Financial Statement Presentation	9 Months Ended
Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Financial Statement Presentation	Financial Statement Presentation In the opinion of management, the accompanying consolidated financial statements of NewMarket Corporation and its subsidiaries contain all necessary adjustments for the fair statement of, in all material respects, our consolidated financial position as of September 30, 2018 and December 31, 2017, our consolidated results of operations and comprehensive income for the third quarter and nine months ended September 30, 2018 and September 30, 2017, and our changes in shareholders' equity, and cash flows for the nine months ended September 30, 2018 and September 30, 2017. All adjustments are of a normal, recurring nature, unless otherwise disclosed. These financial statements should be read in conjunction with the consolidated financial statements and related notes included in the NewMarket Corporation Annual Report on Form 10-K for the year ended December 31, 2017 (2017 Annual Report), as filed with the Securities and Exchange Commission (SEC). The results of operations for the nine month period ended September 30, 2018 are not necessarily indicative of the results to be expected for the full year ending December 31, 2018. The December 31, 2017 condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America. Unless the context otherwise indicates, all references to “we,” “us,” “our,” the “company,” and “NewMarket” are to NewMarket Corporation and its consolidated subsidiaries. During 2018, we identified fully depreciated property, plant, and equipment that is no longer in use and should have been written off in prior periods. During 2018, we reduced both property, plant, and equipment, at cost and accumulated depreciation and amortization on the Condensed Consolidated Balance Sheet by $86 million each. There was no impact to net property, plant, and equipment. Prior period amounts were not revised as the adjustments were not considered material. Prior period amounts on the Consolidated Statements of Income have been reclassified to reflect the retroactive adoption of Accounting Standard Update No. 2017-07, "Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost". See Note 13 for further information.

Financial Statement Presentation

In the opinion of management, the accompanying consolidated financial statements of NewMarket Corporation and its subsidiaries contain all necessary adjustments for the fair statement of, in all material respects, our consolidated financial position as of September 30, 2018 and December 31, 2017, our consolidated results of operations and comprehensive income for the third quarter and nine months ended September 30, 2018 and September 30, 2017, and our changes in shareholders' equity, and cash flows for the nine months ended September 30, 2018 and September 30, 2017. All adjustments are of a normal, recurring nature, unless otherwise disclosed. These financial statements should be read in conjunction with the consolidated financial statements and related notes included in the NewMarket Corporation Annual Report on Form 10-K for the year ended December 31, 2017 (2017 Annual Report), as filed with the Securities and Exchange Commission (SEC). The results of operations for the nine month period ended September 30, 2018 are not necessarily indicative of the results to be expected for the full year ending December 31, 2018. The December 31, 2017 condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America.

Unless the context otherwise indicates, all references to “we,” “us,” “our,” the “company,” and “NewMarket” are to NewMarket Corporation and its consolidated subsidiaries.

During 2018, we identified fully depreciated property, plant, and equipment that is no longer in use and should have been written off in prior periods. During 2018, we reduced both property, plant, and equipment, at cost and accumulated depreciation and amortization on the Condensed Consolidated Balance Sheet by $86 million each. There was no impact to net property, plant, and equipment. Prior period amounts were not revised as the adjustments were not considered material.

Prior period amounts on the Consolidated Statements of Income have been reclassified to reflect the retroactive adoption of Accounting Standard Update No. 2017-07, "Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost". See Note 13 for further information.