Document and Entity Information Document Information [Table] Document Information [Line Items] Document Type Document Type Document Quarterly Report Document Quarterly Report Document Period End Date Document Period End Date Document Transition Report Document Transition Report Securities Act File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag CONDENSED CONSOLIDATED BALANCE SHEETS Statement [Table] Statement [Table] Related and Nonrelated Parties [Axis] Related Party Related and Nonrelated Parties [Domain] Related Party Related Party [Member] Related Party Statement [Line Items] Statement [Line Items] Assets [Abstract] ASSETS Assets, Current [Abstract] Current assets: Cash and Cash Equivalent Cash and cash equivalents Restricted Cash and Cash Equivalent, Current Restricted cash equivalents Marketable Securities, Current Marketable securities, current Marketable securities Market value, current Accounts and Other Receivables, Net, Current Accounts and other receivables, net Total Inventory, Net Inventories, net Total Prepaid Expense and Other Assets, Current Prepaid expenses and other Assets, Current Total current assets Other noncurrent assets Other assets: Marketable Securities, Noncurrent Marketable securities, noncurrent Marketable securities Market value, noncurrent Goodwill Goodwill Deferred Income Tax Assets, Net Deferred income taxes Financing Receivable, after Allowance for Credit Loss, Noncurrent Note receivables - Owner Participation Agreement ("OPA") Other Assets, Noncurrent Other assets Total Assets noncurrent excluding property plant and equipment net. Assets Noncurrent Excluding Property Plant And Equipment Net Total other assets Property, Plant and Equipment, Net [Abstract] Property and equipment: Land Land Buildings and Improvements, Gross Buildings Machinery and Equipment, Gross Equipment Mining properties consist of buildings and equipment used in mining operations and costs associated with the development of new mine areas. Mining Properties Mining properties Construction in Progress, Gross Construction in progress Property, Plant and Equipment, Gross Gross property and equipment Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Less accumulated depreciation and amortization Property, Plant and Equipment, Net Net property and equipment Assets Total assets Liabilities and Equity [Abstract] LIABILITIES AND STOCKHOLDERS' EQUITY Liabilities, Current [Abstract] Current liabilities: Long-Term Debt and Lease Obligation, Current Current maturities of long-term debt Less current maturities Accounts Payable and Accrued Liabilities, Current Accounts payable and accrued liabilities Total Accrued Income Taxes, Current Income taxes Liabilities, Current Total current liabilities Liabilities, Noncurrent [Abstract] Noncurrent liabilities: Long-Term Debt and Lease Obligation Long-term debt (including affiliate debt of $77.3 million and $61.3 million at December 31, 2025 and June 30, 2026, respectively) Long-term debt Liability, Defined Benefit Pension Plan, Noncurrent Accrued pension costs Accrued Environmental Loss Contingencies, Noncurrent Accrued environmental remediation and related costs Noncurrent liabilities Deferred Tax Liabilities, Gross Deferred income taxes Other Liabilities, Noncurrent Other liabilities Total Liabilities, Noncurrent Total noncurrent liabilities Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Equity: Preferred Stock, Value, Issued Preferred stock Common Stock, Value, Issued Common stock Additional Paid in Capital Additional paid-in capital Retained Earnings (Accumulated Deficit) Retained earnings Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive loss Treasury Stock, Value Treasury stock, at cost Equity, Attributable to Parent Balance at end of period Balance at beginning of period Total Valhi stockholders' equity Equity, Attributable to Noncontrolling Interest Noncontrolling interest in subsidiaries Equity, Including Portion Attributable to Noncontrolling Interest Balance Balance Total equity Liabilities and Equity Total liabilities and equity Commitments and Contingencies. Commitments and contingencies (Notes 13 and 16) CONDENSED CONSOLIDATED STATEMENTS OF INCOME Revenues and other income. Revenues And Other Income [Abstract] Revenues and other income: Revenue from Contract with Customer, Excluding Assessed Tax Net sales Other Income Other income, net Total Revenues and other income net. Revenues And Other Income Net Total revenues and other income Costs and Expenses [Abstract] Cost and other expense: Cost of Product and Service Sold Cost of sales Selling, General and Administrative Expense Selling, general and administrative Amount of post retirement benefit plan cost (credit), classified as other. Includes, but not limited to defined benefit and defined contribution plans. Other Components Of Net Periodic Pension And OPEB Expense Credit Other components of net periodic pension and OPEB expense Other components of net periodic pension and OPEB expense Interest Expense, Nonoperating Interest Costs and Expenses Total cost and other expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income before income taxes Income Tax Expense (Benefit) Income tax expense Income tax expense Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income Net income Net income Net Income (Loss) Attributable to Noncontrolling Interest Noncontrolling interest in net income of subsidiaries Noncontrolling interest in net income (loss) of subsidiaries Net Income (Loss) Attributable to Parent Net income attributable to Valhi stockholders Net Income (Loss) Attributable to Parent [Abstract] Amounts attributable to Valhi stockholders: Earnings Per Share, Basic Basic net income per share (in dollars per share) Earnings Per Share, Diluted Diluted net income per share (in dollars per share) Weighted Average Number of Shares Outstanding, Basic Weighted average shares outstanding - basic (in shares) Weighted Average Number of Shares Outstanding, Diluted Weighted average shares outstanding - diluted (in shares) CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Other Comprehensive Income (Loss), Net of Tax [Abstract] Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Currency translation Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent Defined benefit pension plans Amount, after tax and reclassification adjustment, of (increase) decrease in accumulated other comprehensive income for other income, attributable to parent. Other Comprehensive Income Loss Other After Tax And Reclassification Adjustment Attributable To Parent Total Other Other Comprehensive Income (Loss), Net of Tax Total other comprehensive income (loss), net Other comprehensive income, net Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income attributable to noncontrolling interest Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive income attributable to Valhi stockholders CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY Equity Components [Axis] Equity Components Equity Component [Domain] Equity Component Common Stock [Member] Common stock Additional Paid-in Capital [Member] Additional paid-in capital Retained Earnings [Member] Retained earnings AOCI Attributable to Parent [Member] Accumulated other comprehensive loss Total Accumulated Other Comprehensive Loss Treasury Stock, Common [Member] Treasury stock Noncontrolling Interest [Member] Non-controlling interest Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Dividends paid to noncontrolling interest Dividends, Common Stock, Cash Cash dividends Net increase or decrease included in the statement of changes in stockholders' equity as a result of transactions with noncontrolling interests and other. Equity Transactions With Noncontrolling Interest Net And Other Equity transactions with noncontrolling interest, net and other Common Stock, Dividends, Per Share, Cash Paid Cash dividends per share CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Cash flows from operating activities: Depreciation, Depletion and Amortization, Nonproduction Depreciation Operating Lease, Right-of-Use Asset, Periodic Reduction Amortization of operating lease right-of-use assets Defined benefit plan net periodic benefit cost greater than or in excess of cash funding during the period. Defined Benefit Plan Net Periodic Benefit Cost Greater Less Than Funding Benefit plan expense less than cash funding Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations excluding deferred tax expense (benefit) attributable to uncertain tax positions. Deferred Income Tax Expense Benefit Excluding Tax Contingencies Deferred income taxes Gain (Loss) on Disposition of Property Plant Equipment Gain on building sale Gain on building sale Other Noncash Income (Expense) Other, net Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Change in assets and liabilities: Increase (Decrease) in Accounts and Other Receivables Accounts and other receivables, net Increase (Decrease) in Inventories Inventories, net The increase (decrease) during the reporting period in the value of real estate development property (current and noncurrent portions). Increase Decrease In Real Estate Development Property Land held for development, net Increase (Decrease) in Accounts Payable and Accrued Liabilities Accounts payable and accrued liabilities Environmental Expense and Liabilities Accrued environmental remediation and related costs Increase (Decrease) in Income Taxes Payable Income taxes Increase (Decrease) Due from Affiliates Accounts with affiliates Increase (Decrease) in Other Operating Assets and Liabilities, Net Other, net Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Net cash provided by (used in) operating activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Cash flows from investing activities: Payments to Acquire Property, Plant, and Equipment Capital expenditures Payments to Acquire Marketable Securities Purchases of marketable securities Proceeds from Sale and Maturity of Marketable Securities Proceeds from disposal of marketable securities Proceeds from Sale of Buildings Proceeds from building sale Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Net cash used in investing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Cash flows from financing activities: Proceeds from Lines of Credit Borrowings on credit facilities Borrowings Repayments of Long-Term Lines of Credit Payments Repayments of credit facility Repayments of Long-Term Debt Payments on long-term debt Payments of Ordinary Dividends, Common Stock Valhi cash dividends paid Payments of Ordinary Dividends, Noncontrolling Interest Distributions to noncontrolling interest in subsidiaries Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Net cash provided by (used in) financing activities Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Excluding Exchange Rate Effect, Including Discontinued Operation [Abstract] Cash, cash equivalents and restricted cash and cash equivalents - net change from: Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Excluding Exchange Rate Effect, Including Discontinued Operation Operating, investing and financing activities Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation Effect of exchange rates on cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation Balance at end of period Balance at beginning of period Supplemental Cash Flow Information [Abstract] Supplemental disclosures: Cash paid for. Cash Paid For [Abstract] Cash paid for: Interest Paid, Excluding Capitalized Interest, Operating Activity Interest, net of amounts capitalized Income Taxes Paid, Net Income taxes, net Noncash investing activities. Noncash Investing Activities [Abstract] Noncash investing activities: Capital Expenditures Incurred but Not yet Paid Change in accruals for capital expenditures Organization and basis of presentation Basis of presentation and significant accounting policies. Basis Of Presentation And Significant Accounting Policies [Table] Basis Of Presentation And Significant Accounting Policies [Table] Basis of presentation and significant accounting policies. Basis Of Presentation And Significant Accounting Policies [Line Items] Organization and basis of presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Organization and basis of presentation Business segment information Schedule of Segment Reporting Information, by Segment [Table] Schedule Of Segment Reporting Information By Segment [Table] Segment Reporting Information [Line Items] Business segment information Segment Reporting Disclosure [Text Block] Business segment information Accounts and other receivables, net Receivables. Receivables [Table] Receivables [Table] Receivables. Receivables [Line Items] Accounts and other receivables, net Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Accounts and other receivables, net Inventories, net Inventory, Current [Table] Inventory Current [Table] Inventory [Line Items] Inventories, net Inventory Disclosure [Text Block] Inventories, net Marketable securities Marketable Securities [Table] Marketable Securities [Line Items] Marketable securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Marketable securities Other noncurrent assets text block. Other Noncurrent Assets [Text Block] Other noncurrent assets Long-term debt Schedule of Long-Term Debt Instruments [Table] Debt Instrument [Table]