Spirit of Texas Bancshares (STXB) 10-Q 7 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 01, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	STXB
Entity Registrant Name	Spirit of Texas Bancshares, Inc.
Entity Central Index Key	1,499,453
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		9,812,481

CONSOLIDATED BALANCE SHEETS (Un

CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Assets:
Cash and due from banks		$ 18,212	$ 19,054
Interest-bearing deposits in other banks		25,926	38,895
Total cash and cash equivalents		44,138	57,949
Time deposits in other banks		245	245
Investment securities:
Available for sale securities, at fair value		33,449	37,243
Total investment securities		33,449	37,243
Loans held for sale		5,500	3,814
Loans:
Loans held for investment	[1]	954,074	869,119
Less: allowance for loan and lease losses		(6,156)	(5,652)
Loans, net		947,918	863,467
Premises and equipment, net		46,135	42,189
Accrued interest receivable		3,715	3,466
Other real estate owned and repossessed assets		289	21
Goodwill		4,485	4,485
Core deposit intangible		2,959	3,486
SBA servicing asset		3,561	3,411
Deferred tax asset, net		1,667	1,480
Bank-owned life insurance		483	479
Federal Home Loan Bank and other bank stock, at cost		4,861	4,812
Other assets		2,806	3,751
Total assets		1,102,211	1,030,298
Transaction accounts:
Noninterest-bearing		207,727	176,726
Interest-bearing		222,245	250,491
Total transaction accounts		429,972	427,217
Time deposits		442,638	408,151
Total deposits		872,610	835,368
Accrued interest payable		475	407
Short-term borrowings		10,000	15,000
Long-term borrowings		64,961	76,411
Other liabilities		3,272	3,973
Total liabilities		951,318	931,159
Commitments and contingencies (Note 11)
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; 9,812,481 and 7,280,183 shares issued and outstanding		127,541	82,615
Retained earnings		24,490	17,025
Accumulated other comprehensive income (loss)		(1,138)	(501)
Total stockholders' equity		150,893	99,139
Total liabilities and stockholders' equity		$ 1,102,211	$ 1,030,298
[1]	Balance includes $(3.6) million and $(3.4) million of deferred fees, cost, premium and discount as of September 30, 2018 and December 31, 2017, respectively.

CONSOLIDATED BALANCE SHEETS (_2

CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
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	9,812,481	7,280,183
Common stock, shares, outstanding	9,812,481	7,280,183

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest income:
Interest and fees on loans	$ 13,901	$ 11,842	$ 39,270	$ 33,515
Interest and dividends on investment securities	202	202	611	316
Other interest income	173	200	536	784
Total interest income	14,276	12,244	40,417	34,615
Interest expense:
Interest on deposits	2,197	1,684	5,869	4,913
Interest on FHLB advances and other borrowings	389	405	1,395	1,180
Total interest expense	2,586	2,089	7,264	6,093
Net interest income	11,690	10,155	33,153	28,522
Provision for loan losses	486	604	1,460	1,804
Net interest income after provision for loan losses	11,204	9,551	31,693	26,718
Noninterest income:
Service charges and fees	462	362	1,238	1,095
SBA loan servicing fees	529	207	1,701	1,378
Mortgage referral fees	160	158	524	531
Gain on sales of loans, net	1,369	1,392	3,884	4,710
Gain (loss) on sales of other assets		(70)	(25)	(47)
Other noninterest income	47	44	136	55
Total noninterest income	2,567	2,093	7,458	7,722
Noninterest expense:
Salaries and employee benefits	6,623	5,271	19,524	17,774
Occupancy and equipment expenses	1,279	1,239	3,736	3,742
Loan and other real estate related expenses	94	20	171	244
Professional services	624	410	1,249	1,159
Data processing and network	302	317	936	899
Regulatory assessments and insurance	266	221	787	689
Amortization of intangibles	176	176	527	527
Advertising	83	147	300	431
Marketing	115	118	354	399
Telephone expense	120	109	332	325
Other operating expenses	599	511	1,872	1,754
Total noninterest expense	10,281	8,539	29,788	27,943
Income before income tax expense	3,490	3,105	9,363	6,497
Income tax expense	719	1,103	1,898	2,267
Net income	$ 2,771	$ 2,002	$ 7,465	$ 4,230
Earnings per common share:
Basic	$ 0.28	$ 0.28	$ 0.86	$ 0.58
Diluted	$ 0.27	$ 0.26	$ 0.82	$ 0.56
Weighted average common shares outstanding:
Basic	9,792,032	7,279,178	8,673,106	7,218,147
Diluted	10,360,301	7,565,239	9,094,691	7,504,208

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 2,771	$ 2,002	$ 7,465	$ 4,230
Other comprehensive income (loss):
Unrealized net holding gains (losses) on investment securities available for sale, net of taxes of $16, $13, $169 and $79, respectively	(61)	(25)	(637)	(153)
Total other comprehensive income (loss)	(61)	(25)	(637)	(153)
Total comprehensive income	$ 2,710	$ 1,977	$ 6,828	$ 4,077

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Unrealized net holding gains (losses) on investment securities available for sale, tax	$ 16	$ 13	$ 169	$ 79
Reclassification adjustment for realized (gains) losses on investment securities available for sale included in net income, tax	$ 0	$ 0	$ 0	$ 0

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Preferred Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2016	$ 92,896	$ 78,871	$ 1,753	$ 12,272
Balance (in shares) at Dec. 31, 2016		7,069,527	170,236
Net income	4,230			4,230
Conversion of preferred stock		$ 1,753	$ (1,753)
Conversion of preferred stock (in shares)		170,236	(170,236)
Issuance of common stock (in shares)		1
Exercise of stock options and warrants	471	$ 471
Exercise of stock options and warrants (in shares)		40,419
Stock-based compensation	1,361	$ 1,361
Other comprehensive income (loss)	(153)				$ (153)
Balance at Sep. 30, 2017	98,805	$ 82,456		16,502	(153)
Balance (in shares) at Sep. 30, 2017		7,280,183
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	42,058	$ 42,058
Issuance of common stock (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

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows From Operating Activities:
Net income	$ 7,465	$ 4,230
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for loan losses	1,460	1,804
Depreciation and amortization	1,410	1,320
Net amortization (accretion) of premium (discount) on investment securities	234	140
Amortization of intangible assets	527	527
Accretion of discount on retained SBA loans	(672)	(1,219)
Deferred tax expense (benefit)	(18)	(683)
Originations of loans held for sale	(50,963)	(55,206)
Proceeds from loans held for sale	53,152	60,335
Net gains on sale of loans held for sale	(3,884)	(4,710)
(Gain) loss on sale of other real estate owned	11	(2)
Fair value adjustment on SBA servicing asset	805	770
Stock-based compensation	506	1,361
Increase in cash surrender value of BOLI	(4)	(2)
Net change in operating assets and liabilities:
Net change in accrued interest receivable	(249)	(452)
Net change in accrued interest payable	68	93
Net change in other assets	945	835
Net change in other liabilities	(701)	(971)
Net cash provided by (used in) operating activities	10,092	8,170
Cash Flows From Investing Activities:
Purchase of investment securities available for sale		(40,419)
Paydown and maturities of investment securities available for sale	2,754	1,219
Net purchase of FHLB and other bank stock	(49)	(47)
Proceeds from the sale of loans held for investment	1,451
Net change in loans	(87,937)	(91,800)
Proceeds from the sale of other real estate owned	22	499
Purchase of premises and equipment	(5,356)	(7,709)
Proceeds from the sale of premises and equipment		55
Net cash provided by (used in) investing activities	(89,115)	(138,202)
Cash Flows From Financing Activities:
Net change in deposits	37,242	28,705
Proceeds from long-term borrowings		16,762
Repayment of long-term borrowings	(11,450)	(4,956)
Proceeds from short-term borrowings	10,000	10,000
Repayment of short-term borrowings	(15,000)	(10,000)
Shares issued in offering, net	42,058
Exercise of stock options and warrants	2,362	471
Net cash provided by (used in) financing activities	65,212	40,982
Net Change in Cash and Cash Equivalents	(13,811)	(89,050)
Cash and Cash Equivalents at Beginning of Period	57,949	152,232
Cash and Cash Equivalents at End of Period	44,138	63,182
Supplemental Disclosures of Cash Flow Information:
Interest paid	5,802	4,820
Income taxes paid	2,850	1,695
Supplemental disclosure of noncash investing and financing activities:
Transfer of loans to other real estate owned and repossessed assets	$ 301	$ 450

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	NOTE 1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Nature of Operations Spirit of Texas Bancshares, Inc. (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 in Texas, which are primarily agricultural, light industrial and commercial areas. On March 16, 2017, the Company filed a Second Amended and Restated Certificate of Formation with the Texas Secretary of State to affect a reverse stock split of its outstanding common stock which became effective on March 16, 2017. As a result of the reverse stock split, every two shares of the Company’s issued and outstanding common stock were consolidated into one issued and outstanding share of common stock. The computations of all share and per share amounts in this Quarterly Report on Form 10-Q (this “Form 10-Q”) have been adjusted retroactively to reflect the reverse stock split. 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. 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, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018 and should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2017 included in our prospectus filed with the Securities and Exchange Commission (“SEC”) pursuant to Rule 424(b) of the Securities Act of 1933, as amended, on May 4, 2018, related to our initial public offering 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. Accounting Policies Recently Adopted and Pending Accounting Pronouncements Accounting Standards Update (ASU) 2018-15, “Intangibles – Goodwill and Other – Internal Use Software – Issued in August 2018, ASU No. 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The amendments of ASU 2018-15 are effective for public entities for interim and annual periods beginning after December 15, 2019 and for other entities for periods beginning after December 15, 2020. Management will early adopt ASU 2018-15 as of January 1, 2019 as early adoption is permitted and is currently evaluating the impact the ASU will have on the consolidated financial statements. 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 will adopt the provisions of this ASU removing fair value disclosure requirements as of December 31, 2018 as early adoption of the removal provisions is 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. Management is currently evaluating the effects the adoption of ASU 2018-09 will have on the consolidated financial statements, results of operations and cash flows. ASU 2018-07, “Compensation-Stock Compensation.” Issued in June 2018, ASU 2018-07 expands the scope of ASC 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The amendments also clarify that ASC 718 does not apply to share-based payments used to provide either financing to the issuer or awards granted in conjunction with selling goods or services to customers under a contract subject to ASC 606, Revenue from Contracts with Customers. The amendments of ASU 2018-07 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. Management will adopt ASU 2018-07 using the public company effective date as early adoption is permitted and is currently evaluating the impact the ASU will have on the consolidated financial statements. ASU 2017-08, “Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities.” Issued in March 2017, ASU 2017-08 amends the amortization period for certain purchased callable debt securities held at a premium. In particular, the amendments in ASU 2017-08 require the premium to be amortized to the earliest call date. The amendments do not, however, require an accounting change for securities held at a discount; instead, the discount continues to be amortized to maturity. Notably, the amendments in this ASU more closely align the amortization period of premiums and discounts to expectations incorporated in market pricing on the underlying securities. Securities within the scope of ASU 2017-08 are purchased debt securities that have explicit, non-contingent call features that are callable at fixed prices and on preset dates. The amendments of ASU 2017-08 become effective for public entities for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018 and for other entities for periods beginning after December 15, 2019. Management will adopt this ASU using the public company effective date as early adoption is permitted and is currently evaluating the impact this ASU will have on the consolidated financial statements; however, the adoption of ASU 2017-08 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 2017-01, “Business Combinations (Topic 805) - Clarifying the Definition of a Business.” Issued in January 2017, ASU 2017-01 clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses, which determines whether goodwill should be recorded or not. The amendments in ASU No. 2017-01 provide a screen to determine when a set of assets and activities (collectively, a “set”) is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. If, however, the screen is not met, then the amendments in ASU 2017-01 require that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output and remove the evaluation of whether a market participant could replace missing elements. The revised definition will result in more transactions being recorded as asset acquisitions or dispositions as opposed to business acquisitions or dispositions. The amendments of ASU 2017-01 are effective for public business entities for fiscal years beginning after December 15, 2017, and for private companies for fiscal years beginning after December 15, 2018. Management has elected to adopt this ASU using the private company effective date and is currently evaluating the impact this ASU will have on the consolidated financial statements; however, the adoption of ASU 2017-01 is not expected to have a material impact on the Company ’s consolidated financial statements. In October 2016, the FASB issued ASU No. 2016-16, "Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory." 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 are 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. Earlier application is permitted for interim and annual periods beginning after December 15, 2018. Management has elected to adopt this ASU using the 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, i n 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. Management will adopt these ASU’s using the public company effective date as early adoption is permitted and is currently evaluating the impact to the consolidated financial statements and related method of adoption, specifically, we are in the process of reviewing service contracts to determine if right-of-use assets exist. ASU 2014-09, “Revenue from Contracts with Customers (Topic 606).” Issued in May 2014, ASU 2014-09 will add FASB ASC Topic 606, “Revenue from Contracts with Customers,” and will supersede revenue recognition requirements in FASB ASC Topic 605, “Revenue Recognition,” as well as certain cost guidance in FASB ASC Topic 605-35, “Revenue Recognition – Construction-Type and Production-Type Contracts.” ASU 2014-09 provides a framework for revenue recognition that replaces the existing industry and transaction specific requirements under the existing standards. ASU 2014-09 requires an entity to apply a five-step model to determine when to recognize revenue and at what amount. The model specifies that revenue should be recognized when (or as) an entity transfers control of goods or services to a customer at the amount in which the entity expects to be entitled. Depending on whether certain criteria are met, revenue should be recognized either over time, in a manner that depicts the entity’s performance, or at a point in time, when control of the goods or services are transferred to the customer. ASU 2014-09 provides that an entity should apply the following steps: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. In addition, the existing requirements for the recognition of a gain or loss on the transfer of non-financial assets that are not in a contract with a customer are amended to be consistent with the guidance on recognition and measurement in ASU 2014-09. The amendments of ASU 2014-09 may be applied either retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying ASU 2014-09 recognized at the date of initial application. If the transition method of application is elected, the entity should also provide the additional disclosures in reporting periods that include the date of initial application of (1) the amount by which each financial statement line item is affected in the current reporting period, as compared to the guidance that was in effect before the change, and (2) an explanation of the reasons for significant changes. issued in August 2015, defers the effective date of ASU 2014-09 by one year. ASU 2015-14 provides that the amendments of ASU 2014-09 become effective for public business entities for fiscal years beginning after December 15, 2017, and for private companies for fiscal years beginning after December 15, 2018. All subsequently issued ASU’s which provide additional guidance and clarifications to various aspects of FASB ASC Topic 606 will become effective when the amendments of ASU 2014-09 become effective. These subsequently issued ASU’s include ASU 2016-08 ASU 2016-10 and ASU 2016-12 These amendments clarify the main provisions of ASU-2014-09 with respect to specific revenue types based upon implementation questions submitted. Specifically, revenue in which a third party satisfies a portion of the performance obligations, revenue from licensing activities, and the assessment of collectability, treatment of sales taxes, non-cash consideration, and contract modifications at transition. Management has elected to adopt this ASU using the private company effective date and has completed an analysis to determine which revenue streams are within the scope of ASU 2014-09 and the associated impact on those revenue streams. Management has determined that approximately 5% of the revenues earned by the Company are within the scope of ASU 2014-09, and, for most of the revenue streams within the scope of ASU 2014-09, the amendments do not change the timing or amount of revenue recognized. Management will adopt this ASU using the modified retrospective method of application and does not anticipate recording a cumulative adjustment for prior periods presented.

Investment Securities

Investment Securities	9 Months Ended
	Sep. 30, 2018
Investments Debt And Equity Securities [Abstract]
Investment Securities	NOTE 2. 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, 2018 Cost Gains Losses Value (Dollars in thousands) Available for sale: U.S. Government agencies $ 2,014 $ — $ 108 $ 1,906 Residential mortgage-backed securities 27,197 — 1,149 26,048 Corporate bonds and other debt securities 5,678 — 183 5,495 Total available for sale $ 34,889 $ — $ 1,440 $ 33,449 Amortized Unrealized Fair December 31, 2017 Cost Gains Losses Value (Dollars in thousands) Available for sale: U.S. Government agencies $ 2,010 $ — $ 61 $ 1,949 Residential mortgage-backed securities 30,156 — 527 29,629 Corporate bonds and other debt securities 5,711 — 46 5,665 Total available for sale $ 37,877 $ — $ 634 $ 37,243 There were no securities pledged at September 30, 2018 or December 31, 2017, respectively. The amortized cost and estimated fair value of securities available for sale, by contractual maturity, are as follows: Amortized Fair September 30, 2018 Cost Value (Dollars in thousands) Available for sale: Due in one year or less $ — $ — Due after one year through five years 4,117 3,998 Due after five years through ten years 3,098 2,954 Due after ten years 477 449 Residential mortgage-backed securities 27,197 26,048 Total available for sale $ 34,889 $ 33,449 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, 2018 Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss (Dollars in thousands) Available for sale: U.S. Government agencies $ — $ — $ 1,906 $ 108 $ 1,906 $ 108 Residential mortgage-backed securities 1,121 63 24,925 1,086 26,046 1,149 Corporate bonds and other debt securities 2,551 81 2,944 102 5,495 183 Total available for sale $ 3,672 $ 144 $ 29,775 $ 1,296 $ 33,447 $ 1,440 Less than 12 Months 12 Months or More Total December 31, 2017 Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss (Dollars in thousands) Available for sale: U.S. Government agencies $ 1,949 $ 61 $ — $ — $ 1,949 $ 61 Residential mortgage-backed securities 29,627 527 — — 29,627 527 Corporate bonds and other debt securities 5,665 46 — — 5,665 46 Total available for sale $ 37,241 $ 634 $ — $ — $ 37,241 $ 634 At September 30, 2018, the Company’s securities portfolio consisted of 50 securities, 49 of which were in an unrealized loss position. Six of the 49 securities in an unrealized loss position at September 30, 2018 were in an unrealized loss position for less 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, 2018. The following describes the basis under which the Company has evaluated OTTI: U.S. Government Agencies and Residential Mortgage-Backed Securities (“MBS”): The unrealized losses associated with 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 or nine months ended September 30, 2018 or 2017.

Loans, Net

Loans, Net	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Loans, Net	NOTE 3. LOANS, NET Loans consisted of the following at September 30, 2018 and December 31, 2017: September 30, 2018 December 31, 2017 (Dollars in thousands) Commercial and industrial loans (1) $ 159,776 $ 135,040 Real estate: 1-4 single family residential loans 244,633 232,510 Construction, land and development 155,778 139,470 Commercial real estate loans (including multifamily) 324,212 285,731 Consumer loans and leases 18,174 22,736 Municipal and other loans 51,501 53,632 Total loans held in portfolio (2) $ 954,074 $ 869,119 Allowance for loan losses (6,156 ) (5,652 ) Loans held in portfolio, net $ 947,918 $ 863,467 (1) Balance includes $75.9 million and $67.1 million of the unguaranteed portion of SBA loans as of September 30, 2018 and December 31, 2017, respectively. (2) Balance includes $(3.6) million and $(3.4) million of deferred fees, cost, premium and discount as of September 30, 2018 and December 31, 2017, respectively. At September 30, 2018 and December 31, 2017, the Company had pledged loans as collateral for FHLB advances of $376.4 million and $358.2 million, respectively. There were no recorded investments of consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings are in process as of September 30, 2018 and December 31, 2017. 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, 2018 and 2017, the Company sold approximately $19.0 million and $16.9 million, respectively, in loans to third parties. The loan sales resulted in realized gains of $1.4 million and $1.4 million for the three months ended September 30, 2018 and 2017, respectively. During the nine months ended September 30, 2018 and 2017, the Company sold approximately $49.0 million and $52.3 million, respectively, in loans to third parties. The loan sales resulted in realized gains of $3.9 million and $4.7 million for the nine months ended September 30, 2018 and 2017, respectively. During the second quarter of 2018, the Company sold a loan to one of its directors for $1.5 million. No gain or loss was recognized on this transaction. 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: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (Dollars in thousands) Principal outstanding, beginning of year $ 421 $ 516 $ 463 $ 9,036 Additions (reductions) of affiliations — — — (8,425 ) New loans made in current year — — — — Repayments (1) (19 ) (26 ) (61 ) (121 ) Principal outstanding, end of year $ 402 $ 490 $ 402 $ 490 (1) During the three months ended June 30, 2017 there was a reclassification of repayments to reductions of affiliations. There were no unfunded commitments to related parties at September 30, 2018 or December 31, 2017.

Allowance for Loan and Lease Lo

Allowance for Loan and Lease Losses	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Allowance for Loan and Lease Losses	NOTE 4. 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. During 2017, the Company refined its allowance for loan loss methodology based upon management’s judgment and applicable regulatory guidance. The calculation of reserves on loans collectively evaluated for impairment was altered to reflect five years of historical loss experience which more appropriately matches the weighted average life of loans in the portfolio. Additionally, the calculated historical loss experience is now allocated across the portfolio’s risk rates using a probability of default curve constructed from the Bank’s historical default data. Management also updated the qualitative component of the reserve on loans collectively evaluated for impairment to allow for a greater sensitivity to current trends. 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. As of September 30, 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. The following tables present information related to allowance for loan and lease losses for the periods presented: 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 Three Months Ended September 30, 2017 Beginning Balance Charge-offs Recoveries Provision Ending Balance (Dollars in thousands) Commercial and industrial loans $ 2,582 $ (15 ) $ — $ 20 $ 2,587 Real estate: 1-4 single family residential loans 732 — — 201 933 Construction, land and development loans 412 — — 103 515 Commercial real estate loans (including multifamily) 800 — — 255 1,055 Consumer loans and leases 204 (16 ) — (15 ) 173 Municipal and other loans 161 — — 40 201 Ending allowance balance $ 4,891 $ (31 ) $ — $ 604 $ 5,464 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 Allowance Rollforward Nine Months Ended September 30, 2017 Beginning Balance Charge-offs Recoveries Provision Ending Balance (Dollars in thousands) Commercial and industrial loans $ 2,347 $ (555 ) $ 2 $ 793 $ 2,587 Real estate: 1-4 single family residential loans 647 — — 286 933 Construction, land and development loans 364 — — 151 515 Commercial real estate loans (including multifamily) 667 (15 ) — 403 1,055 Consumer loans and leases 186 (129 ) — 116 173 Municipal and other loans 146 — — 55 201 Ending allowance balance $ 4,357 $ (699 ) $ 2 $ 1,804 $ 5,464 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: Accruing September 30, 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 $ 155,996 $ 1,246 $ 113 $ — $ 2,421 $ 159,776 Real estate: 1-4 single family residential loans 242,606 776 — 426 825 244,633 Construction, land and development 155,767 11 — — — 155,778 Commercial real estate loans (including multifamily) 324,212 — — — — 324,212 Consumer loans and leases 18,051 37 14 — 72 18,174 Municipal and other loans 51,501 — — — — 51,501 Total loans $ 948,133 $ 2,070 $ 127 $ 426 $ 3,318 $ 954,074 Accruing December 31, 2017 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 $ 132,775 $ 302 $ 3 $ 33 $ 1,927 $ 135,040 Real estate: 1-4 single family residential loans 230,738 637 — — 1,135 232,510 Construction, land and development 139,470 — — — — 139,470 Commercial real estate loans (including multifamily) 284,869 415 — — 447 285,731 Consumer loans and leases 22,538 98 47 — 53 22,736 Municipal and other loans 53,632 — — — — 53,632 Total loans $ 864,022 $ 1,452 $ 50 $ 33 $ 3,562 $ 869,119 There was one loan 90 days or more past due and still accruing at September 30, 2018 with a recorded investment of $426 thousand. There was one loan 90 days or more past due and still accruing at December 31, 2017 with a recorded investment of $33 thousand. At September 30, 2018, non-accrual loans that were 30 to 59 days past due were $355 thousand, non-accrual loans that were 60 to 89 days past due were $337 thousand, and non-accrual loans that were 90 days or more past due were $917 thousand. At December 31, 2017, non-accrual loans that were 30 to 59 days past due were $209 thousand, non-accrual loans that were 60 to 89 days past due were $57 thousand, and non-accrual loans that were 90 days or more past due were $427 thousand. 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 table summarizes the Company’s loans by key indicators of credit quality: September 30, 2018 Pass Special Mention Substandard Doubtful (Dollars in thousands) Commercial and industrial loans $ 151,088 $ 2,904 $ 5,597 $ 187 Real estate: 1-4 single family residential loans 240,081 — 4,552 — Construction, land and development 154,305 315 1,158 — Commercial real estate loans (including multifamily) 312,574 9,786 1,852 — Consumer loans and leases 18,046 — 128 — Municipal and other loans 51,501 — — — Total loans $ 927,595 $ 13,005 $ 13,287 $ 187 December 31, 2017 Pass Special Mention Substandard Doubtful (Dollars in thousands) Commercial and industrial loans $ 129,288 $ 2,331 $ 3,421 $ — Real estate: 1-4 single family residential loans 228,450 1,090 2,970 — Construction, land and development 137,760 1,403 307 — Commercial real estate loans (including multifamily) 276,096 5,877 3,758 — Consumer loans and leases 22,528 — 208 — Municipal and other loans 53,632 — — — Total loans $ 847,754 $ 10,701 $ 10,664 $ — 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 table shows the Company’s investment in loans disaggregated based on the method of evaluating impairment: Loans - Recorded Investment Allowance for Credit Loss September 30, 2018 Individually Evaluated for Impairment Collectively Evaluated for Impairment Individually Evaluated for Impairment Collectively Evaluated for Impairment (Dollars in thousands) Commercial and industrial loans $ 2,494 $ 157,282 $ 1,085 $ 3,606 Real estate: 1-4 single family residential loans 970 243,663 — 102 Construction, land and development — 155,778 — 451 Commercial real estate loans (including multifamily) — 324,212 — 728 Consumer loans and leases 72 18,102 24 158 Municipal and other loans — 51,501 — 2 Total loans $ 3,536 $ 950,538 $ 1,109 $ 5,047 Loans - Recorded Investment Allowance for Credit Loss December 31, 2017 Individually Evaluated for Impairment Collectively Evaluated for Impairment Individually Evaluated for Impairment Collectively Evaluated for Impairment (Dollars in thousands) Commercial and industrial loans $ 2,194 $ 132,846 $ 1,226 $ 1,820 Real estate: 1-4 single family residential loans 1,292 231,218 119 783 Construction, land and development — 139,470 — 441 Commercial real estate loans (including multifamily) 447 285,284 — 898 Consumer loans and leases 53 22,683 16 182 Municipal and other loans — 53,632 — 167 Total loans $ 3,986 $ 865,133 $ 1,361 $ 4,291 The following tables set forth certain information regarding the Company’s impaired loans that were evaluated for specific reserves: Impaired Loans - With Allowance Impaired Loans - With no Allowance September 30, 2018 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance (Dollars in thousands) Commercial and industrial loans $ 1,784 $ 6,159 $ 1,085 $ 710 $ 1,514 Real estate: 1-4 single family residential loans — — — 970 1,000 Construction, land and development — — — — — Commercial real estate loans (including multifamily) — — — — — Consumer loans and leases 54 55 24 18 18 Municipal and other loans — — — — — Total loans $ 1,838 $ 6,214 $ 1,109 $ 1,698 $ 2,532 Impaired Loans - With Allowance Impaired Loans - With no Allowance December 31, 2017 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance (Dollars in thousands) Commercial and industrial loans $ 1,811 $ 1,850 $ 1,226 $ 383 $ 386 Real estate: 1-4 single family residential loans 119 119 119 1,173 1,174 Construction, land and development — — — — — Commercial real estate loans (including multifamily) — — — 447 447 Consumer loans and leases 53 52 16 — — Municipal and other loans — — — — — Total loans $ 1,983 $ 2,021 $ 1,361 $ 2,003 $ 2,007 Three Months Ended September 30, 2018 2017 Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized (Dollars in thousands) Commercial and industrial loans $ 2,571 $ — $ 2,220 $ — Real estate: 1-4 single family residential loans 975 — 750 — Construction, land and development — — 312 — Commercial real estate loans (including multifamily) — — 1,997 — Consumer loans and leases 72 — 55 — Municipal and other loans — — — — Total loans $ 3,618 $ — $ 5,334 $ — Nine Months Ended September 30, 2018 2017 Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized (Dollars in thousands) Commercial and industrial loans $ 2,774 $ — $ 2,363 $ — Real estate: 1-4 single family residential loans 990 — 756 — Construction, land and development — — 316 — Commercial real estate loans (including multifamily) — — 1,983 — Consumer loans and leases 76 — 56 — Municipal and other loans — — — — Total loans $ 3,840 $ — $ 5,474 $ — Troubled Debt Restructurings: The following table provides a summary of troubled debt restructurings (“TDRs”) based upon delinquency status, all of which are considered impaired: September 30, 2018 December 31, 2017 Number of contracts Recorded Investment Number of contracts Recorded Investment (Dollars in thousands) Performing TDRs: Commercial and industrial loans 4 $ 73 5 $ 270 Real estate: 1-4 single family residential loans 2 145 — — Construction, land and development — — — — Commercial real estate loans (including multifamily) — — — — Consumer loans and leases — — — — Municipal and other loans — — — — Total performing TDRs 6 218 5 270 Nonperforming TDRs 5 470 10 651 Total TDRs 11 $ 688 15 $ 921 Allowance attributable to TDRs $ 113 $ 411 The following table summarizes TDRs and includes newly designated TDRs as well as modifications made to existing TDRs. 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, 2018 2017 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 — $ — $ — $ — 2 $ 38 $ 38 $ — 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, 2018 2017 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 7 $ 442 $ 442 $ 113 10 $ 465 $ 465 $ 126 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

Goodwill and Intangibles	9 Months Ended
	Sep. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangibles	NOTE 5. GOODWILL AND INTANGIBLES Goodwill and other intangible assets, which consist of core deposit intangibles, are summarized as follows: September 30, 2018 December 31, 2017 (Dollars in thousands) Goodwill $ 4,485 $ 4,485 Core deposit intangible 7,179 7,179 Total 11,664 11,664 Less: Accumulated amortization (4,220 ) (3,693 ) Total, net $ 7,444 $ 7,971 Amortization expense for core deposit intangibles for the nine months ended September 30, 2018 and 2017 totaled $527 thousand each. The estimated amount of amortization expense for core deposit intangible assets to be recognized over the next five fiscal years is as follows: Type of intangibles Remainder of 2018 2019 2020 2021 2022 2023 (Dollars in thousands) Core deposit intangible $ 176 $ 703 $ 703 $ 607 $ 371 $ 239

SBA Servicing Asset

SBA Servicing Asset	9 Months Ended
	Sep. 30, 2018
Transfers And Servicing Of Financial Assets [Abstract]
SBA Servicing Asset	NOTE 6. 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 loans serviced for others were $299.6 million and $275.2 million at September 30, 2018 and December 31, 2017, 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, 2018 and 2017: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (Dollars in thousands) Beginning balance $ 3,521 $ 3,515 $ 3,411 $ 3,132 Origination of servicing assets 376 367 955 1,132 Change in fair value: Due to run-off (254 ) (216 ) (707 ) (600 ) Due to market changes (82 ) (172 ) (98 ) (170 ) Ending balance $ 3,561 $ 3,494 $ 3,561 $ 3,494

Deposits

Deposits	9 Months Ended
	Sep. 30, 2018
Banking And Thrift [Abstract]
Deposits	NOTE 7. DEPOSITS The following table sets forth the Company’s deposits by category: September 30, 2018 December 31, 2017 (Dollars in thousands) Noninterest-bearing demand deposits $ 207,727 $ 176,726 Interest-bearing NOW accounts 7,865 7,318 Savings and money market accounts 214,380 243,173 Time deposits 442,638 408,151 Total deposits $ 872,610 $ 835,368 Time deposits $100,000 and greater $ 346,844 $ 314,102 Time deposits $250,000 and greater 90,056 82,816 Related party deposits (executive officers and directors) 12,983 13,914 The aggregate amount of overdraft demand deposits reclassified to loans was $15 thousand and $27 thousand at September 30, 2018 and December 31, 2017, respectively. The aggregate amount of maturities for time deposits for each of the five years following the latest balance sheet date totaled $267.8 million, $132.9 million, $22.7 million, $9.7 million and $9.5 million, respectively.

Stock-Based Compensation and Ot

Stock-Based Compensation and Other Benefit Plans	9 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation and Other Benefit Plans	NOTE 8. 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, 2018 1,415,350 $ 12.59 Granted — Exercised (192,928 ) $ 10.63 $ 2,114 Forfeited (1) (18,750 ) $ 13.33 $ 155 Expired — Outstanding at September 30, 2018 1,203,672 $ 12.89 $ 10,472 4.92 Exercisable at September 30, 2018 990,457 $ 12.58 $ 8,924 4.47 Vested at September 30, 2018 990,457 $ 12.58 $ 8,924 4.47 (1) Forfeitures are accounted for in the period they occur. The total unrecognized compensation cost of $764 thousand related to the 2008 Stock Plan for the share awards outstanding at September 30, 2018 will be recognized over a weighted average remaining period of 2.00 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, 2018 127,927 $ 15.00 Granted 83,340 20.69 $ 75 Exercised — Forfeited (1) — Expired — Outstanding at September 30, 2018 211,267 $ 17.25 $ 917 8.89 Exercisable at September 30, 2018 77,335 $ 15.00 $ 510 8.41 Vested at September 30, 2018 77,335 $ 15.00 $ 510 8.41 (1) Forfeitures are accounted for in the period they occur. The fair values of the stock options granted for the nine months ended September 30, 2018 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, 2018 Expected volatility 23 % Expected dividend yield 0.0 % Expected term (years) 7.5 Risk-free interest rate 2.36 - 2.87% Weighted average grant date fair value $ 6.77 The expected volatility is based on 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 $687 thousand related to the 2017 Stock Plan for the share awards outstanding at September 30, 2018 will be recognized over a weighted average remaining period of 4.31 years. Warrants Activity for the Spirit of Texas Bancshares, Inc. 2008 Warrants for the period indicated is summarized as follows: Spirit of Texas Bancshares, Inc. 2008 Warrants Warrants Weighted Average Exercise Price Aggregate Intrinsic Value (in thousands) Weighted Average Remaining Contractual Life (Years) Outstanding at January 1, 2018 105,000 $ 10.00 Granted — Exercised (45,000 ) $ 10.00 $ 522 Forfeited (1) — Expired — Outstanding at September 30, 2018 60,000 $ 10.00 $ 695 0.13 Exercisable at September 30, 2018 60,000 $ 10.00 $ 695 0.13 Vested at September 30, 2018 60,000 $ 10.00 $ 695 0.13 (1) Forfeitures are accounted for in the period they occur. There is no remaining expense to be recognized on the Spirit of Texas Bancshares, Inc. 2008 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, 2018 12,072 $ 10.50 Granted — Exercised (1,362 ) $ 10.50 $ 15 Forfeited (1) — Expired — Outstanding at September 30, 2018 10,710 $ 10.50 $ 119 1.90 Exercisable at September 30, 2018 10,710 $ 10.50 $ 119 1.90 Vested at September 30, 2018 10,710 $ 10.50 $ 119 1.90 (1) Forfeitures are accounted for in the period they occur. There was no activity during the nine months ended September 30, 2018 on the Oasis Warrants.

Basic and Diluted Earnings Per

Basic and Diluted Earnings Per Common Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Basic and Diluted Earnings Per Common Share	NOTE 9. BASIC AND DILUTED EARNINGS PER COMMON SHARE The following table presents the computation of basic and diluted EPS: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (Dollars in thousands, except per share data) Net income as reported $ 2,771 $ 2,002 $ 7,465 $ 4,230 Less: Participated securities share of undistributed earnings — — — 27 Net income available to common stockholders $ 2,771 $ 2,002 $ 7,465 $ 4,203 Weighted average number of common shares - basic 9,792,032 7,279,178 8,673,106 7,218,147 Effect of dilutive securities: Employee stock-based compensation awards and warrants 568,269 286,061 421,585 286,061 Weighted average number of common shares - diluted 10,360,301 7,565,239 9,094,691 7,504,208 Basic earnings per common share $ 0.28 $ 0.28 $ 0.86 $ 0.58 Diluted earnings per common share $ 0.27 $ 0.26 $ 0.82 $ 0.56 Anti-dilutive warrants and stock options 7,246 261,475 78,490 261,475

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	NOTE 10. INCOME TAXES The Company estimates both permanent and temporary differences in computing its interim tax provision. This effective tax rate is based on actual pre-tax income which approximates the effective tax rate based on forecasted annual pre-tax income, permanent tax differences and statutory tax rates. The effective tax rates for the three months ended September 30, 2018 and 2017 were 20.6% and 35.5%, respectively. The decrease in the effective tax rate for the three months ended September 30, 2018 was primarily due to the enactment of the 2017 Tax Cuts and Jobs Act (the “Tax Reform”) which reduced the corporate tax rate from 34.0% to 21.0%. The effective tax rates for the nine months ended September 30, 2018 and 2017 were 20.3% and 34.9%, respectively. The decrease in the effective tax rate for the nine months ended September 30, 2018 was primarily due to the enactment of the Tax Reform which reduced the corporate tax rate from 34.0% to 21.0%. The Company recorded an uncertain tax position at December 31, 2017 arising from a deduction taken on the 2016 federal return related to a request for change in accounting method. The total amount of the recorded uncertain tax position at December 31, 2017 was $903 thousand and is included in other liabilities. During the second quarter of 2018, the Company filed an amended return and the uncertain tax position was settled against the balance left on account with the IRS. The Company’s policy is to classify interest and penalties associated with income taxes within other expenses. The Company did not record interest and penalties associated with income taxes for the three or nine months ended September 30, 2018 or 2017.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE 11. 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, 2018 and December 31, 2017, the Company’s reserve for unfunded commitments totaled $40 thousand. 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: September 30, 2018 December 31, 2017 (Dollars in thousands) Unfunded loan commitments $ 142,657 $ 134,536 Commercial and standby letters of credit 85 91 Total $ 142,742 $ 134,627 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, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	NOTE 12. 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 table presents the assets and liabilities measured at fair value on a recurring basis: September 30, 2018 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: U.S. Government agencies $ — $ 1,906 $ — $ 1,906 Residential mortgage-backed securities — 26,048 — 26,048 Corporate bonds and other debt securities — 5,495 — 5,495 SBA servicing rights — — 3,561 3,561 Total $ — $ 33,449 $ 3,561 $ 37,010 December 31, 2017 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: U.S. Government agencies $ — $ 1,949 $ — $ 1,949 Residential mortgage-backed securities — 29,629 — 29,629 Corporate bonds and other debt securities — 5,665 — 5,665 SBA servicing rights — — 3,411 3,411 Total $ — $ 37,243 $ 3,411 $ 40,654 There were no transfers of financial assets between levels of the fair value hierarchy during the three or nine months ended September 30, 2018. 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, 2018 December 31, 2017 (Dollars in thousands) Assets (classified in Level 3): Impaired loans $ 1,913 $ 2,553 Other real estate and repossessed assets 289 21 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, 2018 Non-recurring: Impaired loans $ 1,913 Third party appraisals Collateral discounts 0.0% - 100.0% (84.7%) Other real estate owned 289 Third party appraisals Collateral discounts and estimated cost to sell 10.0 % Recurring: SBA servicing assets 3,561 Discounted cash flows Conditional prepayment rate 7.1 % Discount rate 14.3 % December 31, 2017 Non-recurring: Impaired loans $ 2,553 Third party appraisals Collateral discounts 0.0% - 100.0% (11.6%) Other real estate owned 21 Third party appraisals Collateral discounts and estimated cost to sell 10.0 % Recurring: SBA servicing assets 3,411 Discounted cash flows Conditional prepayment rate 6.7 % Discount rate 14.1 % 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: September 30, 2018 Carrying Value Fair Value Level 1 Level 2 Level 3 (Dollars in thousands) Financial Assets: Cash and cash equivalents $ 44,138 $ 44,138 $ 44,138 $ — $ — Time deposits in other banks 245 245 245 — — Available for sale securities 33,449 33,449 — 33,449 — FHLB and other bank stock 4,861 4,861 — 4,861 — Loans, net 947,918 942,987 — — 942,987 Loans held for sale 5,500 5,880 — 5,880 — Accrued interest receivable 3,715 3,715 — 3,715 — Bank-owned life insurance 483 483 — 483 — SBA servicing rights 3,561 3,561 — — 3,561 Financial Liabilities: Deposits $ 872,610 $ 843,522 $ — $ 843,522 $ — Accrued interest payable 475 475 — 475 — Short-term borrowings 10,000 10,000 — 10,000 — Long-term borrowings 64,961 63,233 — 63,233 — December 31, 2017 Carrying Value Fair Value Level 1 Level 2 Level 3 (Dollars in thousands) Financial Assets: Cash and cash equivalents $ 57,949 $ 57,949 $ 57,949 $ — $ — Time deposits in other banks 245 245 245 — — Available for sale securities 37,243 37,243 — 37,243 — FHLB and other bank stock 4,812 4,812 — 4,812 — Loans, net 863,467 870,749 — — 870,749 Loans held for sale 3,814 4,188 — 4,188 — Accrued interest receivable 3,466 3,466 — 3,466 — Bank-owned life insurance 479 479 — 479 — SBA servicing rights 3,411 3,411 — — 3,411 Financial Liabilities: Deposits $ 835,368 $ 840,645 $ — $ 840,645 $ — Accrued interest payable 407 407 — 407 — Short-term borrowings 15,000 15,000 — 15,000 — Long-term borrowings 76,411 67,310 — 67,310 — 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, 2018 and December 31, 2017, include cash and cash equivalents, time deposits in other banks and accrued interest receivable and payable. The following methods and assumptions were used to estimate the fair value of each class of financial instruments. FHLB and Other Bank Stock: FHLB and other bank stock can be liquidated only by redemption by the issuer, as there is no market for these securities. These securities are carried at par, which has historically represented the redemption price and is therefore considered to approximate fair value. Loans: Fair values for loans are based on a discounted cash flow methodology that considers various factors, including the type of loan and related collateral, classification status, fixed or variable interest rate, term of loan, whether or not the loan was amortizing and current discount rates. A basis point adjustment for the liquidity premium curve was added to the discounted cash flow methodology to obtain the estimated exit price of the portfolio. Loans are grouped together according to similar characteristics and are treated in the aggregate when applying various valuation techniques. The discount rates used for loans are based on current market rates for new originations of comparable credit risk and include adjustments for liquidity concerns. The allowance for loan and lease losses is considered a reasonable estimate of the required adjustment to fair value to reflect the impact of credit risk. This estimate is intended to represent an exit value as defined in ASC 820. Loans Held for Sale: SBA loans held for sale are carried at the lower of cost or fair value. The fair values of SBA loans held for sale is determined, when possible, using quoted secondary-market prices and are classified within Level 2 of the fair value hierarchy. If no such quoted prices exist, the fair value of a loan is determined using quoted prices for a similar loan or loans, adjusted for the specific attributes of that loan. Bank-owned Life Insurance: The Company holds life insurance policies on certain officers. The carrying value of these policies approximates fair value as it is based on the cash surrender value adjusted for other charges or amounts due that are probable at settlement. Deposits: The fair value of demand deposits, savings accounts and money market deposits is the amount payable on demand at the reporting date. The fair value of fixed-maturity certificates of deposit is estimated using discounted cash flow analysis and using the rates currently offered for deposits of similar remaining maturities. Short-term and Long-term Borrowings: The fair value of advances from the FHLB and other borrowings are estimated by discounting the future cash flows using the current rate at which similar borrowings with similar remaining maturities could be obtained.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations Spirit of Texas Bancshares, Inc. (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 in Texas, which are primarily agricultural, light industrial and commercial areas. On March 16, 2017, the Company filed a Second Amended and Restated Certificate of Formation with the Texas Secretary of State to affect a reverse stock split of its outstanding common stock which became effective on March 16, 2017. As a result of the reverse stock split, every two shares of the Company’s issued and outstanding common stock were consolidated into one issued and outstanding share of common stock. The computations of all share and per share amounts in this Quarterly Report on Form 10-Q (this “Form 10-Q”) have been adjusted retroactively to reflect the reverse stock split. 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.
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, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018 and should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2017 included in our prospectus filed with the Securities and Exchange Commission (“SEC”) pursuant to Rule 424(b) of the Securities Act of 1933, as amended, on May 4, 2018, related to our initial public offering 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.
Accounting Policies Recently Adopted and Pending Accounting Pronouncements	Accounting Policies Recently Adopted and Pending Accounting Pronouncements Accounting Standards Update (ASU) 2018-15, “Intangibles – Goodwill and Other – Internal Use Software – Issued in August 2018, ASU No. 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The amendments of ASU 2018-15 are effective for public entities for interim and annual periods beginning after December 15, 2019 and for other entities for periods beginning after December 15, 2020. Management will early adopt ASU 2018-15 as of January 1, 2019 as early adoption is permitted and is currently evaluating the impact the ASU will have on the consolidated financial statements. 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 will adopt the provisions of this ASU removing fair value disclosure requirements as of December 31, 2018 as early adoption of the removal provisions is 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. Management is currently evaluating the effects the adoption of ASU 2018-09 will have on the consolidated financial statements, results of operations and cash flows. ASU 2018-07, “Compensation-Stock Compensation.” Issued in June 2018, ASU 2018-07 expands the scope of ASC 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The amendments also clarify that ASC 718 does not apply to share-based payments used to provide either financing to the issuer or awards granted in conjunction with selling goods or services to customers under a contract subject to ASC 606, Revenue from Contracts with Customers. The amendments of ASU 2018-07 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. Management will adopt ASU 2018-07 using the public company effective date as early adoption is permitted and is currently evaluating the impact the ASU will have on the consolidated financial statements. ASU 2017-08, “Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities.” Issued in March 2017, ASU 2017-08 amends the amortization period for certain purchased callable debt securities held at a premium. In particular, the amendments in ASU 2017-08 require the premium to be amortized to the earliest call date. The amendments do not, however, require an accounting change for securities held at a discount; instead, the discount continues to be amortized to maturity. Notably, the amendments in this ASU more closely align the amortization period of premiums and discounts to expectations incorporated in market pricing on the underlying securities. Securities within the scope of ASU 2017-08 are purchased debt securities that have explicit, non-contingent call features that are callable at fixed prices and on preset dates. The amendments of ASU 2017-08 become effective for public entities for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018 and for other entities for periods beginning after December 15, 2019. Management will adopt this ASU using the public company effective date as early adoption is permitted and is currently evaluating the impact this ASU will have on the consolidated financial statements; however, the adoption of ASU 2017-08 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 2017-01, “Business Combinations (Topic 805) - Clarifying the Definition of a Business.” Issued in January 2017, ASU 2017-01 clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses, which determines whether goodwill should be recorded or not. The amendments in ASU No. 2017-01 provide a screen to determine when a set of assets and activities (collectively, a “set”) is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. If, however, the screen is not met, then the amendments in ASU 2017-01 require that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output and remove the evaluation of whether a market participant could replace missing elements. The revised definition will result in more transactions being recorded as asset acquisitions or dispositions as opposed to business acquisitions or dispositions. The amendments of ASU 2017-01 are effective for public business entities for fiscal years beginning after December 15, 2017, and for private companies for fiscal years beginning after December 15, 2018. Management has elected to adopt this ASU using the private company effective date and is currently evaluating the impact this ASU will have on the consolidated financial statements; however, the adoption of ASU 2017-01 is not expected to have a material impact on the Company ’s consolidated financial statements. In October 2016, the FASB issued ASU No. 2016-16, "Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory." 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 are 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. Earlier application is permitted for interim and annual periods beginning after December 15, 2018. Management has elected to adopt this ASU using the 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, i n 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. Management will adopt these ASU’s using the public company effective date as early adoption is permitted and is currently evaluating the impact to the consolidated financial statements and related method of adoption, specifically, we are in the process of reviewing service contracts to determine if right-of-use assets exist. ASU 2014-09, “Revenue from Contracts with Customers (Topic 606).” Issued in May 2014, ASU 2014-09 will add FASB ASC Topic 606, “Revenue from Contracts with Customers,” and will supersede revenue recognition requirements in FASB ASC Topic 605, “Revenue Recognition,” as well as certain cost guidance in FASB ASC Topic 605-35, “Revenue Recognition – Construction-Type and Production-Type Contracts.” ASU 2014-09 provides a framework for revenue recognition that replaces the existing industry and transaction specific requirements under the existing standards. ASU 2014-09 requires an entity to apply a five-step model to determine when to recognize revenue and at what amount. The model specifies that revenue should be recognized when (or as) an entity transfers control of goods or services to a customer at the amount in which the entity expects to be entitled. Depending on whether certain criteria are met, revenue should be recognized either over time, in a manner that depicts the entity’s performance, or at a point in time, when control of the goods or services are transferred to the customer. ASU 2014-09 provides that an entity should apply the following steps: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. In addition, the existing requirements for the recognition of a gain or loss on the transfer of non-financial assets that are not in a contract with a customer are amended to be consistent with the guidance on recognition and measurement in ASU 2014-09. The amendments of ASU 2014-09 may be applied either retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying ASU 2014-09 recognized at the date of initial application. If the transition method of application is elected, the entity should also provide the additional disclosures in reporting periods that include the date of initial application of (1) the amount by which each financial statement line item is affected in the current reporting period, as compared to the guidance that was in effect before the change, and (2) an explanation of the reasons for significant changes. issued in August 2015, defers the effective date of ASU 2014-09 by one year. ASU 2015-14 provides that the amendments of ASU 2014-09 become effective for public business entities for fiscal years beginning after December 15, 2017, and for private companies for fiscal years beginning after December 15, 2018. All subsequently issued ASU’s which provide additional guidance and clarifications to various aspects of FASB ASC Topic 606 will become effective when the amendments of ASU 2014-09 become effective. These subsequently issued ASU’s include ASU 2016-08 ASU 2016-10 and ASU 2016-12 These amendments clarify the main provisions of ASU-2014-09 with respect to specific revenue types based upon implementation questions submitted. Specifically, revenue in which a third party satisfies a portion of the performance obligations, revenue from licensing activities, and the assessment of collectability, treatment of sales taxes, non-cash consideration, and contract modifications at transition. Management has elected to adopt this ASU using the private company effective date and has completed an analysis to determine which revenue streams are within the scope of ASU 2014-09 and the associated impact on those revenue streams. Management has determined that approximately 5% of the revenues earned by the Company are within the scope of ASU 2014-09, and, for most of the revenue streams within the scope of ASU 2014-09, the amendments do not change the timing or amount of revenue recognized. Management will adopt this ASU using the modified retrospective method of application and does not anticipate recording a cumulative adjustment for prior periods presented.

Investment Securities (Tables)

Investment Securities (Tables)	9 Months Ended
	Sep. 30, 2018
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, 2018 Cost Gains Losses Value (Dollars in thousands) Available for sale: U.S. Government agencies $ 2,014 $ — $ 108 $ 1,906 Residential mortgage-backed securities 27,197 — 1,149 26,048 Corporate bonds and other debt securities 5,678 — 183 5,495 Total available for sale $ 34,889 $ — $ 1,440 $ 33,449 Amortized Unrealized Fair December 31, 2017 Cost Gains Losses Value (Dollars in thousands) Available for sale: U.S. Government agencies $ 2,010 $ — $ 61 $ 1,949 Residential mortgage-backed securities 30,156 — 527 29,629 Corporate bonds and other debt securities 5,711 — 46 5,665 Total available for sale $ 37,877 $ — $ 634 $ 37,243
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: Amortized Fair September 30, 2018 Cost Value (Dollars in thousands) Available for sale: Due in one year or less $ — $ — Due after one year through five years 4,117 3,998 Due after five years through ten years 3,098 2,954 Due after ten years 477 449 Residential mortgage-backed securities 27,197 26,048 Total available for sale $ 34,889 $ 33,449
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, 2018 Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss (Dollars in thousands) Available for sale: U.S. Government agencies $ — $ — $ 1,906 $ 108 $ 1,906 $ 108 Residential mortgage-backed securities 1,121 63 24,925 1,086 26,046 1,149 Corporate bonds and other debt securities 2,551 81 2,944 102 5,495 183 Total available for sale $ 3,672 $ 144 $ 29,775 $ 1,296 $ 33,447 $ 1,440 Less than 12 Months 12 Months or More Total December 31, 2017 Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss (Dollars in thousands) Available for sale: U.S. Government agencies $ 1,949 $ 61 $ — $ — $ 1,949 $ 61 Residential mortgage-backed securities 29,627 527 — — 29,627 527 Corporate bonds and other debt securities 5,665 46 — — 5,665 46 Total available for sale $ 37,241 $ 634 $ — $ — $ 37,241 $ 634

Loans, Net (Tables)

Loans, Net (Tables)	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Summary of Loans	Loans consisted of the following at September 30, 2018 and December 31, 2017: September 30, 2018 December 31, 2017 (Dollars in thousands) Commercial and industrial loans (1) $ 159,776 $ 135,040 Real estate: 1-4 single family residential loans 244,633 232,510 Construction, land and development 155,778 139,470 Commercial real estate loans (including multifamily) 324,212 285,731 Consumer loans and leases 18,174 22,736 Municipal and other loans 51,501 53,632 Total loans held in portfolio (2) $ 954,074 $ 869,119 Allowance for loan losses (6,156 ) (5,652 ) Loans held in portfolio, net $ 947,918 $ 863,467 (1) Balance includes $75.9 million and $67.1 million of the unguaranteed portion of SBA loans as of September 30, 2018 and December 31, 2017, respectively. (2) Balance includes $(3.6) million and $(3.4) million of deferred fees, cost, premium and discount as of September 30, 2018 and December 31, 2017, 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: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (Dollars in thousands) Principal outstanding, beginning of year $ 421 $ 516 $ 463 $ 9,036 Additions (reductions) of affiliations — — — (8,425 ) New loans made in current year — — — — Repayments (1) (19 ) (26 ) (61 ) (121 ) Principal outstanding, end of year $ 402 $ 490 $ 402 $ 490 (1) During the three months ended June 30, 2017 there was a reclassification of repayments to reductions of affiliations.

Allowance for Loan and Lease _2

Allowance for Loan and Lease Losses (Tables)	9 Months Ended
	Sep. 30, 2018
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, 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 Three Months Ended September 30, 2017 Beginning Balance Charge-offs Recoveries Provision Ending Balance (Dollars in thousands) Commercial and industrial loans $ 2,582 $ (15 ) $ — $ 20 $ 2,587 Real estate: 1-4 single family residential loans 732 — — 201 933 Construction, land and development loans 412 — — 103 515 Commercial real estate loans (including multifamily) 800 — — 255 1,055 Consumer loans and leases 204 (16 ) — (15 ) 173 Municipal and other loans 161 — — 40 201 Ending allowance balance $ 4,891 $ (31 ) $ — $ 604 $ 5,464 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 Allowance Rollforward Nine Months Ended September 30, 2017 Beginning Balance Charge-offs Recoveries Provision Ending Balance (Dollars in thousands) Commercial and industrial loans $ 2,347 $ (555 ) $ 2 $ 793 $ 2,587 Real estate: 1-4 single family residential loans 647 — — 286 933 Construction, land and development loans 364 — — 151 515 Commercial real estate loans (including multifamily) 667 (15 ) — 403 1,055 Consumer loans and leases 186 (129 ) — 116 173 Municipal and other loans 146 — — 55 201 Ending allowance balance $ 4,357 $ (699 ) $ 2 $ 1,804 $ 5,464
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: Accruing September 30, 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 $ 155,996 $ 1,246 $ 113 $ — $ 2,421 $ 159,776 Real estate: 1-4 single family residential loans 242,606 776 — 426 825 244,633 Construction, land and development 155,767 11 — — — 155,778 Commercial real estate loans (including multifamily) 324,212 — — — — 324,212 Consumer loans and leases 18,051 37 14 — 72 18,174 Municipal and other loans 51,501 — — — — 51,501 Total loans $ 948,133 $ 2,070 $ 127 $ 426 $ 3,318 $ 954,074 Accruing December 31, 2017 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 $ 132,775 $ 302 $ 3 $ 33 $ 1,927 $ 135,040 Real estate: 1-4 single family residential loans 230,738 637 — — 1,135 232,510 Construction, land and development 139,470 — — — — 139,470 Commercial real estate loans (including multifamily) 284,869 415 — — 447 285,731 Consumer loans and leases 22,538 98 47 — 53 22,736 Municipal and other loans 53,632 — — — — 53,632 Total loans $ 864,022 $ 1,452 $ 50 $ 33 $ 3,562 $ 869,119
Summary of Loans by Key Indicators of Credit Quality	The following table summarizes the Company’s loans by key indicators of credit quality: September 30, 2018 Pass Special Mention Substandard Doubtful (Dollars in thousands) Commercial and industrial loans $ 151,088 $ 2,904 $ 5,597 $ 187 Real estate: 1-4 single family residential loans 240,081 — 4,552 — Construction, land and development 154,305 315 1,158 — Commercial real estate loans (including multifamily) 312,574 9,786 1,852 — Consumer loans and leases 18,046 — 128 — Municipal and other loans 51,501 — — — Total loans $ 927,595 $ 13,005 $ 13,287 $ 187 December 31, 2017 Pass Special Mention Substandard Doubtful (Dollars in thousands) Commercial and industrial loans $ 129,288 $ 2,331 $ 3,421 $ — Real estate: 1-4 single family residential loans 228,450 1,090 2,970 — Construction, land and development 137,760 1,403 307 — Commercial real estate loans (including multifamily) 276,096 5,877 3,758 — Consumer loans and leases 22,528 — 208 — Municipal and other loans 53,632 — — — Total loans $ 847,754 $ 10,701 $ 10,664 $ —
Summary of Investment in Loans Disaggregated Based on Method of Evaluating Impairment	The following table shows the Company’s investment in loans disaggregated based on the method of evaluating impairment: Loans - Recorded Investment Allowance for Credit Loss September 30, 2018 Individually Evaluated for Impairment Collectively Evaluated for Impairment Individually Evaluated for Impairment Collectively Evaluated for Impairment (Dollars in thousands) Commercial and industrial loans $ 2,494 $ 157,282 $ 1,085 $ 3,606 Real estate: 1-4 single family residential loans 970 243,663 — 102 Construction, land and development — 155,778 — 451 Commercial real estate loans (including multifamily) — 324,212 — 728 Consumer loans and leases 72 18,102 24 158 Municipal and other loans — 51,501 — 2 Total loans $ 3,536 $ 950,538 $ 1,109 $ 5,047 Loans - Recorded Investment Allowance for Credit Loss December 31, 2017 Individually Evaluated for Impairment Collectively Evaluated for Impairment Individually Evaluated for Impairment Collectively Evaluated for Impairment (Dollars in thousands) Commercial and industrial loans $ 2,194 $ 132,846 $ 1,226 $ 1,820 Real estate: 1-4 single family residential loans 1,292 231,218 119 783 Construction, land and development — 139,470 — 441 Commercial real estate loans (including multifamily) 447 285,284 — 898 Consumer loans and leases 53 22,683 16 182 Municipal and other loans — 53,632 — 167 Total loans $ 3,986 $ 865,133 $ 1,361 $ 4,291
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: Impaired Loans - With Allowance Impaired Loans - With no Allowance September 30, 2018 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance (Dollars in thousands) Commercial and industrial loans $ 1,784 $ 6,159 $ 1,085 $ 710 $ 1,514 Real estate: 1-4 single family residential loans — — — 970 1,000 Construction, land and development — — — — — Commercial real estate loans (including multifamily) — — — — — Consumer loans and leases 54 55 24 18 18 Municipal and other loans — — — — — Total loans $ 1,838 $ 6,214 $ 1,109 $ 1,698 $ 2,532 Impaired Loans - With Allowance Impaired Loans - With no Allowance December 31, 2017 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance (Dollars in thousands) Commercial and industrial loans $ 1,811 $ 1,850 $ 1,226 $ 383 $ 386 Real estate: 1-4 single family residential loans 119 119 119 1,173 1,174 Construction, land and development — — — — — Commercial real estate loans (including multifamily) — — — 447 447 Consumer loans and leases 53 52 16 — — Municipal and other loans — — — — — Total loans $ 1,983 $ 2,021 $ 1,361 $ 2,003 $ 2,007 Three Months Ended September 30, 2018 2017 Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized (Dollars in thousands) Commercial and industrial loans $ 2,571 $ — $ 2,220 $ — Real estate: 1-4 single family residential loans 975 — 750 — Construction, land and development — — 312 — Commercial real estate loans (including multifamily) — — 1,997 — Consumer loans and leases 72 — 55 — Municipal and other loans — — — — Total loans $ 3,618 $ — $ 5,334 $ — Nine Months Ended September 30, 2018 2017 Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized (Dollars in thousands) Commercial and industrial loans $ 2,774 $ — $ 2,363 $ — Real estate: 1-4 single family residential loans 990 — 756 — Construction, land and development — — 316 — Commercial real estate loans (including multifamily) — — 1,983 — Consumer loans and leases 76 — 56 — Municipal and other loans — — — — Total loans $ 3,840 $ — $ 5,474 $ —
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: September 30, 2018 December 31, 2017 Number of contracts Recorded Investment Number of contracts Recorded Investment (Dollars in thousands) Performing TDRs: Commercial and industrial loans 4 $ 73 5 $ 270 Real estate: 1-4 single family residential loans 2 145 — — Construction, land and development — — — — Commercial real estate loans (including multifamily) — — — — Consumer loans and leases — — — — Municipal and other loans — — — — Total performing TDRs 6 218 5 270 Nonperforming TDRs 5 470 10 651 Total TDRs 11 $ 688 15 $ 921 Allowance attributable to TDRs $ 113 $ 411
Summary of TDRs Includes Newly Designated TDRs and Modifications to Existing TDRs	The following table summarizes TDRs and includes newly designated TDRs as well as modifications made to existing TDRs. 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, 2018 2017 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 — $ — $ — $ — 2 $ 38 $ 38 $ — 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, 2018 2017 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 7 $ 442 $ 442 $ 113 10 $ 465 $ 465 $ 126 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, 2018
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: September 30, 2018 December 31, 2017 (Dollars in thousands) Goodwill $ 4,485 $ 4,485 Core deposit intangible 7,179 7,179 Total 11,664 11,664 Less: Accumulated amortization (4,220 ) (3,693 ) Total, net $ 7,444 $ 7,971
Schedule of Estimated Amortization Expense for Intangible Assets	The estimated amount of amortization expense for core deposit intangible assets to be recognized over the next five fiscal years is as follows: Type of intangibles Remainder of 2018 2019 2020 2021 2022 2023 (Dollars in thousands) Core deposit intangible $ 176 $ 703 $ 703 $ 607 $ 371 $ 239

SBA Servicing Asset (Tables)

SBA Servicing Asset (Tables)	9 Months Ended
	Sep. 30, 2018
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, 2018 and 2017: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (Dollars in thousands) Beginning balance $ 3,521 $ 3,515 $ 3,411 $ 3,132 Origination of servicing assets 376 367 955 1,132 Change in fair value: Due to run-off (254 ) (216 ) (707 ) (600 ) Due to market changes (82 ) (172 ) (98 ) (170 ) Ending balance $ 3,561 $ 3,494 $ 3,561 $ 3,494

Deposits (Tables)

Deposits (Tables)	9 Months Ended
	Sep. 30, 2018
Banking And Thrift [Abstract]
Summary of Deposits by Category	The following table sets forth the Company’s deposits by category: September 30, 2018 December 31, 2017 (Dollars in thousands) Noninterest-bearing demand deposits $ 207,727 $ 176,726 Interest-bearing NOW accounts 7,865 7,318 Savings and money market accounts 214,380 243,173 Time deposits 442,638 408,151 Total deposits $ 872,610 $ 835,368 Time deposits $100,000 and greater $ 346,844 $ 314,102 Time deposits $250,000 and greater 90,056 82,816 Related party deposits (executive officers and directors) 12,983 13,914

Stock-Based Compensation and _2

Stock-Based Compensation and Other Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2018
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, 2018 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, 2018 Expected volatility 23 % Expected dividend yield 0.0 % Expected term (years) 7.5 Risk-free interest rate 2.36 - 2.87% Weighted average grant date fair value $ 6.77
2008 Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Summary of Warrant Activity	Activity for the Spirit of Texas Bancshares, Inc. 2008 Warrants for the period indicated is summarized as follows: Spirit of Texas Bancshares, Inc. 2008 Warrants Warrants Weighted Average Exercise Price Aggregate Intrinsic Value (in thousands) Weighted Average Remaining Contractual Life (Years) Outstanding at January 1, 2018 105,000 $ 10.00 Granted — Exercised (45,000 ) $ 10.00 $ 522 Forfeited (1) — Expired — Outstanding at September 30, 2018 60,000 $ 10.00 $ 695 0.13 Exercisable at September 30, 2018 60,000 $ 10.00 $ 695 0.13 Vested at September 30, 2018 60,000 $ 10.00 $ 695 0.13
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, 2018 12,072 $ 10.50 Granted — Exercised (1,362 ) $ 10.50 $ 15 Forfeited (1) — Expired — Outstanding at September 30, 2018 10,710 $ 10.50 $ 119 1.90 Exercisable at September 30, 2018 10,710 $ 10.50 $ 119 1.90 Vested at September 30, 2018 10,710 $ 10.50 $ 119 1.90
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, 2018 1,415,350 $ 12.59 Granted — Exercised (192,928 ) $ 10.63 $ 2,114 Forfeited (1) (18,750 ) $ 13.33 $ 155 Expired — Outstanding at September 30, 2018 1,203,672 $ 12.89 $ 10,472 4.92 Exercisable at September 30, 2018 990,457 $ 12.58 $ 8,924 4.47 Vested at September 30, 2018 990,457 $ 12.58 $ 8,924 4.47 (1) Forfeitures are accounted for in the period they occur.
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, 2018 127,927 $ 15.00 Granted 83,340 20.69 $ 75 Exercised — Forfeited (1) — Expired — Outstanding at September 30, 2018 211,267 $ 17.25 $ 917 8.89 Exercisable at September 30, 2018 77,335 $ 15.00 $ 510 8.41 Vested at September 30, 2018 77,335 $ 15.00 $ 510 8.41 (1) Forfeitures are accounted for in the period they occur.

Basic and Diluted Earnings Pe_2

Basic and Diluted Earnings Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted EPS	The following table presents the computation of basic and diluted EPS: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (Dollars in thousands, except per share data) Net income as reported $ 2,771 $ 2,002 $ 7,465 $ 4,230 Less: Participated securities share of undistributed earnings — — — 27 Net income available to common stockholders $ 2,771 $ 2,002 $ 7,465 $ 4,203 Weighted average number of common shares - basic 9,792,032 7,279,178 8,673,106 7,218,147 Effect of dilutive securities: Employee stock-based compensation awards and warrants 568,269 286,061 421,585 286,061 Weighted average number of common shares - diluted 10,360,301 7,565,239 9,094,691 7,504,208 Basic earnings per common share $ 0.28 $ 0.28 $ 0.86 $ 0.58 Diluted earnings per common share $ 0.27 $ 0.26 $ 0.82 $ 0.56 Anti-dilutive warrants and stock options 7,246 261,475 78,490 261,475

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Schedule of Unfunded Commitments	Unfunded commitments are as follows: September 30, 2018 December 31, 2017 (Dollars in thousands) Unfunded loan commitments $ 142,657 $ 134,536 Commercial and standby letters of credit 85 91 Total $ 142,742 $ 134,627

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents the assets and liabilities measured at fair value on a recurring basis: September 30, 2018 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: U.S. Government agencies $ — $ 1,906 $ — $ 1,906 Residential mortgage-backed securities — 26,048 — 26,048 Corporate bonds and other debt securities — 5,495 — 5,495 SBA servicing rights — — 3,561 3,561 Total $ — $ 33,449 $ 3,561 $ 37,010 December 31, 2017 Level 1 Level 2 Level 3 Total (Dollars in thousands) Assets: U.S. Government agencies $ — $ 1,949 $ — $ 1,949 Residential mortgage-backed securities — 29,629 — 29,629 Corporate bonds and other debt securities — 5,665 — 5,665 SBA servicing rights — — 3,411 3,411 Total $ — $ 37,243 $ 3,411 $ 40,654
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, 2018 December 31, 2017 (Dollars in thousands) Assets (classified in Level 3): Impaired loans $ 1,913 $ 2,553 Other real estate and repossessed assets 289 21
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, 2018 Non-recurring: Impaired loans $ 1,913 Third party appraisals Collateral discounts 0.0% - 100.0% (84.7%) Other real estate owned 289 Third party appraisals Collateral discounts and estimated cost to sell 10.0 % Recurring: SBA servicing assets 3,561 Discounted cash flows Conditional prepayment rate 7.1 % Discount rate 14.3 % December 31, 2017 Non-recurring: Impaired loans $ 2,553 Third party appraisals Collateral discounts 0.0% - 100.0% (11.6%) Other real estate owned 21 Third party appraisals Collateral discounts and estimated cost to sell 10.0 % Recurring: SBA servicing assets 3,411 Discounted cash flows Conditional prepayment rate 6.7 % Discount rate 14.1 %
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: September 30, 2018 Carrying Value Fair Value Level 1 Level 2 Level 3 (Dollars in thousands) Financial Assets: Cash and cash equivalents $ 44,138 $ 44,138 $ 44,138 $ — $ — Time deposits in other banks 245 245 245 — — Available for sale securities 33,449 33,449 — 33,449 — FHLB and other bank stock 4,861 4,861 — 4,861 — Loans, net 947,918 942,987 — — 942,987 Loans held for sale 5,500 5,880 — 5,880 — Accrued interest receivable 3,715 3,715 — 3,715 — Bank-owned life insurance 483 483 — 483 — SBA servicing rights 3,561 3,561 — — 3,561 Financial Liabilities: Deposits $ 872,610 $ 843,522 $ — $ 843,522 $ — Accrued interest payable 475 475 — 475 — Short-term borrowings 10,000 10,000 — 10,000 — Long-term borrowings 64,961 63,233 — 63,233 — December 31, 2017 Carrying Value Fair Value Level 1 Level 2 Level 3 (Dollars in thousands) Financial Assets: Cash and cash equivalents $ 57,949 $ 57,949 $ 57,949 $ — $ — Time deposits in other banks 245 245 245 — — Available for sale securities 37,243 37,243 — 37,243 — FHLB and other bank stock 4,812 4,812 — 4,812 — Loans, net 863,467 870,749 — — 870,749 Loans held for sale 3,814 4,188 — 4,188 — Accrued interest receivable 3,466 3,466 — 3,466 — Bank-owned life insurance 479 479 — 479 — SBA servicing rights 3,411 3,411 — — 3,411 Financial Liabilities: Deposits $ 835,368 $ 840,645 $ — $ 840,645 $ — Accrued interest payable 407 407 — 407 — Short-term borrowings 15,000 15,000 — 15,000 — Long-term borrowings 76,411 67,310 — 67,310 —

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, $ in Thousands	May 04, 2018USD ($)$ / sharesshares	Mar. 16, 2017	Sep. 30, 2018USD ($)shares	Sep. 30, 2017shares
Subsidiary Sale Of Stock [Line Items]
Reverse stock split, description			As a result of the reverse stock split, every two shares of the Company’s issued and outstanding common stock were consolidated into one issued and outstanding share of common stock. The computations of all share and per share amounts in this Quarterly Report on Form 10-Q (this “Form 10-Q”) have been adjusted retroactively to reflect the reverse stock split.
Reverse split of issued and outstanding common stock, ratio		0.5
Net proceeds from initial public offering | $			$ 42,058
Percentage of Revenue earned with in the scope of ASU201-09			5.00%
Common Stock
Subsidiary Sale Of Stock [Line Items]
Number of shares issued and sold | shares			2,300,000	1
Common Stock | Initial Public Offering
Subsidiary Sale Of Stock [Line Items]
Number of shares issued and sold | shares	2,300,000
Stock issued, price per share | $ / shares	$ 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 | shares	300,000

Investment Securities - Schedul

Investment Securities - Schedule of Fair Values of Securities Available for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Securities available for sale, Amortized Cost	$ 34,889	$ 37,877
Securities available for sale, Unrealized Losses	1,440	634
Available for sale securities, at fair value	33,449	37,243
U.S. Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Securities available for sale, Amortized Cost	2,014	2,010
Securities available for sale, Unrealized Losses	108	61
Available for sale securities, at fair value	1,906	1,949
Residential Mortgage-backed Securities
Schedule Of Available For Sale Securities [Line Items]
Securities available for sale, Amortized Cost	27,197	30,156
Securities available for sale, Unrealized Losses	1,149	527
Available for sale securities, at fair value	26,048	29,629
Corporate Bonds and Other Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Securities available for sale, Amortized Cost	5,678	5,711
Securities available for sale, Unrealized Losses	183	46
Available for sale securities, at fair value	$ 5,495	$ 5,665

Investment Securities - Additio

Investment Securities - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)Security	Sep. 30, 2017Security	Sep. 30, 2018USD ($)Security	Sep. 30, 2017Security	Dec. 31, 2017USD ($)
Investments Debt And Equity Securities [Abstract]
Available for sale securities pledged | $	$ 0		$ 0		$ 0
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	50		50
Available for sale, securities in unrealized loss positions, number of positions	49		49
Available for sale, securities in unrealized loss positions, number of positions, less than 12 months	6		6
Available for sale securities, gross realized gain (loss), excluding other than temporary impairments | $			$ 0
Number of securities sold	0	0	0	0

Investment Securities - Sched_2

Investment Securities - Schedule of Securities Available for Sale by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Available for sale:
Due after one year through five years, Amortized Cost	$ 4,117
Due after five years through ten years, Amortized Cost	3,098
Due after ten years, Amortized Cost	477
Total available for sale, Amortized Cost	34,889	$ 37,877
Available for sale:
Due after one year through five years. Fair Value	3,998
Due after five years through ten years. Fair Value	2,954
Due after ten years. Fair Value	449
Total available for sale, Fair Value	33,449	37,243
Residential Mortgage-backed Securities
Available for sale:
Total available for sale, Amortized Cost	27,197	30,156
Available for sale:
Total available for sale, Fair Value	$ 26,048	$ 29,629

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, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Investment Securities, Available for sale, Fair Value, Less than 12 Months	$ 3,672	$ 37,241
Investment Securities, Available for sale, Unrealized Loss, Less than 12 Months	144	634
Investment Securities, Available for sale, Fair Value, 12 Months or More	29,775
Investment Securities, Available for sale, Unrealized Loss, 12 Months or More	1,296
Investment Securities, Available for sale, Fair Value	33,447	37,241
Investment Securities, Available for sale, Unrealized Loss	1,440	634
U.S. Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Investment Securities, Available for sale, Fair Value, Less than 12 Months		1,949
Investment Securities, Available for sale, Unrealized Loss, Less than 12 Months		61
Investment Securities, Available for sale, Fair Value, 12 Months or More	1,906
Investment Securities, Available for sale, Unrealized Loss, 12 Months or More	108
Investment Securities, Available for sale, Fair Value	1,906	1,949
Investment Securities, Available for sale, Unrealized Loss	108	61
Residential Mortgage-backed Securities
Schedule Of Available For Sale Securities [Line Items]
Investment Securities, Available for sale, Fair Value, Less than 12 Months	1,121	29,627
Investment Securities, Available for sale, Unrealized Loss, Less than 12 Months	63	527
Investment Securities, Available for sale, Fair Value, 12 Months or More	24,925
Investment Securities, Available for sale, Unrealized Loss, 12 Months or More	1,086
Investment Securities, Available for sale, Fair Value	26,046	29,627
Investment Securities, Available for sale, Unrealized Loss	1,149	527
Corporate Bonds and Other Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Investment Securities, Available for sale, Fair Value, Less than 12 Months	2,551	5,665
Investment Securities, Available for sale, Unrealized Loss, Less than 12 Months	81	46
Investment Securities, Available for sale, Fair Value, 12 Months or More	2,944
Investment Securities, Available for sale, Unrealized Loss, 12 Months or More	102
Investment Securities, Available for sale, Fair Value	5,495	5,665
Investment Securities, Available for sale, Unrealized Loss	$ 183	$ 46

Loans, Net - Summary of Loans (

Loans, Net - Summary of Loans (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio	[1]	$ 954,074		$ 869,119
Allowance for loan losses		(6,156)	$ (6,015)	(5,652)	$ (5,464)	$ (4,891)	$ (4,357)
Loans, net		947,918		863,467
Commercial and Industrial Loans
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio	[2]	159,776		135,040
Consumer Loans and Leases
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio		18,174		22,736
Municipal and Other Loans
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio		51,501		53,632
Real Estate | 1-4 Single Family Residential Loans
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio		244,633		232,510
Real Estate | Construction, Land and Development
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio		155,778		139,470
Real Estate | Commercial Real Estate Loans (Including Multifamily)
Accounts Notes And Loans Receivable [Line Items]
Total loans held in portfolio		$ 324,212		$ 285,731
[1]	Balance includes $(3.6) million and $(3.4) million of deferred fees, cost, premium and discount as of September 30, 2018 and December 31, 2017, respectively.
[2]	Balance includes $75.9 million and $67.1 million of the unguaranteed portion of SBA loans as of September 30, 2018 and December 31, 2017, respectively.

Loans, Net - Summary of Loans_2

Loans, Net - Summary of Loans (Parenthetical) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Deferred fees, cost, premium and discount	$ (3.6)	$ (3.4)
SBA Loans
Accounts Notes And Loans Receivable [Line Items]
Unguaranteed portion of loans	$ 75.9	$ 67.1

Loans, Net - Additional Informa

Loans, Net - Additional Information (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Pledged loans, collateral for FHLB advances	$ 376,400,000			$ 376,400,000		$ 358,200,000
Unfunded commitments to related parties	142,742,000			142,742,000		134,627,000
Executive Officers and Directors
Accounts Notes And Loans Receivable [Line Items]
Unfunded commitments to related parties	0			0		0
Consumer Mortgage Loans
Accounts Notes And Loans Receivable [Line Items]
Recorded mortgage loans in process of foreclosure	0			0		$ 0
SBA Loans | Director
Accounts Notes And Loans Receivable [Line Items]
Servicing loans sold		$ 1,500,000
Realized gains on servicing loans sold		$ 0
SBA Loans | Third Party
Accounts Notes And Loans Receivable [Line Items]
Servicing loans sold	19,000,000		$ 16,900,000	49,000,000	$ 52,300,000
Realized gains on servicing loans sold	$ 1,400,000		$ 1,400,000	$ 3,900,000	$ 4,700,000

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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Receivables [Abstract]
Principal outstanding, beginning of year		$ 421	$ 516	$ 463	$ 9,036
Additions (reductions) of affiliations					(8,425)
Repayments	[1]	(19)	(26)	(61)	(121)
Principal outstanding, end of year		$ 402	$ 490	$ 402	$ 490
[1]	During the three months ended June 30, 2017 there was a reclassification of repayments to reductions of affiliations.

Allowance for Loan and Lease _3

Allowance for Loan and Lease Losses - Additional Information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)Loan	Dec. 31, 2017USD ($)Loan
Financing Receivable Recorded Investment Past Due [Line Items]
Amount of defaults Lookback period	5 years
Historical loss experience period	5 years
Recorded investment, 90 days past due and still accruing	$ 426	$ 33
Non-accrual loans, Past due	$ 3,318	$ 3,562
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	1
Non-accrual loans, Past due	$ 917	$ 427
Financing Receivables, 30 to 59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Non-accrual loans, Past due	355	209
Financing Receivables, 60 to 89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Non-accrual loans, Past due	$ 337	$ 57

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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	$ 6,015	$ 4,891	$ 5,652	$ 4,357
Charge-offs	(349)	(31)	(1,029)	(699)
Recoveries	4		73	2
Provision	486	604	1,460	1,804
Ending Balance	6,156	5,464	6,156	5,464
Commercial and Industrial Loans
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	4,886	2,582	3,046	2,347
Charge-offs	(275)	(15)	(920)	(555)
Recoveries	4		73	2
Provision	76	20	2,492	793
Ending Balance	4,691	2,587	4,691	2,587
Real Estate | 1-4 Single Family Residential Loans
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	318	732	902	647
Charge-offs			(5)
Provision	(216)	201	(795)	286
Ending Balance	102	933	102	933
Real Estate | Construction, Land and Development Loans
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	195	412	441	364
Provision	256	103	10	151
Ending Balance	451	515	451	515
Real Estate | Commercial Real Estate Loans (Including Multifamily)
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	233	800	898	667
Charge-offs				(15)
Provision	495	255	(170)	403
Ending Balance	728	1,055	728	1,055
Consumer Loans and Leases
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	346	204	198	186
Charge-offs	(74)	(16)	(104)	(129)
Provision	(90)	(15)	88	116
Ending Balance	182	173	182	173
Municipal and Other Loans
Loans And Leases Receivable Disclosure [Line Items]
Beginning Balance	37	161	167	146
Provision	(35)	40	(165)	55
Ending Balance	$ 2	$ 201	$ 2	$ 201

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, 2018	Dec. 31, 2017
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	$ 948,133	$ 864,022
Recorded investment, Non-accrual	3,318	3,562
Recorded investment, Total	954,074	869,119
Financing Receivables, 30 to 59 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	2,070	1,452
Recorded investment, Non-accrual	355	209
Financing Receivables, 60 to 89 Days Past Due
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Past due	127	50
Recorded investment, Non-accrual	337	57
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	426	33
Recorded investment, Non-accrual	917	427
Commercial and Industrial Loans
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	155,996	132,775
Recorded investment, Non-accrual	2,421	1,927
Recorded investment, Total	159,776	135,040
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	1,246	302
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	113	3
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		33
Real Estate | 1-4 Single Family Residential Loans
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	242,606	230,738
Recorded investment, Non-accrual	825	1,135
Recorded investment, Total	244,633	232,510
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	776	637
Real Estate | 1-4 Single Family Residential 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	426
Real Estate | Construction, Land and Development
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	155,767	139,470
Recorded investment, Total	155,778	139,470
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	324,212	284,869
Recorded investment, Non-accrual		447
Recorded investment, Total	324,212	285,731
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		415
Consumer Loans and Leases
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	18,051	22,538
Recorded investment, Non-accrual	72	53
Recorded investment, Total	18,174	22,736
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	37	98
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	14	47
Municipal and Other Loans
Financing Receivable Recorded Investment Past Due [Line Items]
Recorded investment, Accruing, Current	51,501	53,632
Recorded investment, Total	$ 51,501	$ 53,632

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, 2018	Dec. 31, 2017
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 954,074	$ 869,119
Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	927,595	847,754
Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	13,005	10,701
Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	13,287	10,664
Doubtful
Financing Receivable Recorded Investment [Line Items]
Total loans	187
Commercial and Industrial Loans
Financing Receivable Recorded Investment [Line Items]
Total loans	159,776	135,040
Commercial and Industrial Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	151,088	129,288
Commercial and Industrial Loans | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	2,904	2,331
Commercial and Industrial Loans | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	5,597	3,421
Commercial and Industrial Loans | Doubtful
Financing Receivable Recorded Investment [Line Items]
Total loans	187
Real Estate | 1-4 Single Family Residential Loans
Financing Receivable Recorded Investment [Line Items]
Total loans	244,633	232,510
Real Estate | 1-4 Single Family Residential Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	240,081	228,450
Real Estate | 1-4 Single Family Residential Loans | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans		1,090
Real Estate | 1-4 Single Family Residential Loans | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	4,552	2,970
Real Estate | Construction, Land and Development
Financing Receivable Recorded Investment [Line Items]
Total loans	155,778	139,470
Real Estate | Construction, Land and Development | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	154,305	137,760
Real Estate | Construction, Land and Development | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	315	1,403
Real Estate | Construction, Land and Development | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	1,158	307
Real Estate | Commercial Real Estate Loans (Including Multifamily)
Financing Receivable Recorded Investment [Line Items]
Total loans	324,212	285,731
Real Estate | Commercial Real Estate Loans (Including Multifamily) | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	312,574	276,096
Real Estate | Commercial Real Estate Loans (Including Multifamily) | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	9,786	5,877
Real Estate | Commercial Real Estate Loans (Including Multifamily) | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	1,852	3,758
Consumer Loans and Leases
Financing Receivable Recorded Investment [Line Items]
Total loans	18,174	22,736
Consumer Loans and Leases | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	18,046	22,528
Consumer Loans and Leases | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	128	208
Municipal and Other Loans
Financing Receivable Recorded Investment [Line Items]
Total loans	51,501	53,632
Municipal and Other Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 51,501	$ 53,632

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, 2018	Dec. 31, 2017
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Individually Evaluated for Impairment	$ 3,536	$ 3,986
Loans - Recorded Investment, Collectively Evaluated for Impairment	950,538	865,133
Allowance for Credit Loss, Individually Evaluated for Impairment	1,109	1,361
Allowance for Credit Loss, Collectively Evaluated for Impairment	5,047	4,291
Commercial and Industrial Loans
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Individually Evaluated for Impairment	2,494	2,194
Loans - Recorded Investment, Collectively Evaluated for Impairment	157,282	132,846
Allowance for Credit Loss, Individually Evaluated for Impairment	1,085	1,226
Allowance for Credit Loss, Collectively Evaluated for Impairment	3,606	1,820
Real Estate | 1-4 Single Family Residential Loans
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Individually Evaluated for Impairment	970	1,292
Loans - Recorded Investment, Collectively Evaluated for Impairment	243,663	231,218
Allowance for Credit Loss, Individually Evaluated for Impairment		119
Allowance for Credit Loss, Collectively Evaluated for Impairment	102	783
Real Estate | Construction, Land and Development
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Collectively Evaluated for Impairment	155,778	139,470
Allowance for Credit Loss, Collectively Evaluated for Impairment	451	441
Real Estate | Commercial Real Estate Loans (Including Multifamily)
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Individually Evaluated for Impairment		447
Loans - Recorded Investment, Collectively Evaluated for Impairment	324,212	285,284
Allowance for Credit Loss, Collectively Evaluated for Impairment	728	898
Consumer Loans and Leases
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Individually Evaluated for Impairment	72	53
Loans - Recorded Investment, Collectively Evaluated for Impairment	18,102	22,683
Allowance for Credit Loss, Individually Evaluated for Impairment	24	16
Allowance for Credit Loss, Collectively Evaluated for Impairment	158	182
Municipal and Other Loans
Financing Receivable Allowance For Credit Losses [Line Items]
Loans - Recorded Investment, Collectively Evaluated for Impairment	51,501	53,632
Allowance for Credit Loss, Collectively Evaluated for Impairment	$ 2	$ 167

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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Financing Receivable Impaired [Line Items]
Impaired Loans - With Allowance, Recorded Investment	$ 1,838		$ 1,838		$ 1,983
Impaired Loans - With Allowance, Unpaid Principal Balance	6,214		6,214		2,021
Impaired Loans - With Allowance, Related Allowance	1,109		1,109		1,361
Impaired Loans - With no Allowance, Recorded Investment	1,698		1,698		2,003
Impaired Loans - With no Allowance, Unpaid Principal Balance	2,532		2,532		2,007
Average Recorded Investment	3,618	$ 5,334	3,840	$ 5,474
Commercial and Industrial Loans
Financing Receivable Impaired [Line Items]
Impaired Loans - With Allowance, Recorded Investment	1,784		1,784		1,811
Impaired Loans - With Allowance, Unpaid Principal Balance	6,159		6,159		1,850
Impaired Loans - With Allowance, Related Allowance	1,085		1,085		1,226
Impaired Loans - With no Allowance, Recorded Investment	710		710		383
Impaired Loans - With no Allowance, Unpaid Principal Balance	1,514		1,514		386
Average Recorded Investment	2,571	2,220	2,774	2,363
Real Estate | 1-4 Single Family Residential Loans
Financing Receivable Impaired [Line Items]
Impaired Loans - With Allowance, Recorded Investment					119
Impaired Loans - With Allowance, Unpaid Principal Balance					119
Impaired Loans - With Allowance, Related Allowance					119
Impaired Loans - With no Allowance, Recorded Investment	970		970		1,173
Impaired Loans - With no Allowance, Unpaid Principal Balance	1,000		1,000		1,174
Average Recorded Investment	975	750	990	756
Real Estate | Construction, Land and Development
Financing Receivable Impaired [Line Items]
Average Recorded Investment		312		316
Real Estate | Commercial Real Estate Loans (Including Multifamily)
Financing Receivable Impaired [Line Items]
Impaired Loans - With no Allowance, Recorded Investment					447
Impaired Loans - With no Allowance, Unpaid Principal Balance					447
Average Recorded Investment		1,997		1,983
Consumer Loans and Leases
Financing Receivable Impaired [Line Items]
Impaired Loans - With Allowance, Recorded Investment	54		54		53
Impaired Loans - With Allowance, Unpaid Principal Balance	55		55		52
Impaired Loans - With Allowance, Related Allowance	24		24		$ 16
Impaired Loans - With no Allowance, Recorded Investment	18		18
Impaired Loans - With no Allowance, Unpaid Principal Balance	18		18
Average Recorded Investment	$ 72	$ 55	$ 76	$ 56

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, 2017Contract	Sep. 30, 2018USD ($)Contract	Sep. 30, 2017Contract	Dec. 31, 2017USD ($)Contract
Financing Receivable Modifications [Line Items]
Number of contracts		11		15
Recorded Investment | $		$ 688		$ 921
Allowance attributable to TDRs | $		$ 113		$ 411
Commercial and Industrial Loans
Financing Receivable Modifications [Line Items]
Number of contracts	2	7	10
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 | $		$ 218		$ 270
Performing TDRs | Commercial and Industrial Loans
Financing Receivable Modifications [Line Items]
Number of contracts		4		5
Recorded Investment | $		$ 73		$ 270
Performing TDRs | Real Estate | 1-4 Single Family Residential Loans
Financing Receivable Modifications [Line Items]
Number of contracts		2
Recorded Investment | $		$ 145
Nonperforming TDRs
Financing Receivable Modifications [Line Items]
Number of contracts		5		10
Recorded Investment | $		$ 470		$ 651

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, 2017USD ($)Contract	Sep. 30, 2018USD ($)Contract	Sep. 30, 2017USD ($)Contract	Dec. 31, 2017Contract
Financing Receivable Modifications [Line Items]
Number of contracts | Contract		11		15
Commercial and Industrial Loans
Financing Receivable Modifications [Line Items]
Number of contracts | Contract	2	7	10
Pre- Modification Outstanding Recorded Investment	$ 38	$ 442	$ 465
Post- Modification Outstanding Recorded Investment	$ 38	442	465
Related Allowance		$ 113	$ 126
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	Sep. 30, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill	$ 4,485	$ 4,485
Core deposit intangible	7,179	7,179
Total	11,664	11,664
Less: Accumulated amortization	(4,220)	(3,693)
Total, net	$ 7,444	$ 7,971

Goodwill and Intangibles - Addi

Goodwill and Intangibles - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 176	$ 176	$ 527	$ 527
Core Deposit Intangible
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets			$ 527	$ 527

Goodwill and Intangibles - Sc_2

Goodwill and Intangibles - Schedule of Estimated Amortization Expense for Intangible Assets (Details) - Core Deposit Intangible $ in Thousands	Sep. 30, 2018USD ($)
Finite Lived Intangible Assets [Line Items]
Remainder of 2018	$ 176
2,019	703
2,020	703
2,021	607
2,022	371
2,023	$ 239

SBA Servicing Asset - Additiona

SBA Servicing Asset - Additional Information (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Transfers And Servicing Of Financial Assets [Abstract]
Unpaid principal balances of loans serviced	$ 299.6	$ 275.2

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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Transfers And Servicing Of Financial Assets [Abstract]
Beginning balance	$ 3,521	$ 3,515	$ 3,411	$ 3,132
Origination of servicing assets	376	367	955	1,132
Change in fair value:
Due to run-off	(254)	(216)	(707)	(600)
Due to market changes	(82)	(172)	(98)	(170)
Ending balance	$ 3,561	$ 3,494	$ 3,561	$ 3,494

Deposits - Summary of Deposits

Deposits - Summary of Deposits by Category (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Banking And Thrift [Abstract]
Noninterest-bearing demand deposits	$ 207,727	$ 176,726
Interest-bearing NOW accounts	7,865	7,318
Savings and money market accounts	214,380	243,173
Time deposits	442,638	408,151
Total deposits	872,610	835,368
Time deposits $100,000 and greater	346,844	314,102
Time deposits $250,000 and greater	90,056	82,816
Related party deposits (executive officers and directors)	$ 12,983	$ 13,914

Deposits - Additional Informati

Deposits - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Banking And Thrift [Abstract]
Aggregate amount of overdraft demand deposits reclassified to loans	$ 15	$ 27
Aggregate amount of maturities for time deposits, period	5 years
Aggregate amount of maturities for time deposits, year one	$ 267,800
Aggregate amount of maturities for time deposits, year two	132,900
Aggregate amount of maturities for time deposits, year three	22,700
Aggregate amount of maturities for time deposits, year four	9,700
Aggregate amount of maturities for time deposits, year five	$ 9,500

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, 2018USD ($)$ / sharesshares
2008 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options, Outstanding | shares	1,415,350
Options, Exercised | shares	(192,928)
Options, Forfeited | shares	(18,750)	[1]
Options, Outstanding | shares	1,203,672
Options, Exercisable | shares	990,457
Options, Vested | shares	990,457
Weighted Average Exercise Price, Outstanding | $ / shares	$ 12.59
Weighted Average Exercise Price, Exercised | $ / shares	10.63
Weighted Average Exercise Price, Forfeited | $ / shares	13.33	[1]
Weighted Average Exercise Price, Outstanding | $ / shares	12.89
Weighted Average Exercise Price, Exercisable | $ / shares	12.58
Weighted Average Exercise Price, Vested | $ / shares	$ 12.58
Aggregate Intrinsic Value, Exercised | $	$ 2,114
Aggregate Intrinsic Value, Forfeited | $	155
Aggregate Intrinsic Value, Outstanding | $	10,472
Aggregate Intrinsic Value, Exercisable | $	8,924
Aggregate Intrinsic Value, Vested | $	$ 8,924
Weighted Average Remaining Contractual Life (Years), Outstanding	4 years 11 months 1 day
Weighted Average Remaining Contractual Life (Years), Exercisable	4 years 5 months 19 days
Weighted Average Remaining Contractual Life (Years), Vested	4 years 5 months 19 days
2017 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options, Outstanding | shares	127,927
Options, Granted | shares	83,340
Options, Outstanding | shares	211,267
Options, Exercisable | shares	77,335
Options, Vested | shares	77,335
Weighted Average Exercise Price, Outstanding | $ / shares	$ 15
Weighted Average Exercise Price, Granted | $ / shares	20.69
Weighted Average Exercise Price, Outstanding | $ / shares	17.25
Weighted Average Exercise Price, Exercisable | $ / shares	15
Weighted Average Exercise Price, Vested | $ / shares	$ 15
Aggregate Intrinsic Value, Granted | $	$ 75
Aggregate Intrinsic Value, Outstanding | $	917
Aggregate Intrinsic Value, Exercisable | $	510
Aggregate Intrinsic Value, Vested | $	$ 510
Weighted Average Remaining Contractual Life (Years), Outstanding	8 years 10 months 20 days
Weighted Average Remaining Contractual Life (Years), Exercisable	8 years 4 months 28 days
Weighted Average Remaining Contractual Life (Years), Vested	8 years 4 months 28 days
[1]	Forfeitures are accounted for in the period they occur.

Stock-Based Compensation and _4

Stock-Based Compensation and Other Benefit Plans - Additional Information (Details)	9 Months Ended
	Sep. 30, 2018USD ($)shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option activity | shares	0
2008 Warrant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining compensation expense to be recognized	$ 0
2008 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost	$ 764,000
Compensation cost recognized weighted average remaining period	2 years
2017 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost	$ 687,000
Compensation cost recognized weighted average remaining period	4 years 3 months 21 days

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, 2018$ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	23.00%
Expected dividend yield	0.00%
Expected term (years)	7 years 6 months
Risk-free interest rate, minimum	2.36%
Risk-free interest rate, maximum	2.87%
Weighted average grant date fair value	$ 6.77

Stock-Based Compensation and _6

Stock-Based Compensation and Other Benefit Plans - Summary of Activity for the Spirit of Texas Bancshares, Inc (Details) - 2008 Warrants $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants, Outstanding | shares	105,000
Warrants, Exercised | shares	(45,000)
Warrants, Outstanding | shares	60,000
Warrants, Exercisable | shares	60,000
Warrants, Vested | shares	60,000
Weighted Average Exercise Price, Outstanding | $ / shares	$ 10
Weighted Average Exercise Price, Exercised | $ / shares	10
Weighted Average Exercise Price, Outstanding | $ / shares	10
Weighted Average Exercise Price, Exercisable | $ / shares	10
Weighted Average Exercise Price, Vested | $ / shares	$ 10
Aggregate Intrinsic Value, Exercised | $	$ 522
Aggregate Intrinsic Value, Outstanding | $	695
Aggregate Intrinsic Value, Exercisable | $	695
Aggregate Intrinsic Value, Vested | $	$ 695
Weighted Average Remaining Contractual Life (Years), Outstanding	1 year 3 months 18 days
Weighted Average Remaining Contractual Life (Years), Exercisable	1 year 3 months 18 days
Weighted Average Remaining Contractual Life (Years), Vested	1 year 3 months 18 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, 2018USD ($)$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants, Outstanding | shares	12,072,000
Warrants, Exercised | shares	(1,362,000)
Warrants, Outstanding | shares	10,710,000
Warrants, Exercisable | shares	10,710,000
Warrants, Vested | shares	10,710,000
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, Exercisable | $ / shares	10.50
Weighted Average Exercise Price, Vested | $ / shares	$ 10.50
Aggregate Intrinsic Value, Exercised | $	$ 15
Aggregate Intrinsic Value, Outstanding | $	119
Aggregate Intrinsic Value, Exercisable | $	119
Aggregate Intrinsic Value, Vested | $	$ 119
Weighted Average Remaining Contractual Life (Years), Outstanding	1 year 10 months 24 days
Weighted Average Remaining Contractual Life (Years), Exercisable	1 year 10 months 24 days
Weighted Average Remaining Contractual Life (Years), Vested	1 year 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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income as reported	$ 2,771	$ 2,002	$ 7,465	$ 4,230
Less: Participated securities share of undistributed earnings				27
Net income available to common stockholders	$ 2,771	$ 2,002	$ 7,465	$ 4,203
Weighted average number of common shares - basic	9,792,032	7,279,178	8,673,106	7,218,147
Effect of dilutive securities:
Employee stock-based compensation awards and warrants	568,269	286,061	421,585	286,061
Weighted average number of common shares - diluted	10,360,301	7,565,239	9,094,691	7,504,208
Basic earnings per common share	$ 0.28	$ 0.28	$ 0.86	$ 0.58
Diluted earnings per common share	$ 0.27	$ 0.26	$ 0.82	$ 0.56
Anti-dilutive warrants and stock options	7,246	261,475	78,490	261,475

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Contingency [Line Items]
Effective tax rate	20.60%	35.50%	20.30%	34.90%
Effective statutory tax rate	21.00%		21.00%		34.00%
Interest and penalties associated with income taxes	$ 0	$ 0	$ 0	$ 0
Other Liabilities
Income Tax Contingency [Line Items]
Uncertain tax position					$ 903,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Unfunded Commitments | Commitments for Exposure to Credit Loss
Loss Contingencies [Line Items]
Reserve for unfunded commitments	$ 40	$ 40

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Unfunded Commitments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Supply Commitment [Line Items]
Unfunded commitments, Total	$ 142,742	$ 134,627
Commercial and Standby Letters of Credit
Supply Commitment [Line Items]
Unfunded commitments, Total	85	91
Unfunded Loan Commitments
Supply Commitment [Line Items]
Unfunded commitments, Total	$ 142,657	$ 134,536

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, 2018	Dec. 31, 2017
Assets:
Total available for sale, Fair Value	$ 33,449	$ 37,243
U.S. Government Agencies
Assets:
Total available for sale, Fair Value	1,906	1,949
Residential Mortgage-backed Securities
Assets:
Total available for sale, Fair Value	26,048	29,629
Corporate Bonds and Other Debt Securities
Assets:
Total available for sale, Fair Value	5,495	5,665
Level 2
Assets:
Total available for sale, Fair Value	33,449	37,243
Fair Value Measurements on Recurring Basis
Assets:
Total available for sale, Fair Value	37,010	40,654
Fair Value Measurements on Recurring Basis | U.S. Government Agencies
Assets:
Total available for sale, Fair Value	1,906	1,949
Fair Value Measurements on Recurring Basis | Residential Mortgage-backed Securities
Assets:
Total available for sale, Fair Value	26,048	29,629
Fair Value Measurements on Recurring Basis | Corporate Bonds and Other Debt Securities
Assets:
Total available for sale, Fair Value	5,495	5,665
Fair Value Measurements on Recurring Basis | SBA Servicing Rights
Assets:
Total available for sale, Fair Value	3,561	3,411
Fair Value Measurements on Recurring Basis | Level 2
Assets:
Total available for sale, Fair Value	33,449	37,243
Fair Value Measurements on Recurring Basis | Level 2 | U.S. Government Agencies
Assets:
Total available for sale, Fair Value	1,906	1,949
Fair Value Measurements on Recurring Basis | Level 2 | Residential Mortgage-backed Securities
Assets:
Total available for sale, Fair Value	26,048	29,629
Fair Value Measurements on Recurring Basis | Level 2 | Corporate Bonds and Other Debt Securities
Assets:
Total available for sale, Fair Value	5,495	5,665
Fair Value Measurements on Recurring Basis | Level 3
Assets:
Total available for sale, Fair Value	3,561	3,411
Fair Value Measurements on Recurring Basis | Level 3 | SBA Servicing Rights
Assets:
Total available for sale, Fair Value	$ 3,561	$ 3,411

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)
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, 2018	Dec. 31, 2017
Assets (classified in Level 3):
Other real estate owned and repossessed assets	$ 289	$ 21
Fair Value Measurements on Non-Recurring Basis | Level 3
Assets (classified in Level 3):
Impaired loans	1,913	2,553
Other real estate owned and repossessed assets	$ 289	$ 21

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, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other real estate owned	$ 289		$ 21
SBA servicing asset	3,561	$ 3,521	3,411	$ 3,494	$ 3,515	$ 3,132
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
SBA servicing asset	3,561		3,411
Level 3 | Fair Value Measurements on Non-Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impaired loans	1,913		2,553
Other real estate owned	$ 289		$ 21
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	84.70%		11.60%
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 Recurring Basis | Weighted Average | Conditional Prepayment Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Range/Weighted Average	7.10%		6.70%
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	14.30%		14.10%
Level 3 | Third Party Appraisals | Fair Value Measurements on Non-Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impaired loans	$ 1,913		$ 2,553
Other real estate owned	289		21
Level 3 | Discounted Cash Flows | Fair Value Measurements on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
SBA servicing asset	$ 3,561		$ 3,411

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Financial Assets:
Total available for sale, Fair Value	$ 33,449		$ 37,243
SBA servicing rights	3,561	$ 3,521	3,411	$ 3,494	$ 3,515	$ 3,132
Level 1
Financial Assets:
Cash and cash equivalents	44,138		57,949
Time deposits in other banks	245		245
Level 2
Financial Assets:
Total available for sale, Fair Value	33,449		37,243
FHLB and other bank stock	4,861		4,812
Loans held for sale	5,880		4,188
Accrued interest receivable	3,715		3,466
Bank-owned life insurance	483		479
Financial Liabilities:
Deposits	843,522		840,645
Accrued interest payable	475		407
Short-term borrowings	10,000		15,000
Long-term borrowings	63,233		67,310
Level 3
Financial Assets:
Loans, net	942,987		870,749
SBA servicing rights	3,561		3,411
Carrying Value
Financial Assets:
Cash and cash equivalents	44,138		57,949
Time deposits in other banks	245		245
Total available for sale, Fair Value	33,449		37,243
FHLB and other bank stock	4,861		4,812
Loans, net	947,918		863,467
Loans held for sale	5,500		3,814
Accrued interest receivable	3,715		3,466
Bank-owned life insurance	483		479
SBA servicing rights	3,561		3,411
Financial Liabilities:
Deposits	872,610		835,368
Accrued interest payable	475		407
Short-term borrowings	10,000		15,000
Long-term borrowings	64,961		76,411
Fair Value
Financial Assets:
Cash and cash equivalents	44,138		57,949
Time deposits in other banks	245		245
Total available for sale, Fair Value	33,449		37,243
FHLB and other bank stock	4,861		4,812
Loans, net	942,987		870,749
Loans held for sale	5,880		4,188
Accrued interest receivable	3,715		3,466
Bank-owned life insurance	483		479
SBA servicing rights	3,561		3,411
Financial Liabilities:
Deposits	843,522		840,645
Accrued interest payable	475		407
Short-term borrowings	10,000		15,000
Long-term borrowings	$ 63,233		$ 67,310