and recorded in the same period as the referral occurs and the card is issued. Other transaction based service charges on deposit accounts include revenue from processing wire transfers, issuing cashier’s checks, processing check orders, and renting safe deposit boxes. The Company’s performance obligation related to these service charges is largely satisfied, and related revenue recognized, when the services are rendered or upon completion. Payment is typically received immediately or charged to the customers’ account in the period the service is provided. Safe deposit box rental fees are charged to the customer on an annual basis and recognized upon receipt of payment. The Company determined that since rentals and renewals occur fairly consistently over time, revenue is recognized on a basis consistent with the duration of the performance obligation. Mortgage Referral Fees Mortgage referral fees are also transaction based fee income. The Company’s performance obligation for fees is largely satisfied when the services are rendered or upon completion. Payment is typically received immediately. The following presents non-interest income, segregated by revenue streams in-scope and out-of-scope of Topic 606, for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Non-Interest Income In-scope of Topic 606 Deposit accounts core service charges $ 135 $ 88 $ 396 $ 233 Deposit account transaction based fee income 748 378 2,208 1,017 Mortgage referral fees 173 160 481 524 Non-Interest Income (in-scope of Topic 606) 1,056 626 3,085 1,774 Non-Interest Income (out-of-scope of Topic 606) 1,625 1,941 6,428 5,684 Total Non-Interest Income $ 2,681 $ 2,567 $ 9,513 $ 7,458 Contract Balances A contract asset balance occurs when an entity performs a service for a customer before the customer pays consideration (resulting in a contract receivable) or before payment is due (resulting in a contract asset). A contract liability balance is an entity’s obligation to transfer a service to a customer for which the entity has already received payment (or payment is due) from the customer. The Company’s non-interest revenue streams are largely based on transactional activity, or standard month-end revenue accruals. Consideration is often received immediately or shortly after the Company satisfies its performance obligation and revenue is recognized. The Company does not typically enter into long-term revenue contracts with customers, and therefore, does not experience significant contract balances. The Company did not have any significant contract balances at September 30, 2019 or December 31, 2018. Contract Acquisition Costs In connection with the adoption of Topic 606, an entity is required to capitalize, and subsequently amortize into expense, certain incremental costs of obtaining a contract with a customer if these costs are expected to be recovered. The incremental costs of obtaining a contract are those costs that an entity incurs to obtain a contract with a customer that it would not have incurred if the contract had not been obtained (for example, sales commission). The Company utilizes the practical expedient which allows entities to immediately expense contract acquisition costs when the asset that would have resulted from capitalizing these costs would have been amortized in one year or less. Upon adoption of Topic 606, the Company did not capitalize any contract acquisition cost.

Business Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Business Combinations	NOTE 3. BUSINESS COMBINATIONS Comanche National Corporation On November 14, 2018, Spirit of Texas Bancshares, Inc. (the “Company” or “Spirit”) completed its acquisition of Comanche National Corporation and its subsidiary, The Comanche National Bank (together, “Comanche”). This transaction resulted in 8 additional branches in the North Texas region. The Company issued 2,142,811 shares of its common stock as well as a net cash payment to Comanche shareholders of $12.2 million, for a total consideration of $52.9 million, for all outstanding stock of Comanche and resulted in 100% ownership interest. The Company has recognized total goodwill of $13.8 million which is calculated as the excess of both the consideration exchanged and liabilities assumed compared to the fair market value of identifiable assets acquired. The fair value of the consideration exchanged related to the Company’s common stock was calculated based upon the closing market price of the Company’s common stock as of November 14, 2018. None of the goodwill recognized is expected to be deductible for income tax purposes. The Company did not incur any expenses related to the acquisition for the three months ended September, 30 2019 and incurred approximately $1.2 million for the nine months ended September 30, 2019, which are included in noninterest expense in consolidated statements of income. The Company incurred $43 thousand of expenses related to the acquisition during the three and nine months ended September 30, 2018. Non-credit impaired loans had a fair value of $116.2 million at the acquisition date and contractual balance of $117.2 million. As of the acquisition date, the Company expects that an insignificant amount of the contractual balance of these loans will be uncollectible. The difference of $946 thousand will be recognized into interest income as an adjustment to yield over the life of the loans. Fair values of the assets acquired and liabilities assumed in this transaction as of the closing date are as follows: Assets of acquired bank (Dollars in thousands): Cash and cash equivalents $ 57,135 Securities available for sale 144,735 Loans held for investment 116,220 Premises and equipment, net 6,634 Other real estate owned 33 Goodwill 13,768 Core deposit intangible 5,988 Other assets 11,712 Total assets acquired $ 356,225 Liabilities of acquired bank: Deposits $ 297,778 Trust preferred securities 2,811 Other liabilities 2,698 Total liabilities assumed $ 303,287 Common stock issued at $18.99 per share $ 40,692 Cash paid $ 12,246 As of June 30, 2019, management has completed its evaluation of the fair values of other assets and other liabilities. Amounts shown above are considered finalized. Revenues and earnings of the acquired company since the acquisition date have not been disclosed as Comanche was merged into the Company and separate financial information is not readily available. First Beeville Financial Corporation On April 2, 2019 Spirit completed its acquisition of First Beeville Financial Corporation and its subsidiary, The First National Bank of Beeville (together, “Beeville”). This transaction resulted in three additional branches and two loan production offices in the South Texas region. The Company issued 1,579,191 shares of its common stock as well as a net cash payment to Beeville shareholders of $32.4 million, for a total consideration of $65.9 million, for all outstanding stock of Beeville and resulted in 100% ownership interest. The Company has recognized total goodwill of $24.8 million which is calculated as the excess of both the consideration exchanged and liabilities assumed compared to the fair market value of identifiable assets acquired. The fair value of the consideration exchanged related to the Company’s common stock was calculated based upon the closing market price of the Company’s common The Company incurred expenses related to the acquisition of approximately $823 thousand and $2.5 million for the three and nine months ended September 30, 2019, respectively, which are included in noninterest expense in consolidated statements of income. The Company incurred $2 thousand of expenses related to the acquisition during the three and nine months ended September 30, 2018. Non-credit impaired loans had a fair value of $296.9 million at the acquisition date and contractual balance of $298.9 million. As of the acquisition date, the Company expects that an insignificant amount of the contractual balance of these loans will be uncollectible. The difference of $2.0 million will be recognized into interest income as an adjustment to yield over the life of the loans. Estimated fair values of the assets acquired and liabilities assumed in this transaction as of the closing date are as follows: Assets of acquired bank (Dollars in thousands): Cash and cash equivalents $ 60,491 Securities available for sale 57,206 Loans held for investment 296,871 Premises and equipment, net 6,067 Other real estate owned 1,359 Goodwill 24,843 Core deposit intangible 5,695 Other assets 12,929 Total assets acquired $ 465,461 Liabilities of acquired bank: Deposits $ 399,062 Other liabilities 543 Total liabilities assumed $ 399,605 Common stock issued at $21.20 per share $ 33,479 Cash paid $ 32,377 As of September 30, 2019, management is still evaluating the fair values of other assets and other liabilities. Amounts shown above are preliminary and the Company expects to finalize these values by the fourth quarter of 2019. Revenues and earnings of the acquired company since the conversion date have not been disclosed as Beeville was merged into the Company and separate financial information is not readily available.

Investment Securities

Investment Securities	9 Months Ended
	Sep. 30, 2019
Investments Debt And Equity Securities [Abstract]
Investment Securities	NOTE 4. INVESTMENT SECURITIES The amortized cost, gross unrealized gains and losses and approximate fair values of securities available for sale are as follows: Amortized Unrealized Fair September 30, 2019 Cost Gains Losses Value (Dollars in thousands) Available for sale: U.S. Treasury securities $ 32,541 $ 23 $ 1 $ 32,563 U.S. Government agencies 4,074 67 — 4,141 State and municipal obligations 24,795 833 — 25,628 Residential mortgage-backed securities 95,737 2,921 13 98,645 Corporate bonds and other debt securities 5,633 59 — 5,692 Total available for sale $ 162,780 $ 3,903 $ 14 $ 166,669 Amortized Unrealized Fair December 31, 2018 Cost Gains Losses Value (Dollars in thousands) Available for sale: U.S. Government agencies $ 2,015 $ — $ 81 $ 1,934 State and municipal obligations 17,201 847 — 18,048 Residential mortgage-backed securities 152,232 2,614 872 153,974 Corporate bonds and other debt securities 5,667 — 162 5,505 Total available for sale $ 177,115 $ 3,461 $ 1,115 $ 179,461 Taxable interest and dividends on investment securities were $998 thousand and $202 thousand for the three months ended September 30, 2019 and 2018, respectively. Tax-exempt interest and dividends on investment securities were $146 thousand for the three months ended September 30, 2019. There were no tax-exempt interest or dividends on investment securities for the three months ended September 30, 2018. Taxable interest and dividends on investment securities were $3.2 million and $611 thousand for the nine months ended September 30, 2019 and 2018, respectively. Tax-exempt interest and dividends on investment securities were $411 thousand for the nine months ended September 30, 2019. There were no tax-exempt interest or dividends on investment securities for the nine months ended September 30, 2018. There were $140.8 million and $106.6 million of securities pledged to collateralize public funds at September 30, 2019 The amortized cost and estimated fair value of securities available for sale, by contractual maturity, are as follows for the period presented: Amortized Fair September 30, 2019 Cost Value (Dollars in thousands) Available for sale: Due in one year or less $ 19,377 $ 19,412 Due after one year through five years 35,152 35,427 Due after five years through ten years 6,863 7,066 Due after ten years 5,651 6,119 Residential mortgage-backed securities 95,737 98,645 Total available for sale $ 162,780 $ 166,669 For purposes of the maturity table, residential mortgage-backed securities, the principal of which are repaid periodically, are presented as a single amount. The expected lives of these securities will differ from contractual maturities because borrowers may have the right to prepay the underlying loans with or without prepayment penalties. The following tables present the estimated fair values and gross unrealized losses on investment securities available for sale, aggregated by investment category and length of time individual securities have been in a continuous unrealized loss position as of the periods presented: Less than 12 Months 12 Months or More Total September 30, 2019 Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss (Dollars in thousands) Available for sale: U.S. Treasury securities $ 2,998 $ 1 $ — $ — $ 2,998 $ 1 U.S. Government agencies — — — — — — State and municipal obligations — — — — — — Residential mortgage-backed securities — — 4,994 13 4,994 13 Corporate bonds and other debt securities — — — — — — Total available for sale $ 2,998 $ 1 $ 4,994 $ 13 $ 7,992 $ 14 Less than 12 Months 12 Months or More Total December 31, 2018 Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss (Dollars in thousands) Available for sale: U.S. Government agencies $ — $ — $ 1,934 $ 81 $ 1,934 $ 81 State and municipal obligations — — — — — — Residential mortgage-backed securities 1 — 25,479 872 25,480 872 Corporate bonds and other debt securities — — 5,505 162 5,505 162 Total available for sale $ 1 $ — $ 32,918 $ 1,115 $ 32,919 $ 1,115 At September 30, 2019, the Company’s securities portfolio consisted of 227 securities, 9 of which were in an unrealized loss position. Eight of the nine securities in an unrealized loss position at September 30, 2019 were in an unrealized loss position for more than 12 months. The unrealized losses for these securities resulted primarily from changes in interest rates and spreads. The Company monitors its investment securities for other-than-temporary-impairment (“OTTI”). Impairment is evaluated on an individual security basis considering numerous factors, and its relative significance. The Company has evaluated the nature of unrealized losses in the investment securities portfolio to determine if OTTI exists. The unrealized losses relate to changes in market interest rates and specific market conditions that do not represent credit-related impairments. Furthermore, the Company does not intend to sell nor is it more likely than not that it will be required to sell these investments before the recovery of their amortized cost basis. Management has completed an assessment of each security in an unrealized loss position for credit impairment and has determined that no individual security was other-than-temporarily impaired at September 30, 2019. The following describes the basis under which the Company has evaluated OTTI: U.S. Treasury Securities, U.S. Government Agencies and Residential Mortgage-Backed Securities (“MBS”): The unrealized losses associated with U.S. Treasury securities, U.S. Government agencies and residential MBS are primarily driven by changes in interest rates. These securities have either an explicit or implicit U.S. government guarantee. Corporate Bonds & Other Debt Securities: Securities are generally underwritten in accordance with the Company’s investment standards prior to the decision to purchase, without relying on a bond issuer’s guarantee in making the investment decision. These investments are investment grade and will continue to be monitored as part of the Company’s ongoing impairment analysis, but are expected to perform in accordance with their terms. There were no securities sold for the three months ended September 30, 2019. Sale proceeds from the sale of available for sale securities for the nine months ended September 30, 2019 were $79.9 million which resulted in gross realized gains of $2.1 million. There were no securities sold for the three or nine months ended September 30, 2018.

Loans, Net

Loans, Net	9 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Loans, Net	NOTE 5. LOANS, NET Loans, net consisted of the following at September 30, 2019 and December 31, 2018: September 30, 2019 December 31, 2018 (Dollars in thousands) Commercial and industrial loans (1) $ 248,745 $ 173,892 Real estate: 1-4 single family residential loans 321,044 279,665 Construction, land and development 233,830 159,734 Commercial real estate loans (including multifamily) 597,415 403,800 Consumer loans and leases 17,663 24,378 Municipal and other loans 68,905 61,339 Total loans held in portfolio (2) $ 1,487,602 $ 1,102,808 Allowance for loan losses (6,565 ) (6,286 ) Loans held in portfolio, net $ 1,481,037 $ 1,096,522 (1) Balance includes $78.7 million and $76.9 million of the unguaranteed portion of Small Business Administration (“SBA”) loans as of September 30, 2019 and December 31, 2018, respectively. (2) Balance includes $(7.1) million and $(4.9) million of deferred fees, cost, premium and discount as of September 30, 2019 and December 31, 2018, respectively. At September 30, 2019 and December 31, 2018, the Company had pledged loans as collateral for Federal Home Loan Bank (“FHLB”) advances of $664.7 million and $385.5 million, respectively. There were no recorded investments of consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings were in process as of September 30, 2019 and December 31, 2018. The Company originates and sells loans secured by the SBA. The Company retains the unguaranteed portion of the loan and servicing on the loans sold and receives a fee based upon the principal balance outstanding. During the three months ended September 30, 2019 and 2018, the Company sold approximately $13.8 million and $19.0 million, respectively, in SBA loans to third parties. The loan sales resulted in realized gains of $1.2 million and $1.4 million for the three months ended September 30, 2019 and 2018, respectively. During the nine months ended September 30, 2019 and 2018, the Company sold approximately $40.3 and $49.0 million, respectively, in SBA loans to third parties. The SBA loan sales resulted in realized gains of $3.3 million and $3.9 million for the nine months ended September 30, 2019 and 2018, respectively. Due to the rights retained on certain loan participations sold, the Company is deemed to have retained effective control over these loans under ASC 860, “Transfers and Servicing.” These loans can no longer be reported as sold, and must be reported on the balance sheet as loans held for investment regardless of whether the Company intends to exercise its rights. These loans are reported as loans held for investment with the offsetting liability recorded as long-term borrowings. The amount of secured borrowings included in loans held for investment and long-term borrowings at September 30, 2019 and December 31, 2018 was $18.6 million and $9.9 million, respectively. Loans serviced for others are not included in the accompanying balance sheets. The unpaid principal balances of loans serviced for others, including SBA loans, were $233.7 million and $234.9 million at September 30, 2019 and December 31, 2018, respectively. In the ordinary course of business, the Company makes loans to executive officers and directors. Loans to these related parties, including companies in which they are principal owners, are as follows for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (Dollars in thousands) Principal outstanding, beginning of year $ 2,433 $ 421 $ 107 $ 463 Additions (reductions) of affiliations — — 2,352 — New loans made in current year 4,035 — 4,035 — Repayments (57 ) (19 ) (83 ) (61 ) Principal outstanding, end of year $ 6,411 $ 402 $ 6,411 $ 402 There were $1.3 million in unfunded commitments to related parties at September 30, 2019. There were no unfunded commitments to related parties at December 31, 2018.

Allowance for Loan and Lease Lo

Allowance for Loan and Lease Losses	9 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Allowance for Loan and Lease Losses	NOTE 6. ALLOWANCE FOR LOAN AND LEASE LOSSES The allowance for loan and lease losses is a reserve established through a provision for loan losses charged to expense, which represents management’s best estimate of probable losses that have been incurred within the existing portfolio of loans. The allowance, in the judgment of management, is necessary to reserve for estimated loan losses and risks inherent in the loan portfolio. The methodology is based on historical loss experience by type of credit and internal risk grade, changes in the composition and volume of the portfolio, and specific loss allocations, with adjustments for current events and conditions. The Company’s process for determining the appropriate level of the allowance for loan and lease losses is designated to account for credit deterioration as it occurs. Prior to the second quarter of 2018, the Company was utilizing a peer bank allowance coverage ratio in the qualitative reserve calculation, as the Company did not have enough historical defaults to rely on its own loss factors. Beginning the second quarter of 2018, the Company had a sufficient amount of defaults over the five year lookback period to transition over to relying more on its own historical loss data versus peer data. While this did not result in a significant change to the allowance for loan and lease losses as a whole, it continues to impact the provision for certain loan categories in which the Company had experienced more historical defaults. On November 14, 2018, the Company closed its acquisition of Comanche. At the date of acquisition, Comanche had $117.2 million in loans. In accordance with ASC 805, “Business Combinations,” the Company utilized a third party to value the loan portfolio as of the acquisition date. Based upon the third party valuation, the fair value of the loans was approximately $116.2 million at the acquisition date. The overall discount calculated was $ 946 thousand and will be accreted into interest income over the life of the loans. On April 2, 2019, the Company closed its acquisition of Beeville. At the date of acquisition, Beeville had $298.9 million in loans. In accordance with ASC 805, “Business Combinations,” the Company utilized a third party to value the loan portfolio as of the acquisition date. Based upon the third party valuation, the fair value of the loans was approximately $296.3 million at the acquisition date. The overall discount calculated was $2.6 million and will be accreted into interest income over the life of the loans. As of September 30, 2019, all purchased loans were excluded from the allowance for loan and lease losses calculation given there was no deterioration between the acquisition date and the end of the third quarter of 2019. Purchased credit impaired loans were insignificant. Going forward, management will evaluate the remaining credit quality, credit discount and charge-offs associated with these purchased loans to determine if an additional allowance is deemed necessary. The following tables present information related to allowance for loan and lease losses for the periods presented: Allowance Rollforward Three Months Ended September 30, 2019 Beginning Balance Charge-offs Recoveries Provision Ending Balance (Dollars in thousands) Commercial and industrial loans $ 4,217 $ (687 ) $ 36 $ 669 $ 4,235 Real estate: 1-4 single family residential loans 32 — 65 (66 ) 31 Construction, land and development loans 794 — — 90 884 Commercial real estate loans (including multifamily) 1,191 — — 127 1,318 Consumer loans and leases 35 (26 ) — 85 94 Municipal and other loans 8 — — (5 ) 3 Ending allowance balance $ 6,277 $ (713 ) $ 101 $ 900 $ 6,565 Allowance Rollforward Three Months Ended September 30, 2018 Beginning Balance Charge-offs Recoveries Provision Ending Balance (Dollars in thousands) Commercial and industrial loans $ 4,886 $ (275 ) $ 4 $ 76 $ 4,691 Real estate: 1-4 single family residential loans 318 — — (216 ) 102 Construction, land and development loans 195 — — 256 451 Commercial real estate loans (including multifamily) 233 — — 495 728 Consumer loans and leases 346 (74 ) — (90 ) 182 Municipal and other loans 37 — — (35 ) 2 Ending allowance balance $ 6,015 $ (349 ) $ 4 $ 486 $ 6,156 Allowance Rollforward Nine Months Ended September 30, 2019 Beginning Balance Charge-offs Recoveries Provision Ending Balance (Dollars in thousands) Commercial and industrial loans $ 4,453 $ (1,908 ) $ 95 $ 1,595 $ 4,235 Real estate: 1-4 single family residential loans 59 — 65 (93 ) 31 Construction, land and development loans 731 — — 153 884 Commercial real estate loans (including multifamily) 960 — — 358 1,318 Consumer loans and leases 80 (60 ) 5 69 94 Municipal and other loans 3 — 1 (1 ) 3 Ending allowance balance $ 6,286 $ (1,968 ) $ 166 $ 2,081 $ 6,565 Allowance Rollforward Nine Months Ended September 30, 2018 Beginning Balance Charge-offs Recoveries Provision Ending Balance (Dollars in thousands) Commercial and industrial loans $ 3,046 $ (920 ) $ 73 $ 2,492 $ 4,691 Real estate: 1-4 single family residential loans 902 (5 ) — (795 ) 102 Construction, land and development loans 441 — — 10 451 Commercial real estate loans (including multifamily) 898 — — (170 ) 728 Consumer loans and leases 198 (104 ) — 88 182 Municipal and other loans 167 — — (165 ) 2 Ending allowance balance $ 5,652 $ (1,029 ) $ 73 $ 1,460 $ 6,156 Credit Quality Indicators In evaluating credit risk, the Company looks at multiple factors; however, management considers delinquency status to be the most meaningful indicator of the credit quality of 1-4 single family residential, home equity loans and lines of credit and consumer loans. Delinquency statistics are updated at least monthly. Internal risk ratings are considered the most meaningful indicator of credit quality for commercial, construction, land and development and commercial real estate loans. Internal risk ratings are updated on a continuous basis. The following tables present an aging analysis of the recorded investment for delinquent loans by portfolio and segment for the periods presented: Accruing September 30, 2019 Current 30 to 59 Days Past Due 60 to 89 Days Past Due 90 Days or More Past Due Non- Accrual Total (Dollars in thousands) Commercial and industrial loans $ 241,710 $ 517 $ 215 $ 120 $ 6,183 $ 248,745 Real estate: 1-4 single family residential loans 318,304 1,287 113 — 1,340 321,044 Construction, land and development 233,614 — — — 216 233,830 Commercial real estate loans (including multifamily) 593,794 1,851 601 — 1,169 597,415 Consumer loans and leases 17,371 176 40 — 76 17,663 Municipal and other loans 68,867 — — — 38 68,905 Total loans $ 1,473,660 $ 3,831 $ 969 $ 120 $ 9,022 $ 1,487,602 Accruing December 31, 2018 Current 30 to 59 Days Past Due 60 to 89 Days Past Due 90 Days or More Past Due Non- Accrual Total (Dollars in thousands) Commercial and industrial loans $ 169,206 $ 605 $ 223 $ 288 $ 3,570 $ 173,892 Real estate: 1-4 single family residential loans 277,930 581 64 — 1,090 279,665 Construction, land and development 159,723 11 — — — 159,734 Commercial real estate loans (including multifamily) 402,406 451 589 — 354 403,800 Consumer loans and leases 24,109 208 44 — 17 24,378 Municipal and other loans 61,289 50 — — — 61,339 Total loans $ 1,094,663 $ 1,906 $ 920 $ 288 $ 5,031 $ 1,102,808 There was one loan 90 days or more past due and still accruing at September 30, 2019 with a recorded investment of $120 thousand. There were four loans 90 days or more past due and still accruing at December 31, 2018 with a recorded investment of $288 thousand. At September 30, 2019, non-accrual loans that were 30 to 59 days past due were $928 thousand, non-accrual loans that were 60 to 89 days past due were $125 thousand, and non-accrual loans that were 90 days or more past due were $4.7 million. At December 31, 2018 , non-accrual loans that were 30 to 59 days past due were $ 175 thousand, non-accrual loans that were 60 to 89 days past due were $ 143 thousand, and non-accrual loans that were 90 days or more past due were $ 2.0 million . Loans exhibiting potential credit weaknesses that deserve management’s close attention and that if left uncorrected may result in deterioration of the repayment capacity of the borrower are categorized as special mention. Loans with well-defined credit weaknesses including payment defaults, declining collateral values, frequent overdrafts, operating losses, increasing balance sheet leverage, inadequate cash flow, project cost overruns, unreasonable construction delays, past due real estate taxes or exhausted interest reserves are assigned an internal risk rating of substandard. Loans classified as substandard can be on an accrual or non-accrual basis, as determined by its unique characteristics. A loan with a weakness so severe that collection in full is highly questionable or improbable will be assigned an internal risk rating of doubtful. The following tables summarize the Company’s loans by key indicators of credit quality for the periods presented: September 30, 2019 Pass Special Mention Substandard Doubtful (Dollars in thousands) Commercial and industrial loans $ 234,989 $ 3,246 $ 10,510 $ — Real estate: 1-4 single family residential loans 318,562 281 2,201 — Construction, land and development 232,792 — 1,038 — Commercial real estate loans (including multifamily) 582,481 4,603 10,331 — Consumer loans and leases 17,533 — 130 — Municipal and other loans 68,860 — 45 — Total loans $ 1,455,217 $ 8,130 $ 24,255 $ — December 31, 2018 Pass Special Mention Substandard Doubtful (Dollars in thousands) Commercial and industrial loans $ 163,908 $ 3,170 $ 6,601 $ 213 Real estate: 1-4 single family residential loans 274,860 1,714 2,547 544 Construction, land and development 157,688 24 2,022 — Commercial real estate loans (including multifamily) 389,170 12,412 1,806 412 Consumer loans and leases 20,798 1,836 180 1,564 Municipal and other loans 60,837 484 — 18 Total loans $ 1,067,261 $ 19,640 $ 13,156 $ 2,751 Internal risk ratings and other credit metrics are key factors in identifying loans to be individually evaluated for impairment and impact management’s estimates of loss factors used in determining the amount of the allowance for loan and lease losses. The following tables show the Company’s investment in loans disaggregated based on the method of evaluating impairment for the periods presented: Loans - Recorded Investment Allowance for Credit Loss September 30, 2019 Individually Evaluated for Impairment Collectively Evaluated for Impairment Individually Evaluated for Impairment Collectively Evaluated for Impairment (Dollars in thousands) Commercial and industrial loans $ 2,638 $ 246,107 $ 1,194 $ 3,041 Real estate: 1-4 single family residential loans 1,399 319,645 4 27 Construction, land and development 216 233,614 — 884 Commercial real estate loans (including multifamily) 236 597,179 — 1,318 Consumer loans and leases 21 17,642 5 89 Municipal and other loans — 68,905 — 3 Total loans $ 4,510 $ 1,483,092 $ 1,203 $ 5,362 Loans - Recorded Investment Allowance for Credit Loss December 31, 2018 Individually Evaluated for Impairment Collectively Evaluated for Impairment Individually Evaluated for Impairment Collectively Evaluated for Impairment (Dollars in thousands) Commercial and industrial loans $ 3,640 $ 170,252 $ 1,234 $ 3,219 Real estate: 1-4 single family residential loans 1,193 278,472 29 30 Construction, land and development — 159,734 — 731 Commercial real estate loans (including multifamily) — 403,800 — 960 Consumer loans and leases 17 24,361 4 76 Municipal and other loans — 61,339 — 3 Total loans $ 4,850 $ 1,097,958 $ 1,267 $ 5,019 The following tables set forth certain information regarding the Company’s impaired loans that were evaluated for specific reserves for the periods presented: Impaired Loans - With Allowance Impaired Loans - With no Allowance September 30, 2019 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance (Dollars in thousands) Commercial and industrial loans $ 2,158 $ 4,565 $ 1,194 $ 480 $ 2,298 Real estate: 1-4 single family residential loans 14 16 4 1,385 1,452 Construction, land and development — — — 216 223 Commercial real estate loans (including multifamily) — — — 236 244 Consumer loans and leases 21 21 5 — — Municipal and other loans — — — — — Total loans $ 2,193 $ 4,602 $ 1,203 $ 2,317 $ 4,217 Impaired Loans - With Allowance Impaired Loans - With no Allowance December 31, 2018 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance (Dollars in thousands) Commercial and industrial loans $ 1,843 $ 5,392 $ 1,234 $ 1,797 $ 3,500 Real estate: 1-4 single family residential loans 116 124 29 1,077 1,086 Construction, land and development — — — — — Commercial real estate loans (including multifamily) — — — — — Consumer loans and leases 17 17 4 — — Municipal and other loans — — — — — Total loans $ 1,976 $ 5,533 $ 1,267 $ 2,874 $ 4,586 Three Months Ended September 30, 2019 2018 Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized (Dollars in thousands) Commercial and industrial loans $ 2,758 $ — $ 2,571 $ — Real estate: 1-4 single family residential loans 1,409 — 975 — Construction, land and development 216 — — — Commercial real estate loans (including multifamily) 238 — — — Consumer loans and leases 22 — 72 — Municipal and other loans — — — — Total loans $ 4,643 $ — $ 3,618 $ — Nine Months Ended September 30, 2019 2018 Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized (Dollars in thousands) Commercial and industrial loans $ 2,905 $ — $ 2,774 $ — Real estate: 1-4 single family residential loans 1,434 — 990 — Construction, land and development 220 — — — Commercial real estate loans (including multifamily) 243 — — — Consumer loans and leases 24 — 76 — Municipal and other loans — — — — Total loans $ 4,826 $ — $ 3,840 $ — Troubled Debt Restructurings: The following table provides a summary of troubled debt restructurings (“TDRs”) based upon delinquency status, all of which are considered impaired, for the periods presented: September 30, 2019 December 31, 2018 Number of contracts Recorded Investment Number of contracts Recorded Investment (Dollars in thousands) Performing TDRs: Commercial and industrial loans 3 $ 118 3 $ 69 Real estate: 1-4 single family residential loans 3 157 2 141 Construction, land and development — — — — Commercial real estate loans (including multifamily) — — — — Consumer loans and leases — — — — Municipal and other loans — — — — Total performing TDRs 6 275 5 210 Nonperforming TDRs 8 403 7 448 Total TDRs 14 $ 678 12 $ 658 Allowance attributable to TDRs $ 265 $ 149 The following tables summarize TDRs, and includes newly designated TDRs as well as modifications made to existing TDRs, for the periods presented. Modifications may include, but are not limited to, granting a material extension of time, entering into a forbearance agreement, adjusting the interest rate, accepting interest only payments for an extended period of time, a change in the amortization period or a combination of any of these. Post-modification balances represent the recorded investment at the end of Day 2 in which the modification was made. Three Months Ended September 30, 2019 2018 Number of Contracts Pre- Modification Outstanding Recorded Investment Post- Modification Outstanding Recorded Investment Related Allowance Number of Contracts Pre- Modification Outstanding Recorded Investment Post- Modification Outstanding Recorded Investment Related Allowance (Dollars in thousands) Commercial and industrial loans 1 $ 13 $ 13 $ — — $ — $ — $ — Real estate: 1-4 single family residential loans — — — — — — — — Construction, land and development — — — — — — — — Commercial real estate loans (including multifamily) — — — — — — — — Consumer loans and leases — — — — — — — — Municipal and other loans — — — — — — — — Nine Months Ended September 30, 2019 2018 Number of Contracts Pre- Modification Outstanding Recorded Investment Post- Modification Outstanding Recorded Investment Related Allowance Number of Contracts Pre- Modification Outstanding Recorded Investment Post- Modification Outstanding Recorded Investment Related Allowance (Dollars in thousands) Commercial and industrial loans 3 $ 141 $ 141 $ 90 7 $ 442 $ 442 $ 113 Real estate: 1-4 single family residential loans — — — — 1 34 34 — Construction, land and development — — — — — — — — Commercial real estate loans (including multifamily) — — — — — — — — Consumer loans and leases — — — — — — — — Municipal and other loans — — — — — — — — There have been no defaults of troubled debt restructurings that took place within the three or nine months ended September 30, 2019 and 2018.

Goodwill and Intangibles

Goodwill and Intangibles	9 Months Ended
	Sep. 30, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangibles	NOTE 7. GOODWILL AND INTANGIBLES Goodwill and other intangible assets, which consist of core deposit intangibles, are summarized as follows: Nine Months Ended September 30, 2019 Year Ended December 31, 2018 (Dollars in thousands) Beginning goodwill $ 18,253 $ 4,485 Arising from business combination 24,833 13,768 Ending goodwill $ 43,086 $ 18,253 Core deposit intangible 8,558 13,166 Arising from business combination 10,304 — Less: Accumulated amortization (7,234 ) (4,608 ) Core deposit intangible, net $ 11,628 $ 8,558 Amortization expense for core deposit intangibles for the three months ended September 30, 2019 and 2018 totaled $1.0 million and $176 thousand, respectively. Amortization expense for core deposit intangibles for the nine months ended September 30, 2019 and 2018 totaled $2.6 million and $527 thousand, respectively. The estimated amount of amortization expense for core deposit intangibles to be recognized over the next five fiscal years is as follows: Type of intangibles Remainder of 2019 2020 2021 2022 2023 2024 (Dollars in thousands) Core deposit intangible $ 975 $ 3,518 $ 2,865 $ 2,072 $ 1,384 $ 653

SBA Servicing Asset

SBA Servicing Asset	9 Months Ended
	Sep. 30, 2019
Transfers And Servicing Of Financial Assets [Abstract]
SBA Servicing Asset	NOTE 8. SBA SERVICING ASSET SBA servicing assets are recognized separately when rights are acquired through the sale of the guaranteed portion of SBA loans. These servicing rights are initially measured at fair value at the date of sale and included in the gain on sale. Updated fair values are obtained from an independent third party on a quarterly basis and adjustments are presented in SBA loan servicing fees on the consolidated statements of income. To determine the fair value of SBA servicing rights, the Company uses market prices for comparable servicing contracts, when available, or alternatively, uses a valuation model that calculates the present value of estimated future net servicing income. Loans serviced for others are not included in the accompanying balance sheets. The unpaid principal balances of SBA loans serviced for others were $215.2 million and $225.0 million at September 30, 2019 and December 31, 2018, respectively. SBA loan servicing fees were $234 thousand and $529 thousand for the three months ended September 30, 2019 and 2018, respectively. SBA loan servicing fees were $538 thousand and $1.7 million for the nine months ended September 30, 2019 and 2018, respectively. The risks inherent in the SBA servicing asset relate primarily to changes in prepayments that result from shifts in interest rates. The following summarizes the activity pertaining to SBA servicing rights, which are in the consolidated balance sheets, for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (Dollars in thousands) Beginning balance $ 3,570 $ 3,521 $ 3,965 $ 3,411 Origination of servicing assets 264 376 784 955 Change in fair value: Due to run-off (241 ) (254 ) (645 ) (707 ) Due to market changes (45 ) (82 ) (556 ) (98 ) Ending balance $ 3,548 $ 3,561 $ 3,548 $ 3,561

Deposits

Deposits	9 Months Ended
	Sep. 30, 2019
Banking And Thrift [Abstract]
Deposits	NOTE 9. DEPOSITS The following table sets forth the Company’s deposits by category for the periods presented: September 30, 2019 December 31, 2018 (Dollars in thousands) Noninterest-bearing demand deposits $ 366,209 $ 256,784 Interest-bearing demand deposits 303,037 124,933 Interest-bearing NOW accounts 8,626 7,961 Savings and money market accounts 281,401 245,928 Time deposits 625,940 547,042 Total deposits $ 1,585,213 $ 1,182,648 Time deposits $100,000 and greater $ 496,874 $ 422,447 Time deposits $250,000 and greater 176,922 129,424 Related party deposits (executive officers and directors) 16,195 7,847 The aggregate amount of overdraft demand deposits reclassified to loans was $69 thousand and $93 thousand at September 30, 2019 and December 31, 2018, respectively. The aggregate amount of maturities for time deposits for each of the five years following the latest balance sheet date totaled $505.1 million, $85.8 million, $18.8 million, $10.9 million and $5.3 million, respectively. The Company held brokered certificates of deposit of $ 1.0 million at September 30, 2019. The Company held no brokered certificates of deposit as of December 31, 2018.

Stock-Based Compensation and Ot

Stock-Based Compensation and Other Benefit Plans	9 Months Ended
	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation and Other Benefit Plans	NOTE 10. STOCK-BASED COMPENSATION AND OTHER BENEFIT PLANS Spirit of Texas Bancshares, Inc. 2008 Stock Plan (the “2008 Stock Plan”) Option activity for the period indicated is summarized as follows: 2008 Stock Plan Options Weighted Average Exercise Price Aggregate Intrinsic Value (in thousands) Weighted Average Remaining Contractual Life (Years) Outstanding at January 1, 2019 1,116,672 $ 13.04 Granted — Exercised (165,850 ) $ 11.33 $ 1,695 Forfeited (7,600 ) $ 14.66 Expired — Outstanding at September 30, 2019 943,222 $ 13.33 $ 7,753 4.57 Vested and exercisable at September 30, 2019 832,597 $ 13.19 $ 6,961 4.34 The total unrecognized compensation cost of $317 thousand related to the 2008 Stock Plan for the share awards outstanding at September 30, 2019 will be recognized over a weighted average remaining period of 1.49 years. Spirit of Texas Bancshares, Inc. 2017 Stock Plan (the “2017 Stock Plan”) Option activity for the period indicated is summarized as follows: 2017 Stock Plan Options Weighted Average Exercise Price Aggregate Intrinsic Value (in thousands) Weighted Average Remaining Contractual Life (Years) Outstanding at January 1, 2019 205,725 $ 17.45 Granted 850 $ 23.18 Exercised (5,000 ) $ 15.00 $ 33 Forfeited (1,502 ) $ 18.22 Expired — Outstanding at September 30, 2019 200,073 $ 17.53 $ 804 7.95 Vested and exercisable at September 30, 2019 91,589 $ 16.04 $ 505 7.63 The fair values of the stock options granted for the nine months ended September 30, 2019 were determined utilizing the Black-Scholes pricing model methodology. A summary of assumptions used to calculate the fair values of the 2017 Stock Plan awards is presented below: 2017 Stock Plan Nine Months Ended September 30, 2019 Expected volatility 23.3 % Expected dividend yield 0.0 % Expected term (years) 7.5 Risk-free interest rate 2.58 % Weighted average grant date fair value $ 7.57 The expected volatility is based on the combination of the Company’s historical volatility and the volatility of comparable peer banks. The expected term represents the period of time that the 2017 Stock Plan awards are expected to be outstanding from the date of grant. The risk-free interest rate is based on the U.S. Treasury yields for the expected term of the instrument. The total unrecognized compensation cost of $551 thousand related to the 2017 Stock Plan for the share awards outstanding at September 30, 2019 will be recognized over a weighted average remaining period of 3.13 years. 2017 Stock Plan – Restricted Stock Unit Awards On four different dates during the period ended September 30, 2019, the Company granted a total of 54,780 restricted stock units to employees and directors that vest in full (i.e. cliff vesting) on the five year anniversary of the grant date. The fair value of the restricted stock units on the grant date was $1.2 million and will be recognized as compensation expense over the requisite vesting period ending on the respective five year anniversary of the restricted stock unit award’s grant date. The following table presents the activity during the period related to restricted stock units from the 2017 Stock Plan: 2017 Stock Plan Restricted Stock Unit Awards Shares Weighted Average Grant Date Fair Value Outstanding at January 1, 2019 — $ — Granted 54,780 $ 22.18 Vested — Forfeited — Outstanding at September 30, 2019 54,780 $ 22.18 A summary of selected data related to stock-based compensation expense for the nine months ended September 30, 2019 and 2018 are as follows: Restricted Stock Unit Awards September 30, 2019 2018 (Dollars in thousands) Stock-based compensation expense $ 77 $ — Unrecognized compensation expense related to stock-based compensation $ 1,138 $ — Weighted-average life over which expense is expected to be recognized (years) 4.44 — Warrants Activity for the Bank4Texas Warrants for the period indicated is summarized as follows: Bank4Texas Warrants Warrants Weighted Average Exercise Price Aggregate Intrinsic Value (in thousands) Weighted Average Remaining Contractual Life (Years) Outstanding at January 1, 2019 10,710 $ 10.50 Granted — Exercised (838 ) $ 10.50 $ 9 Forfeited (1) — Expired — Outstanding at September 30, 2019 9,872 $ 10.50 $ 109 0.90 Vested and exercisable at September 30, 2019 9,872 $ 10.50 $ 109 0.90 There was no activity during the three or nine months ended September 30, 2019 on the Oasis Warrants.

Basic and Diluted Earnings Per

Basic and Diluted Earnings Per Common Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Basic and Diluted Earnings Per Common Share	NOTE 11. BASIC AND DILUTED EARNINGS PER COMMON SHARE The following table presents the computation of basic and diluted EPS for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (Dollars in thousands, except per share data) Net income available to common stockholders $ 5,330 $ 2,771 $ 14,967 $ 7,465 Weighted average number of common shares - basic 15,370,480 9,792,032 13,774,776 8,673,106 Effect of dilutive securities: Employee stock-based compensation awards and warrants 400,769 568,269 424,150 421,585 Weighted average number of common shares - diluted 15,771,249 10,360,301 14,198,926 9,094,691 Basic earnings per common share $ 0.35 $ 0.28 $ 1.09 $ 0.86 Diluted earnings per common share $ 0.34 $ 0.27 $ 1.05 $ 0.82 Anti-dilutive warrants and stock options 119,078 7,246 148,578 78,490

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	NOTE 12. INCOME TAXES The effective tax rates for the three months ended September 30, 2019 and 2018 were 20.5% and 20.6%, respectively. The effective tax rates for the nine months ended September 30, 2019 and 2018 were 20.0% and 20.3%, respectively. The decrease in the effective tax rate for the nine months ended September 30, 2019 was primarily due to a return to provision adjustment recorded during the first quarter of 2019.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE 13. COMMITMENTS AND CONTINGENCIES The Company issues off-balance sheet financial instruments in connection with its lending activities and to meet the financing needs of its customers. These financial instruments include commitments to fund loans and lines of credit as well as commercial and standby letters of credit. These commitments expose the Company to varying degrees of credit and market risk which are essentially the same as those involved in extending loans to customers. The Company follows the same credit policies in making commitments as it does for instruments recorded on the Company’s consolidated balance sheet. Collateral is obtained based on management’s assessment of the customer’s credit risk. The Company’s exposure to credit loss is represented by the contractual amount of these commitments. As of September 30, 2019 and December 31, 2018, the Company’s reserve for unfunded commitments totaled $55 thousand and $48 thousand, respectively. Fees collected on off-balance sheet financial instruments represent the fair value of those commitments and are deferred and amortized over their term. Financial Instruments Commitments Unfunded commitments are as follows for the periods presented: September 30, 2019 December 31, 2018 (Dollars in thousands) Unfunded loan commitments $ 237,768 $ 176,156 Commercial and standby letters of credit 581 547 Total $ 238,349 $ 176,703 Unfunded loan commitments: 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 drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if it is deemed necessary by the Company upon extension of credit, is based upon management’s credit evaluation of the counterparty. Collateral held varies but may include accounts receivable, inventory, property, plant and equipment, and income-producing commercial properties. Commercial and standby letters of credit: Letters of credit are conditional commitments issued by the Company to guarantee the performance of a customer to a third party. Letters of credit are primarily issued to support trade transactions or guarantee arrangements. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. The Company generally holds collateral supporting those commitments if deemed necessary. Other Commitments and Contingencies Legal Proceedings The Company, from time to time, is involved as plaintiff or defendant in various legal actions arising in the normal course of business. While the ultimate outcome of any such proceedings cannot be predicted with certainty, it is the opinion of management, based upon advice of legal counsel, that no proceedings exist, either individually or in the aggregate, which, if determined adversely to the Company, would have a material effect on the Company’s consolidated balance sheet, results of operations or cash flows.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	NOTE 14. FAIR VALUE MEASUREMENTS When determining the fair value measurements for assets and liabilities and the related fair value hierarchy, the Company considers the principal or most advantageous market in which it would transact and the assumptions that market participants would use when pricing the asset or liability. When possible, the Company looks to active and observable markets to price identical assets or liabilities. When identical assets and liabilities are not traded in active markets, the Company looks to market observable data for similar assets and liabilities. It is the Company’s policy to maximize the use of observable inputs, minimize the use of unobservable inputs and use unobservable inputs to measure fair value to the extent that observable inputs are not available. The need to use unobservable inputs generally results from the lack of market liquidity, resulting in diminished observability of both actual trades and assumptions that would otherwise be available to value these instruments, or the value of the underlying collateral is not market observable. Although third party price indications may be available for an asset or liability, limited trading activity would make it difficult to support the observability of these quotations. Financial Instruments Carried at Fair Value on a Recurring Basis The following is a description of the valuation methodologies used for financial instruments measured at fair value on a recurring basis, as well as the general classification of each instrument under the valuation hierarchy. Investment Securities—Investment securities available for sale are carried at fair value on a recurring basis. When available, fair value is based on quoted prices for the identical security in an active market and as such, would be classified as Level 1. If quoted market prices are not available, fair values are estimated using quoted prices of securities with similar characteristics, discounted cash flows or matrix pricing models. Investment securities available for sale for which Level 1 valuations are not available are classified as Level 2, and include U.S. Government agencies and sponsored enterprises obligations and agency mortgage-backed securities; state and municipal obligations; asset-backed securities; and corporate debt and other securities. Pricing of these securities is generally spread driven. Observable inputs that may impact the valuation of these securities include benchmark yield curves, credit spreads, reported trades, dealer quotes, bids, issuer spreads, current rating, historical constant prepayment rates, historical voluntary prepayment rates, structural and waterfall features of individual securities, published collateral data, and for certain securities, historical constant default rates and default severities. SBA Servicing Asset—The SBA Servicing Asset is carried at fair value on a recurring basis. To determine the fair value of SBA servicing rights, The Company uses market prices for comparable servicing contracts, when available, or alternatively, uses a valuation model that calculates the present value of estimated future net servicing income. In using this valuation method, the Company incorporates assumptions that market participants would use in estimating future net servicing income, which includes estimates of the cost to service, the discount rate, custodial earnings rate, an inflation rate, ancillary income, prepayment speeds, default rates, late fees and losses. The SBA Servicing Asset is classified as Level 3. The following tables present the assets and liabilities measured at fair value on a recurring basis for the periods presented: September 30, 2019 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: U.S. Treasury securities $ 32,563 $ — $ — $ 32,563 U.S. Government agencies — 4,141 — 4,141 State and municipal obligations — 25,628 — 25,628 Residential mortgage-backed securities — 98,645 — 98,645 Corporate bonds and other debt securities — 5,692 — 5,692 SBA servicing rights — — 3,548 3,548 Total $ 32,563 $ 134,106 $ 3,548 $ 170,217 December 31, 2018 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: U.S. Government agencies $ — $ 1,934 $ — $ 1,934 State and municipal obligations — 18,048 — 18,048 Residential mortgage-backed securities — 153,974 — 153,974 Corporate bonds and other debt securities — 5,505 — 5,505 SBA servicing rights — — 3,965 3,965 Total $ — $ 179,461 $ 3,965 $ 183,426 There were no transfers of financial assets between levels of the fair value hierarchy during the three or nine months ended September 30, 2019. Financial Instruments Measured at Fair Value on a Non-Recurring Basis The following is a description of the methodologies used to estimate the fair values of assets and liabilities measured at fair value on a non-recurring basis, and the level within the fair value hierarchy in which those measurements are typically classified. Impaired loans and other real estate owned (“OREO”)—The carrying amount of collateral dependent impaired loans is typically based on the fair value of the underlying collateral, which may be real estate or other business assets, less estimated costs to sell. The carrying value of OREO is initially measured based on the fair value, less estimated cost to sell, of the real estate acquired in foreclosure and subsequently adjusted to the lower of cost or estimated fair value, less estimated cost to sell. Fair values of real estate collateral are typically based on real estate appraisals which utilize market and income valuation techniques incorporating both observable and unobservable inputs. When current appraisals are not available, the Company may use brokers’ price opinions, home price indices, or other available information about changes in real estate market conditions to adjust the latest appraised value available. These adjustments to appraised values may be subjective and involve significant management judgment. The fair value of collateral consisting of other business assets is generally based on appraisals that use market approaches to valuation, incorporating primarily unobservable inputs. Fair value measurements related to collateral dependent impaired loans and OREO are classified within Level 3 of the fair value hierarchy. The following tables provide information about certain assets measured at fair value on a non-recurring basis: Estimated Fair Value September 30, 2019 December 31, 2018 (Dollars in thousands) Assets (classified in Level 3): Impaired loans $ 2,346 $ 2,696 Other real estate and repossessed assets 1,042 782 Impairment charges resulting from the non-recurring changes in fair value of underlying collateral of impaired loans are included in the provision for loan losses in the consolidated statement of income. Impairment charges resulting from the non-recurring changes in fair value of OREO are included in other real estate and acquired assets resolution expenses in the consolidated statement of income. The following tables show significant unobservable inputs used in the recurring and non-recurring fair value measurements of Level 3 assets: Level 3 Asset Fair Value Valuation Technique Unobservable Inputs Range/Weighted Average September 30, 2019 Non-recurring: Impaired loans $ 2,346 Third party appraisals Collateral discounts 0.0% - 100.0% (28.3%) Other real estate owned 1,042 Third party appraisals Collateral discounts and estimated cost to sell 10.0 % Recurring: SBA servicing assets 3,548 Discounted cash flows Conditional prepayment rate 13.1 % Discount rate 11.0 % December 31, 2018 Non-recurring: Impaired loans $ 2,696 Third party appraisals Collateral discounts 0.0% - 100.0% (19.2%) Other real estate owned 782 Third party appraisals Collateral discounts and estimated cost to sell 10.0 % Recurring: SBA servicing assets 3,965 Discounted cash flows Conditional prepayment rate 11.8 % Discount rate 11.5 % The carrying amounts and estimated fair values, as well as the level within the fair value hierarchy, of the Company’s financial instruments are as follows for the periods presented: September 30, 2019 Carrying Value Fair Value Level 1 Level 2 Level 3 (Dollars in thousands) Financial Assets: Cash and cash equivalents $ 151,543 $ 151,543 $ 151,543 $ — $ — Time deposits in other banks 1,225 1,225 1,225 Available for sale securities 166,669 166,669 32,563 134,106 — FHLB and other bank stock 6,233 6,233 — 6,233 — Loans, net 1,481,037 1,479,485 — — 1,479,485 Loans held for sale 2,784 2,998 — 2,998 — Accrued interest receivable 6,319 6,319 — 6,319 — Bank-owned life insurance 15,521 15,521 — 15,521 — SBA servicing rights 3,548 3,548 — — 3,548 Financial Liabilities: Deposits $ 1,585,213 $ 1,545,765 $ — $ 1,545,765 $ — Accrued interest payable 1,002 1,002 — 1,002 — Long-term borrowings 74,165 60,003 — 60,003 — December 31, 2018 Carrying Value Fair Value Level 1 Level 2 Level 3 (Dollars in thousands) Financial Assets: Cash and cash equivalents $ 89,015 $ 89,015 $ 89,015 $ — $ — Available for sale securities 179,461 179,461 — 179,461 — FHLB and other bank stock 5,304 5,304 — 5,304 — Loans, net 1,096,522 1,085,120 — — 1,085,120 Loans held for sale 3,945 4,200 — 4,200 — Accrued interest receivable 4,934 4,934 — 4,934 — Bank-owned life insurance 7,401 7,401 — 7,401 — SBA servicing rights 3,965 3,965 — — 3,965 Financial Liabilities: Deposits $ 1,182,648 $ 1,181,606 $ — $ 1,181,606 $ — Accrued interest payable 702 702 — 702 — Short-term borrowings 12,500 12,500 — 12,500 — Long-term borrowings 77,784 76,603 — 76,603 — Certain financial instruments are carried at amounts that approximate fair value due to their short-term nature and generally negligible credit risk. Financial instruments for which fair value approximates the carrying amount at September 30, 2019 and December 31, 2018, include cash and cash equivalents, time deposits in other banks and accrued interest receivable and payable.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	NOTE 15. SUBSEQUENT EVENTS On November 5, 2019, the Company completed its acquisition of Chandler and its subsidiary, Citizens State Bank. This transaction resulted in seven additional branches in the North East Texas market. The Company issued 2,100,000 shares of its common stock as well as a net cash payment to the sole shareholder of Chandler of $17.9 million, for total consideration of $62.5 million based upon the closing price of the Company’s common stock on the date the acquisition was completed, for all outstanding stock of Chandler and resulted in 100% ownership interest. The Company is still evaluating the fair values of the assets acquired and liabilities assumed in the Chandler acquisition.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations Spirit of Texas Bancshares, Inc. (“Spirit,” “STXB,” the “Holding Company” or “Company”) is a bank holding company headquartered in Conroe, Texas that provides, through its bank subsidiary, a variety of financial services to individuals and corporate customers located largely in the State of Texas, and which customers are primarily involved in agricultural, light industrial and commercial arenas. The Company consummated the underwritten initial public offering of its common stock in May 2018. In connection with the initial public offering, the Company issued and sold 2,300,000 shares of its common stock, including 300,000 shares of common stock sold pursuant to the underwriters’ full exercise of their option to purchase additional shares, at an offering price of $21.00 per share, for aggregate gross proceeds of $48.3 million before deducting underwriting discounts and offering expenses, and aggregate net proceeds of $42.1 million after deducting underwriting discounts and offering expenses. In addition, the Company consummated an underwritten public offering of its common stock on July 25, 2019 (the “2019 Offering”). In connection with the 2019 Offering, the Company issued and sold 2,300,000 shares of its common stock, including 300,000 shares sold pursuant to the Underwriters’ full exercise of their option to purchase additional shares, at a public offering price of $21.50 per share for net proceeds of approximately $46.5 million after deducting underwriting discounts and commissions and estimated offering expenses. The Company used $21.0 million of the net proceeds from the Offering to pay off a line of credit with a third-party lender and approximately $17.9 million of the net proceeds from the Offering to fund the cash portion of the merger consideration paid to the sole shareholder of Chandler Bancorp, Inc. (“Chandler”) in the Company’s acquisition of Chandler and its subsidiary, Citizens State Bank. The remaining net proceeds will be used by the Company for other general corporate purposes in order to support its continued growth, including investments in its bank subsidiary and future strategic acquisitions.
Basis of Presentation	Basis of Presentation The consolidated financial statements include the accounts of the Holding Company and the accounts of its wholly-owned subsidiary, Spirit of Texas Bank, SSB (the “Bank”). All significant intercompany balances and transactions have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and Article 8 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. Operating results for the period ended September 30, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 and should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2018 previously filed with the Securities and Exchange Commission in the Company’s Annual Report on Form 10-K In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for the fair presentation of these consolidated financial statements have been included. The preparation of financial statements in conformity with these accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and income and expense during the reporting periods and the related disclosures. Although management’s estimates and assumptions are based on current expectations, estimates, forecasts and projections about future performance of the Company, such estimates and assumptions are not guarantees of future performance and involve certain risks, uncertainties and assumptions that are difficult for the Company to assess. Operating results for the interim periods disclosed herein are not necessarily indicative of the results that may be expected for a full year or any future period.
Correction of an Immaterial Error on the Consolidated Balance Sheet	Correction of an Immaterial Error on the Consolidated Balance Sheet and Cash Flow The Company identified an immaterial error pertaining to the accounting of certain loan participations sold impacting its consolidated balance sheet and its consolidated statement of cash flows. Due to the rights retained on certain loan participations sold, the Company is deemed to have retained effective control over these loans under Financial Accounting Standards Board (“FASB”)’s Accounting Standards Codification (“ASC”) Topic 860, “Transfers and Servicing”, and therefore these participations sold must be accounted for as a secured borrowing. The Company reviewed the impact of this error on the prior periods and determined that the error was not material to the prior period consolidated financial statements. The Company has corrected the immaterial error in the consolidated balance sheet as of December 31, 2018 by revising the previously reported loans held for investment and long-term borrowings. The impact of the immaterial error correction increased loans held for investment and long-term borrowings by $ 9.9 million. The Company has also made revisions to correct the immaterial errors in the consolidated statement of cash flows for the nine months ended September 30, 2018 by increasing investing cash flows by $ 2.0 million an d decreasing financing cash flows by $ 2.0 million from amounts previously reported .
Accounting Policies Recently Adopted and Pending Accounting Pronouncements	Accounting Policies Recently Adopted and Pending Accounting Pronouncements ASU 2019-04, “Codification Improvements to Topic 326, Financial Instruments-Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments” – Issued in April 2019, Accounting Standards Update (“ASU”) No. 2019-04 clarifies a number of issues discussed at the June 2018 and November 2018 Credit Losses Transition Resource Group meetings. The clarifications address a variety of identified issues including but not limited to the treatment of accrued interest receivable as it relates to the allowance for credit losses, transfers between loan classifications and categories, recoveries, and using projections of future interest rate environments in expected cash flow calculations. Management is evaluating these clarifications concurrently with our assessment of ASU 2016-13. ASU 2018-13, “Fair Value Measurement Disclosure Framework” – Issued in August 2018, ASU No. 2018-13 modifies the disclosure requirements on fair value measurements outlined in Topic 820, Fair Value Measurements. Specifically the amendments in the ASU remove the requirements to disclose the amount and reasons for transfers between fair value hierarchy levels, the policy for timing of transfers between levels, the valuation processes for Level 3 fair value measurements, and for nonpublic entities, disclosure of the changes in unrealized gains and losses for the period included in earnings for recurring Level 3 fair value measurements. Additionally, the ASU adds disclosure requirements regarding changes in unrealized gains and losses for the period included in other comprehensive income related to Level 3 fair value measurements, and disclosure of the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. The amendments of ASU 2018-13 are effective for all entities for interim and annual periods beginning after December 15, 2019. Management adopted the provisions of this ASU removing fair value disclosure requirements as of December 31, 2018 as early adoption of the removal provisions was allowed and will adopt the remaining provisions of the ASU as of the effective date. ASU 2018-09, “Codification Improvements.” - Issued in July 2018, ASU No. 2018-09 makes changes to a variety of topics to clarify, correct errors in, or make minor improvements to the Accounting Standards Codification. The majority of the amendments in ASU 2018-09 will be effective in annual periods beginning after December 15, 2018. ASU 2018-09 is not expected to have a material impact on the Company’s consolidated financial statements. ASU 2017-04, “Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” Issued in January 2017, ASU 2017-04 simplifies the manner in which an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. In computing the implied fair value of goodwill under Step 2, an entity, prior to the amendments in ASU 2017-04, had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities, including unrecognized assets and liabilities, in accordance with the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. However, under the amendments in ASU 2017-04, an entity should (1) perform its annual or interim goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount, and (2) recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, with the understanding that the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, ASU 2017-04 removes the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails such qualitative test, to perform Step 2 of the goodwill impairment test. ASU 2017-04 is effective prospectively for public entities for annual, or any interim, goodwill impairment tests in fiscal years beginning after December 15, 2019 and for all other entities for impairment tests in fiscal years beginning after December 15, 2021. Management will adopt this ASU using the public company effective date as early adoption is permitted and will continue to evaluate the impact this ASU will have on the consolidated financial statements through its effective date; however, the adoption of ASU 2017-04 is not expected to have a material impact on the Company’s consolidated financial statements. ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” Issued in June 2016, ASU 2016-13 will add FASB ASC Topic 326, “Financial Instruments-Credit Losses,” and finalizes amendments to FASB ASC Subtopic 825-15, “Financial Instruments-Credit Losses.” The amendments of ASU 2016-13 are intended to provide financial statement users with more decision-useful information related to expected credit losses on financial instruments and other commitments to extend credit by replacing the current incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. The amendments of ASU 2016-13 eliminate the probable initial recognition threshold and, in turn, reflect an entity’s current estimate of all expected credit losses. ASU 2016-13 does not specify the method for measuring expected credit losses, and an entity is allowed to apply methods that reasonably reflect its expectations of the credit loss estimate. Additionally, the amendments of ASU 2016-13 require that credit losses on available for sale debt securities be presented as an allowance rather than as a write-down. The amendments of ASU 2016-13 were originally effective for public entities for interim and annual periods beginning after December 15, 2019 and for all other entities for periods beginning after December 15, 2020. Issued in November 2018, ASU 2018-19 , “ Codification Improvements to Topic 326, Financial Instruments-Credit Losses , ” alters the effective date of ASU 2016-13 for private companies. Under the provisions of ASU 2018-19, ASU 2016-13 is now effective for fiscal years beginning after December 15, 2021 including interim periods within those years for non-public business entities. Earlier application is permitted for interim and annual periods beginning after December 15, 2018. Management has elected to adopt this ASU using the updated private company effective date and is currently evaluating the impact this ASU will have on the consolidated financial statements and that evaluation will depend on economic conditions and the composition of the Company’s loan and lease portfolio at the time of adoption. ASU 2016-02, “Leases (Topic 842).” Issued in February 2016, ASU 2016-02 was issued by the FASB to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and by disclosing key information about leasing arrangements. ASU 2016-02 will, among other things, require 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, the ASU contains some targeted improvements that are intended to align, where necessary, lessor accounting with the lessee accounting model and with the updated revenue recognition guidance issued in 2014. The amendments of ASU 2016-02 are effective for public entities for interim and annual periods beginning after December 15, 2018 and for other entities for periods beginning after December 15, 2019. The adoption of this ASU will result in an increase to the Consolidated Balance Sheets for right-of-use assets and associated lease liabilities for operating leases in which the Company is the lessee. Under current accounting standards, all of the Company's leases are classified as operating leases and, as such, are not recognized on the Company's Consolidated Balance Sheet. Additionally, in July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases and ASU No. 2018-11, Leases, Targeted Improvements. The amendments in these updates provide additional clarification and implementation guidance on certain aspects of ASU 2016-02 and have the same effective and transition requirements as ASU 2016-02. Specifically, ASU 2018-11 creates an additional transition method option allowing entities to record a cumulative effect adjustment to opening retained earnings in the year of adoption. In December 2018, the FASB further issued ASU 2018-20, . The amendments in this update permits lessors to make an accounting policy election to not evaluate whether certain sales taxes and other similar taxes are lessor costs or lessee costs and instead account for the costs as if they were lessee costs. Additionally, the amendment requires lessors to exclude from variable payments, and therefore revenue, lessor costs paid by lessees directly to third parties. The amendments also require lessors to account for costs excluded from the consideration of a contract that are paid by the lessor and reimbursed by the lessee as variable payments. In March 2019, the FASB also issued ASU 2019-01, to further clarify certain identified issues regarding implementation of ASU 2016-02. Specifically, the amendments in ASU 2019-01 clarify the determination of fair value of underlying assets by lessors that are not manufacturers or dealers, the cash flow presentation of sales-type or direct financing leases, and transition disclosures for interim periods. Management will adopt these ASUs using the private company effective date of January 1, 2020 and is currently evaluating the impact to the consolidated financial statements and related method of adoption, specifically, management is in the process of determining an appropriate discount rate to record identified right-of-use assets.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2019
Revenue From Contract With Customer [Abstract]
Schedule of Non-Interest Income, Segregated by Revenue Streams in-Scope and Out-of-Scope of Topic 606	The following presents non-interest income, segregated by revenue streams in-scope and out-of-scope of Topic 606, for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Non-Interest Income In-scope of Topic 606 Deposit accounts core service charges $ 135 $ 88 $ 396 $ 233 Deposit account transaction based fee income 748 378 2,208 1,017 Mortgage referral fees 173 160 481 524 Non-Interest Income (in-scope of Topic 606) 1,056 626 3,085 1,774 Non-Interest Income (out-of-scope of Topic 606) 1,625 1,941 6,428 5,684 Total Non-Interest Income $ 2,681 $ 2,567 $ 9,513 $ 7,458

Business Combinations (Tables)

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2019
Comanche National Corporation
Fair Values of Assets Acquired and Liabilities Assumed	Fair values of the assets acquired and liabilities assumed in this transaction as of the closing date are as follows: Assets of acquired bank (Dollars in thousands): Cash and cash equivalents $ 57,135 Securities available for sale 144,735 Loans held for investment 116,220 Premises and equipment, net 6,634 Other real estate owned 33 Goodwill 13,768 Core deposit intangible 5,988 Other assets 11,712 Total assets acquired $ 356,225 Liabilities of acquired bank: Deposits $ 297,778 Trust preferred securities 2,811 Other liabilities 2,698 Total liabilities assumed $ 303,287 Common stock issued at $18.99 per share $ 40,692 Cash paid $ 12,246
First Beeville Financial Corporation
Fair Values of Assets Acquired and Liabilities Assumed	Estimated fair values of the assets acquired and liabilities assumed in this transaction as of the closing date are as follows: Assets of acquired bank (Dollars in thousands): Cash and cash equivalents $ 60,491 Securities available for sale 57,206 Loans held for investment 296,871 Premises and equipment, net 6,067 Other real estate owned 1,359 Goodwill 24,843 Core deposit intangible 5,695 Other assets 12,929 Total assets acquired $ 465,461 Liabilities of acquired bank: Deposits $ 399,062 Other liabilities 543 Total liabilities assumed $ 399,605 Common stock issued at $21.20 per share $ 33,479 Cash paid $ 32,377

Investment Securities (Tables)

Investment Securities (Tables)	9 Months Ended
	Sep. 30, 2019
Investments Debt And Equity Securities [Abstract]
Schedule of Fair Values of Securities Available for Sale	The amortized cost, gross unrealized gains and losses and approximate fair values of securities available for sale are as follows: Amortized Unrealized Fair September 30, 2019 Cost Gains Losses Value (Dollars in thousands) Available for sale: U.S. Treasury securities $ 32,541 $ 23 $ 1 $ 32,563 U.S. Government agencies 4,074 67 — 4,141 State and municipal obligations 24,795 833 — 25,628 Residential mortgage-backed securities 95,737 2,921 13 98,645 Corporate bonds and other debt securities 5,633 59 — 5,692 Total available for sale $ 162,780 $ 3,903 $ 14 $ 166,669 Amortized Unrealized Fair December 31, 2018 Cost Gains Losses Value (Dollars in thousands) Available for sale: U.S. Government agencies $ 2,015 $ — $ 81 $ 1,934 State and municipal obligations 17,201 847 — 18,048 Residential mortgage-backed securities 152,232 2,614 872 153,974 Corporate bonds and other debt securities 5,667 — 162 5,505 Total available for sale $ 177,115 $ 3,461 $ 1,115 $ 179,461
Schedule of Securities Available for Sale by Contractual Maturity	The amortized cost and estimated fair value of securities available for sale, by contractual maturity, are as follows for the period presented: Amortized Fair September 30, 2019 Cost Value (Dollars in thousands) Available for sale: Due in one year or less $ 19,377 $ 19,412 Due after one year through five years 35,152 35,427 Due after five years through ten years 6,863 7,066 Due after ten years 5,651 6,119 Residential mortgage-backed securities 95,737 98,645 Total available for sale $ 162,780 $ 166,669
Schedule of Investment Securities Available for Sale and Aggregated by Investment Category and Length of Time Individual Securities in Continuous Unrealized Loss Position	The following tables present the estimated fair values and gross unrealized losses on investment securities available for sale, aggregated by investment category and length of time individual securities have been in a continuous unrealized loss position as of the periods presented: Less than 12 Months 12 Months or More Total September 30, 2019 Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss (Dollars in thousands) Available for sale: U.S. Treasury securities $ 2,998 $ 1 $ — $ — $ 2,998 $ 1 U.S. Government agencies — — — — — — State and municipal obligations — — — — — — Residential mortgage-backed securities — — 4,994 13 4,994 13 Corporate bonds and other debt securities — — — — — — Total available for sale $ 2,998 $ 1 $ 4,994 $ 13 $ 7,992 $ 14 Less than 12 Months 12 Months or More Total December 31, 2018 Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss (Dollars in thousands) Available for sale: U.S. Government agencies $ — $ — $ 1,934 $ 81 $ 1,934 $ 81 State and municipal obligations — — — — — — Residential mortgage-backed securities 1 — 25,479 872 25,480 872 Corporate bonds and other debt securities — — 5,505 162 5,505 162 Total available for sale $ 1 $ — $ 32,918 $ 1,115 $ 32,919 $ 1,115

Loans, Net (Tables)

Loans, Net (Tables)	9 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Summary of Loans, Net	Loans, net consisted of the following at September 30, 2019 and December 31, 2018: September 30, 2019 December 31, 2018 (Dollars in thousands) Commercial and industrial loans (1) $ 248,745 $ 173,892 Real estate: 1-4 single family residential loans 321,044 279,665 Construction, land and development 233,830 159,734 Commercial real estate loans (including multifamily) 597,415 403,800 Consumer loans and leases 17,663 24,378 Municipal and other loans 68,905 61,339 Total loans held in portfolio (2) $ 1,487,602 $ 1,102,808 Allowance for loan losses (6,565 ) (6,286 ) Loans held in portfolio, net $ 1,481,037 $ 1,096,522 (1) Balance includes $78.7 million and $76.9 million of the unguaranteed portion of Small Business Administration (“SBA”) loans as of September 30, 2019 and December 31, 2018, respectively.
Summary of Loans to Related Parties and Principal Owners	In the ordinary course of business, the Company makes loans to executive officers and directors. Loans to these related parties, including companies in which they are principal owners, are as follows for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (Dollars in thousands) Principal outstanding, beginning of year $ 2,433 $ 421 $ 107 $ 463 Additions (reductions) of affiliations — — 2,352 — New loans made in current year 4,035 — 4,035 — Repayments (57 ) (19 ) (83 ) (61 ) Principal outstanding, end of year $ 6,411 $ 402 $ 6,411 $ 402

Allowance for Loan and Lease _2

Allowance for Loan and Lease Losses (Tables)	9 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Allowance for Loan and Lease Losses	The following tables present information related to allowance for loan and lease losses for the periods presented: Allowance Rollforward Three Months Ended September 30, 2019 Beginning Balance Charge-offs Recoveries Provision Ending Balance (Dollars in thousands) Commercial and industrial loans $ 4,217 $ (687 ) $ 36 $ 669 $ 4,235 Real estate: 1-4 single family residential loans 32 — 65 (66 ) 31 Construction, land and development loans 794 — — 90 884 Commercial real estate loans (including multifamily) 1,191 — — 127 1,318 Consumer loans and leases 35 (26 ) — 85 94 Municipal and other loans 8 — — (5 ) 3 Ending allowance balance $ 6,277 $ (713 ) $ 101 $ 900 $ 6,565 Allowance Rollforward Three Months Ended September 30, 2018 Beginning Balance Charge-offs Recoveries Provision Ending Balance (Dollars in thousands) Commercial and industrial loans $ 4,886 $ (275 ) $ 4 $ 76 $ 4,691 Real estate: 1-4 single family residential loans 318 — — (216 ) 102 Construction, land and development loans 195 — — 256 451 Commercial real estate loans (including multifamily) 233 — — 495 728 Consumer loans and leases 346 (74 ) — (90 ) 182 Municipal and other loans 37 — — (35 ) 2 Ending allowance balance $ 6,015 $ (349 ) $ 4 $ 486 $ 6,156 Allowance Rollforward Nine Months Ended September 30, 2019 Beginning Balance Charge-offs Recoveries Provision Ending Balance (Dollars in thousands) Commercial and industrial loans $ 4,453 $ (1,908 ) $ 95 $ 1,595 $ 4,235 Real estate: 1-4 single family residential loans 59 — 65 (93 ) 31 Construction, land and development loans 731 — — 153 884 Commercial real estate loans (including multifamily) 960 — — 358 1,318 Consumer loans and leases 80 (60 ) 5 69 94 Municipal and other loans 3 — 1 (1 ) 3 Ending allowance balance $ 6,286 $ (1,968 ) $ 166 $ 2,081 $ 6,565 Allowance Rollforward Nine Months Ended September 30, 2018 Beginning Balance Charge-offs Recoveries Provision Ending Balance (Dollars in thousands) Commercial and industrial loans $ 3,046 $ (920 ) $ 73 $ 2,492 $ 4,691 Real estate: 1-4 single family residential loans 902 (5 ) — (795 ) 102 Construction, land and development loans 441 — — 10 451 Commercial real estate loans (including multifamily) 898 — — (170 ) 728 Consumer loans and leases 198 (104 ) — 88 182 Municipal and other loans 167 — — (165 ) 2 Ending allowance balance $ 5,652 $ (1,029 ) $ 73 $ 1,460 $ 6,156
Summary of Aging Analysis of Recorded Investment for Delinquent Loans by Portfolio and Segment	The following tables present an aging analysis of the recorded investment for delinquent loans by portfolio and segment for the periods presented: Accruing September 30, 2019 Current 30 to 59 Days Past Due 60 to 89 Days Past Due 90 Days or More Past Due Non- Accrual Total (Dollars in thousands) Commercial and industrial loans $ 241,710 $ 517 $ 215 $ 120 $ 6,183 $ 248,745 Real estate: 1-4 single family residential loans 318,304 1,287 113 — 1,340 321,044 Construction, land and development 233,614 — — — 216 233,830 Commercial real estate loans (including multifamily) 593,794 1,851 601 — 1,169 597,415 Consumer loans and leases 17,371 176 40 — 76 17,663 Municipal and other loans 68,867 — — — 38 68,905 Total loans $ 1,473,660 $ 3,831 $ 969 $ 120 $ 9,022 $ 1,487,602 Accruing December 31, 2018 Current 30 to 59 Days Past Due 60 to 89 Days Past Due 90 Days or More Past Due Non- Accrual Total (Dollars in thousands) Commercial and industrial loans $ 169,206 $ 605 $ 223 $ 288 $ 3,570 $ 173,892 Real estate: 1-4 single family residential loans 277,930 581 64 — 1,090 279,665 Construction, land and development 159,723 11 — — — 159,734 Commercial real estate loans (including multifamily) 402,406 451 589 — 354 403,800 Consumer loans and leases 24,109 208 44 — 17 24,378 Municipal and other loans 61,289 50 — — — 61,339 Total loans $ 1,094,663 $ 1,906 $ 920 $ 288 $ 5,031 $ 1,102,808
Summary of Loans by Key Indicators of Credit Quality	The following tables summarize the Company’s loans by key indicators of credit quality for the periods presented: September 30, 2019 Pass Special Mention Substandard Doubtful (Dollars in thousands) Commercial and industrial loans $ 234,989 $ 3,246 $ 10,510 $ — Real estate: 1-4 single family residential loans 318,562 281 2,201 — Construction, land and development 232,792 — 1,038 — Commercial real estate loans (including multifamily) 582,481 4,603 10,331 — Consumer loans and leases 17,533 — 130 — Municipal and other loans 68,860 — 45 — Total loans $ 1,455,217 $ 8,130 $ 24,255 $ — December 31, 2018 Pass Special Mention Substandard Doubtful (Dollars in thousands) Commercial and industrial loans $ 163,908 $ 3,170 $ 6,601 $ 213 Real estate: 1-4 single family residential loans 274,860 1,714 2,547 544 Construction, land and development 157,688 24 2,022 — Commercial real estate loans (including multifamily) 389,170 12,412 1,806 412 Consumer loans and leases 20,798 1,836 180 1,564 Municipal and other loans 60,837 484 — 18 Total loans $ 1,067,261 $ 19,640 $ 13,156 $ 2,751
Summary of Investment in Loans Disaggregated Based on Method of Evaluating Impairment	The following tables show the Company’s investment in loans disaggregated based on the method of evaluating impairment for the periods presented: Loans - Recorded Investment Allowance for Credit Loss September 30, 2019 Individually Evaluated for Impairment Collectively Evaluated for Impairment Individually Evaluated for Impairment Collectively Evaluated for Impairment (Dollars in thousands) Commercial and industrial loans $ 2,638 $ 246,107 $ 1,194 $ 3,041 Real estate: 1-4 single family residential loans 1,399 319,645 4 27 Construction, land and development 216 233,614 — 884 Commercial real estate loans (including multifamily) 236 597,179 — 1,318 Consumer loans and leases 21 17,642 5 89 Municipal and other loans — 68,905 — 3 Total loans $ 4,510 $ 1,483,092 $ 1,203 $ 5,362 Loans - Recorded Investment Allowance for Credit Loss December 31, 2018 Individually Evaluated for Impairment Collectively Evaluated for Impairment Individually Evaluated for Impairment Collectively Evaluated for Impairment (Dollars in thousands) Commercial and industrial loans $ 3,640 $ 170,252 $ 1,234 $ 3,219 Real estate: 1-4 single family residential loans 1,193 278,472 29 30 Construction, land and development — 159,734 — 731 Commercial real estate loans (including multifamily) — 403,800 — 960 Consumer loans and leases 17 24,361 4 76 Municipal and other loans — 61,339 — 3 Total loans $ 4,850 $ 1,097,958 $ 1,267 $ 5,019
Summary of Information Regarding Impaired Loans Evaluated for Specific Reserves	The following tables set forth certain information regarding the Company’s impaired loans that were evaluated for specific reserves for the periods presented: Impaired Loans - With Allowance Impaired Loans - With no Allowance September 30, 2019 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance (Dollars in thousands) Commercial and industrial loans $ 2,158 $ 4,565 $ 1,194 $ 480 $ 2,298 Real estate: 1-4 single family residential loans 14 16 4 1,385 1,452 Construction, land and development — — — 216 223 Commercial real estate loans (including multifamily) — — — 236 244 Consumer loans and leases 21 21 5 — — Municipal and other loans — — — — — Total loans $ 2,193 $ 4,602 $ 1,203 $ 2,317 $ 4,217 Impaired Loans - With Allowance Impaired Loans - With no Allowance December 31, 2018 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance (Dollars in thousands) Commercial and industrial loans $ 1,843 $ 5,392 $ 1,234 $ 1,797 $ 3,500 Real estate: 1-4 single family residential loans 116 124 29 1,077 1,086 Construction, land and development — — — — — Commercial real estate loans (including multifamily) — — — — — Consumer loans and leases 17 17 4 — — Municipal and other loans — — — — — Total loans $ 1,976 $ 5,533 $ 1,267 $ 2,874 $ 4,586 Three Months Ended September 30, 2019 2018 Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized (Dollars in thousands) Commercial and industrial loans $ 2,758 $ — $ 2,571 $ — Real estate: 1-4 single family residential loans 1,409 — 975 — Construction, land and development 216 — — — Commercial real estate loans (including multifamily) 238 — — — Consumer loans and leases 22 — 72 — Municipal and other loans — — — — Total loans $ 4,643 $ — $ 3,618 $ — Nine Months Ended September 30, 2019 2018 Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized (Dollars in thousands) Commercial and industrial loans $ 2,905 $ — $ 2,774 $ — Real estate: 1-4 single family residential loans 1,434 — 990 — Construction, land and development 220 — — — Commercial real estate loans (including multifamily) 243 — — — Consumer loans and leases 24 — 76 — Municipal and other loans — — — — Total loans $ 4,826 $ — $ 3,840 $ —
Summary of Troubled Debt Restructurings (TDRs) Based Upon Delinquency Status	The following table provides a summary of troubled debt restructurings (“TDRs”) based upon delinquency status, all of which are considered impaired, for the periods presented: September 30, 2019 December 31, 2018 Number of contracts Recorded Investment Number of contracts Recorded Investment (Dollars in thousands) Performing TDRs: Commercial and industrial loans 3 $ 118 3 $ 69 Real estate: 1-4 single family residential loans 3 157 2 141 Construction, land and development — — — — Commercial real estate loans (including multifamily) — — — — Consumer loans and leases — — — — Municipal and other loans — — — — Total performing TDRs 6 275 5 210 Nonperforming TDRs 8 403 7 448 Total TDRs 14 $ 678 12 $ 658 Allowance attributable to TDRs $ 265 $ 149
Summary of TDRs Includes Newly Designated TDRs and Modifications to Existing TDRs	The following tables summarize TDRs, and includes newly designated TDRs as well as modifications made to existing TDRs, for the periods presented. Modifications may include, but are not limited to, granting a material extension of time, entering into a forbearance agreement, adjusting the interest rate, accepting interest only payments for an extended period of time, a change in the amortization period or a combination of any of these. Post-modification balances represent the recorded investment at the end of Day 2 in which the modification was made. Three Months Ended September 30, 2019 2018 Number of Contracts Pre- Modification Outstanding Recorded Investment Post- Modification Outstanding Recorded Investment Related Allowance Number of Contracts Pre- Modification Outstanding Recorded Investment Post- Modification Outstanding Recorded Investment Related Allowance (Dollars in thousands) Commercial and industrial loans 1 $ 13 $ 13 $ — — $ — $ — $ — Real estate: 1-4 single family residential loans — — — — — — — — Construction, land and development — — — — — — — — Commercial real estate loans (including multifamily) — — — — — — — — Consumer loans and leases — — — — — — — — Municipal and other loans — — — — — — — — Nine Months Ended September 30, 2019 2018 Number of Contracts Pre- Modification Outstanding Recorded Investment Post- Modification Outstanding Recorded Investment Related Allowance Number of Contracts Pre- Modification Outstanding Recorded Investment Post- Modification Outstanding Recorded Investment Related Allowance (Dollars in thousands) Commercial and industrial loans 3 $ 141 $ 141 $ 90 7 $ 442 $ 442 $ 113 Real estate: 1-4 single family residential loans — — — — 1 34 34 — Construction, land and development — — — — — — — — Commercial real estate loans (including multifamily) — — — — — — — — Consumer loans and leases — — — — — — — — Municipal and other loans — — — — — — — —

Goodwill and Intangibles (Table

Goodwill and Intangibles (Tables)	9 Months Ended
	Sep. 30, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Goodwill and Other Intangible Assets	Goodwill and other intangible assets, which consist of core deposit intangibles, are summarized as follows: Nine Months Ended September 30, 2019 Year Ended December 31, 2018 (Dollars in thousands) Beginning goodwill $ 18,253 $ 4,485 Arising from business combination 24,833 13,768 Ending goodwill $ 43,086 $ 18,253 Core deposit intangible 8,558 13,166 Arising from business combination 10,304 — Less: Accumulated amortization (7,234 ) (4,608 ) Core deposit intangible, net $ 11,628 $ 8,558
Schedule of Estimated Amortization Expense for Intangibles	The estimated amount of amortization expense for core deposit intangibles to be recognized over the next five fiscal years is as follows: Type of intangibles Remainder of 2019 2020 2021 2022 2023 2024 (Dollars in thousands) Core deposit intangible $ 975 $ 3,518 $ 2,865 $ 2,072 $ 1,384 $ 653

SBA Servicing Asset (Tables)

SBA Servicing Asset (Tables)	9 Months Ended
	Sep. 30, 2019
Transfers And Servicing Of Financial Assets [Abstract]
Summary of Activity Pertaining to SBA Servicing Rights	The following summarizes the activity pertaining to SBA servicing rights, which are in the consolidated balance sheets, for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (Dollars in thousands) Beginning balance $ 3,570 $ 3,521 $ 3,965 $ 3,411 Origination of servicing assets 264 376 784 955 Change in fair value: Due to run-off (241 ) (254 ) (645 ) (707 ) Due to market changes (45 ) (82 ) (556 ) (98 ) Ending balance $ 3,548 $ 3,561 $ 3,548 $ 3,561

Deposits (Tables)

Deposits (Tables)	9 Months Ended
	Sep. 30, 2019
Banking And Thrift [Abstract]
Summary of Deposits by Category	The following table sets forth the Company’s deposits by category for the periods presented: September 30, 2019 December 31, 2018 (Dollars in thousands) Noninterest-bearing demand deposits $ 366,209 $ 256,784 Interest-bearing demand deposits 303,037 124,933 Interest-bearing NOW accounts 8,626 7,961 Savings and money market accounts 281,401 245,928 Time deposits 625,940 547,042 Total deposits $ 1,585,213 $ 1,182,648 Time deposits $100,000 and greater $ 496,874 $ 422,447 Time deposits $250,000 and greater 176,922 129,424 Related party deposits (executive officers and directors) 16,195 7,847

Stock-Based Compensation and _2

Stock-Based Compensation and Other Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Summary of Assumptions Used to Calculated Fair Value Utilizing Black-Scholes Pricing Model	The fair values of the stock options granted for the nine months ended September 30, 2019 were determined utilizing the Black-Scholes pricing model methodology. A summary of assumptions used to calculate the fair values of the 2017 Stock Plan awards is presented below: 2017 Stock Plan Nine Months Ended September 30, 2019 Expected volatility 23.3 % Expected dividend yield 0.0 % Expected term (years) 7.5 Risk-free interest rate 2.58 % Weighted average grant date fair value $ 7.57
Summary of Activity Related to Restricted Stock Units	The following table presents the activity during the period related to restricted stock units from the 2017 Stock Plan: 2017 Stock Plan Restricted Stock Unit Awards Shares Weighted Average Grant Date Fair Value Outstanding at January 1, 2019 — $ — Granted 54,780 $ 22.18 Vested — Forfeited — Outstanding at September 30, 2019 54,780 $ 22.18
Summary of Stock Based Compensation Expense	A summary of selected data related to stock-based compensation expense for the nine months ended September 30, 2019 and 2018 are as follows: Restricted Stock Unit Awards September 30, 2019 2018 (Dollars in thousands) Stock-based compensation expense $ 77 $ — Unrecognized compensation expense related to stock-based compensation $ 1,138 $ — Weighted-average life over which expense is expected to be recognized (years) 4.44 —
Bank4Texas Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Summary of Warrant Activity	Activity for the Bank4Texas Warrants for the period indicated is summarized as follows: Bank4Texas Warrants Warrants Weighted Average Exercise Price Aggregate Intrinsic Value (in thousands) Weighted Average Remaining Contractual Life (Years) Outstanding at January 1, 2019 10,710 $ 10.50 Granted — Exercised (838 ) $ 10.50 $ 9 Forfeited (1) — Expired — Outstanding at September 30, 2019 9,872 $ 10.50 $ 109 0.90 Vested and exercisable at September 30, 2019 9,872 $ 10.50 $ 109 0.90
2008 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Summary of Option Activity	Option activity for the period indicated is summarized as follows: 2008 Stock Plan Options Weighted Average Exercise Price Aggregate Intrinsic Value (in thousands) Weighted Average Remaining Contractual Life (Years) Outstanding at January 1, 2019 1,116,672 $ 13.04 Granted — Exercised (165,850 ) $ 11.33 $ 1,695 Forfeited (7,600 ) $ 14.66 Expired — Outstanding at September 30, 2019 943,222 $ 13.33 $ 7,753 4.57 Vested and exercisable at September 30, 2019 832,597 $ 13.19 $ 6,961 4.34
2017 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Summary of Option Activity	Option activity for the period indicated is summarized as follows: 2017 Stock Plan Options Weighted Average Exercise Price Aggregate Intrinsic Value (in thousands) Weighted Average Remaining Contractual Life (Years) Outstanding at January 1, 2019 205,725 $ 17.45 Granted 850 $ 23.18 Exercised (5,000 ) $ 15.00 $ 33 Forfeited (1,502 ) $ 18.22 Expired — Outstanding at September 30, 2019 200,073 $ 17.53 $ 804 7.95 Vested and exercisable at September 30, 2019 91,589 $ 16.04 $ 505 7.63

Basic and Diluted Earnings Pe_2

Basic and Diluted Earnings Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted EPS	The following table presents the computation of basic and diluted EPS for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (Dollars in thousands, except per share data) Net income available to common stockholders $ 5,330 $ 2,771 $ 14,967 $ 7,465 Weighted average number of common shares - basic 15,370,480 9,792,032 13,774,776 8,673,106 Effect of dilutive securities: Employee stock-based compensation awards and warrants 400,769 568,269 424,150 421,585 Weighted average number of common shares - diluted 15,771,249 10,360,301 14,198,926 9,094,691 Basic earnings per common share $ 0.35 $ 0.28 $ 1.09 $ 0.86 Diluted earnings per common share $ 0.34 $ 0.27 $ 1.05 $ 0.82 Anti-dilutive warrants and stock options 119,078 7,246 148,578 78,490

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Schedule of Unfunded Commitments	Unfunded commitments are as follows for the periods presented: September 30, 2019 December 31, 2018 (Dollars in thousands) Unfunded loan commitments $ 237,768 $ 176,156 Commercial and standby letters of credit 581 547 Total $ 238,349 $ 176,703

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following tables present the assets and liabilities measured at fair value on a recurring basis for the periods presented: September 30, 2019 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: U.S. Treasury securities $ 32,563 $ — $ — $ 32,563 U.S. Government agencies — 4,141 — 4,141 State and municipal obligations — 25,628 — 25,628 Residential mortgage-backed securities — 98,645 — 98,645 Corporate bonds and other debt securities — 5,692 — 5,692 SBA servicing rights — — 3,548 3,548 Total $ 32,563 $ 134,106 $ 3,548 $ 170,217 December 31, 2018 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: U.S. Government agencies $ — $ 1,934 $ — $ 1,934 State and municipal obligations — 18,048 — 18,048 Residential mortgage-backed securities — 153,974 — 153,974 Corporate bonds and other debt securities — 5,505 — 5,505 SBA servicing rights — — 3,965 3,965 Total $ — $ 179,461 $ 3,965 $ 183,426
Schedule of Assets Measured at Fair Value on Non-Recurring Basis	The following tables provide information about certain assets measured at fair value on a non-recurring basis: Estimated Fair Value September 30, 2019 December 31, 2018 (Dollars in thousands) Assets (classified in Level 3): Impaired loans $ 2,346 $ 2,696 Other real estate and repossessed assets 1,042 782
Significant Unobservable Inputs Used in Recurring and Non-Recurring Fair Value Measurements	The following tables show significant unobservable inputs used in the recurring and non-recurring fair value measurements of Level 3 assets: Level 3 Asset Fair Value Valuation Technique Unobservable Inputs Range/Weighted Average September 30, 2019 Non-recurring: Impaired loans $ 2,346 Third party appraisals Collateral discounts 0.0% - 100.0% (28.3%) Other real estate owned 1,042 Third party appraisals Collateral discounts and estimated cost to sell 10.0 % Recurring: SBA servicing assets 3,548 Discounted cash flows Conditional prepayment rate 13.1 % Discount rate 11.0 % December 31, 2018 Non-recurring: Impaired loans $ 2,696 Third party appraisals Collateral discounts 0.0% - 100.0% (19.2%) Other real estate owned 782 Third party appraisals Collateral discounts and estimated cost to sell 10.0 % Recurring: SBA servicing assets 3,965 Discounted cash flows Conditional prepayment rate 11.8 % Discount rate 11.5 %
Summary of Carrying Amounts and Estimated Fair Values of Financial Instruments	The carrying amounts and estimated fair values, as well as the level within the fair value hierarchy, of the Company’s financial instruments are as follows for the periods presented: September 30, 2019 Carrying Value Fair Value Level 1 Level 2 Level 3 (Dollars in thousands) Financial Assets: Cash and cash equivalents $ 151,543 $ 151,543 $ 151,543 $ — $ — Time deposits in other banks 1,225 1,225 1,225 Available for sale securities 166,669 166,669 32,563 134,106 — FHLB and other bank stock 6,233 6,233 — 6,233 — Loans, net 1,481,037 1,479,485 — — 1,479,485 Loans held for sale 2,784 2,998 — 2,998 — Accrued interest receivable 6,319 6,319 — 6,319 — Bank-owned life insurance 15,521 15,521 — 15,521 — SBA servicing rights 3,548 3,548 — — 3,548 Financial Liabilities: Deposits $ 1,585,213 $ 1,545,765 $ — $ 1,545,765 $ — Accrued interest payable 1,002 1,002 — 1,002 — Long-term borrowings 74,165 60,003 — 60,003 — December 31, 2018 Carrying Value Fair Value Level 1 Level 2 Level 3 (Dollars in thousands) Financial Assets: Cash and cash equivalents $ 89,015 $ 89,015 $ 89,015 $ — $ — Available for sale securities 179,461 179,461 — 179,461 — FHLB and other bank stock 5,304 5,304 — 5,304 — Loans, net 1,096,522 1,085,120 — — 1,085,120 Loans held for sale 3,945 4,200 — 4,200 — Accrued interest receivable 4,934 4,934 — 4,934 — Bank-owned life insurance 7,401 7,401 — 7,401 — SBA servicing rights 3,965 3,965 — — 3,965 Financial Liabilities: Deposits $ 1,182,648 $ 1,181,606 $ — $ 1,181,606 $ — Accrued interest payable 702 702 — 702 — Short-term borrowings 12,500 12,500 — 12,500 — Long-term borrowings 77,784 76,603 — 76,603 —

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		Jul. 25, 2019	May 04, 2018	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Subsidiary Sale Of Stock [Line Items]
Net proceeds from initial public offering					$ 46,542	$ 42,058
Loans held for investment	[1]			$ 1,487,602	1,487,602		$ 1,102,808
Long-term borrowings				$ 74,165	$ 74,165		77,784
Immaterial Error Corrections
Subsidiary Sale Of Stock [Line Items]
Loans held for investment							9,900
Long-term borrowings							$ 9,900
Increase in investing activities of cash flow						2,000
Decrease in financing activities of cash flow						$ (2,000)
2019 Offering
Subsidiary Sale Of Stock [Line Items]
Net proceeds from initial public offering		$ 46,500
2019 Offering | Line of Credit
Subsidiary Sale Of Stock [Line Items]
Proceeds from offering, pay off a line of credit		21,000
2019 Offering | Citizens
Subsidiary Sale Of Stock [Line Items]
Business acquisition, cash paid		$ 17,900
Common Stock
Subsidiary Sale Of Stock [Line Items]
Number of shares issued and sold				2,300,000	2,300,000	2,300,000
Common Stock | Initial Public Offering
Subsidiary Sale Of Stock [Line Items]
Number of shares issued and sold			2,300,000
Stock issued, price per share			$ 21
Gross proceeds before deducting underwriting discounts and offering expenses			$ 48,300
Net proceeds from initial public offering			$ 42,100
Common Stock | Underwriters
Subsidiary Sale Of Stock [Line Items]
Number of shares issued and sold		300,000	300,000
Common Stock | 2019 Offering
Subsidiary Sale Of Stock [Line Items]
Number of shares issued and sold		2,300,000
Public offering price		$ 21.50
[1]	Balance includes $(7.1) million and $(4.9) million of deferred fees, cost, premium and discount as of September 30, 2019 and December 31, 2018, respectively.

Revenue Recognition - Schedule

Revenue Recognition - Schedule of Non-Interest Income, Segregated by Revenue Streams in-Scope and Out-of-Scope of Topic 606 (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Noninterest income:
Non-Interest Income	$ 2,681	$ 2,567	$ 9,513	$ 7,458
Accounting Standards Update 2014-09
Noninterest income:
Non-Interest Income (in-scope of Topic 606)	1,056	626	3,085	1,774
Out-of-scope of Topic 606
Noninterest income:
Non-Interest Income	1,625	1,941	6,428	5,684
Deposit accounts core service charges | Accounting Standards Update 2014-09
Noninterest income:
Non-Interest Income (in-scope of Topic 606)	135	88	396	233
Deposit account transaction based fee income | Accounting Standards Update 2014-09
Noninterest income:
Non-Interest Income (in-scope of Topic 606)	748	378	2,208	1,017
Mortgage referral fees | Accounting Standards Update 2014-09
Noninterest income:
Non-Interest Income (in-scope of Topic 606)	$ 173	$ 160	$ 481	$ 524

Business Combinations - Additio

Business Combinations - Additional Information (Details)	Apr. 02, 2019USD ($)Branchofficeshares	Nov. 14, 2018USD ($)Branchshares	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Business Acquisition [Line Items]
Goodwill			$ 43,086,000		$ 43,086,000		$ 18,253,000	$ 4,485,000
Comanche National Corporation
Business Acquisition [Line Items]
Business acquisition date					Nov. 14, 2018
Business acquisition, shares issued | shares		2,142,811
Business acquisition, cash paid		$ 12,246,000
Business acquisition, total consideration		$ 52,900,000
Acquired ownership interest		100.00%
Goodwill		$ 13,768,000
Goodwill recognized expected to be deductible for income tax purposes		0
Acquisition expenses			0	$ 43,000	$ 1,200,000	$ 43,000
Non-credit impaired loans fair value		116,200,000
Contractual balance		117,200,000
Interest income		$ 946,000
Comanche National Corporation | North/South Texas
Business Acquisition [Line Items]
Number of additional branches | Branch		8
First Beeville Financial Corporation
Business Acquisition [Line Items]
Business acquisition date					Apr. 2, 2019
Business acquisition, shares issued | shares	1,579,191
Business acquisition, cash paid	$ 32,377,000
Business acquisition, total consideration	$ 65,900,000
Acquired ownership interest	100.00%
Goodwill	$ 24,843,000
Goodwill recognized expected to be deductible for income tax purposes	0
Acquisition expenses			$ 823,000	$ 2,000	$ 2,500,000	$ 2,000
Non-credit impaired loans fair value	296,900,000
Contractual balance	298,900,000
Interest income	$ 2,000,000
First Beeville Financial Corporation | North/South Texas
Business Acquisition [Line Items]
Number of additional branches | Branch	3
Number of loan production offices | office	2

Business Combinations - Fair Va

Business Combinations - Fair Value of Asset Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Apr. 02, 2019	Nov. 14, 2018	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill			$ 43,086	$ 18,253	$ 4,485
Comanche National Corporation
Business Acquisition [Line Items]
Cash and cash equivalents		$ 57,135
Securities available for sale		144,735
Loans held for investment		116,220
Premises and equipment, net		6,634
Other real estate owned		33
Goodwill		13,768
Core deposit intangible		5,988
Other assets		11,712
Total assets acquired		356,225
Deposits		297,778
Trust preferred securities		2,811
Other liabilities		2,698
Total liabilities assumed		303,287
Common stock issued		40,692
Business acquisition, cash paid		$ 12,246
First Beeville Financial Corporation
Business Acquisition [Line Items]
Cash and cash equivalents	$ 60,491
Securities available for sale	57,206
Loans held for investment	296,871
Premises and equipment, net	6,067
Other real estate owned	1,359
Goodwill	24,843
Core deposit intangible	5,695
Other assets	12,929
Total assets acquired	465,461
Deposits	399,062
Other liabilities	543
Total liabilities assumed	399,605
Common stock issued	33,479
Business acquisition, cash paid	$ 32,377

Business Combinations - Fair _2

Business Combinations - Fair Value of Asset Acquired and Liabilities Assumed (Parenthetical) (Details) - Common Stock - $ / shares	Apr. 02, 2019	Nov. 14, 2018
Comanche National Corporation
Business Acquisition [Line Items]
Shares issued, price per share		$ 18.99
First Beeville Financial Corporation
Business Acquisition [Line Items]
Shares issued, price per share	$ 21.20

Investment Securities - Schedul

Investment Securities - Schedule of Fair Values of Securities Available for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Securities available for sale, Amortized Cost	$ 162,780	$ 177,115
Securities available for sale, Unrealized Gains	3,903	3,461
Securities available for sale, Unrealized Losses	14	1,115
Available for sale securities, at fair value	166,669	179,461
U.S. Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Securities available for sale, Amortized Cost	32,541
Securities available for sale, Unrealized Gains	23
Securities available for sale, Unrealized Losses	1
Available for sale securities, at fair value	32,563
U.S. Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Securities available for sale, Amortized Cost	4,074	2,015
Securities available for sale, Unrealized Gains	67
Securities available for sale, Unrealized Losses		81
Available for sale securities, at fair value	4,141	1,934
State and Municipal Obligations
Schedule Of Available For Sale Securities [Line Items]
Securities available for sale, Amortized Cost	24,795	17,201
Securities available for sale, Unrealized Gains	833	847
Available for sale securities, at fair value	25,628	18,048
Residential Mortgage-backed Securities
Schedule Of Available For Sale Securities [Line Items]
Securities available for sale, Amortized Cost	95,737	152,232
Securities available for sale, Unrealized Gains	2,921	2,614
Securities available for sale, Unrealized Losses	13	872
Available for sale securities, at fair value	98,645	153,974
Corporate Bonds and Other Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Securities available for sale, Amortized Cost	5,633	5,667
Securities available for sale, Unrealized Gains	59
Securities available for sale, Unrealized Losses		162
Available for sale securities, at fair value	$ 5,692	$ 5,505

Investment Securities - Additio

Investment Securities - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)Security	Sep. 30, 2018USD ($)Security	Sep. 30, 2019USD ($)Security	Sep. 30, 2018USD ($)Security	Dec. 31, 2018USD ($)
Investments Debt And Equity Securities [Abstract]
Taxable interest and dividends on investment securities	$ 998,000	$ 202,000	$ 3,200,000	$ 611,000
Tax-exempt interest on investment securities	146,000	$ 0	411,000	$ 0
Available for sale securities pledged	$ 140,800,000		$ 140,800,000		$ 106,600,000
Debt Securities, Available-for-sale, Restriction Type [Extensible List]	us-gaap:CollateralPledgedMember		us-gaap:CollateralPledgedMember		us-gaap:CollateralPledgedMember
Available for sale, securities number of positions | Security	227		227
Available for sale, securities in unrealized loss positions, number of positions | Security	9		9
Available for sale, securities in unrealized loss positions, number of positions, more than 12 months | Security	8		8
Available for sale securities, gross realized gain (loss), excluding other than temporary impairments			$ 0
Sales of investment securities available for sale			79,920,000
Gross realized gains			$ 2,100,000
Number of securities sold | Security	0	0		0

Investment Securities - Sched_2

Investment Securities - Schedule of Securities Available for Sale by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Available for sale:
Due in one year or less, Amortized Cost	$ 19,377
Due after one year through five years, Amortized Cost	35,152
Due after five years through ten years, Amortized Cost	6,863
Due after ten years, Amortized Cost	5,651
Total available for sale, Amortized Cost	162,780	$ 177,115
Available for sale:
Due in one year or less, Fair Value	19,412
Due after one year through five years. Fair Value	35,427
Due after five years through ten years. Fair Value	7,066
Due after ten years. Fair Value	6,119
Total available for sale, Fair Value	166,669	179,461
Residential Mortgage-backed Securities
Available for sale:
Total available for sale, Amortized Cost	95,737	152,232
Available for sale:
Total available for sale, Fair Value	$ 98,645	$ 153,974

Investment Securities - Sched_3

Investment Securities - Schedule of Investment Securities Available for Sale and Aggregated by Investment Category and Length of Time Individual Securities in Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Investment Securities, Available for sale, Fair Value, Less than 12 Months	$ 2,998	$ 1
Investment Securities, Available for sale, Unrealized Loss, Less than 12 Months	1
Investment Securities, Available for sale, Fair Value, 12 Months or More	4,994	32,918
Investment Securities, Available for sale, Unrealized Loss, 12 Months or More	13	1,115
Investment Securities, Available for sale, Fair Value	7,992	32,919
Investment Securities, Available for sale, Unrealized Loss	14	1,115
U.S. Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Investment Securities, Available for sale, Fair Value, Less than 12 Months	2,998
Investment Securities, Available for sale, Unrealized Loss, Less than 12 Months	1
Investment Securities, Available for sale, Fair Value	2,998
Investment Securities, Available for sale, Unrealized Loss	1
U.S. Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Investment Securities, Available for sale, Fair Value, 12 Months or More		1,934
Investment Securities, Available for sale, Unrealized Loss, 12 Months or More		81
Investment Securities, Available for sale, Fair Value		1,934
Investment Securities, Available for sale, Unrealized Loss		81
Residential Mortgage-backed Securities
Schedule Of Available For Sale Securities [Line Items]
Investment Securities, Available for sale, Fair Value, Less than 12 Months		1
Investment Securities, Available for sale, Fair Value, 12 Months or More	4,994	25,479
Investment Securities, Available for sale, Unrealized Loss, 12 Months or More	13	872
Investment Securities, Available for sale, Fair Value	4,994	25,480
Investment Securities, Available for sale, Unrealized Loss	$ 13	872
Corporate Bonds and Other Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Investment Securities, Available for sale, Fair Value, 12 Months or More		5,505
Investment Securities, Available for sale, Unrealized Loss, 12 Months or More		162
Investment Securities, Available for sale, Fair Value		5,505
Investment Securities, Available for sale, Unrealized Loss		$ 162

Loans, Net - Summary of Loans,

Loans, Net - Summary of Loans, Net (Details) - USD ($) $ in Thousands		Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio	[1]	$ 1,487,602		$ 1,102,808
Allowance for loan losses		(6,565)	$ (6,277)	(6,286)	$ (6,156)	$ (6,015)	$ (5,652)
Loans, net		1,481,037		1,096,522
Commercial and Industrial Loans
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio	[2]	248,745		173,892
Consumer Loans and Leases
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio		17,663		24,378
Municipal and Other Loans
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio		68,905		61,339
Real Estate | 1-4 Single Family Residential Loans
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio		321,044		279,665
Real Estate | Construction, Land and Development
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio		233,830		159,734
Real Estate | Commercial Real Estate Loans (Including Multifamily)
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio		$ 597,415		$ 403,800
[1]	Balance includes $(7.1) million and $(4.9) million of deferred fees, cost, premium and discount as of September 30, 2019 and December 31, 2018, respectively.
[2]	Balance includes $78.7 million and $76.9 million of the unguaranteed portion of Small Business Administration (“SBA”) loans as of September 30, 2019 and December 31, 2018, respectively.

Loans, Net - Summary of Loans_2

Loans, Net - Summary of Loans, Net (Parenthetical) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Accounts Notes And Loans Receivable [Line Items]
Deferred fees, cost, premium and discount	$ (7.1)	$ (4.9)
SBA Loans
Accounts Notes And Loans Receivable [Line Items]
Unguaranteed portion of loans	$ 78.7	$ 76.9

Loans, Net - Additional Informa

Loans, Net - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Accounts Notes And Loans Receivable [Line Items]
Pledged loans, collateral for FHLB advances	$ 664,700,000		$ 664,700,000		$ 385,500,000
Unpaid principal balances of loans serviced	215,200,000		215,200,000		225,000,000
Unfunded commitments to related parties	238,349,000		238,349,000		176,703,000
Executive Officers and Directors
Accounts Notes And Loans Receivable [Line Items]
Unfunded commitments to related parties	1,300,000		1,300,000		0
Loan Held for Investment and Long-term Borrowings
Accounts Notes And Loans Receivable [Line Items]
Secured borrowings	18,600,000		18,600,000		9,900,000
Consumer Mortgage Loans
Accounts Notes And Loans Receivable [Line Items]
Recorded mortgage loans in process of foreclosure	0		0		0
SBA Loans
Accounts Notes And Loans Receivable [Line Items]
Unpaid principal balances of loans serviced	233,700,000		233,700,000		$ 234,900,000
SBA Loans | Third Party
Accounts Notes And Loans Receivable [Line Items]
Servicing loans sold	13,800,000	$ 19,000,000	40,300,000	$ 49,000,000
Realized gains on servicing loans sold	$ 1,200,000	$ 1,400,000	$ 3,300,000	$ 3,900,000

Loans, Net - Summary of Loans t

Loans, Net - Summary of Loans to Related Parties and Principal Owners (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Receivables [Abstract]
Principal outstanding, beginning of year	$ 2,433	$ 421	$ 107	$ 463
Additions (reductions) of affiliations			2,352
New loans made in current year	4,035		4,035
Repayments	(57)	(19)	(83)	(61)
Principal outstanding, end of year	$ 6,411	$ 402	$ 6,411	$ 402

Allowance for Loan and Lease _3

Allowance for Loan and Lease Losses - Additional Information (Details) $ in Thousands	Apr. 02, 2019USD ($)	Nov. 14, 2018USD ($)	Sep. 30, 2019USD ($)Loan	Dec. 31, 2018USD ($)Loan
Financing Receivable Recorded Investment Past Due [Line Items]
Amount of defaults Lookback period			5 years
Recorded investment, 90 days past due and still accruing			$ 120	$ 288
Non-accrual loans, Past due			$ 9,022	$ 5,031
Financing Receivables, Past Due Greater Than 90 Days or More and Still Accruing
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, 90 days past due and still accruing number of loans | Loan			1	4
Non-accrual loans, Past due			$ 4,700	$ 2,000
Financing Receivables, 30 to 59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Non-accrual loans, Past due			928	175
Financing Receivables, 60 to 89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Non-accrual loans, Past due			$ 125	$ 143
Comanche
Financing Receivable Recorded Investment Past Due [Line Items]
Business combination loan in acquiree, amount		$ 117,200
Business combination loan In acquiree, fair value		116,200
Business combination loan in acquiree, discount		$ 946
Beeville
Financing Receivable Recorded Investment Past Due [Line Items]
Business combination loan in acquiree, amount	$ 298,900
Business combination loan In acquiree, fair value	296,300
Business combination loan in acquiree, discount	$ 2,600

Allowance for Loan and Lease _4

Allowance for Loan and Lease Losses - Allowance for Loan and Lease Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	$ 6,277	$ 6,015	$ 6,286	$ 5,652
Charge-offs	(713)	(349)	(1,968)	(1,029)
Recoveries	101	4	166	73
Provision	900	486	2,081	1,460
Ending Balance	6,565	6,156	6,565	6,156
Commercial and Industrial Loans
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	4,217	4,886	4,453	3,046
Charge-offs	(687)	(275)	(1,908)	(920)
Recoveries	36	4	95	73
Provision	669	76	1,595	2,492
Ending Balance	4,235	4,691	4,235	4,691
Real Estate | 1-4 Single Family Residential Loans
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	32	318	59	902
Charge-offs				(5)
Recoveries	65		65
Provision	(66)	(216)	(93)	(795)
Ending Balance	31	102	31	102
Real Estate | Construction, Land and Development Loans
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	794	195	731	441
Provision	90	256	153	10
Ending Balance	884	451	884	451
Real Estate | Commercial Real Estate Loans (Including Multifamily)
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	1,191	233	960	898
Provision	127	495	358	(170)
Ending Balance	1,318	728	1,318	728
Consumer Loans and Leases
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	35	346	80	198
Charge-offs	(26)	(74)	(60)	(104)
Recoveries			5
Provision	85	(90)	69	88
Ending Balance	94	182	94	182
Municipal and Other Loans
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	8	37	3	167
Recoveries			1
Provision	(5)	(35)	(1)	(165)
Ending Balance	$ 3	$ 2	$ 3	$ 2

Allowance for Loan and Lease _5

Allowance for Loan and Lease Losses - Summary of Aging Analysis of Recorded Investment for Delinquent Loans by Portfolio and Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	$ 1,473,660	$ 1,094,663
Recorded investment, Non-accrual	9,022	5,031
Recorded investment, Total	1,487,602	1,102,808
Financing Receivables, 30 to 59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	3,831	1,906
Recorded investment, Non-accrual	928	175
Financing Receivables, 60 to 89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	969	920
Recorded investment, Non-accrual	125	143
Financing Receivables, Past Due Greater Than 90 Days or More and Still Accruing
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	120	288
Recorded investment, Non-accrual	4,700	2,000
Commercial and Industrial Loans
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	241,710	169,206
Recorded investment, Non-accrual	6,183	3,570
Recorded investment, Total	248,745	173,892
Commercial and Industrial Loans | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	517	605
Commercial and Industrial Loans | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	215	223
Commercial and Industrial Loans | Financing Receivables, Past Due Greater Than 90 Days or More and Still Accruing
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	120	288
Real Estate | 1-4 Single Family Residential Loans
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	318,304	277,930
Recorded investment, Non-accrual	1,340	1,090
Recorded investment, Total	321,044	279,665
Real Estate | 1-4 Single Family Residential Loans | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	1,287	581
Real Estate | 1-4 Single Family Residential Loans | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	113	64
Real Estate | Construction, Land and Development
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	233,614	159,723
Recorded investment, Non-accrual	216
Recorded investment, Total	233,830	159,734
Real Estate | Construction, Land and Development | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due		11
Real Estate | Commercial Real Estate Loans (Including Multifamily)
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	593,794	402,406
Recorded investment, Non-accrual	1,169	354
Recorded investment, Total	597,415	403,800
Real Estate | Commercial Real Estate Loans (Including Multifamily) | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	1,851	451
Real Estate | Commercial Real Estate Loans (Including Multifamily) | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	601	589
Consumer Loans and Leases
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	17,371	24,109
Recorded investment, Non-accrual	76	17
Recorded investment, Total	17,663	24,378
Consumer Loans and Leases | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	176	208
Consumer Loans and Leases | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	40	44
Municipal and Other Loans
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	68,867	61,289
Recorded investment, Non-accrual	38
Recorded investment, Total	$ 68,905	61,339
Municipal and Other Loans | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due		$ 50

Allowance for Loan and Lease _6

Allowance for Loan and Lease Losses - Summary of Loans by Key Indicators of Credit Quality (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 1,487,602	$ 1,102,808
Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	1,455,217	1,067,261
Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	8,130	19,640
Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	24,255	13,156
Doubtful
Financing Receivable Recorded Investment [Line Items]
Total loans		2,751
Commercial and Industrial Loans
Financing Receivable Recorded Investment [Line Items]
Total loans	248,745	173,892
Commercial and Industrial Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	234,989	163,908
Commercial and Industrial Loans | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	3,246	3,170
Commercial and Industrial Loans | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	10,510	6,601
Commercial and Industrial Loans | Doubtful
Financing Receivable Recorded Investment [Line Items]
Total loans		213
Real Estate | 1-4 Single Family Residential Loans
Financing Receivable Recorded Investment [Line Items]
Total loans	321,044	279,665
Real Estate | 1-4 Single Family Residential Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	318,562	274,860
Real Estate | 1-4 Single Family Residential Loans | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	281	1,714
Real Estate | 1-4 Single Family Residential Loans | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	2,201	2,547
Real Estate | 1-4 Single Family Residential Loans | Doubtful
Financing Receivable Recorded Investment [Line Items]
Total loans		544
Real Estate | Construction, Land and Development
Financing Receivable Recorded Investment [Line Items]
Total loans	233,830	159,734
Real Estate | Construction, Land and Development | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	232,792	157,688
Real Estate | Construction, Land and Development | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans		24
Real Estate | Construction, Land and Development | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	1,038	2,022
Real Estate | Commercial Real Estate Loans (Including Multifamily)
Financing Receivable Recorded Investment [Line Items]
Total loans	597,415	403,800
Real Estate | Commercial Real Estate Loans (Including Multifamily) | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	582,481	389,170
Real Estate | Commercial Real Estate Loans (Including Multifamily) | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	4,603	12,412
Real Estate | Commercial Real Estate Loans (Including Multifamily) | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	10,331	1,806
Real Estate | Commercial Real Estate Loans (Including Multifamily) | Doubtful
Financing Receivable Recorded Investment [Line Items]
Total loans		412
Consumer Loans and Leases
Financing Receivable Recorded Investment [Line Items]
Total loans	17,663	24,378
Consumer Loans and Leases | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	17,533	20,798
Consumer Loans and Leases | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans		1,836
Consumer Loans and Leases | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	130	180
Consumer Loans and Leases | Doubtful
Financing Receivable Recorded Investment [Line Items]
Total loans		1,564
Municipal and Other Loans
Financing Receivable Recorded Investment [Line Items]
Total loans	68,905	61,339
Municipal and Other Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	68,860	60,837
Municipal and Other Loans | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans		484
Municipal and Other Loans | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 45
Municipal and Other Loans | Doubtful
Financing Receivable Recorded Investment [Line Items]
Total loans		$ 18

Allowance for Loan and Lease _7

Allowance for Loan and Lease Losses - Summary of Investment in Loans Disaggregated Based on Method of Evaluating Impairment (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Individually Evaluated for Impairment	$ 4,510	$ 4,850
Loans - Recorded Investment, Collectively Evaluated for Impairment	1,483,092	1,097,958
Allowance for Credit Loss, Individually Evaluated for Impairment	1,203	1,267
Allowance for Credit Loss, Collectively Evaluated for Impairment	5,362	5,019
Commercial and Industrial Loans
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Individually Evaluated for Impairment	2,638	3,640
Loans - Recorded Investment, Collectively Evaluated for Impairment	246,107	170,252
Allowance for Credit Loss, Individually Evaluated for Impairment	1,194	1,234
Allowance for Credit Loss, Collectively Evaluated for Impairment	3,041	3,219
Real Estate | 1-4 Single Family Residential Loans
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Individually Evaluated for Impairment	1,399	1,193
Loans - Recorded Investment, Collectively Evaluated for Impairment	319,645	278,472
Allowance for Credit Loss, Individually Evaluated for Impairment	4	29
Allowance for Credit Loss, Collectively Evaluated for Impairment	27	30
Real Estate | Construction, Land and Development
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Individually Evaluated for Impairment	216
Loans - Recorded Investment, Collectively Evaluated for Impairment	233,614	159,734
Allowance for Credit Loss, Collectively Evaluated for Impairment	884	731
Real Estate | Commercial Real Estate Loans (Including Multifamily)
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Individually Evaluated for Impairment	236
Loans - Recorded Investment, Collectively Evaluated for Impairment	597,179	403,800
Allowance for Credit Loss, Collectively Evaluated for Impairment	1,318	960
Consumer Loans and Leases
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Individually Evaluated for Impairment	21	17
Loans - Recorded Investment, Collectively Evaluated for Impairment	17,642	24,361
Allowance for Credit Loss, Individually Evaluated for Impairment	5	4
Allowance for Credit Loss, Collectively Evaluated for Impairment	89	76
Municipal and Other Loans
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Collectively Evaluated for Impairment	68,905	61,339
Allowance for Credit Loss, Collectively Evaluated for Impairment	$ 3	$ 3

Allowance for Loan and Lease _8

Allowance for Loan and Lease Losses - Summary of Information Regarding Impaired Loans Evaluated for Specific Reserves (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Financing Receivable Impaired [Line Items]
Impaired Loans - With Allowance, Recorded Investment	$ 2,193		$ 2,193		$ 1,976
Impaired Loans - With Allowance, Unpaid Principal Balance	4,602		4,602		5,533
Impaired Loans - With Allowance, Related Allowance	1,203		1,203		1,267
Impaired Loans - With no Allowance, Recorded Investment	2,317		2,317		2,874
Impaired Loans - With no Allowance, Unpaid Principal Balance	4,217		4,217		4,586
Average Recorded Investment	4,643	$ 3,618	4,826	$ 3,840
Commercial and Industrial Loans
Financing Receivable Impaired [Line Items]
Impaired Loans - With Allowance, Recorded Investment	2,158		2,158		1,843
Impaired Loans - With Allowance, Unpaid Principal Balance	4,565		4,565		5,392
Impaired Loans - With Allowance, Related Allowance	1,194		1,194		1,234
Impaired Loans - With no Allowance, Recorded Investment	480		480		1,797
Impaired Loans - With no Allowance, Unpaid Principal Balance	2,298		2,298		3,500
Average Recorded Investment	2,758	2,571	2,905	2,774
Real Estate | 1-4 Single Family Residential Loans
Financing Receivable Impaired [Line Items]
Impaired Loans - With Allowance, Recorded Investment	14		14		116
Impaired Loans - With Allowance, Unpaid Principal Balance	16		16		124
Impaired Loans - With Allowance, Related Allowance	4		4		29
Impaired Loans - With no Allowance, Recorded Investment	1,385		1,385		1,077
Impaired Loans - With no Allowance, Unpaid Principal Balance	1,452		1,452		1,086
Average Recorded Investment	1,409	975	1,434	990
Real Estate | Construction, Land and Development
Financing Receivable Impaired [Line Items]
Impaired Loans - With no Allowance, Recorded Investment	216		216
Impaired Loans - With no Allowance, Unpaid Principal Balance	223		223
Average Recorded Investment	216		220
Real Estate | Commercial Real Estate Loans (Including Multifamily)
Financing Receivable Impaired [Line Items]
Impaired Loans - With no Allowance, Recorded Investment	236		236
Impaired Loans - With no Allowance, Unpaid Principal Balance	244		244
Average Recorded Investment	238		243
Consumer Loans and Leases
Financing Receivable Impaired [Line Items]
Impaired Loans - With Allowance, Recorded Investment	21		21		17
Impaired Loans - With Allowance, Unpaid Principal Balance	21		21		17
Impaired Loans - With Allowance, Related Allowance	5		5		$ 4
Average Recorded Investment	$ 22	$ 72	$ 24	$ 76

Allowance for Loan and Lease _9

Allowance for Loan and Lease Losses - Summary of Troubled Debt Restructurings (TDRs) Based Upon Delinquency Status (Details) $ in Thousands	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2019USD ($)Contract	Sep. 30, 2019USD ($)Contract	Sep. 30, 2018Contract	Dec. 31, 2018USD ($)Contract
Financing Receivable Modifications [Line Items]
Number of contracts		14		12
Recorded Investment | $	$ 678	$ 678		$ 658
Allowance attributable to TDRs | $	$ 265	$ 265		$ 149
Commercial and Industrial Loans
Financing Receivable Modifications [Line Items]
Number of contracts	1	3	7
Real Estate | 1-4 Single Family Residential Loans
Financing Receivable Modifications [Line Items]
Number of contracts			1
Performing TDRs
Financing Receivable Modifications [Line Items]
Number of contracts		6		5
Recorded Investment | $	$ 275	$ 275		$ 210
Performing TDRs | Commercial and Industrial Loans
Financing Receivable Modifications [Line Items]
Number of contracts		3		3
Recorded Investment | $	118	$ 118		$ 69
Performing TDRs | Real Estate | 1-4 Single Family Residential Loans
Financing Receivable Modifications [Line Items]
Number of contracts		3		2
Recorded Investment | $	157	$ 157		$ 141
Nonperforming TDRs
Financing Receivable Modifications [Line Items]
Number of contracts		8		7
Recorded Investment | $	$ 403	$ 403		$ 448

Allowance for Loan and Lease_10

Allowance for Loan and Lease Losses - Summary of TDRs Includes Newly Designated TDRs and Modifications to Existing TDRs (Details) $ in Thousands	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2019USD ($)Contract	Sep. 30, 2019USD ($)Contract	Sep. 30, 2018USD ($)Contract	Dec. 31, 2018Contract
Financing Receivable Modifications [Line Items]
Number of contracts | Contract		14		12
Commercial and Industrial Loans
Financing Receivable Modifications [Line Items]
Number of contracts | Contract	1	3	7
Pre-Modification Outstanding Recorded Investment	$ 13	$ 141	$ 442
Post-Modification Outstanding Recorded Investment	$ 13	141	442
Related Allowance		$ 90	$ 113
Real Estate | 1-4 Single Family Residential Loans
Financing Receivable Modifications [Line Items]
Number of contracts | Contract			1
Pre-Modification Outstanding Recorded Investment			$ 34
Post-Modification Outstanding Recorded Investment			$ 34

Goodwill and Intangibles - Sche

Goodwill and Intangibles - Schedule of Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Beginning goodwill	$ 18,253	$ 4,485
Arising from business combination	24,833	13,768
Ending goodwill	43,086	18,253
Core deposit intangible	8,558	13,166
Arising from business combination	10,304
Less: Accumulated amortization	(7,234)	(4,608)
Core deposit intangible, net	$ 11,628	$ 8,558

Goodwill and Intangibles - Addi

Goodwill and Intangibles - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 1,015	$ 176	$ 2,624	$ 527
Core Deposit Intangible
Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 1,000	$ 176	$ 2,600	$ 527

Goodwill and Intangibles - Sc_2

Goodwill and Intangibles - Schedule of Estimated Amortization Expense for Intangibles (Details) - Core Deposit Intangible $ in Thousands	Sep. 30, 2019USD ($)
Finite Lived Intangible Assets [Line Items]
Remainder of 2019	$ 975
2020	3,518
2021	2,865
2022	2,072
2023	1,384
2024	$ 653

SBA Servicing Asset - Additiona

SBA Servicing Asset - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Transfers And Servicing Of Financial Assets [Abstract]
Unpaid principal balances of loans serviced	$ 215,200		$ 215,200		$ 225,000
Loan expenses	$ 234	$ 529	$ 538	$ 1,700

SBA Servicing Asset - Summary o

SBA Servicing Asset - Summary of Activity Pertaining to SBA Servicing Rights (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Transfers And Servicing Of Financial Assets [Abstract]
Beginning balance	$ 3,570	$ 3,521	$ 3,965	$ 3,411
Origination of servicing assets	264	376	784	955
Change in fair value:
Due to run-off	(241)	(254)	(645)	(707)
Due to market changes	(45)	(82)	(556)	(98)
Ending balance	$ 3,548	$ 3,561	$ 3,548	$ 3,561

Deposits - Summary of Deposits

Deposits - Summary of Deposits by Category (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Banking And Thrift [Abstract]
Noninterest-bearing demand deposits	$ 366,209	$ 256,784
Interest-bearing demand deposits	303,037	124,933
Interest-bearing NOW accounts	8,626	7,961
Savings and money market accounts	281,401	245,928
Time deposits	625,940	547,042
Total deposits	1,585,213	1,182,648
Time deposits $100,000 and greater	496,874	422,447
Time deposits $250,000 and greater	176,922	129,424
Related party deposits (executive officers and directors)	$ 16,195	$ 7,847

Deposits - Additional Informati

Deposits - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Banking And Thrift [Abstract]
Aggregate amount of overdraft demand deposits reclassified to loans	$ 69,000	$ 93,000
Aggregate amount of maturities for time deposits, period	5 years
Aggregate amount of maturities for time deposits, year one	$ 505,100,000
Aggregate amount of maturities for time deposits, year two	85,800,000
Aggregate amount of maturities for time deposits, year three	18,800,000
Aggregate amount of maturities for time deposits, year four	10,900,000
Aggregate amount of maturities for time deposits, year five	5,300,000
Brokered certificates of deposits	$ 1,000,000	$ 0

Stock-Based Compensation and _3

Stock-Based Compensation and Other Benefit Plans - Summary of Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)$ / sharesshares
2008 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options, Outstanding | shares	1,116,672
Options, Exercised | shares	(165,850)
Options, Forfeited | shares	(7,600)
Options, Outstanding | shares	943,222
Options, Vested and exercisable | shares	832,597
Weighted Average Exercise Price, Outstanding | $ / shares	$ 13.04
Weighted Average Exercise Price, Exercised | $ / shares	11.33
Weighted Average Exercise Price, Forfeited | $ / shares	14.66
Weighted Average Exercise Price, Outstanding | $ / shares	13.33
Weighted Average Exercise Price, Vested and exercisable | $ / shares	$ 13.19
Aggregate Intrinsic Value, Exercised | $	$ 1,695
Aggregate Intrinsic Value, Outstanding | $	7,753
Vested and exercisable at September 30, 2019 | $	$ 6,961
Weighted Average Remaining Contractual Life (Years), Outstanding	4 years 6 months 25 days
Weighted Average Remaining Contractual Life (Years), Vested and Exercisable	4 years 4 months 2 days
2017 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options, Outstanding | shares	205,725
Options, Granted | shares	850
Options, Exercised | shares	(5,000)
Options, Forfeited | shares	(1,502)
Options, Outstanding | shares	200,073
Options, Vested and exercisable | shares	91,589
Weighted Average Exercise Price, Outstanding | $ / shares	$ 17.45
Weighted Average Exercise Price, Granted | $ / shares	23.18
Weighted Average Exercise Price, Exercised | $ / shares	15
Weighted Average Exercise Price, Forfeited | $ / shares	18.22
Weighted Average Exercise Price, Outstanding | $ / shares	17.53
Weighted Average Exercise Price, Vested and exercisable | $ / shares	$ 16.04
Aggregate Intrinsic Value, Exercised | $	$ 33
Aggregate Intrinsic Value, Outstanding | $	804
Vested and exercisable at September 30, 2019 | $	$ 505
Weighted Average Remaining Contractual Life (Years), Outstanding	7 years 11 months 12 days
Weighted Average Remaining Contractual Life (Years), Vested and Exercisable	7 years 7 months 17 days

Stock-Based Compensation and _4

Stock-Based Compensation and Other Benefit Plans - Additional Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)shares	Sep. 30, 2019USD ($)shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option activity | shares	0	0
2008 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost	$ 317	$ 317
Compensation cost recognized weighted average remaining period		1 year 5 months 26 days
2017 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost	551	$ 551
Compensation cost recognized weighted average remaining period		3 years 1 month 17 days
2017 Stock Plan | Restricted Stock Unit Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost	$ 1,138	$ 1,138
Compensation cost recognized weighted average remaining period		4 years 5 months 8 days
Restricted stock units granted | shares		54,780
Fair value of restricted stock		$ 1,200

Stock-Based Compensation and _5

Stock-Based Compensation and Other Benefit Plans - Summary of Assumptions Used to Calculated Fair Value Utilizing Black-Scholes Pricing Model (Details) - 2017 Stock Plan	9 Months Ended
	Sep. 30, 2019$ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	23.30%
Expected dividend yield	0.00%
Expected term (years)	7 years 6 months
Risk-free interest rate, minimum	2.58%
Weighted average grant date fair value	$ 7.57

Stock-Based Compensation and _6

Stock-Based Compensation and Other Benefit Plans - Summary of Activity Related to Restricted Stock Units (Details) - 2017 Stock Plan - Restricted Stock Unit Awards	9 Months Ended
	Sep. 30, 2019$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Granted | shares	54,780
Shares, Outstanding, Ending balance | shares	54,780
Weighted-Average Grant Date Fair Value, Granted | $ / shares	$ 22.18
Weighted-Average Grant Date Fair Value, Outstanding | $ / shares	$ 22.18

Stock Based Compensation and Ot

Stock Based Compensation and Other Benefit Plans - Summary of Stock Based Compensation Expense (Details) - 2017 Stock Plan $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense related to stock-based compensation	$ 551
Weighted-average life over which expense is expected to be recognized (years)	3 years 1 month 17 days
Restricted Stock Unit Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 77
Unrecognized compensation expense related to stock-based compensation	$ 1,138
Weighted-average life over which expense is expected to be recognized (years)	4 years 5 months 8 days

Stock-Based Compensation and _7

Stock-Based Compensation and Other Benefit Plans - Summary of Activity for the Bank4Texas Warrants (Details) - Bank4Texas Warrants $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants, Outstanding | shares	10,710,000
Warrants, Exercised | shares	(838,000)
Warrants, Outstanding | shares	9,872,000
Warrants, Vested and exercisable | shares	9,872,000
Weighted Average Exercise Price, Outstanding | $ / shares	$ 10.50
Weighted Average Exercise Price, Exercised | $ / shares	10.50
Weighted Average Exercise Price, Outstanding | $ / shares	10.50
Weighted Average Exercise Price, Vested and exercisable | $ / shares	$ 10.50
Aggregate Intrinsic Value, Exercised | $	$ 9
Aggregate Intrinsic Value, Outstanding | $	109
Vested and exercisable at September 30, 2019 | $	$ 109
Weighted Average Remaining Contractual Life (Years), Outstanding	10 months 24 days
Vested and exercisable at September 30, 2019	10 months 24 days

Basic and Diluted Earnings Pe_3

Basic and Diluted Earnings Per Common Share - Schedule of Computation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income available to common stockholders	$ 5,330	$ 2,771	$ 14,967	$ 7,465
Weighted average number of common shares - basic	15,370,480	9,792,032	13,774,776	8,673,106
Effect of dilutive securities:
Employee stock-based compensation awards and warrants	400,769	568,269	424,150	421,585
Weighted average number of common shares - diluted	15,771,249	10,360,301	14,198,926	9,094,691
Basic earnings per common share	$ 0.35	$ 0.28	$ 1.09	$ 0.86
Diluted earnings per common share	$ 0.34	$ 0.27	$ 1.05	$ 0.82
Anti-dilutive warrants and stock options	119,078	7,246	148,578	78,490

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Effective tax rate	20.50%	20.60%	20.00%	20.30%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Unfunded Commitments | Commitments for Exposure to Credit Loss
Loss Contingencies [Line Items]
Reserve for unfunded commitments	$ 55	$ 48

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Unfunded Commitments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Supply Commitment [Line Items]
Unfunded commitments, Total	$ 238,349	$ 176,703
Commercial and Standby Letters of Credit
Supply Commitment [Line Items]
Unfunded commitments, Total	581	547
Unfunded Loan Commitments
Supply Commitment [Line Items]
Unfunded commitments, Total	$ 237,768	$ 176,156

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets:
Total available for sale, Fair Value	$ 166,669	$ 179,461
U.S. Treasury Securities
Assets:
Total available for sale, Fair Value	32,563
U.S. Government Agencies
Assets:
Total available for sale, Fair Value	4,141	1,934
State and Municipal Obligations
Assets:
Total available for sale, Fair Value	25,628	18,048
Residential Mortgage-backed Securities
Assets:
Total available for sale, Fair Value	98,645	153,974
Corporate Bonds and Other Debt Securities
Assets:
Total available for sale, Fair Value	5,692	5,505
Level 1
Assets:
Total available for sale, Fair Value	32,563
Level 2
Assets:
Total available for sale, Fair Value	134,106	179,461
Fair Value Measurements on Recurring Basis
Assets:
Total available for sale, Fair Value	170,217	183,426
Fair Value Measurements on Recurring Basis | U.S. Treasury Securities
Assets:
Total available for sale, Fair Value	32,563
Fair Value Measurements on Recurring Basis | U.S. Government Agencies
Assets:
Total available for sale, Fair Value	4,141	1,934
Fair Value Measurements on Recurring Basis | State and Municipal Obligations
Assets:
Total available for sale, Fair Value	25,628	18,048
Fair Value Measurements on Recurring Basis | Residential Mortgage-backed Securities
Assets:
Total available for sale, Fair Value	98,645	153,974
Fair Value Measurements on Recurring Basis | Corporate Bonds and Other Debt Securities
Assets:
Total available for sale, Fair Value	5,692	5,505
Fair Value Measurements on Recurring Basis | SBA Servicing Rights
Assets:
Total available for sale, Fair Value	3,548	3,965
Fair Value Measurements on Recurring Basis | Level 1
Assets:
Total available for sale, Fair Value	32,563
Fair Value Measurements on Recurring Basis | Level 1 | U.S. Treasury Securities
Assets:
Total available for sale, Fair Value	32,563
Fair Value Measurements on Recurring Basis | Level 2
Assets:
Total available for sale, Fair Value	134,106	179,461
Fair Value Measurements on Recurring Basis | Level 2 | U.S. Government Agencies
Assets:
Total available for sale, Fair Value	4,141	1,934
Fair Value Measurements on Recurring Basis | Level 2 | State and Municipal Obligations
Assets:
Total available for sale, Fair Value	25,628	18,048
Fair Value Measurements on Recurring Basis | Level 2 | Residential Mortgage-backed Securities
Assets:
Total available for sale, Fair Value	98,645	153,974
Fair Value Measurements on Recurring Basis | Level 2 | Corporate Bonds and Other Debt Securities
Assets:
Total available for sale, Fair Value	5,692	5,505
Fair Value Measurements on Recurring Basis | Level 3
Assets:
Total available for sale, Fair Value	3,548	3,965
Fair Value Measurements on Recurring Basis | Level 3 | SBA Servicing Rights
Assets:
Total available for sale, Fair Value	$ 3,548	$ 3,965

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)
Fair Value Disclosures [Abstract]
Fair value, assets, level 1 to level 2 transfers	$ 0	$ 0
Fair value, assets, level 2 to level 1 transfers	0	0
Fair value, assets, transfers into level 3	0	0
Fair value, assets, transfers out of level 3	$ 0	$ 0

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Assets Measured at Fair Value on Non-Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets (classified in Level 3):
Other real estate owned and repossessed assets	$ 1,042	$ 782
Level 3 | Fair Value Measurements on Non-Recurring Basis
Assets (classified in Level 3):
Impaired loans	2,346	2,696
Other real estate owned and repossessed assets	$ 1,042	$ 782

Fair Value Measurements - Signi

Fair Value Measurements - Significant Unobservable Inputs Used in Recurring and Non-Recurring Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other real estate owned	$ 1,042		$ 782
SBA servicing asset	3,548	$ 3,570	3,965	$ 3,561	$ 3,521	$ 3,411
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
SBA servicing asset	3,548		3,965
Level 3 | Fair Value Measurements on Non-Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impaired loans	2,346		2,696
Other real estate owned	$ 1,042		$ 782
Level 3 | Fair Value Measurements on Non-Recurring Basis | Weighted Average | Collateral Discounts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Range/Weighted Average	28.30%		19.20%
Level 3 | Fair Value Measurements on Non-Recurring Basis | Weighted Average | Collateral Discounts and Estimated Cost to Sell
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Range/Weighted Average	10.00%		10.00%
Level 3 | Fair Value Measurements on Non-Recurring Basis | Minimum | Collateral Discounts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Range/Weighted Average	0.00%		0.00%
Level 3 | Fair Value Measurements on Non-Recurring Basis | Maximum | Collateral Discounts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Range/Weighted Average	100.00%		100.00%
Level 3 | Fair Value Measurements on Non-Recurring Basis | Third Party Appraisals
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impaired loans	$ 2,346		$ 2,696
Other real estate owned	$ 1,042		$ 782
Level 3 | Fair Value Measurements on Recurring Basis | Weighted Average | Conditional Prepayment Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Range/Weighted Average	13.10%		11.80%
Level 3 | Fair Value Measurements on Recurring Basis | Weighted Average | Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Range/Weighted Average	11.00%		11.50%
Level 3 | Fair Value Measurements on Recurring Basis | Discounted Cash Flows
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
SBA servicing asset	$ 3,548		$ 3,965

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Financial Assets:
Total available for sale, Fair Value	$ 166,669		$ 179,461
SBA servicing rights	3,548	$ 3,570	3,965	$ 3,561	$ 3,521	$ 3,411
Level 1
Financial Assets:
Cash and cash equivalents	151,543		89,015
Time deposits in other banks	1,225
Total available for sale, Fair Value	32,563
Level 2
Financial Assets:
Total available for sale, Fair Value	134,106		179,461
FHLB and other bank stock	6,233		5,304
Loans held for sale	2,998		4,200
Accrued interest receivable	6,319		4,934
Bank-owned life insurance	15,521		7,401
Financial Liabilities:
Deposits	1,545,765		1,181,606
Accrued interest payable	1,002		702
Short-term borrowings			12,500
Long-term borrowings	60,003		76,603
Level 3
Financial Assets:
Loans, net	1,479,485		1,085,120
SBA servicing rights	3,548		3,965
Carrying Value
Financial Assets:
Cash and cash equivalents	151,543		89,015
Time deposits in other banks	1,225
Total available for sale, Fair Value	166,669		179,461
FHLB and other bank stock	6,233		5,304
Loans, net	1,481,037		1,096,522
Loans held for sale	2,784		3,945
Accrued interest receivable	6,319		4,934
Bank-owned life insurance	15,521		7,401
SBA servicing rights	3,548		3,965
Financial Liabilities:
Deposits	1,585,213		1,182,648
Accrued interest payable	1,002		702
Short-term borrowings			12,500
Long-term borrowings	74,165		77,784
Fair Value
Financial Assets:
Cash and cash equivalents	151,543		89,015
Time deposits in other banks	1,225
Total available for sale, Fair Value	166,669		179,461
FHLB and other bank stock	6,233		5,304
Loans, net	1,479,485		1,085,120
Loans held for sale	2,998		4,200
Accrued interest receivable	6,319		4,934
Bank-owned life insurance	15,521		7,401
SBA servicing rights	3,548		3,965
Financial Liabilities:
Deposits	1,545,765		1,181,606
Accrued interest payable	1,002		702
Short-term borrowings			12,500
Long-term borrowings	$ 60,003		$ 76,603

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - Chandler Bancorp, Inc. shares in Thousands, $ in Millions	Nov. 05, 2019USD ($)Branchshares	Sep. 30, 2019
Subsequent Event [Line Items]
Business acquisition date		Nov. 5, 2019
Subsequent Event
Subsequent Event [Line Items]
Business acquisition, shares issued | shares	2,100,000
Business acquisition, cash paid	$ 17.9
Business acquisition, total consideration	$ 62.5
Acquired ownership interest	100.00%
Subsequent Event | North East Texas
Subsequent Event [Line Items]
Number of additional branches | Branch	7