Commitments and contingencies - Additional Information (Detail) $ in Thousands			1 Months Ended						3 Months Ended	12 Months Ended
	Feb. 10, 2025 USD ($)	Jul. 24, 2019 USD ($) defendant installment	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($) site	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Site Contingency [Line Items]
Recognized accretion expense										$ 479	$ 695	$ 908
Accrual for reasonably estimable environmental remediation and related matters										69,278	91,106	92,358	$ 92,940
Litigation settlement amount payable									$ 56,100
Aggregate income										31,400
Insurance recoveries										$ 1,369	$ 464	$ 93
Subsequent Event
Site Contingency [Line Items]
Litigation settlement amount	$ 151,100
Litigation settlement amount payable									56,100
Litigation settlement interest									500
Litigation settlement from other party									9,600
Component Products | Customer Concentration Risk | Top Ten Customers | Sales Revenue
Site Contingency [Line Items]
Concentration risk percentage										47.00%	52.00%	52.00%
Component Products | Customer Concentration Risk | Customer Two | Sales Revenue | CompX Security Products Business
Site Contingency [Line Items]
Concentration risk percentage										21.00%	24.00%	14.00%
Component Products | Customer Concentration Risk | Customer Two | Sales Revenue | CompX Security Products Business | Pilot project
Site Contingency [Line Items]
Concentration risk percentage											11.00%
Component Products | Customer Concentration Risk | One customer | Sales Revenue | CompX Security Products Business
Site Contingency [Line Items]
Concentration risk percentage												12.00%
Environmental Remediation Sites NL Named As PRP Or Defendant
Site Contingency [Line Items]
Number of sites associated with remediation and related costs | site										30
Number of sites currently not able to reasonably estimate a range of costs | site										5
Maximum
Site Contingency [Line Items]
Accrual for reasonably estimable environmental remediation and related matters									$ 38,000
Lead Pigment Litigation
Site Contingency [Line Items]
Description of defendants										on July 24, 2019, an order approving a global settlement agreement entered into among all of the plaintiffs and the three defendants remaining in the case (the Sherwin Williams Company, ConAgra Grocery Products and us) was entered by the court and the case was dismissed with prejudice. The global settlement agreement provides that an aggregate $305 million will be paid collectively by the three co-defendants in full satisfaction of all claims resulting in a dismissal of the case with prejudice and the resolution of (i) all pending and future claims by the plaintiffs in the case, and (ii) all potential claims for contribution or indemnity between us and our co-defendants in respect to the case
Litigation settlement amount		$ 305,000
Number of defendants | defendant		3
NL's portion of global settlement amount, gross value		$ 101,700
Litigation initial payment made 60 days after litigation settlement		25,000
Remaining litigation settlement charge		$ 76,700
Number of annual installments | installment		6
Remaining litigation settlement payment due in first year		$ 12,000
Remaining litigation settlement payment due in second year		12,000
Remaining litigation settlement payment due in third year		12,000
Remaining litigation settlement payment due in forth year		12,000
Remaining litigation settlement payment due in fifth year		12,000
Remaining litigation settlement payment due in sixth year		16,700
Escrow deposit		$ 9,000
Litigation initial payment			$ 12,000	$ 12,000	$ 12,000	$ 12,000	$ 12,000	$ 25,000		$ 12,000
Discounted rate for estimated present value of remaining litigation amount		1.90%
Litigation settlement estimated net present value		$ 96,300
Recognized accretion expense										500	$ 700	$ 900
Insurance recoveries										$ 1,400	$ 500