Basis of Presentation	9 Months Ended
Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements and notes thereto contain all adjustments, consisting only of normal recurring adjustments, necessary to present fairly, in accordance with accounting principles generally accepted in the United States of America (“GAAP”), the financial position of MidSouth Bancorp, Inc. (the “Company”) and its subsidiaries as of September 30, 2015 and the results of their operations and their cash flows for the periods presented. The interim financial information should be read in conjunction with the annual consolidated financial statements and the notes thereto included in the Company’s 2014 Annual Report on Form 10-K. The results of operations for the nine-month period ended September 30, 2015 are not necessarily indicative of the results to be expected for the entire year. Use of Estimates — The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reported period. Actual results could differ from those estimates. Summary of Significant Accounting Policies — The accounting and reporting policies of the Company conform with GAAP and general practices within the banking industry. There have been no material changes or developments in the application of accounting principles or in our evaluation of the accounting estimates and the underlying assumptions or methodologies that we believe to be Critical Accounting Policies and Estimates as disclosed in our 2014 Annual Report on Form 10-K. Recent Accounting Pronouncements — ASU 2015-01, Income Statement - Extraordinary and Unusual Items (Subtopic 225-20): Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items was issued as part of the FASB's simplification initiative. ASU 2015-01 eliminates the concept of extraordinary items. The effective date of this Update is for fiscal years beginning on or after December 15, 2015 and interim periods within those annual periods. Adoption of this Update is not expected to have a material effect on the Company’s consolidated financial statements or the interim notes to the consolidated financial statements. ASU 2015-03, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs was also issued as part of the FASB's simplification initiative. The amendments in this ASU require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. Currently, debt issuance costs are presented as an asset on the balance sheet. The FASB notes within the ASU, capitalized debt issuance costs do not meet the definition of an asset and are more akin to a debt discount, thereby reducing the carrying amount of the proceeds received. The effective date of this Update is for fiscal years beginning on or after December 15, 2015 and interim periods within those annual periods. Adoption of this Update is not expected to have a material effect on the Company’s consolidated financial statements or the interim notes to the consolidated financial statements. Louisiana Business Corporation Act — Effective January 1, 2015, companies incorporated under Louisiana law became subject to the Louisiana Business Corporation Act. Provisions of the Louisiana Business Corporation Act eliminate the concept of treasury stock. Rather, shares purchased by the Company constitute authorized but unissued shares. Accounting principles generally accepted in the United States of America state that accounting for treasury stock shall conform to state law. The Company's consolidated financial statements as of September 30, 2015 reflect this change. The cost of shares purchased by the Company has been allocated to common stock and additional paid-in capital balances.

Basis of Presentation

The accompanying unaudited consolidated financial statements and notes thereto contain all adjustments, consisting only of normal recurring adjustments, necessary to present fairly, in accordance with accounting principles generally accepted in the United States of America (“GAAP”), the financial position of MidSouth Bancorp, Inc. (the “Company”) and its subsidiaries as of September 30, 2015 and the results of their operations and their cash flows for the periods presented. The interim financial information should be read in conjunction with the annual consolidated financial statements and the notes thereto included in the Company’s 2014 Annual Report on Form 10-K.

The results of operations for the nine-month period ended September 30, 2015 are not necessarily indicative of the results to be expected for the entire year.

Use of Estimates — The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reported period. Actual results could differ from those estimates.

Summary of Significant Accounting Policies — The accounting and reporting policies of the Company conform with GAAP and general practices within the banking industry. There have been no material changes or developments in the application of accounting principles or in our evaluation of the accounting estimates and the underlying assumptions or methodologies that we believe to be Critical Accounting Policies and Estimates as disclosed in our 2014 Annual Report on Form 10-K.

Recent Accounting Pronouncements — ASU 2015-01, Income Statement - Extraordinary and Unusual Items (Subtopic 225-20): Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items was issued as part of the FASB's simplification initiative. ASU 2015-01 eliminates the concept of extraordinary items. The effective date of this Update is for fiscal years beginning on or after December 15, 2015 and interim periods within those annual periods. Adoption of this Update is not expected to have a material effect on the Company’s consolidated financial statements or the interim notes to the consolidated financial statements.

ASU 2015-03, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs was also issued as part of the FASB's simplification initiative. The amendments in this ASU require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. Currently, debt issuance costs are presented as an asset on the balance sheet. The FASB notes within the ASU, capitalized debt issuance costs do not meet the definition of an asset and are more akin to a debt discount, thereby reducing the carrying amount of the proceeds received. The effective date of this Update is for fiscal years beginning on or after December 15, 2015 and interim periods within those annual periods. Adoption of this Update is not expected to have a material effect on the Company’s consolidated financial statements or the interim notes to the consolidated financial statements.

Louisiana Business Corporation Act — Effective January 1, 2015, companies incorporated under Louisiana law became subject to the Louisiana Business Corporation Act. Provisions of the Louisiana Business Corporation Act eliminate the concept of treasury stock. Rather, shares purchased by the Company constitute authorized but unissued shares. Accounting principles generally accepted in the United States of America state that accounting for treasury stock shall conform to state law. The Company's consolidated financial statements as of September 30, 2015 reflect this change. The cost of shares purchased by the Company has been allocated to common stock and additional paid-in capital balances.