NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES	9 Months Ended
Sep. 30, 2017
Accounting Policies [Abstract]
NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES	NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES Nature of Operations-Allegiance Bancshares, Inc. (“Allegiance”) and its wholly-owned subsidiary, Allegiance Bank, (the “Bank”, and together with Allegiance, collectively referred to as the “Company”) provide commercial and retail loans and commercial banking services. The Company derives substantially all of its revenues and income from the operation of the Bank. The Company is focused on delivering a wide variety of relationship-driven commercial banking products and community-oriented services tailored to meet the needs of small to mid-sized businesses, professionals and individuals through its 16 offices and one loan production office in Houston, Texas and the surrounding region. The Bank provides its customers with a variety of banking services including checking accounts, savings accounts and certificates of deposit, and its primary lending products are commercial, personal, automobile, mortgage and home improvement loans. The Bank also offers safe deposit boxes, automated teller machines, drive-through services and 24-hour depository facilities. Basis of Presentation-The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial information and in accordance with guidance provided by the Securities and Exchange Commission. Accordingly, the condensed consolidated financial statements do not include all of the information and footnotes required by GAAP for complete financial statements. The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments considered necessary for a fair presentation of the financial position, results of operations and cash flows of the Company on a consolidated basis, and all such adjustments are of a normal recurring nature. Transactions with Allegiance have been eliminated. The condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and footnotes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016. Operating results for the three and nine months ended September 30, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017. Significant Accounting and Reporting Policies The Company’s significant accounting and reporting policies can be found in Note 1 of the Company’s annual financial statements included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016. New Accounting Standards Newly Issued But Not Yet Effective Accounting Standards ASU 2014-09 “Revenue from Contracts with Customers (Topic 606).” ASU 2014-09 supersedes the revenue recognition requirements in Revenue Recognition (Topic 605), and most industry-specific guidance throughout the Industry Topics of the Codification. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 is effective for the Company beginning on January 1, 2018, with retrospective application to each prior reporting period presented. The Company expects to adopt ASU 2014-09 in the first quarter 2018 using the modified retrospective approach, which includes presenting the cumulative effect of initial application along with supplementary disclosures. The Company is evaluating the full effect that ASU 2014-09 will have on its consolidated financial statements and related disclosures; however, adoption of the ASU is not expected to have a significant impact. The Company’s primary sources of revenues are derived from interest and dividends earned on loans, investment securities and other financial instruments that are not within the scope of ASU 2014-09. ASU 2016-02 “Leases (Topic 842)." 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, certain changes were made to align, where necessary, lessor accounting with the lessee accounting model and ASC Topic 606, “Revenue from Contracts with Customers.” ASU 2016-02 will be effective for the Company on January 1, 2019 and will require transition using a modified retrospective approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. Early application of this ASU is permitted for all entities. Adoption of ASU 2016-02 is not expected to have a material impact on the Company’s financial statements. The Company leases certain properties and equipment under operating leases that will result in the recognition of lease assets and lease liabilities on the Company’s balance sheet under the ASU. ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” Among other things, ASU 2016-13 requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better form their credit loss estimates. Many of the loss estimation techniques applied today will still be permitted, although the inputs to those techniques will change to reflect the full amount of expected credit losses. In addition, ASU 2016-13 amends the accounting for credit losses on available for sale debt securities and purchased financial assets with credit deterioration. ASU 2016-13 is effective for the Company on January 1, 2020 and must be applied using the modified retrospective approach with limited exceptions. Early adoption is permitted for fiscal years, and interim periods within those years, beginning after December 15, 2018. The Company is currently assessing the impact that the adoption of this standard will have on the financial condition and results of operations of the Company. The Company has formed a team that is assessing its data and system needs and is evaluating the impact of adoption. The Company expects to recognize a one-time cumulative effect adjustment to the allowance for loan losses as of the beginning of the first reporting period in which the new standard is effective, but has not yet determined the magnitude of any such one-time adjustment or the overall impact on the Company’s financial statements. ASU No. 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” ASU 2017-04 intends to simplify goodwill impairment testing by eliminating the second step of the analysis under which the implied fair value of goodwill is determined as if the reporting unit were being acquired in a business combination. The update instead requires entities to compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for any amount by which the carrying amount exceeds the reporting unit’s fair value, to the extent that the loss recognized does not exceed the amount of goodwill allocated to that reporting unit. ASU 2017-04 must be applied prospectively and is effective for the Company on January 1, 2020. Early adoption is permitted. The Company does not expect the new guidance to have a material impact on its financial condition or results of operation. ASU 2017-08 “Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20) - Premium Amortization on Purchased Callable Debt Securities.” ASU 2017-08 shortens the amortization period for certain callable debt securities held at a premium to require such premiums to be amortized to the earliest call date unless applicable guidance related to certain pools of securities is applied to consider estimated prepayments. Under prior guidance, entities were generally required to amortize premiums on individual, non-pooled callable debt securities as a yield adjustment over the contractual life of the security. ASU 2017-08 does not change the accounting for callable debt securities held at a discount. ASU 2017-08 will be effective for the Company on January 1, 2019, with early adoption permitted. The Company is currently evaluating the potential impact of ASU 2017-08 on its financial statements.

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES

Nature of Operations-Allegiance Bancshares, Inc. (“Allegiance”) and its wholly-owned subsidiary, Allegiance Bank, (the “Bank”, and together with Allegiance, collectively referred to as the “Company”) provide commercial and retail loans and commercial banking services. The Company derives substantially all of its revenues and income from the operation of the Bank. The Company is focused on delivering a wide variety of relationship-driven commercial banking products and community-oriented services tailored to meet the needs of small to mid-sized businesses, professionals and individuals through its 16 offices and one loan production office in Houston, Texas and the surrounding region. The Bank provides its customers with a variety of banking services including checking accounts, savings accounts and certificates of deposit, and its primary lending products are commercial, personal, automobile, mortgage and home improvement loans. The Bank also offers safe deposit boxes, automated teller machines, drive-through services and 24-hour depository facilities.

Basis of Presentation-The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial information and in accordance with guidance provided by the Securities and Exchange Commission. Accordingly, the condensed consolidated financial statements do not include all of the information and footnotes required by GAAP for complete financial statements. The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates.

In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments considered necessary for a fair presentation of the financial position, results of operations and cash flows of the Company on a consolidated basis, and all such adjustments are of a normal recurring nature. Transactions with Allegiance have been eliminated. The condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and footnotes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016. Operating results for the three and nine months ended September 30, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017.

Significant Accounting and Reporting Policies

The Company’s significant accounting and reporting policies can be found in Note 1 of the Company’s annual financial statements included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016.

New Accounting Standards

Newly Issued But Not Yet Effective Accounting Standards

ASU 2014-09 “Revenue from Contracts with Customers (Topic 606).” ASU 2014-09 supersedes the revenue recognition requirements in Revenue Recognition (Topic 605), and most industry-specific guidance throughout the Industry Topics of the Codification. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 is effective for the Company beginning on January 1, 2018, with retrospective application to each prior reporting period presented. The Company expects to adopt ASU 2014-09 in the first quarter 2018 using the modified retrospective approach, which includes presenting the cumulative effect of initial application along with supplementary disclosures. The Company is evaluating the full effect that ASU 2014-09 will have on its consolidated financial statements and related disclosures; however, adoption of the ASU is not expected to have a significant impact. The Company’s primary sources of revenues are derived from interest and dividends earned on loans, investment securities and other financial instruments that are not within the scope of ASU 2014-09.

ASU 2016-02 “Leases (Topic 842)." 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, certain changes were made to align, where necessary, lessor accounting with the lessee accounting model and ASC Topic 606, “Revenue from Contracts with Customers.” ASU 2016-02 will be effective for the Company on January 1, 2019 and will require transition using a modified retrospective approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. Early application of this ASU is permitted for all entities. Adoption of ASU 2016-02 is not expected to have a material impact on the Company’s financial statements. The Company leases certain properties and equipment under operating leases that will result in the recognition of lease assets and lease liabilities on the Company’s balance sheet under the ASU.

ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” Among other things, ASU 2016-13 requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better form their credit loss estimates. Many of the loss estimation techniques applied today will still be permitted, although the inputs to those techniques will change to reflect the full amount of expected credit losses. In addition, ASU 2016-13 amends the accounting for credit losses on available for sale debt securities and purchased financial assets with credit deterioration. ASU 2016-13 is effective for the Company on January 1, 2020 and must be applied using the modified retrospective approach with limited exceptions. Early adoption is permitted for fiscal years, and interim periods within those years, beginning after December 15, 2018. The Company is currently assessing the impact that the adoption of this standard will have on the financial condition and results of operations of the Company. The Company has formed a team that is assessing its data and system needs and is evaluating the impact of adoption. The Company expects to recognize a one-time cumulative effect adjustment to the allowance for loan losses as of the beginning of the first reporting period in which the new standard is effective, but has not yet determined the magnitude of any such one-time adjustment or the overall impact on the Company’s financial statements.

ASU No. 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” ASU 2017-04 intends to simplify goodwill impairment testing by eliminating the second step of the analysis under which the implied fair value of goodwill is determined as if the reporting unit were being acquired in a business combination. The update instead requires entities to compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for any amount by which the carrying amount exceeds the reporting unit’s fair value, to the extent that the loss recognized does not exceed the amount of goodwill allocated to that reporting unit. ASU 2017-04 must be applied prospectively and is effective for the Company on January 1, 2020. Early adoption is permitted. The Company does not expect the new guidance to have a material impact on its financial condition or results of operation.

ASU 2017-08 “Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20) - Premium Amortization on Purchased Callable Debt Securities.” ASU 2017-08 shortens the amortization period for certain callable debt securities held at a premium to require such premiums to be amortized to the earliest call date unless applicable guidance related to certain pools of securities is applied to consider estimated prepayments. Under prior guidance, entities were generally required to amortize premiums on individual, non-pooled callable debt securities as a yield adjustment over the contractual life of the security. ASU 2017-08 does not change the accounting for callable debt securities held at a discount. ASU 2017-08 will be effective for the Company on January 1, 2019, with early adoption permitted. The Company is currently evaluating the potential impact of ASU 2017-08 on its financial statements.