Accounting Principles and Practices	6 Months Ended
Accounting Principles and Practices	Jun. 30, 2024
Accounting Policies [Abstract]
Accounting Principles and Practices	Accounting Principles and Practices We have not made any changes in our significant accounting policies from those disclosed in our Annual Report on Form 10-K for the year ended December 31, 2023 filed with the SEC, except for those described below, which have been added in connection with the acquisition of NFP. Summary of Significant Accounting Principles and Practices Contingent Consideration Contingent consideration may be paid to the former owners of the business and typically will involve the acquired entity reaching specific financial results over a designated period. Contingent consideration payables are recorded at fair value and are included in the purchase price consideration at the time of the acquisition. Subsequent changes in the fair value of contingent consideration obligations are recorded in the Condensed Consolidated Statements of Income. The fair value of contingent consideration payables is based on the expected future payments to be made to the sellers of the acquired businesses in accordance with the provisions outlined in the respective purchase agreements. In determining fair value of the contingent consideration, the acquired business’s future performance is estimated using financial projections for the acquired business and measured against performance targets specified in each purchase agreement. Contingent consideration liabilities are classified as Level 3 because of the Company’s reliance on unobservable inputs. Principles of Consolidations The accompanying Condensed Consolidated Financial Statements include the accounts of Aon plc and those entities in which the Company has a controlling financial interest. To determine if Aon holds a controlling financial interest in an entity, the Company first evaluates if it is required to apply the variable interest model to the entity, otherwise, the entity is evaluated under the voting interest model. When Aon holds rights that give it the power to direct the activities of a VIE that most significantly impact the VIE’s economic performance, combined with a variable interest that gives the right to receive potentially significant benefits or the obligation to absorb potentially significant losses, the Company has a controlling financial interest in that VIE. If the Company is the primary beneficiary of a VIE, the Company consolidates the entity and reflects any relevant noncontrolling interest of other beneficiaries of that entity on the Statement of Consolidated Financial Position. Aon’s interest in VIEs as of June 30, 2024 predominantly relates to assets and liabilities acquired through the acquisition of NFP and are subject to purchase accounting adjustments. Total assets related to consolidated VIEs are approximately 1% of the Company’s Total assets on the Condensed Consolidated Statements of Financial Position for the period ended June 30, 2024. Aon holds a controlling financial interest in entities that are not VIEs when it, directly or indirectly holds more than 50% of the voting rights and the noncontrolling interest holders do not hold substantive participating rights. Redeemable Noncontrolling Interests Redeemable noncontrolling interests represent interests for certain consolidated entities which are subject to redemption rights held by the noncontrolling interests owners outside of the Company’s control at fixed or determinable prices and dates. The interests are initially recorded at fair value and in subsequent reporting periods are adjusted to the estimated redemption value. The adjustments to the redemption value are recorded to additional paid-in capital or retained earnings, when appropriate, on the Condensed Consolidated Statements of Financial Position. The Redeemable noncontrolling interests are considered temporary equity and reported outside of permanent equity on the Condensed Consolidated Statements of Financial Position. The interests are recorded at the greater of the carrying amount adjusted for the noncontrolling interest’s share of net income (loss) and distributions or its redemption value. New Accounting Pronouncements Accounting Standards Issued But Not Yet Adopted Improvements to Reportable Segment Disclosures In November 2023, the FASB issued new accounting guidance, requiring new segment disclosures under ASC 280, Segment Reporting, including disclosure of significant segment expense categories and amounts that are regularly reported to the CODM and included in the segment’s profit or loss. Additionally, all disclosure requirements under ASC 280, including new requirements under this new guidance, will be required on an interim basis. The new guidance is effective for Aon for the year ended December 31, 2024 and interim periods thereafter, with early adoption permitted. An entity will apply the new guidance on a retrospective basis for all periods presented. The Company is currently evaluating the impact the guidance will have on the Notes to Consolidated Financial Statements. Improvements to Income Tax Disclosures In December 2023, the FASB issued new accounting guidance under ASC 740, Income Taxes, which requires additional income tax disclosures on an annual basis, including disaggregation of information presented within the reconciliation of the expected tax to the reported tax by specific categories, with certain reconciling items 5% or greater broken out by nature and/or jurisdiction. The new guidance also requires disclosure of income taxes paid, net of refunds, broken out by federal, state/local, and foreign, including disclosure of individual jurisdictions when greater than 5% of total net income taxes paid. The new guidance is effective for Aon for the year ended December 31, 2025, with early adoption permitted. The Company is evaluating the period of adoption and transition approach, as well as the impact the disclosures will have on the Notes to Consolidated Financial Statements. Securities and Exchange Commission Final Rules The Enhancement and Standardization of Climate-Related Disclosures for Investors In March 2024, the SEC adopted final rules to enhance and standardize climate-related disclosures. The final rules will require the Company to provide certain climate-related information in Item 7, Management’s Discussion and Analysis regarding material climate-related risks, activities to mitigate or adapt to such risks, information regarding oversight and management of climate-related risks, information on climate-related targets or goals, and disclosure of Scope 1 and 2 GHG emissions. Additionally, within the Notes to Consolidated Financial Statements, the Company will be required to disclose the financial statement effects of severe weather events and other natural conditions. The final rules are effective for Aon for the year ended December 31, 2025, with the exception of GHG emissions disclosures which are effective for Aon for the year ended December 31, 2026. After the adoption of the final rules, the final rules became subject to several legal challenges, and on April 4, 2024 the SEC voluntarily stayed the final rules pending judicial review. The Company is currently evaluating the impact that the guidance will have on our disclosures and will monitor the judicial process for impacts on the disclosure requirements.