Valhi Stockholders' Equity - Schedule of Common Stock Outstanding (Detail) - shares shares in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Schedule Of Stockholders Equity [Line Items]
Shares of common stock, Issued, beginning balance	355.3	355.3
Shares of common stock, Issued, Director shares issued	0.1
Shares of common stock, Issued, ending balance	355.4	355.3
Shares of common stock, Treasury, beginning balance	(13.2)	(13.2)
Shares of common stock, Treasury, ending balance	(13.2)	(13.2)
Shares of common stock, Outstanding, beginning balance	355.3
Shares of common stock, Outstanding, ending balance	355.4	355.3
Excluding Stock Ownership By Subsidiary Considered To Be Held In Treasury
Schedule Of Stockholders Equity [Line Items]
Shares of common stock, Outstanding, beginning balance	342.0	342.0
Shares of common stock, Outstanding, director shares issued	0.1
Shares of common stock, Outstanding, ending balance	342.1	342.0

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

Name:	us-gaap_CommonStockSharesIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockSharesOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of shares issued in lieu of cash for services contributed to the entity. Number of shares includes, but is not limited to, shares issued for services contributed by vendors and founders.

+ References

No definition available.

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesIssuedForServices
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29,30)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

+ Details

Name:	us-gaap_TreasuryStockShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Common stock shares director shares.

+ References

No definition available.

+ Details

Name:	vhi_CommonStockSharesDirectorShares
Namespace Prefix:	vhi_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Schedule of stockholders equity.

+ References

No definition available.

+ Details

Name:	vhi_ScheduleOfStockholdersEquityLineItems
Namespace Prefix:	vhi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_StatementEquityComponentsAxis=vhi_ExcludingStockOwnershipBySubsidiaryConsideredToBeHeldInTreasuryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: