Item 6. Selected Financial Data

In 2017, the Company recorded a one-time additional income tax expense of $658 million, or $1.90 per diluted share, related to the enactment of the United States "Tax Cuts and Jobs Act." Refer to Note 6. Income Taxes in Item 8. Financial Statements and Supplementary Data for further information.

Certain reclassifications of prior year data have been made to conform to current year reporting, including the adoption of new accounting guidance as discussed below.

In March 2016, the FASB issued authoritative guidance that included several changes to simplify the accounting for stock-based compensation, including the accounting for income taxes, forfeitures, statutory tax withholding requirements and classification of tax benefits in the statement of cash flows. Among the more significant changes, the new guidance requires that the income tax effects associated with the settlement of stock-based awards after adoption of the guidance be recognized through income tax expense rather than directly in equity. Additionally, the income tax effects related to excess tax benefits should be presented within operating cash flows in the statement of cash flows rather than as a financing activity. Excess tax benefits recognized in equity under the prior guidance were $29 million and $20 million for the years ended December 31, 2016 and 2015, respectively. The Company adopted the new guidance effective January 1, 2017 and applied the new guidance prospectively. Excess tax benefits of $28 million, $10 million and $50 million were included in Income taxes in the statement of income for the years ended December 31, 2019, 2018 and 2017, respectively. The expected effect on income tax expense or net cash provided from operating activities related to future stock-based award settlements will vary each period and will depend on inputs such as the stock price at the time of settlement and the number of awards settled in the period presented.

Additional information on the comparability of results is included in Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations.