Basis of Presentation

12 Months Ended

Dec. 31, 2013

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

Basis of Presentation

The accompanying Consolidated Financial Statements and Notes thereto have been prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP"). The Consolidated Financial Statements include the accounts of Aon plc and all controlled subsidiaries ("Aon" or the "Company"). All intercompany accounts and transactions have been eliminated. The Consolidated Financial Statements include, in the opinion of management, all adjustments (consisting of normal recurring adjustments and reclassifications) necessary to present fairly the Company's consolidated financial position, results of operations and cash flows for all periods presented.

Reclassification

Certain amounts in prior year's consolidated financial statements and related notes have been reclassified to conform to the 2013 presentation. In prior periods, income or losses from discontinued operations and its related tax expense was recognized in Income (loss) from discontinued operations in the Consolidated Statements of Income. These amounts are now included in Other income in the Consolidated Statements of Income. The amounts reclassified were $1 million loss and $4 million income for the years ended December 31, 2012 and 2011, respectively. There was no earnings per share impact in 2012, and a $0.01 diluted per share impact in 2011.

Use of Estimates

The preparation of the accompanying Consolidated Financial Statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities at the date of the financial statements, and the reported amounts of reserves and expenses. These estimates and assumptions are based on management's best estimates and judgments. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, which management believes to be reasonable under the circumstances. Aon adjusts such estimates and assumptions when facts and circumstances dictate. Illiquid credit markets, volatile equity markets, and foreign currency movements increase the uncertainty inherent in such estimates and assumptions. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates. Changes in estimates resulting from continuing changes in the economic environment will be reflected in the financial statements in future periods.