Preparation of Interim Financial Statements	3 Months Ended
Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Preparation of Interim Financial Statements	PREPARATION OF INTERIM FINANCIAL STATEMENTS Organizational Structure Simmons First National Corporation (the “Company”) is a publicly traded financial holding company that trades on the NASDAQ Market (“NASDAQ”) under the ticker symbol “SFNC” and the parent company of Simmons Bank, an Arkansas state-chartered bank that began as a community bank in 1903. Simmons Bank is the parent company of Simmons First Investment Group, Inc. (a registered broker-dealer), Simmons First Insurance Services, Inc. (an insurance agency), and Simmons First Insurance Services of TN, LLC (an insurance agency). Description of Business The Company is headquartered in Pine Bluff, Arkansas and conducts banking operations in communities throughout Arkansas, Colorado, Kansas, Missouri, Oklahoma, Tennessee and Texas. The Company, through its subsidiaries, offers consumer, real estate and commercial loans, checking, savings and time deposits from 191 financial centers conveniently located throughout its market areas. Additionally, the Company offers specialized products and services such as credit cards, trust and fiduciary services, investments, agricultural finance lending, equipment lending, insurance and small business administration (“SBA”) lending. Basis of Presentation The accompanying unaudited consolidated financial statements have been prepared based upon Securities and Exchange Commission (“SEC”) rules that permit reduced disclosures for interim periods. Certain information and footnote disclosures have been condensed or omitted in accordance with those rules and regulations. The accompanying consolidated balance sheet as of December 31, 2018, was derived from audited financial statements. In the opinion of management, these financial statements reflect all adjustments that are necessary for a fair presentation of interim results of operations, including normal recurring accruals. Significant intercompany accounts and transactions have been eliminated in consolidation. The results for the interim periods are not necessarily indicative of results for the full year. For a more complete discussion of significant accounting policies and certain other information, this report should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018, which was filed with the SEC on February 27, 2019. The preparation of financial statements, in accordance with accounting principles generally accepted in the United States (“US GAAP”), requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, income items and expenses and disclosure of contingent assets and liabilities. The estimates and assumptions used in the accompanying consolidated financial statements are based upon management’s evaluation of the relevant facts and circumstances as of the date of the consolidated financial statements and actual results may differ from these estimates. Such estimates include, but are not limited to, the Company’s allowance for loan losses. Certain prior year amounts have been reclassified to conform to the current year financial statement presentation. These changes and reclassifications did not impact previously reported net income or comprehensive income. Recently Adopted Accounting Standards Cloud Computing Arrangements – In August 2018, the FASB issued ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract (“ASU 2018-15”), that amends the definition of a hosting arrangement and requires a customer in a hosting arrangement that is a service contract to capitalize certain implementation costs as if the arrangement was an internal-use software project. The internal-use software guidance states that only qualifying costs incurred during the application development stage can be capitalized. The effective date is for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted. Entities have the option to apply the guidance prospectively to all implementation costs incurred after the date of adoption or retrospectively in accordance with the applicable guidance. At the time of adoption, entities will be required to disclose the nature of its hosting arrangements that are service contracts and provide disclosures as if the deferred implementation costs were a separate, major depreciable asset class. The Company early adopted ASU 2018-15 in the first quarter 2019 and elected to apply the guidance prospectively to all software implementation costs incurred after the date of adoption. As of March 31, 2019, no applicable software implementation costs have been incurred. Derivatives and Hedging: Targeted Improvements - In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities (“ASU 2017-12”), that changes both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results in order to better align a company’s risk management activities and financial reporting for hedging relationships. In summary, this amendment 1) expands the types of transactions eligible for hedge accounting; 2) eliminates the separate measurement and presentation of hedge ineffectiveness; 3) simplifies the requirements around the assessment of hedge effectiveness; 4) provides companies more time to finalize hedge documentation; and 5) enhances presentation and disclosure requirements. The effective date is for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption permitted. All transition requirements and elections should be applied to existing hedging relationships on the date of adoption and the effects should be reflected as of the beginning of the fiscal year of adoption. As part of this new guidance, entities are allowed to designate as the hedged item, an amount that is not expected to be affected by prepayments, defaults or other events affecting the timing and amount of cash flows in a closed portfolio of prepayable financial instruments (this is referred to as the “last-of-layer” method). Under the last-of-layer method, entities are able to reclassify, only at the time of adoption, eligible callable debt securities from held-to-maturity to available-for-sale without tainting its intentions to hold future debt securities to maturity. The available-for-sale security must be reported at fair value and any unrealized gain or loss must be recorded as an adjustment to other comprehensive income upon adoption. The Company evaluated its held-to-maturity portfolio during the first quarter 2019 and identified certain municipal bonds with a fair value of $216.4 million that met the last-of-layer criteria under ASU 2017-12 and as a result, reclassified those to available-for-sale and recorded an unrealized gain of $2.5 million during the first quarter 2019. Leases - In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), that establishes the principles to report transparent and economically neutral information about the assets and liabilities that arise from leases. The new guidance results in a more consistent representation of the rights and obligations arising from leases by requiring lessees to recognize the lease asset and lease liabilities that arise from leases in the statement of financial position and to disclose qualitative and quantitative information about lease transactions, such as information about variable lease payments and options to renew and terminate leases. The effective date is for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. ASU 2016-02 requires entities to adopt the new lease standard using a modified retrospective transition method, meaning an entity initially applies the new lease standard at the beginning of the earliest period presented in the financial statements. Due to complexities associated with using this method, in July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, to relieve entities of the requirement to present prior comparative years’ results when they adopt the new lease standard and giving entities the option to recognize the cumulative effect of applying the new standard as an adjustment to the opening balance of retained earnings. Adoption of ASU 2016-02 resulted in the recognition of right-of-use assets of $32.8 million and right-of-use liabilities of $32.8 million on the statement of financial position with no material impact to the results of operations. The Company has elected to adopt the guidance using the optional transition method, which allows for a modified retrospective method of adoption with a cumulative effect adjustment to retained earnings without restating comparable periods. The Company also elected the relief package of practical expedients for which there is no requirement to reassess existence of leases, their classification, and initial direct costs as well as an exemption for short-term leases with a term of less than one year, whereby the Company did not recognize a lease liability or right-of-use asset on the statement of financial position but instead will recognize lease payments as an expense over the lease term as appropriate. See Note 6 for additional information related to the Company’s right-of-use lease obligations. Recently Issued Accounting Standards Fair Value Measurement Disclosures – In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), that eliminates, amends and adds disclosure requirements for fair value measurements. These amendments are part of FASB’s disclosure review project and they are expected to reduce costs for preparers while providing more decision-useful information for financial statement users. The eliminated disclosure requirements include the 1) the amount of, and reasons for, transfers between Level 1 and Level 2 of the fair value hierarchy; 2) the policy of timing of transfers between levels of the fair value hierarchy; and 3) the valuation processes for Level 3 fair value measurements. Among other modifications, the amended disclosure requirements remove the term “at a minimum” from the phrase “an entity shall disclose at a minimum” to promote the appropriate exercise of discretion by entities and clarifies that the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as of the reporting date. Under the new disclosure requirements, entities must disclose the changes in unrealized gains or losses included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact this standard will have on its fair value disclosures. Goodwill Impairment – In January 2017, the FASB issued ASU No. 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”), that eliminates Step 2 from the goodwill impairment test which required entities to compare the implied fair value of goodwill to its carrying amount. Under the amendments, the goodwill impairment will be measured as the excess of the reporting unit’s carrying amount over its fair value. An impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The effective date is for fiscal years beginning after December 15, 2019, with early adoption permitted for interim or annual impairment tests beginning in 2017. The Company will early adopt ASU 2017-04 during the second quarter 2019 to coincide with the Company’s formal impairment analysis and it is not expected to have a material effect on the Company’s results of operations, financial position or disclosures. Credit Losses on Financial Instruments – In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires earlier measurement of credit losses, expands the range of information considered in determining expected credit losses and enhances disclosures. The main objective of ASU 2016-13 is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendments replace the incurred loss impairment methodology in current US GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The effective date for these amendments is for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company has formed a cross functional team that continues to assess its data and system needs and evaluate the potential impact of adopting the new guidance. The Company anticipates a significant change in the processes and procedures to calculate the loan losses, including changes in assumptions and estimates to consider expected credit losses over the life of the loan versus the current accounting practice that utilizes the incurred loss model. In December 2018, the Federal Reserve, Office of the Comptroller of the Currency and Federal Deposit Insurance Corporation issued a final rule revising regulatory capital rules in anticipation of the adoption of ASU 2016-13 that provides an option to phase in the day-one impact on earnings and tier one capital. Due to this final rule from the regulatory agencies, the Company is continuing to research and study options for recording a one-time adjustment or structuring any capital impact over an allowable period of time. The Company has not yet determined the magnitude of any such adjustment or the overall impact on its results of operations, financial position or disclosures. However, the Company is continuing its efforts in developing processes and procedures to ensure it is fully compliant at the required adoption date. Among other things, the Company continues to gather data and develop forecast models for asset quality, loan balances, and portfolio net charge-offs and is working with the selected model vendor to produce parallel calculations through the year leading up to implementation. Model inputs began in the fourth quarter 2018 with additional inputs and scenarios to be modeled throughout 2019 with focus on calculating a potential range of financial impact. There have been no other significant changes to the Company’s accounting policies from the 2018 Form 10-K. Presently, the Company is not aware of any other changes to the Accounting Standards Codification that will have a material impact on its present or future financial position or results of operations.

PREPARATION OF INTERIM FINANCIAL STATEMENTS

Organizational Structure

Simmons First National Corporation (the “Company”) is a publicly traded financial holding company that trades on the NASDAQ Market (“NASDAQ”) under the ticker symbol “SFNC” and the parent company of Simmons Bank, an Arkansas state-chartered bank that began as a community bank in 1903. Simmons Bank is the parent company of Simmons First Investment Group, Inc. (a registered broker-dealer), Simmons First Insurance Services, Inc. (an insurance agency), and Simmons First Insurance Services of TN, LLC (an insurance agency).

Description of Business

The Company is headquartered in Pine Bluff, Arkansas and conducts banking operations in communities throughout Arkansas, Colorado, Kansas, Missouri, Oklahoma, Tennessee and Texas. The Company, through its subsidiaries, offers consumer, real estate and commercial loans, checking, savings and time deposits from 191 financial centers conveniently located throughout its market areas. Additionally, the Company offers specialized products and services such as credit cards, trust and fiduciary services, investments, agricultural finance lending, equipment lending, insurance and small business administration (“SBA”) lending.

Basis of Presentation

The accompanying unaudited consolidated financial statements have been prepared based upon Securities and Exchange Commission (“SEC”) rules that permit reduced disclosures for interim periods. Certain information and footnote disclosures have been condensed or omitted in accordance with those rules and regulations. The accompanying consolidated balance sheet as of December 31, 2018, was derived from audited financial statements. In the opinion of management, these financial statements reflect all adjustments that are necessary for a fair presentation of interim results of operations, including normal recurring accruals. Significant intercompany accounts and transactions have been eliminated in consolidation. The results for the interim periods are not necessarily indicative of results for the full year. For a more complete discussion of significant accounting policies and certain other information, this report should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018, which was filed with the SEC on February 27, 2019.

The preparation of financial statements, in accordance with accounting principles generally accepted in the United States (“US GAAP”), requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, income items and expenses and disclosure of contingent assets and liabilities. The estimates and assumptions used in the accompanying consolidated financial statements are based upon management’s evaluation of the relevant facts and circumstances as of the date of the consolidated financial statements and actual results may differ from these estimates. Such estimates include, but are not limited to, the Company’s allowance for loan losses.

Certain prior year amounts have been reclassified to conform to the current year financial statement presentation. These changes and reclassifications did not impact previously reported net income or comprehensive income.

Recently Adopted Accounting Standards

Cloud Computing Arrangements – In August 2018, the FASB issued ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract (“ASU 2018-15”), that amends the definition of a hosting arrangement and requires a customer in a hosting arrangement that is a service contract to capitalize certain implementation costs as if the arrangement was an internal-use software project. The internal-use software guidance states that only qualifying costs incurred during the application development stage can be capitalized. The effective date is for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted. Entities have the option to apply the guidance prospectively to all implementation costs incurred after the date of adoption or retrospectively in accordance with the applicable guidance. At the time of adoption, entities will be required to disclose the nature of its hosting arrangements that are service contracts and provide disclosures as if the deferred implementation costs were a separate, major depreciable asset class. The Company early adopted ASU 2018-15 in the first quarter 2019 and elected to apply the guidance prospectively to all software implementation costs incurred after the date of adoption. As of March 31, 2019, no applicable software implementation costs have been incurred.

Derivatives and Hedging: Targeted Improvements - In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities (“ASU 2017-12”), that changes both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results in order to better align a company’s risk management activities and financial reporting for hedging relationships. In summary, this amendment 1) expands the types of transactions eligible for hedge accounting; 2) eliminates the separate measurement and presentation of hedge ineffectiveness; 3) simplifies the requirements around the assessment of hedge effectiveness; 4) provides companies more time to finalize hedge documentation; and 5) enhances presentation and disclosure requirements. The effective date is for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption permitted. All transition requirements and elections should be applied to existing hedging relationships on the date of adoption and the effects should be reflected as of the beginning of the fiscal year of adoption. As part of this new guidance, entities are allowed to designate as the hedged item, an amount that is not expected to be affected by prepayments, defaults or other events affecting the timing and amount of cash flows in a closed portfolio of prepayable financial instruments (this is referred to as the “last-of-layer” method). Under the last-of-layer method, entities are able to reclassify, only at the time of adoption, eligible callable debt securities from held-to-maturity to available-for-sale without tainting its intentions to hold future debt securities to maturity. The available-for-sale security must be reported at fair value and any unrealized gain or loss must be recorded as an adjustment to other comprehensive income upon adoption. The Company evaluated its held-to-maturity portfolio during the first quarter 2019 and identified certain municipal bonds with a fair value of $216.4 million that met the last-of-layer criteria under ASU 2017-12 and as a result, reclassified those to available-for-sale and recorded an unrealized gain of $2.5 million during the first quarter 2019.

Leases - In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), that establishes the principles to report transparent and economically neutral information about the assets and liabilities that arise from leases. The new guidance results in a more consistent representation of the rights and obligations arising from leases by requiring lessees to recognize the lease asset and lease liabilities that arise from leases in the statement of financial position and to disclose qualitative and quantitative information about lease transactions, such as information about variable lease payments and options to renew and terminate leases. The effective date is for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. ASU 2016-02 requires entities to adopt the new lease standard using a modified retrospective transition method, meaning an entity initially applies the new lease standard at the beginning of the earliest period presented in the financial statements. Due to complexities associated with using this method, in July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, to relieve entities of the requirement to present prior comparative years’ results when they adopt the new lease standard and giving entities the option to recognize the cumulative effect of applying the new standard as an adjustment to the opening balance of retained earnings. Adoption of ASU 2016-02 resulted in the recognition of right-of-use assets of $32.8 million and right-of-use liabilities of $32.8 million on the statement of financial position with no material impact to the results of operations. The Company has elected to adopt the guidance using the optional transition method, which allows for a modified retrospective method of adoption with a cumulative effect adjustment to retained earnings without restating comparable periods. The Company also elected the relief package of practical expedients for which there is no requirement to reassess existence of leases, their classification, and initial direct costs as well as an exemption for short-term leases with a term of less than one year, whereby the Company did not recognize a lease liability or right-of-use asset on the statement of financial position but instead will recognize lease payments as an expense over the lease term as appropriate. See Note 6 for additional information related to the Company’s right-of-use lease obligations.

Recently Issued Accounting Standards

Fair Value Measurement Disclosures – In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), that eliminates, amends and adds disclosure requirements for fair value measurements. These amendments are part of FASB’s disclosure review project and they are expected to reduce costs for preparers while providing more decision-useful information for financial statement users. The eliminated disclosure requirements include the 1) the amount of, and reasons for, transfers between Level 1 and Level 2 of the fair value hierarchy; 2) the policy of timing of transfers between levels of the fair value hierarchy; and 3) the valuation processes for Level 3 fair value measurements. Among other modifications, the amended disclosure requirements remove the term “at a minimum” from the phrase “an entity shall disclose at a minimum” to promote the appropriate exercise of discretion by entities and clarifies that the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as of the reporting date. Under the new disclosure requirements, entities must disclose the changes in unrealized gains or losses included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact this standard will have on its fair value disclosures.

Goodwill Impairment – In January 2017, the FASB issued ASU No. 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”), that eliminates Step 2 from the goodwill impairment test which required entities to compare the implied fair value of goodwill to its carrying amount. Under the amendments, the goodwill impairment will be measured as the excess of the reporting unit’s carrying amount over its fair value. An impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The effective date is for fiscal years beginning after December 15, 2019, with early adoption permitted for interim or annual impairment tests beginning in 2017. The Company will early adopt ASU 2017-04 during the second quarter 2019 to coincide with the Company’s formal impairment analysis and it is not expected to have a material effect on the Company’s results of operations, financial position or disclosures.

Credit Losses on Financial Instruments – In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires earlier measurement of credit losses, expands the range of information considered in determining expected credit losses and enhances disclosures. The main objective of ASU 2016-13 is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendments replace the incurred loss impairment methodology in current US GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The effective date for these amendments is for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company has formed a cross functional team that continues to assess its data and system needs and evaluate the potential impact of adopting the new guidance. The Company anticipates a significant change in the processes and procedures to calculate the loan losses, including changes in assumptions and estimates to consider expected credit losses over the life of the loan versus the current accounting practice that utilizes the incurred loss model. In December 2018, the Federal Reserve, Office of the Comptroller of the Currency and Federal Deposit Insurance Corporation issued a final rule revising regulatory capital rules in anticipation of the adoption of ASU 2016-13 that provides an option to phase in the day-one impact on earnings and tier one capital. Due to this final rule from the regulatory agencies, the Company is continuing to research and study options for recording a one-time adjustment or structuring any capital impact over an allowable period of time. The Company has not yet determined the magnitude of any such adjustment or the overall impact on its results of operations, financial position or disclosures. However, the Company is continuing its efforts in developing processes and procedures to ensure it is fully compliant at the required adoption date. Among other things, the Company continues to gather data and develop forecast models for asset quality, loan balances, and portfolio net charge-offs and is working with the selected model vendor to produce parallel calculations through the year leading up to implementation. Model inputs began in the fourth quarter 2018 with additional inputs and scenarios to be modeled throughout 2019 with focus on calculating a potential range of financial impact.

There have been no other significant changes to the Company’s accounting policies from the 2018 Form 10-K. Presently, the Company is not aware of any other changes to the Accounting Standards Codification that will have a material impact on its present or future financial position or results of operations.