Presentation of Financial Statements	3 Months Ended
Presentation of Financial Statements	Mar. 31, 2022
Presentation of Financial Statements [Abstract]
Presentation of Financial Statements	Presentation of Financial Statements The terms “Omnicom,” “the Company,” “we,” “our” and “us” each refer to Omnicom Group Inc. and its subsidiaries, unless the context indicates otherwise. The accompanying unaudited consolidated financial statements were prepared in accordance with generally accepted accounting principles in the United States, or U.S. GAAP or GAAP, for interim financial information and Article 10 of Regulation S-X of the Securities and Exchange Commission. Accordingly, certain information and footnote disclosure have been condensed or omitted. In our opinion, the accompanying unaudited consolidated financial statements reflect all adjustments, consisting of normal recurring accruals, considered necessary for a fair presentation, in all material respects, of the information contained herein. These unaudited consolidated financial statements should be read in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2021, or 2021 10-K. Results for the interim periods are not necessarily indicative of results that may be expected for the year. Risks and Uncertainties Global economic challenges, including the impact of the war in Ukraine, the COVID-19 pandemic, rising inflation and supply-chain disruptions could cause economic uncertainty and volatility. The impact of these issues on our business will vary by geographic market and discipline. We monitor economic conditions closely, as well as client revenue levels and other factors. In response to reductions in revenue, we can take actions to align our cost structure with changes in client demand and manage our working capital. However, there can be no assurance as to the effectiveness of our efforts to mitigate any impact of the current and future adverse economic conditions, reductions in client revenue, changes in client creditworthiness and other developments. Impact of the War in Ukraine We have historically conducted operations in Russia and Ukraine through local agencies in which we hold a majority stake. The minority partners in these agencies are local management, which report to the applicable network management. During the first quarter of 2022, the war in Ukraine required us to suspend our business operations in Ukraine. The war resulted in the imposition of sanctions by the United States, the United Kingdom, and the European Union, that affect the cross-border operations of businesses operating in Russia. In addition, Russian regulators have imposed currency restrictions and regulations that created uncertainty regarding our ability to recover our investment in our operations in Russia, as well as our ability to exercise control over the operations. Also, many multinational companies, including many of our large clients, ceased or suspended their operations in Russia. Therefore, the ability to continue operations in Russia without additional funding, which we will not provide, is uncertain. As a result, we have sold, or committed to dispose of, all of our businesses in Russia. Accordingly, we recorded pretax charges of $113.4 million in the first quarter of 2022, primarily consisting of the net investment in our Russian businesses, and also including charges related to the suspension of operations in Ukraine. Impact of the COVID-19 Pandemic - Update Beginning in March 2020 and continuing through the first quarter of 2021, our business experienced the effects from reductions in client spending due to the economic impact related to the COVID-19 pandemic. While mixed by business and geography, the spending reductions impacted all our businesses and markets. Globally, the most impacted businesses were our Experiential discipline, especially in our event marketing businesses, and our Execution & Support discipline, primarily in field marketing. Most of our markets began to improve in April 2021, and the improvement continued through the first quarter of 2022 as clients substantially increased their spending on our services.