Organization and Basis of Presentation (Policies)	3 Months Ended
Mar. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	Organization - At March 31, 2019, Valhi, Inc. (NYSE: VHI) held approximately 50% of our outstanding common stock and a wholly-owned subsidiary of NL Industries, Inc. (NYSE: NL) held approximately 30% of our common stock. Valhi owned approximately 83% of NL’s outstanding common stock and a wholly-owned subsidiary of Contran Corporation held approximately 92% of Valhi’s outstanding common stock. All of Contran’s outstanding voting stock is held by a family trust established for the benefit of Lisa K. Simmons and Serena Simmons Connelly and their children, for which Ms. Simmons and Ms. Connelly are co-trustees, or is held directly by Ms. Simmons and Ms. Connelly or entities related to them. Consequently, Ms. Simmons and Ms. Connelly may be deemed to control Contran, Valhi, NL and us.
Basis of Presentation	Basis of presentation - The unaudited Condensed Consolidated Financial Statements contained in this Quarterly Report have been prepared on the same basis as the audited Consolidated Financial Statements in our Annual Report on Form 10-K for the year ended December 31, 2018 that we filed with the Securities and Exchange Commission (SEC) on March 11, 2019 (2018 Annual Report). In our opinion, we have made all necessary adjustments (which include only normal recurring adjustments), in order to state fairly, in all material respects, our consolidated financial position, results of operations and cash flows as of the dates and for the periods presented. We have condensed the Consolidated Balance Sheet at December 31, 2018 contained in this Quarterly Report as compared to our audited Consolidated Financial Statements at that date, and we have omitted certain information and footnote disclosures (including those related to the Consolidated Balance Sheet at December 31, 2018) normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (GAAP). Our results of operations for the interim period ended March 31, 2019 may not be indicative of our operating results for the full year. The Condensed Consolidated Financial Statements contained in this Quarterly Report should be read in conjunction with our 2018 Consolidated Financial Statements contained in our 2018 Annual Report. Unless otherwise indicated, references in this report to “we,” “us” or “our” refer to Kronos Worldwide, Inc. and its subsidiaries (NYSE: KRO) taken as a whole.
Derivatives	We periodically use currency forward contracts to manage a very nominal portion of currency exchange rate risk associated with trade receivables denominated in a currency other than the holder’s functional currency or similar exchange rate risk associated with future sales. Derivatives used to hedge forecasted transactions and specific cash flows associated with financial assets and liabilities denominated in currencies other than the U.S. dollar and which meet the criteria for hedge accounting are designated as cash flow hedges. Consequently, the effective portion of gains and losses is deferred as a component of accumulated other comprehensive income and is recognized in earnings at the time the hedged item affects earnings. Contracts that do not meet the criteria for hedge accounting are marked-to-market at each balance sheet date with any resulting gain or loss recognized in income currently as part of net currency transaction gains and losses.
Recent Accounting Pronouncement	On January 1, 2019, we adopted ASU 2016-02, Leases (Topic 842), which is a comprehensive rewriting of the lease accounting guidance which aims to increase comparability and transparency with regard to lease transactions. The primary change was the recognition of lease assets for the right-of-use of the underlying asset and lease liabilities for the obligation to make payments by lessees on the balance sheet for leases previously classified as operating leases. ASU 2016-02, as amended, also requires increased qualitative disclosure about leases in addition to quantitative disclosures previously required. As permitted, we adopted this ASU prospectively as of January 1, 2019 with no restatement of prior period financial statements. This ASU permits companies to elect certain practical expedients upon adoption, and at adoption we elected the package of practical expedients related to, among other things, lease classification (in which existing leases classified as operating leases under prior GAAP are classified as an operating lease under the new ASU, and existing leases classified as a capital lease under prior GAAP are classified as a finance lease under the new ASU), nonlease components (in which nonlease components associated with a lease and paid by us to the lessor, such as property taxes, insurance and maintenance, are treated as a lease component and considered part of minimum lease rental payments), and short-term leases (in which leases with an original maturity of 12 months or less are excluded from the recognition requirements of the new ASU). Upon adoption of this new ASU, at January 1, 2019 we recognized an aggregate right-of-use operating lease asset of $35.1 million and a corresponding aggregate operating lease liability of $34.5 million (there was no impact to the opening balance of retained earnings at January 1, 2019 as a result of adopting this new ASU). See Note 5.

Organization and Basis of Presentation (Policies)

3 Months Ended

Mar. 31, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization - At March 31, 2019, Valhi, Inc. (NYSE: VHI) held approximately 50% of our outstanding common stock and a wholly-owned subsidiary of NL Industries, Inc. (NYSE: NL) held approximately 30% of our common stock. Valhi owned approximately 83% of NL’s outstanding common stock and a wholly-owned subsidiary of Contran Corporation held approximately 92% of Valhi’s outstanding common stock. All of Contran’s outstanding voting stock is held by a family trust established for the benefit of Lisa K. Simmons and Serena Simmons Connelly and their children, for which Ms. Simmons and Ms. Connelly are co-trustees, or is held directly by Ms. Simmons and Ms. Connelly or entities related to them. Consequently, Ms. Simmons and Ms. Connelly may be deemed to control Contran, Valhi, NL and us.

Basis of Presentation

Basis of presentation - The unaudited Condensed Consolidated Financial Statements contained in this Quarterly Report have been prepared on the same basis as the audited Consolidated Financial Statements in our Annual Report on Form 10-K for the year ended December 31, 2018 that we filed with the Securities and Exchange Commission (SEC) on March 11, 2019 (2018 Annual Report). In our opinion, we have made all necessary adjustments (which include only normal recurring adjustments), in order to state fairly, in all material respects, our consolidated financial position, results of operations and cash flows as of the dates and for the periods presented. We have condensed the Consolidated Balance Sheet at December 31, 2018 contained in this Quarterly Report as compared to our audited Consolidated Financial Statements at that date, and we have omitted certain information and footnote disclosures (including those related to the Consolidated Balance Sheet at December 31, 2018) normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (GAAP). Our results of operations for the interim period ended March 31, 2019 may not be indicative of our operating results for the full year. The Condensed Consolidated Financial Statements contained in this Quarterly Report should be read in conjunction with our 2018 Consolidated Financial Statements contained in our 2018 Annual Report.

Unless otherwise indicated, references in this report to “we,” “us” or “our” refer to Kronos Worldwide, Inc. and its subsidiaries (NYSE: KRO) taken as a whole.

Derivatives

We periodically use currency forward contracts to manage a very nominal portion of currency exchange rate risk associated with trade receivables denominated in a currency other than the holder’s functional currency or similar exchange rate risk associated with future sales. Derivatives used to hedge forecasted transactions and specific cash flows associated with financial assets and liabilities denominated in currencies other than the U.S. dollar and which meet the criteria for hedge accounting are designated as cash flow hedges. Consequently, the effective portion of gains and losses is deferred as a component of accumulated other comprehensive income and is recognized in earnings at the time the hedged item affects earnings. Contracts that do not meet the criteria for hedge accounting are marked-to-market at each balance sheet date with any resulting gain or loss recognized in income currently as part of net currency transaction gains and losses.

Recent Accounting Pronouncement

On January 1, 2019, we adopted ASU 2016-02, Leases (Topic 842), which is a comprehensive rewriting of the lease accounting guidance which aims to increase comparability and transparency with regard to lease transactions. The primary change was the recognition of lease assets for the right-of-use of the underlying asset and lease liabilities for the obligation to make payments by lessees on the balance sheet for leases previously classified as operating leases. ASU 2016-02, as amended, also requires increased qualitative disclosure about leases in addition to quantitative disclosures previously required. As permitted, we adopted this ASU prospectively as of January 1, 2019 with no restatement of prior period financial statements. This ASU permits companies to elect certain practical expedients upon adoption, and at adoption we elected the package of practical expedients related to, among other things, lease classification (in which existing leases classified as operating leases under prior GAAP are classified as an operating lease under the new ASU, and existing leases classified as a capital lease under prior GAAP are classified as a finance lease under the new ASU), nonlease components (in which nonlease components associated with a lease and paid by us to the lessor, such as property taxes, insurance and maintenance, are treated as a lease component and considered part of minimum lease rental payments), and short-term leases (in which leases with an original maturity of 12 months or less are excluded from the recognition requirements of the new ASU). Upon adoption of this new ASU, at January 1, 2019 we recognized an aggregate right-of-use operating lease asset of $35.1 million and a corresponding aggregate operating lease liability of $34.5 million (there was no impact to the opening balance of retained earnings at January 1, 2019 as a result of adopting this new ASU). See Note 5.