Basis of Presentation (Policies)	3 Months Ended
Basis of Presentation (Policies)	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q and therefore do not include all information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. Except as disclosed herein, there has been no material change in the information disclosed in the notes to the consolidated financial statements included in the Annual Report on Form 10-K of Genuine Parts Company (the “Company”) for the year ended December 31, 2015. Accordingly, the unaudited interim condensed consolidated financial statements and related disclosures herein should be read in conjunction with the Company’s 2015 Annual Report on Form 10-K.
Use of Estimates	The preparation of interim financial statements requires management to make estimates and assumptions for the amounts reported in the condensed consolidated financial statements. Specifically, the Company makes estimates and assumptions in its interim condensed consolidated financial statements for inventory adjustments, the accrual of bad debts, customer sales returns, and volume incentives earned, among others. Inventory adjustments (including adjustments for a majority of inventories that are valued under the last-in, first-out (“LIFO”) method) are accrued on an interim basis and adjusted in the fourth quarter based on the annual book to physical inventory adjustment and LIFO valuation, which is performed each year-end. Reserves for bad debts and customer sales returns are estimated and accrued on an interim basis based upon historical experience. Volume incentives are estimated based upon cumulative and projected purchasing levels. The estimates and assumptions for interim reporting may change upon final determination at year-end, and such changes may be significant.
Segment Reporting	Net sales by segment exclude the effect of certain discounts, incentives and freight billed to customers. The line item “Other” represents the net effect of the discounts, incentives and freight billed to customers, which is reported as a component of net sales in the Company’s condensed consolidated statements of income and comprehensive income.
Recent Accounting Pronouncements	In February 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis (“ASU 2015-02”). ASU 2015-02 amends the consolidation requirements and significantly changes the consolidation analysis required. ASU 2015-02 requires management to reevaluate all legal entities under a revised consolidation model to specifically (i) modify the evaluation of whether limited partnership and similar legal entities are variable interest entities (“VIEs”), (ii) eliminate the presumption that a general partner should consolidate a limited partnership, (iii) affect the consolidation analysis of reporting entities that are involved with VIEs particularly those that have fee arrangements and related party relationships, and (iv) provide a scope exception from consolidation guidance for reporting entities with interests in legal entities that are required to comply with or operate in accordance with requirements that are similar to those in Rule 2a-7 of the Investment Act of 1940 for registered money market funds. ASU 2015-02 is effective for the Company’s interim and annual periods beginning after December 15, 2015. The adoption of ASU 2015-02 did not have a material impact to the Company’s condensed consolidated financial statements for the three months ended March 31, 2016 and will not have a material impact on the annual consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”), which requires an entity to recognize a right-of-use asset and a lease liability on the balance sheet for all leases, including operating leases, with a term greater than twelve months. Expanded disclosures with additional qualitative and quantitative information will also be required. This guidance is effective for interim and annual reporting periods beginning after December 15, 2018 and early adoption is permitted. The new standard must be adopted using a modified retrospective transition. The Company is currently evaluating the impact of ASU No. 2016-02 on its condensed consolidated financial statements and related disclosures. In March 2016, The FASB issued ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”) that changes the accounting for certain aspects of share-based compensation to employees including forfeitures, employer tax withholding, and the financial statement presentation of excess tax benefits or expense. ASU 2016-09 also clarifies the statement of cash flows presentation for certain components of share-based compensation. This guidance is effective for interim and annual reporting periods beginning after December 15, 2016 and early adoption is permitted. The Company is currently evaluating the impact of ASU No. 2016-09 on its condensed consolidated financial statements.
Share-based Compensation, Option and Incentive Plans	As more fully discussed in Note 5 of the Company’s notes to the consolidated financial statements in its 2015 Annual Report on Form 10-K, the Company maintains various long-term incentive plans, which provide for the granting of stock options, stock appreciation rights (“SARs”), restricted stock, restricted stock units (“RSUs”), performance awards, dividend equivalents and other share-based awards. SARs represent a right to receive upon exercise an amount, payable in shares of common stock, equal to the excess, if any, of the fair market value of the Company’s common stock on the date of exercise over the base value of the grant. The terms of such SARs require net settlement in shares of common stock and do not provide for cash settlement. RSUs represent a contingent right to receive one share of the Company’s common stock at a future date. The majority of awards previously granted vest on a pro-rata basis for periods ranging from one to five years and are expensed accordingly on a straight-line basis. The Company issues new shares upon exercise or conversion of awards under these plans. Most awards may be exercised or converted to shares not earlier than twelve months nor later than ten years from the date of grant.
Consolidation, Variable Interest Entity	The Company guarantees the borrowings of certain independently controlled automotive parts stores (“independents”) and certain other affiliates in which the Company has a noncontrolling equity ownership interest (“affiliates”). Presently, the independents are generally consolidated by unaffiliated enterprises that have controlling financial interests through ownership of a majority voting interest in the independents. The Company has no voting interest or equity conversion rights in any of the independents. The Company does not control the independents or the affiliates, but receives a fee for the guarantees. The Company has concluded that the independents are variable interest entities, but that the Company is not the primary beneficiary. Specifically, the equity holders of the independents have the power to direct the activities that most significantly impact the entities’ economic performance including, but not limited to, decisions about hiring and terminating personnel, local marketing and promotional initiatives, pricing and selling activities, credit decisions, monitoring and maintaining appropriate inventories, and store hours. Separately, the Company concluded the affiliates are not variable interest entities. The Company’s maximum exposure to loss as a result of its involvement with these independents and affiliates is generally equal to the total borrowings subject to the Company’s guarantees. While such borrowings of the independents and affiliates are outstanding, the Company is required to maintain compliance with certain covenants, including a maximum debt to capitalization ratio and certain limitations on additional borrowings. At March 31, 2016, the Company was in compliance with all such covenants. At March 31, 2016, the total borrowings of the independents and affiliates subject to guarantee by the Company were approximately $350.6 million. These loans generally mature over periods from one to six years. In the event that the Company is required to make payments in connection with guaranteed obligations of the independents or the affiliates, the Company would obtain and liquidate certain collateral (e.g., accounts receivable and inventory) to recover all or a portion of the amounts paid under the guarantees. When it is deemed probable that the Company will incur a loss in connection with a guarantee, a liability is recorded equal to this estimated loss.
Fair Value of Financial Instruments	The carrying amounts reflected in the condensed consolidated balance sheets for cash and cash equivalents, trade accounts receivable, trade accounts payable, and borrowings under the line of credit approximate their respective fair values based on the short-term nature of these instruments. At March 31, 2016, the carrying value and the fair value of fixed rate debt were approximately $500.0 million and $505.5 million, respectively. The fair value of fixed rate debt is designated as Level 2 in the fair value hierarchy (i.e., significant observable inputs) and is based primarily on the discounted value of future cash flows using current market interest rates offered for debt of similar credit risk and maturity. The carrying value of the short-term fixed rate debt of $250.0 million is included in “Current portion of debt”, with the long-term portion of $250.0 million included in “Long-term debt,” in the accompanying condensed consolidated balance sheets.

Disclosure of accounting policy for consolidation to describe the significant judgments and assumptions made in determining whether a variable interest held by the entity requires the variable interest entity to be consolidated and (or) disclose information about its involvement with the variable interest entity; the methodology used by the entity for determining whether or not it is the primary beneficiary of the variable interest entity; and the significant factors considered and judgments made in determining that the power to direct the activities that significantly impact the economic performance of the variable interest entity are shared (as defined).